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Effects of rates and methods of swine slurry application on crop N uptake and N distribution in the soil Khan, Mafiz 1986

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c. E F F E C T S OF R A T E S A N D M E T H O D S OF S W I N E S L U R R Y A P P L I C A T I O N O N C R O P N U P T A K E A N D N D I S T R I B U T I O N IN THE S O I L by M A F I Z K H A N T H E S I S S U B M I T T E D IN THE R E Q U I R E M E N T S D O C T O R OF P A R T I A L F U L F I L M E N T OF FOR THE D E G R E E OF P H I L O S O P H Y in THE F A C U L T Y OF G R A D U A T E S T U D I E S DEPARTMENT OP SOIL SCIENCE W e accept th is t hes i s as c o n f o r m i n g to the requ i red s tandard THE U N I V E R S I T Y OF BRIT ISH C O L U M B I A A p r i l , 1986 ® M a f i z Khan, 1986 In p resen t ing th is t hes i s in par t ia l f u l f i lmen t of the requ i rements fo r an advanced degree at the The U n i v e r s i t y of B r i t i sh C o l u m b i a , I agree that the L ib rary shal l make it f r ee l y ava i l ab le ' fo r re fe rence and s t u d y . I further agree that p e r m i s s i o n fo r ex tens i ve c o p y i n g of th is t hes i s fo r s c h o l a r l y pu rposes m a y be granted by the Head of m y Depar tment or by his or her r ep resen ta t i ves . It is u n d e r s t o o d that c o p y i n g or pub l i ca t i on of th is t hes i s fo r f i nanc ia l ga in sha l l not be a l l o w e d w i thou t my wr i t t en p e r m i s s i o n . The U n i v e r s i t y o f B r i t i sh C o l u m b i a 2075 W e s b r o o k P l a c e V a n c o u v e r , Canada V6T 1W5 Date : ABSTRACT A three year f i e l d s tudy l oca ted app rox ima te l y 60 km east o f V a n c o u v e r , B r i t i sh C o l u m b i a has been conduc ted to s tudy the e f f e c t s o f ra tes and me thods of app l i ca t i on of anae rob i ca l l y s to red s w i n e s lurry on the ava i l ab i l i t y and d is t r ibu t ion of N in the root z o n e . S w i n e s lu r ry ranging f r o m 3.30 to 4.98% dry mat ter w a s app l i ed to a s i l t l oam s o i l pr ior to seed ing s i lage corn ( Z e a , . m a y s L.). Rates supp l y i ng 0, 173, 321 and 653 kg h a 1 o f to ta l N in the f i rs t y e a r ; 0, 157, 336 and 538 kg h a " 1 in the s e c o n d year and 0, 163, 309 and 430 kg h a ' 1 the th i rd year we re in jec ted to a depth of 30 cm or b r o a d c a s t , us ing a B ig A W a s t e A p p l i c a t o r fo r both m e t h o d s . A t the t ime of a p p l i c a t i o n near ly 64% o f the s lu r ry to ta l N w a s in the N H 4 + f o r m . In add i t i on to s lur ry t rea tmen t , s tar ter N and amoun ts of P and K were a p p l i e d , b a s e d on s o i l test v a l u e s . C o r n s i l age y i e l d i nc reased s i g n i f i c a n t l y in al l the years w i th i nc reas ing rates of s lurry N a p p l i c a t i o n up to 330 kg h a " 1 . The 653 kg h a 1 app l i ca t i on rate reduced y i e l d in the f i rs t yea r . A d d i t i o n of 538 and 430 kg h a 1 N in the s e c o n d and the th i rd y e a r s gave no fur ther inc rease in y i e l d s ove r the 330 kg h a - 1 rate. S lu r ry in jec t ion gave an average (over al l app l i ca t i on ra tes) increase in s i l age y i e l d of 18% the f i rs t y e a r , 5% the s e c o n d year and 9% the th i rd year as c o m p a r e d to b roadcas t app l i ca t i on f o l l o w e d by i nco rpo ra t i on . One mon th af ter a p p l i c a t i o n m a x i m u m concen t ra t i ons o f minera l N we re f o u n d in the 0 - 1 5 c m zone w h e n the s lur ry w a s b roadcas t and in the 15 -30 c m zone when it w a s i n jec ted . A greater quant i ty o f m inera l N w a s found in the root zone w h e n the s lu r ry w a s in jec ted than b roadcas t , i nd ica t ing greater c o n s e r v a t i o n of s lu r ry N H 4 + - N by the in jec t ion m e t h o d . M a x i m u m r e c o v e r y of s lu r ry N w a s a s s o c i a t e d w i t h the 80 t h a - ' i i app l i ca t i on and w a s ob ta ined two months af ter a p p l i c a t i o n . The h ighest net m ine ra l i za t i on of s lur ry o rgan ic N occu r red w i th 80 t h a " 1 and the p ropo r t i on m ine ra l i zed w a s l i ke ly de te rm ined by the c l i m a t i c cond i t i ons (espec ia l l y tempera ture and mo is tu re ) . B e t w e e n 6 - 2 8 % of the app l ied N w a s los t dur ing the g r o w i n g s e a s o n when 80 t h a 1 o f s lur ry w a s in jec ted c o m p a r e d to 3 0 - 5 0 % w h e n the s a m e rate w a s b r o a d c a s t . Ove rw in te r N l o s s w a s greater f o r the in jec t ion than the b roadcas t me thod because res idua l s o i l N va lues we re higher fo r the later m e t h o d . V o l a t i l i z a t i o n and i m m o b i l i z a t i o n we re thought to be the major m e c h a n i s m s of N l o s s e s over the g r o w i n g s e a s o n . Ove rw in te r N l o s s e s resu l ted ma in l y f r o m leach ing of N 0 3 ~ and p robab l y den i t r i f i ca t i on as w e l l , as there w a s no ind ica t ion of any s i gn i f i can t f r ac t i on of s lur ry N enter ing into the s o i l o rgan ic p o o l . The amount of fa l l p rec ip i ta t i on and the f o r m of N at the end of the g row ing s e a s o n great ly i n f l uenced the quant i ty of ove rw in te r N l o s s . Greater amoun ts o f ' N w e r e car r ied ove r w h e n the s lur ry w a s in jec ted as o p p o s e d to b r o a d c a s t , and the amoun ts car r ied ove r i nc reased w i t h the inc rease in N app l i ca t i on rate. H o w e v e r , in no c a s e , d id the m a x i m u m amount car r ied ove r exceed 16% o f the app l i ed N. The in jec t ion me thod o f app l i ca t i on w a s found to be more favou rab le for the use o f s lu r ry in c rop p r o d u c t i o n . S lu r ry N app l i ca t i on shou ld be ad jus ted based on target y i e l d , s o i l N supp l y and the me thod of app l i ca t i on be ing u s e d . Fac to rs such as reduced s o i l c o m p a c t i o n i m m e d i a t e l y b e l o w the p lough layer a l s o cou ld have i nc reased c rop y i e l d s as a resul t o f the in jec t ion m e t h o d . i i i Table of Contents Chapter Page I. I N T R O D U C T I O N 1 A . Ag r i cu l t u re in B.C 1 B. P r o b l e m s re la ted to s lur ry management 1 C. D y n a m i c s of s lu r ry N 2 D. S p e c i f i c O b j e c t i v e s 3 II. L I T E R A T U R E R E V I E W 5 A . S w i n e s lurry m a n a g e m e n t : Genera l 5 B. S w i n e s lurry c o m p o s i t i o n 6 C . S lu r ry management : N i t rogen f l o w 10 V o l a t i l i z a t i o n l o s s of N 10 Fac to rs e f f e c t i n g v o l a t i l i z a t i o n of N H 3 15 Leach ing l o s s of N 25 M i n e r a l i z a t i o n of s lur ry N 30 Fac to rs a f f e c t i n g m ine ra l i za t i on of N 33 D. Rate o f s lur ry app l i ca t i on 38 B a s i s of de te rm in ing app l i ca t i on rate 39 E. D is t r i bu t i on o f s lu r ry N f o l l o w i n g app l i ca t i on 41 F. C r o p r e s p o n s e to s lur ry N .41 G . S lu r ry Injector - i ts p o s s i b l e b e n e f i c i a l e f f e c t s on s o i l p roper t i es and c rop y i e l d 43 III. S U M M A R Y OF THE L I T E R A T U R E R E V I E W .46 IV. M A T E R I A L S A N D M E T H O D S 50 A . The s o i l 50 B. The s lur ry 50 C . Inorganic f e r t i l i ze rs 55 D. He rb i c i des 55 iv E. F ie l d me thods 55 F. Ca l i b ra t i on of the equ ipment and s lur ry app l i ca t i on 57 G . Wea the r cond i t i on b e t w e e n s lur ry a p p l i c a t i o n , i nco rpo ra t i on and seed ing of co rn .....59 H. S o i l s a m p l i n g 62 I. L o c a t i n g in jec t ion zones 64 J . P lant s a m p l i n g 64 K. Labo ra to r y me thods 65 L. S t a t i s t i c a l a n a l y s e s 65 V . R E S U L T S A N D D I S C U S S I O N 68 A . C o r n y i e l d 68 B. In ject ion method e f fec t on co rn y i e l d 77 C. C r o p N uptake 80 D. S o i l m inera l N 94 E. V o l a t i l i z a t i o n of N due to b roadcas t t rea tment 109 F. M i n e r a l i z a t i o n of s o i l and s lu r ry o rgan ic N 111 G . Percent accoun tab le s lur ry N 117 H. N ba lance 119 I. Roo t r e s p o n s e to s lu r ry N app l i ca t i on 129 VI . S U M M A R Y A N D C O N C L U S I O N S 130 VII . L I T E R A T U R E CITED 133 A p p e n d i x 1. F i e l d d e s c r i p t i o n o f the s o i l used in the s tudy 161 A p p e n d i x 2. S e l e c t e d p h y s i c a l and c h e m i c a l p rope r t i es of s o i l used in t hes i s r e s e a r c h , 1981-1983 162 A p p e n d i x 3. Ra t i ons supp l i ed to the a n i m a l s 163 A p p e n d i x 4 . C r o p N uptake and d r y mat te r y i e l d (1981) 164 A p p e n d i x 4.1 C r o p N uptake and dry mat ter y i e l d (1982 and 1983) 165 A p p e n d i x 5 C r o p N uptake and T K N b roadcas t and in jec ted (1982 and 1983) 166 v A p p e n d i x 6. S o i l N H / and N 0 3 - N content be fo re and 1, 2 and 4 mon ths af ter app l i ca t i on of sw ine s lur ry (1982 and 1983.) 167 A p p e n d i x 7. Concen t ra t i on of N H 4 * and N O y - N after 120 t h a - 1 s w i n e s lurry app l i ca t i on (1982, 1983.) 168 A p p e n d i x 8. W e e k l y ra in fa l l r e c e i v e d by the exper imen ta l s i te fo r the per iod Oc tobe r 1981 to A p r i l 1982 and Oc tobe r 1982 to A p r i l 1983 169 A p p e n d i x 9. S o m e s e l e c t e d s o i l T K N and organ ic N data at the end o f the three years o f s lu r ry app l i ca t i on 170 A p p e n d i x 10. C o n c e n t r a t i o n of P and K in s w i n e s lur ry used in the exper iment 171 vi LIST OF TABLES Table Page Tab le 1. Nutr ient and dry mat ter conten t of p ig s lur ry used in seve ra l s tud ies 8 Tab le 2. E s t i m a t e d n i t rogen l o s s e s ( N H / - N ) dur ing s t o r a g e , t rea tment and hand l ing fo r va r ious manure manager ia l s y s t e m s (Su t ton , 1981). 13 Tab le 3. N i t r ogen l o s s f r o m s w i n e s lu r ry as a f f e c t e d by m e t h o d of a p p l i c a t i o n (Sut ton , 1981) 14 Tab le 4 . N i t rogen l o s s e s due to a m m o n i a vo la t i l i za t i on f r o m f i e l d sp read manure (Turner, 1975) 16 Tab le 5. Pe rcen tage of n i t rogen los t by leach ing f r o m an ima l manure on arab le land (equi l ibr ium cond i t i on ) . Ko lenbrander , 1978 28 Tab le 6. C o m p o s i t i o n of L iqu id S w i n e S lu r ry U s e d in the Exper imen t 53 Tab le 7. Rates of inorgan ic fe r t i l i ze r app l i ed 56 Tab le 8. S p r i n g Weather c o n d i t i o n s dur ing 1981, 1982 and 1983 at the Expe r imen ta l s i te 60 Tab le 9. Rate of S lu r ry A p p l i c a t i o n 61 .Tab le 10. Pa r t i t i on ing of sum o f squares and degrees o f f r e e d o m fo r plant and s o i l fo r 1981, 1982 and 1983 67 Tab le 11. C o e f f i c i e n t o f va r ia t i on in c rop dry mat ter y i e l d and N uptake at d i f fe ren t s a m p l i n g da tes fo r the s lur ry app l i ca t i on rates used in 1981, 1982 and 1983 69 Tab le 12. S i l a g e Corn Dry Mat te r Y i e l d 71 Tab le 13. C a l c u l a t e d F va lues fo r M e a s u r e d Crop R e s p o n s e s and M e a n Square Error T e r m s ( 1 9 8 l ) 72 Tab le 14. C a l c u l a t e d F va lues fo r M e a s u r e d Crop R e s p o n s e s and M e a n Square Error Te rms (1982, 1983) 73 Tab le 15. G r o w i n g s e a s o n w e e k l y average m a x i m u m and m i n i m u m air t empera tu res and to ta l ra in fa l l (1 M a y - 30 S e p t e m b e r , 1981, 1982 and 1983) 76 Tab le 16a. D ry mat ter y i e l d s at d i f f e ren t s a m p l i n g da tes af ter p lan t ing (1982). 78 Tab le 16b. Dry mat ter y i e l d s at d i f f e ren t s a m p l i n g da tes af ter p lan t ing (1983) 79 Tab le 17A. C r o p N uptake (1981, 1982 and 1983) 82 Tab le 17B. Percen t r e c o v e r y of s lu r ry N (1981, 1982 and 1983) 83 v i i Tab le 18. Plant N concen t ra t i on and c o e f f i c i e n t of va r ia t i on at d i f fe ren t s a m p l i n g pe r i ods for the seve ra l rates o f s lur ry used in 1981, 1982 and 1983 84 Tab le 19. Percent inc rease in c rop N uptake ove r the con t ro l fo r the s lurry a p p l i c a t i o n rates used in 1981, 1982 and 1983 85 Tab le 20. Percent c o e f f i c i e n t o f va r ia t i on in s o i l m inera l N m e a s u r e m e n t s at d i f fe ren t s a m p l i n g da tes for the 0, 80 and 120 t h a - 1 ra tes of s lu r ry used in the exper iment in 1982 and 1983. 98 Tab le 21 . C a l c u l a t e d F va lues fo r S o i l N H / and N 0 3 - - N C o n c e n t r a t i o n s and M e a n Square Error T e r m s (1981) 99 Tab le 22. C a l c u l a t e d F va lues fo r S o i l N H 4 + and N G y - N C o n c e n t r a t i o n s and M e a n Square Error T e r m s (1983) 100 Tab le 23 . S o i l m inera l n i t rogen ( A m m o n i u m + Ni t ra te) be fo re and 1, 2 and 4 m o n t h s af ter app l i ca t i on of s w i n e s lur ry (1981, 1982 and 1983) 101 Tab le 24. M i n e r a l N content of the so i l ( 0 -15 and 15 -30 c m ) 1 month af ter s lur ry app l i ca t i on and N l o s s e s due to b roadcas t t reatment 110 Tab le 25. A m o u n t of s o i l and s lur ry o rgan ic N m ine ra l i zed f r o m in jec t ion t reatment at d i f fe ren t s a m p l i n g pe r i ods (1982 and 1983). 112 Tab le 26. S o i l + C r o p N content at d i f fe ren t s a m p l i n g pe r i ods (1982 and 1983) 116 Tab le 27. Percen t accoun tab le s lur ry N (1981, 1982 and 1983) 118 Tab le 28. N i t r ogen Ba lance - 1981 Exper iment 120 Tab le 29. N i t r o g e n Ba lance - 1982 Exper iment 122 Tab le 30. N i t r ogen Ba lance - 1983 Exper iment 123 Tab le 31 . C a r r y - o v e r N and ove rw in te r N l o s s e s (1981,1982 and 1983) 125 Tab le 32. N ba lance af ter s lur ry app l i ca t i on fo r 3 y e a r s 127 v i i i LIST OF FIGURES Figure Page Figure 1. Re la t i onsh ip be tween dry matter and n i t rogen conten t of p ig s lur ry (Tunney and . M o l l o y , 1975) 9 Figure 2. Re la t i onsh ip be tween dry mat ter and s p e c i f i c g rav i t y of cat t le and pig s lur ry (Tunney and M o l l o y , 1975) 11 F igure 3. A m m o n i a f lux f r o m l iqu id dai ry cat t le manure (Beauchamp et a l . , 1978) 22 Figure 4. N i t rogen l o s s e s on g rass land vs annual quant i ty of chem ica l fe r t i l i ze r n i t rogen app l ied ( G a r w o o d and T y s o n , 1973) 29 Figure 5. Latest c rop (rough pas ture) g rown on the exper imen ta l s i te pr ior to p lough ing in 1981 51 Figure 6. A g i t a t o r used in m ix ing the s lur ry 54 Figure 7. B ig A W a s t e A p p l i c a t o r 58 Figure 8. S o i l S a m p l i n g p lan , D i rec t i on of S e e d i n g and S lu r ry T rea tmen t . ..63 Figure 9. E f f ec t o f S w i n e S lu r ry A p p l i c a t i o n Rate on S i l a g e C o r n Dry Mat ter Y i e l d 74 Figure 10. Re la t i onsh ip be tween N Uptake and Dry Mat te r Y i e l d (1981) 89 Figure 11. Re la t i onsh ip be tween N Uptake and Dry Mat te r Y i e l d (1982 and 1983) 90 Figure 12. Re la t i onsh ip be tween N Uptake and T K N B roadcas t (1982 and 1983) 92 Figure 13. Re la t i onsh ip be tween N Uptake and T K N Injected (1982 and 1983). 93 Figure 14. Ve r t i ca l and lateral N d is t r ibu t ion f o l l o w i n g in jec t ion of 120 t h a - 1 o f s lur ry in 1982 95 Figure 15. A m m o n i u m and Ni t ra te N d is t r ibu t ion (1 month later , 1982) 103 Figure 16. A m m o n i u m and Ni t ra te N d i s t r i bu t i on (2 mon ths later , 1982) ...104 Figure 17. A m m o n i u m and Ni t ra te N d is t r i bu t ion (3 mon ths later , 1982) ...105 Figure 18. A m m o n i u m and Ni t ra te N d is t r i bu t ion (1 month la ter , 1983) 106 Figure 19. A m m o n i u m and Ni t ra te N d is t r ibu t ion (2 mon ths later , 1983) ...107 Figure 20. A m m o n i u m and Ni t ra te N d is t r i bu t ion (3 mon ths later , 1983) ...108 ix ACKNOWLEDGEMENTS I am deep l y indebted to m y s u p e r v i s o r , Dr. A . A . B o m k e fo r h is gu idance and w i s e counse l wh i ch have con t r ibu ted grea t ly to th is research and a l so m y s tudy at U.B.C. I am a l so gra te fu l to the other m e m b e r s of m y S u p e r v i s o r y C o m m i t t e e ; Dr. L. E. L o w e , Dr. R. B u l l e y , and M r . R. Ber t rand fo r their help and cons t ruc t i ve c r i t i c i s m o f th is t h e s i s . Thanks are due to Dr. G . W . E a t o n , Depar tment of P lant S c i e n c e for his adv ice in s ta t i s t i ca l a n a l y s i s ; M r . R. J e s i a k of Ca ro l i ne F a r m s , Lang ley fo r he lp ing me w i th his B ig A W a s t e A p p l i c a t o r and p rov i d i ng the s lur ry used in the r e s e a r c h ; M r . Bar ry Baehr o f Lang ley fo r p repar ing the f i e l d and seed ing the crop and the B.C. M i n i s t r y of Ag r i cu l t u re and F o o d , P roper t y Managemen t Branch fo r p rov i d i ng the exper imen ta l s i t e . F ina l l y I w i s h to thank m y w i f e , R e z i a , fo r her suppor t and pa t ience dur ing my degree p r o g r a m . T o m y s o n s Shuman and S a m u e l , w h o m i s s e d many happy m o m e n t s w i t h their fa ther , I ded ica te th is t h e s i s . I. I N T R O D U C T I O N A . A g r i c u l t u r e in B . C . A n impor tant aspec t of B.C. agr icul ture is i n tens i ve l i ves tock p r o d u c t i o n , m o s t of wh i ch is l o c a t e d in the Lower Fraser V a l l e y . It has been e s t i m a t e d that 50% of the p r o v i n c e ' s to ta l s w i n e , 75% of the da i ry and 90% o f the eggs and pou l t ry meat are p roduced in th is area (Van K leeck and J o h n s o n , 1982). A b o u t 91,000 hectares or 5% of S o u t h w e s t e r n Br i t i sh C o l u m b i a is in f a r m s . The area is w e l l k n o w n fo r i ts va r ie ty of agr icu l tura l r e s o u r c e s . It has a popu la t i on of 1,500,000 w i t h about 22,000 l i v ing on f a r m s , 1/3 o f the to ta l B .C . f a rm popu la t ion (Van K leeck and J o h n s o n , 1982). In 1976, the L o w e r Fraser V a l l e y had 30% of the to ta l agr icu l tura l ho ld ings in the p r o v i n c e . The average f a rm s i ze w a s 15 hec ta res , c o m p a r e d to the p r o v i n c i a l average s i ze o f 126 hec ta res . The s m a l l f a rm s i ze re f l ec t s the numerous ho ld i ngs and in tens ive nature of agr icul ture in th is r eg ion . B. P r o b l e m s r e l a t e d t o s l u r r y m a n a g e m e n t Barber (1978) e s t i m a t e d that l i v e s t o c k w a s t e p roduced per year in the p rov i nce con ta ins a to ta l o f 50,000 tonnes of n i t rogen , phospho rus as P 2 0 5 , and p o t a s s i u m as K 2 0 . The e c o n o m i c va lue of these nutr ients p robab ly e x c e e d s $30 m i l l i o n (Bomke and Khan , 1983). A large po r t i on o f the manure is p r o d u c e d in an ima l c o n f i n e m e n t s y s t e m s such as for s w i n e and pou l t r y . These p roduce rs have se r i ous manure management p r o b l e m s . Fi rst of a l l , m o s t o f t hese p roduce rs do not have an adequate amount of land fo r sp read ing manure on their o w n f a r m s and must re ly on other f a rmers for d i s p o s a l . S e c o n d l y they are o f t e n in c o n f l i c t w i th their non fa rm ing 1 2 ne ighbours due to nox ious o d o u r s . These p r o b l e m s have s t imu la ted research to es tab l i sh more p r e c i s e l y the e c o n o m i c va lue of l i v e s t o c k w a s t e s and to i m p r o v e r e c o m m e n d a t i o n s for land sp read ing p rocedu res . C. Dynamics of slurry N A n i m a l manure can be c o n s i d e r e d as a mixture o f f a e c e s and urine p lus s m a l l e r amoun ts of other o rgan ic mater ia l such as w a s t e f eed and b e d d i n g . A n i m a l s lur ry on the other hand con ta ins al l these p lus va ry i ng amoun ts of add i t i ona l water f r o m va r i ous s o u r c e s depend ing on the c o n d i t i o n s of c o l l e c t i o n . A s v o i d e d by the a n i m a l , the N in the f a e c e s and urine is a l m o s t en t i re ly in o rgan ic f o r m s , but urea and s o m e lab i le o rgan ic c o m p o u n d s are rap id l y c o n v e r t e d to N H 3 . There is c o n s i d e r a b l e va r ia t i on in both the c o m p o s i t i o n and the p ropo r t i on o f N in the inorgan ic f o r m . U s u a l l y , about half o f the N is present as NH„ + , other inorgan ic f o r m s genera l l y be ing absent (Evans et a l . , 1978; M i n i s t r y o f A g r i c u l t u r e , F i she r i es and F o o d (M.A.F.F. , 1976). A s i gn i f i can t po r t i on of the N in the manure is sub jec ted to l o s s to the a t m o s p h e r e , depend ing on hand l ing and s to rage s y s t e m s . V a n d e r h o l m (1975) and G i l b e r t s o n et a l . (1979) repor ted N l o s s e s of 10 -99 % and 10 -75 % r e s p e c t i v e l y depend ing upon t y p e s of manure management and t reatment s y s t e m s . Sa l te r and Scho l l enbe rge r (1939); and Heck (1931) repo r ted 50% l o s s of to ta l N as v o l a t i l e a m m o n i a af ter sp read ing . V a n d e r h o l m (1975) repor ted that p lough ing d o w n manure resu l ted in N H 4 + - N l o s s e s of < 5% in c o m p a r i s o n w i t h 15% by d i sk ing and 3 0 - 9 0 % by su r face a p p l i c a t i o n . Ho f f et a l . (1981) repor ted an 82.5% l o s s of the NhV f r o m s u r f a c e app l i ed f resh s w i n e manure in a green house s tudy s a m p l e d ove r a pe r i od of 8 d a y s . L i t t le i n f o rma t i on is ava i l ab le regard ing N H / - N l o s s f r o m in jec t ion app l i ca t i on s y s t e m s . Su t ton (1981) and Hof f et 3 a l . (1981) repor ted 0 - 2 % and 0 -2 .5% N H / - N l o s s f r o m in jec t ion and 1 0 - 2 5 % and 10-16%, r e s p e c t i v e l y , f r o m sur face b roadcas t s w i n e s lur ry over a pe r i od of 3.5 d a y s . S a f l e y et a l . (1981); K lausner and Gues t (1981); Su t ton et a l . (1982) and Beauchamp (1983) repor ted higher corn y i e l d s when s lur ry w a s in jec ted rather than su r face app l i ed . M c D o w e l l and S m i t h (1958); M c i n t o s h and Freder ick (1958); G a s s e r and R o s s (1975) repor ted on the re ten t i on , reac t ion and d i s t r i bu t i on of anhydrous and aqueous a m m o n i a in jec ted into the s o i l . I n fo rmat ion on the ava i l ab i l i t y o f manure N , i ts t r a n s f o r m a t i o n and d is t r ibu t ion in the s o i l w i th respec t to in jec t ion or b roadcas t app l i ca t i ons are s c a r c e l y ava i lab le (espec ia l l y under the c o o l , humid cond i t i on of S o u t h w e s t e r n Br i t i sh C o l u m b i a ) as they have not been s tud ied adequate ly under f i e l d c o n d i t i o n . D. S p e c i f i c O b j e c t i v e s The o b j e c t i v e s o f the present research we re t o ; 1. C o m p a r e in jec t ion and b roadcas t p lus i nco rpo ra t i on me thods of sw ine s lur ry app l i ca t i on and 2. S tudy the re la t i onsh ip be tween the quant i ty of s lu r ry N app l ied and s i l age co rn dry mat ter p r o d u c t i o n . In the t hes i s research the t w o me thods of app l i ca t i on and four rates of s w i n e s lur ry N we re c o m p a r e d to eva lua te their e f f e c t s o n ; a) C rop N uptake and dry mat ter p roduc t i on at d i f fe ren t s a m p l i n g da tes b) Changes in the quant i ty and f o r m of s o i l and s lur ry N over t ime w i th in the s o i l p ro f i l e and c ) Ve r t i ca l and lateral d i s t r i bu t ion of N sho r t l y 4 f o l l o w i n g manure i n j ec t i on . II. L I T E R A T U R E R E V I E W A . S w i n e s l u r r y m a n a g e m e n t : G e n e r a l From the i n f o rma t i on ava i lab le in B C M A F "Farm and F o o d S t a t i s t i c s , 1983" and Barber , 1978 it has been e s t i m a t e d that about 6 m i l l i o n we t tons (average mo i s tu re content 80%) o f w a s t e s are p roduced annual ly in Br i t i sh C o l u m b i a f r o m the l i ves tock and pou l t r y indust ry . S w i n e s lur ry rep resen ts about 9% of the to ta l or about 18% of the s lur ry p roduced in c o n f i n e m e n t s y s t e m s . Wi th f e w e x c e p t i o n s , s w i n e in B .C. are t o ta l l y c o n f i n e d . O p e n ranges are e m p l o y e d on a l im i ted bas i s by part t ime o p e r a t o r s , and o c c a s i o n a l l y on a short t ime b a s i s fo r b reed ing herds . C o n s i d e r i n g the p rov i nce as a w h o l e , l i t t le or no bedd ing is used in c o m m e r c i a l o p e r a t i o n s . A l m o s t al l s w i n e manure used for land sp read ing is s t o red and hand led as a l iqu id . To ta l s lurry r e c o v e r y is p o s s i b l e ; h o w e v e r , ach ievemen t o f th is goa l is s p o i l e d by an at t i tude in the s w i n e indust ry that e m p h a s i z e s d i s p o s a l rather than u t i l i za t i on . In rea l i t y , and exc lud ing one large ope ra t i on where t reated s lur ry is d i scha rged into the Fraser R i ve r , p robab l y l ess than 75% o f the s w i n e s lurry is r e c o v e r e d and less than 1/4 o f th is is u t i l i zed to g o o d advantage as a fe r t i l i ze r (Barber, 1978). A r o u n d the late 1950's and ear ly 1960's a se r i es o f changes took p lace in m o s t Nor th A m e r i c a n f a rm ing c o m m u n i t i e s . A s the p ro f i t marg in on each unit o f p roduc t i on d e c r e a s e d , l i v e s t o c k p roducers f ound that they had to i n t ens i f y their ope ra t i ons to remain c o m p e t i t i v e and s tay in b u s i n e s s . In the late 1970 's , i nc reas ing p ressure w a s exer ted on the agr icu l tura l indus t ry in Br i t i sh C o l u m b i a to i m p r o v e its p roduc t i on e f f i c i e n c y and to inc rease its to ta l output . The ve ry s u c c e s s o f agr icu l ture in mee t i ng 5 6 th is cha l lenge has resu l ted in an inc rease in the s i ze of con f i nemen t l i v e s t o c k p roduc t i on s y s t e m s . A t a t ime w h e n this i n t ens i f i ca t i on w a s go ing o n , more and m o r e , peop le in the c i t i es and t o w n s began to recogn ize the rural areas as des i rab le p l a c e s to l i ve . Z o n i n g b y - l a w s were ei ther n o n - e x i s t e n t or inadequate and many l i ves tock p roducers f ound t h e m s e l v e s t r y ing to f a rm bes ide a ne ighbour or ne ighbours w h o e n j o y e d the rural se t t i ng but not s o m e of the rea l i t i es of the rural w a y of l i f e . R e l a t i v e l y s p e a k i n g , B.C. l i ves tock and pou l t ry f a r m s are s m a l l . O n l y a f e w f a r m s are of a s i ze that warrant fu l l t ime labour input other than the o w n e r ' s f a m i l y . A ma jo r i t y o f s w i n e f a r m s in the past f e w years have been e s t a b l i s h e d on p rope r t i es of l ess than 8 hec ta res . I n tens i f i ca t i on , s m a l l l a n d - b a s e d and s p e c i a l i z e d fa rm ing have resu l ted in hand l ing of large v o l u m e s of s lur ry and the need to m o v e s lur ry f r o m one fa rm to another , c rea t ing t r anspo r t a t i on , odour and po l l u t i on p r o b l e m s . M o s t o f the s w i n e s lur ry that is c o l l e c t e d is s t o red in earthen or c l o s e d tanks , usua l l y fo r l ess than t w o months and is sp read on fo rage p roduc ing land . Lack of i nexpens i ve and re l iab le oppor tun i t i es fo r d i s p o s a l , c o u p l e d w i t h odours both at the p roduc t i on and sp read ing s i t es have aggrava ted the s lurry hand l ing p r o b l e m o f the s w i n e indus t ry . A great deal o f research w i l l be requ i red to conver t the d i s p o s a l p rob lem to an oppor tun i t y f o r p ro f i t in s w i n e p r o d u c t i o n . B. Sw ine slurry composi t ion The nutr ient and dry mat ter content of s w i n e s lu r ry , and c o n s e q u e n t l y , i ts po ten t ia l fe r t i l i ze r va lue can vary c o n s i d e r a b l y . S e v e r a l f a c t o r s in f luence the nutr ient c o m p o s i t i o n o f s w i n e s lu r ry dur ing i t 's p r o d u c t i o n , c o l l e c t i o n and s to rage pr ior to land a p p l i c a t i o n . They a re : 7 1. C o m p o s i t i o n of ra t ion fed 2. T y p e s of w a s t e handl ing and s to rage s y s t e m 3. A m o u n t of f e e d and water sp i l l age 4. C l i m a t i c c o n d i t i o n s 5. A g e and type of an imal The leve l o f nutr ient in s w i n e ra t ions and the p resence or absence of cer ta in f e e d add i t i ves w i l l be r e f l ec ted in the nutr ient c o m p o s i t i o n of the s lu r ry . A s e x a m p l e s , leve l o f s a l t s , c o p p e r , a r sen i c , sulphur and an t i b i o t i cs in the ra t ions and subsequen t l y in s lur ry are conce rns w i t h land app l i ca t i on of s w i n e s lu r r y . The amount of f eed and water sp i l l age can in f luence the concen t ra t i on o f nutr ients in the s lu r ry hauled to the f i e l d . In add i t i on , c l i m a t i c c o n d i t i o n s , par t i cu la r ly tempera tu re , have an in f luence on h o w fas t the s lur ry is d e c o m p o s e d dur ing natural b i o l o g i c a l p r o c e s s e s . The m o s t in f luent ia l f ac to r a f f ec t i ng the nutr ient c o m p o s i t i o n of s lu r ry is the t ype o f w a s t e managemen t s y s t e m u s e d . S o m e nutr ient concen t ra t i on va lues and dry mat ter con ten ts fo r a s e l e c t e d number of s w i n e s lu r r ies used in seve ra l s tud ies are s u m m a r i z e d in Tab le 1. Tunney (1977) s a m p l e d 20 f a r m s over a pe r i od o f t w o y e a r s . He o b s e r v e d w i d e va r ia t ion in the c o m p o s i t i o n of the s lur ry a m o n g the f a r m s and a t t r ibuted it ma in l y to the d i lu t ion w i th wa te r . Und i lu ted s w i n e s lur ry con ta ins a p p r o x i m a t e l y 9% dry mat ter (O 'Ca l laghan et a l . , 1973). Th is va lue can change depend ing on h o w the s lur ry is hand led , e s p e c i a l l y the amount of wa te r that is added or r e m o v e d f r o m the tank. Tunney and M o l l o y (1975) repor ted that dry matter and the N , P , Ca and M g con ten t of the s w i n e s lur ry w e r e h igh ly p o s i t i v e l y c o r r e l a t e d . The re la t i onsh ip b e t w e e n dry mat ter and the N content of s w i n e s lur ry -Tunney and M o l l o y (1975) - is i l lus t ra ted in F i g . 1. Table 1. Nutrient and dry matter content of pig slurry used in several studies. AUTHOR % DM N NE\-N P K Lanza, 1977 2.4 0.30 — 0.06 0.25 Boschi et a l . , 1977 2.4 0.26 0.13 0.06 0.25 Sutton et a l . , 1978 2.4 0.32 0.18 0.09 0.13 Sutton et a l . , 1982 6.1 0.47 0.28 0.15 0.17 Kofoed, 1977 6.8 0.68 0.48 0.16 0.27 Tunney, 1977 8.0 0.43 — 0.18 0.20 Flowers and Arnold, 1983 8.4 0.42 0.24 — — R E L A T I O N S H I P B E T W E E N D R Y M A T T E R A N D N I T R O G E N C O N T E N T O F P IG S L U R R Y (Tunney ft Mol loy, 1975) 8 12 16 % D R Y M A T T E R (Figure 1 ) CO 10 Tunney and M o l l o y (1975) a l so o b s e r v e d a s im i l a r c l o s e re la t i onsh ip be tween dry mat ter and s p e c i f i c g rav i ty o f s lu r ry . F igure 2, as taken f r o m Tunney and M o l l o y (1975) s h o w s the re la t ionsh ip be tween dry matter and the s p e c i f i c g rav i t y of sw ine s lur ry f r o m a number of f a r m s . C . S l u r r y m a n a g e m e n t : N i t r o g e n f l o w Of the quant i t ies of N f l o w i n g in the human f o o d cha in , about 50 kg N p e r s o n 1 y e a r 1 is used in c rop p roduc t i on and 40 kg N p e r s o n " 1 y e a r 1 is con ta ined in an ima l f e e d . Humans c o n s u m e 4 kg N p e r s o n - 1 y e a r 1 as an imal p ro te in . The ba lance in an imal f e e d , 36 kg N p e r s o n - 1 y e a r 1 , is con ta ined in an imal manure or s lu r ry . S i n c e nine t i m e s more N is con ta i ned in an imal manure than is c o n s u m e d as an ima l p ro te in by humans , the fa te of manure N is o f cons ide rab le impor tance to the f l o w of N in f o o d p roduc t i on (Lauer et a l . , 1976). V o l a t i l i z a t i o n l o s s o f N N H 3 is the th i rd m o s t abundant N s p e c i e s in the t r o p o s p h e r e , exceeded on l y by N 2 and N 2 0 (Levine et a l . , 1980). The c h e m i s t r y , m o v e m e n t , and env i ronmen ta l impact o f N H 3 in the a tmosphe re is not w e l l e s tab l i shed (Lauer et a l . , 1976). R a s o o l (1973) sugges t s a p o s s i b l e e f f ec t o f N H 3 in neut ra l i z ing ac id i t y p roduced by ox ida t i on o f sulphur in the a t m o s p h e r e . Increas ing concen t ra t i on of N H 3 in the a tmosphe re causes a e r o s o l f o r m a t i o n of the c o m p l e x su l f a t es of N H 3 (Be i lke et a l . , 1975; M c K a y , 1971) that are c o m p o n e n t s of s m o g and ac id rain ( D a w s o n , 1977). N H 3 m o v e s in to the air f r o m grazed pas tu res (Denmead et a l . , 1976), f r o m an ima l manure sp read on s o i l (Lauer et a l . , 1976; Ho f f et a l . , 1981 ; Beauchamp et a l . , 1982), f r o m d e c o m p o s i n g f a e c e s ( M a c D i a r m i d and W a t k i n , R E L A T I O N S H I P B E T W E E N D R Y M A T T E R A N D I.QO-1 I i — i 1 1 1 1 1 0 4 8 12 16 % D R Y M A T T E R (Figure 2) 12 1972) , f r o m cat t le urine (Va l l i s et a l . , 1982), f r o m cat t le feed lo ts (Hutch inson et a l . , 1982), and f r o m c rops (Denmead et a l . , 1978; Farquhar et a l . , 1979; and Stut te et a l . , 1979). A l t e r n a t i v e l y , N H 3 m o v e s into the s o i l (Ma lo and P u r v i s , 1964), wa te r (Hutch inson and V i e t s , 1969) and p lan ts (Denmead et a l . , 1978). A t m o s p h e r i c N H 3 a b s o r b e d by wa te r may acce le ra te eu t roph i f i ca t i on because 0.3 mg L" 1 o f inorgan ic N m a y s t imu la te nu isance a lgae b l o o m s in lakes (Sawye r et a l . , 1943). The m o s t se r i ous c o n s e q u e n c e of N H 3 v o l a t i l i z a t i o n f r o m the s lur ry is d i spe rsa l o f N that has u t i l i ty as fe r t i l i ze r f o r c rop p r o d u c t i o n . V o l a t i l i z a t i o n l o s s of N H 3 f r o m s to red and su r face app l i ed s lur ry must be reduced if s lu r ry is to gain further accep tance as po ten t ia l fe r t i l i ze r . M e a s u r e s to reduce such l o s s shou ld be i nexpens i ve s o that c o s t of s lu r ry N does not exceed the cos t o f inorgan ic fe r t i l i ze r N. The e f f e c t s o f va r i ous management s y s t e m s and app l i ca t i on me thods on l o s s of manure N, as taken f r o m Sut ton (198J) , are ind ica ted in T a b l e s 2 and 3 r e s p e c t i v e l y . The grea tes t N l o s s f r o m manure occu rs in t reatment s y s t e m s such as l agoons and ox i da t i on d i t ches or open hous ing units whe re the manure is e x p o s e d to the weather fo r a c o n s i d e r a b l e t i m e . N i t rogen in the f o r m of N H 3 is qu i ck l y los t to the air ( vo la t i l i zed ) as gas and in open lot s y s t e m s leached f r o m manure dur ing rain s t o r m s . W h e n s lu r ry is sp read on top of the g round us ing a tanker w a g o n or i r r iga t ion s y s t e m , 3 0 - 9 0 % o f N H 3 - N can be los t (Vande rho lm , 1975). V i r tua l l y l i t t le or no N is los t w h e n s lur ry is in jec ted or b roadcas t w i t h immed ia te s o i l i n c o r p o r a t i o n . On the other hand , if there is a t ime lag be tween manure a p p l i c a t i o n and i n c o r p o r a t i o n , a s ign i f i can t amount of N can be l os t . The magn i tude of l o s s w i l l be de te rm ined by the t ime lag b e t w e e n app l i ca t i on and i n c o r p o r a t i o n , and a l so by the env i ronmen ta l c o n d i t i o n s ove r Table 2. Estimated nitrogen losses (NH^-N) during storage, treatment and handling for various manure managerial systems (Sutton, 1981). System % Nitrogen loss Deep pit or above ground storage < to 30 Earthen storage pit 20 to 40 Anaerobic lagoon 70 to 80 Oxidation ditch 70 to 90 Bedded confinement 20 to 40 Open lot 40 to 60 Daily scrape and haul 15 to 35 Table 3. Nitrogen los s from swine s l u r r y as a f f e c t e d by method of a p p l i c a t i o n (Sutton, 1981). Method of Type of NII1+-N A p p l i c a t i o n Waste loss % Broadcast s o l i d 15 - 30 l i q u i d 10 - 25 Broadcast s o l i d 1 - 5 W/Cultivation l i q u i d 1 - 5 I n j e c t i o n l i q u i d 0 - 2 I r r i g a t i o n l i q u i d 30 - AO 15 that p e r i o d . A n examp le of such l o s s e s is p resen ted in Tab le 4 f o l l o w i n g Turner (1975). A l t h o u g h N H 4 + - N l o s s e s can be about 30% w i th in three days af ter su r f ace app l i ca t i on o f s w i n e s lur ry under f i e l d c o n d i t i o n s , l o s s e s o f more than 80% w e r e reco rded during a g reenhouse s tudy w i t h 2 2 ° C tempera tu re , 50% re la t i ve humid i t y and s imu la ted w i n d of 19.5 km hr 1 (Hoff et a l . , 1981). T h u s , N l o s s can be cons ide rab le if wea ther c o n d i t i o n s are r ight. A ma jo r i t y of the N is lost w i th in the f i rs t 24 hours af ter su r face app l i ca t i on (about 50%). A f t e r three d a y s , about 75% may be los t (Sut ton,1981) . Fac to rs e f fect ing volat i l izat ion of N H 3 A number o f s lu r ry , s o i l and env i r onmen ta l f a c t o r s a f fec t v o l a t i l i z a t i o n l o s s of N H 3 . A d i s c u s s i o n of s o m e o f the impor tan t ones w i l l he lp in unders tand ing the measures to be taken to reduce such l o s s e s . 1. To ta l N H 3 - N conten t of the s lu r ry and par t ia l p ressure of N H 3 in the air . 2. S lu r ry a p p l i c a t i o n rate and depth of app l i ca t i on 3. pH of the s o i l and s lur ry 4. Bu f fe r i ng c a p a c i t y of the s o i l 5. S o i l and air temperature and s o i l mo is tu re 6. S o i l texture 7. C a t i o n exchange capac i t y o f the s o i l 8. P r e s e n c e of f ree C a C 0 3 and N H 3 l o s s 9. W i n d s p e e d Par t ia l p ressure and N H , l o s s N H 3 v o l a t i l i z e s f r o m the manure to the a tmosphe re because o f a par t ia l p ressure gradient (Lauer et a l . , 1976; A v n i m e l e c h and Laher , 16 Table 4. Nitrogen losses due to ammonia vol a t i l i z a t i o n from f i e l d spread manure (Turner, 1975). Fresh Manure , directly f i e l d spread Time between application and Fraction of total N lost incorporation. % 1 - 4 days, dry s o i l 35 7 days or more, warm dry s o i l 50 1 - 4 days, warm wet s o i l 15 7 days or more, warm wet s o i l 30 '7 days or more, cool wet s o i l 10 17 1977; Bou ld in et a l . , 1974; and H a s h i m o t o and Lud ing ton , 1970). The high to ta l a m m o n i a conten t and pH of the manure ma in ta in a high manure p N H 3 re la t i ve to amb ien t . D ry ing of the manure immed ia te l y af ter sp read ing causes a seve ra l f o l d increase in the p N H 3 of the manure and its pH (Lauer et a l . , 1976). Lauer et a l . (1976) h y p o t h e s i z e d three s tages o f N H 3 v o l a t i l i z a t i o n f r o m bov ine manure . The f i rs t s tage is ve ry rapid in i t ia l l o s s of N H 3 d r i ven by ve ry high p N H 3 va lues resu l t ing f r o m urea h y d r o l y s i s in the manure. H a l f l i v e s o f <1 day charac ter ize f i rs t s tage l o s s e s . S e c o n d s tage N H 3 v o l a t i l i z a t i o n l o s s e s , charac te r i zed by h a l f - l i v e s o f 2 - 4 d a y s , beg in as the manure is sub jec ted to d ry ing ei ther in the f a c i l i t y or af ter s p r e a d i n g . Thi rd s tage l o s s e s occur af ter a large f r ac t i on (> 75%) of N H 3 in the manure has been los t . S lu r ry app l i ca t i on rate and N H , l o s s The amount of N that can be v o l a t i l i z e d f r o m a g i ven s lur ry ove r a pe r iod of t ime is e f f e c t e d by the rate of its app l i ca t i on (Mather and S t e w a r t , 1970; Pe te rs and R e d d e l l , 1976). A greater percen tage of the s lur ry to ta l N is los t through vo l a t i l i za t i on f r o m a sha l l owe r app l i ca t i on than heav ier app l i ca t i on of the s a m e s lur ry under the s a m e tempera ture and humid i t y (Moore and Beeh le r , 1982). Rapid d ry ing of the s lur ry f r o m the s h a l l o w e r rate is thought to be r e s p o n s i b l e fo r th is d i f f e ren t i a l amount of N l o s s e s . Incorpora t ion of NH„ c o m p o u n d s into the s o i l resu l ts in d e c r e a s e d N H 3 l o s s e s w i th the magn i tude of reduc t ion i nc reas ing w i th depth o f i nco rpo ra t i on (Fenn and K i s s e l , 1976). 18 pH and N H , l o s s pH and NHj vo l a t i l i za t i on are ve ry much re l a ted . A favou rab le pH fo r N H 3 vo l a t i l i za t i on is c o n s i d e r e d to be greater than 8.0 (Harmsen and Ko lenbrander , 1965; Webbe r and Lane , 1969), w i th n i t r i f i ca t i on be ing re tarded and N H 3 vo l a t i l i za t i on i nc reased as the pH g o e s a b o v e 7.3 (Olsen et a l . , 1970; S tewa r t , 1970). S o i l pH tends to go up af ter f e r t i l i za t i on w i th urea. U r e a , upon h y d r o l y s i s , r e l eases N H 3 - N wh i ch i nc reases s o i l pH (Watk ins et» a l . , 1972) and the i nc reased pH causes higher vo l a t i l i za t i on o f N H 3 (Ernst and M a s s e y , 1960; Pe te rs and R e d d e l l , 1976). Ernst and M a s s e y (1960) ind ica ted that one of the r easons fo r higher v o l a t i l i z a t i o n l o s s c o u l d be the C a - s a t u r a t i o n of the exchange c o m p l e x and , t he re fo re , l ess adso rp t i on of NH„ + at higher pH or i nc reased O H - ac t i v i t y in the s o i l so lu t i on f avou r i ng v o l a t i l i z a t i o n of g a s e o u s N H 3 . V o l a t i l i z a t i o n l o s s e s o f N f r o m c y l i n d e r s con ta in ing 2.5 L o f wa te r to wh i ch f resh pou l t r y manure w a s added at the rate of 57 g p e r . d a y and the pH of w h i c h we re ma in ta ihed at 7, 8 and 12 by add i t i on o f Ca(OH) 2 or HCI we re found to be 1, 5 and 30% r e s p e c t i v e l y (Edward and R o b i n s o n , 1969). N H 3 v o l a t i l i z a t i o n l o s s f r o m b roadcas t sw ine s lur ry var ied s i g n i f i c a n t l y w i th s o i l and s lur ry pH (Hoff et a l . , 1981). When s lur ry w i th a pH of 7.8 w a s app l i ed to a s o i l hav ing a pH of 7.0 in the g reenhouse , near ly 65% of the app l ied N H 3 w a s v o l a t i l i z e d ove r a pe r i od o f 3.5 d a y s . V o l a t i l i z a t i o n l o s s o f N H 3 w a s reduced s i g n i f i c a n t l y (being on l y 14%) w h e n s lur ry (pH 6.4) w a s app l i ed to s o i l (pH 6.4) fo r the s a m e pe r i od o f t i m e . Bu f fe r c a p a c i t y and N H , l o s s N H 3 is v o l a t i l i z e d due to the d i s s o c i a t i o n of N H 4 + to N H 3 and H + : 19 N H 4 + ^ - ^ N H 3 + H \ A c c o r d i n g l y , it has been s h o w n by many i nves t i ga to r s that N H 3 vo la t i l i za t i on is an impor tant p r o c e s s in bas ic s o i l s (Fenn and K i s s e l , 1973; Fenn and K i s s e l , 1975; and Harmsen and Ko lenb rander , 1965). D u p l e s s i s and Kroont je (1964) t r ied to pred ic t the extent of N H 3 vo la t i l i za t i on through the equat ion i nd i ca ted a b o v e . The p red ic ted va lues w e r e , h o w e v e r , about s ix t i m e s lower than t hose ac tua l l y f o u n d . In add i t ion to the p H , other s o i l p rope r t i es a f fec t the extent o f -NH 3 v o l a t i l i z a t i o n . A c c o r d i n g to G a s s e r (1963), the m o s t impor tan t f ac to r is the s o i l ' s ca t i on exchange c a p a c i t y . Ivanov (1963) and Lehr and W e s e m a e l (1961) have found that the p resence o f ca rbona tes is the dominant f ac to r a f f e c t i n g N H 4 + l o s s e s . A n in te res t ing feature o f the p r o c e s s is i ts app roach to equ i l i b r ium through the a c i d i f i c a t i o n of the m e d i a . A s s h o w n in the equat ion a b o v e , a H* is r e l eased fo r each c o n v e r s i o n of N H 4 + to N H 3 . Thus , the m e d i u m is be ing a c i d i f i e d and the f r a c t i o n o f N H 3 is reduced as the reac t i on p r o g r e s s e s . The rate o f m e d i u m a c i d i f i c a t i o n depends on the in i t ia l and f ina l concen t ra t i on o f N H 4 - as w e l l as on the bu f fe r capac i t y of the m e d i u m ( A v n i m e l e c h and Laher , 1977). The f ina l concen t ra t i on o f N H 4 + he ld by the s o i l i nc reases w i th an inc rease in H + a c t i v i t y , the in i t ia l N H 4 + c o n c e n t r a t i o n , and w i t h par t ia l p ressure of N H 3 in the air . A n inc rease in the bu f fe r c a p a c i t y o f the s o i l leads to a dec rease in the f ina l N H 3 c o n c e n t r a t i o n . The pH of the s o i l is the dominan t f ac to r c o n t r o l l i n g the extent of a m m o n i a v o l a t i l i z a t i o n on l y w h e n the s o i l ' s bu f fe r c a p a c i t y is h igh, or , w h e n the concen t ra t i on of N H 4 + in the s o i l is l o w . A t high pH and high in i t ia l a m m o n i u m c o n c e n t r a t i o n s , the dominan t f ac to r con t ro l l i ng 20 the reac t i on is the bu f fe r c a p a c i t y of the s o i l . The last cond i t i on is o f ten met when l iqu id f e r t i l i ze rs are s p r a y e d on the s o i l su r f ace . Ca t i on Exchange C a p a c i t y . S o i l Texture and N H , l o s s M o s t research conce rn i ng the e f f ec t of ca t i on exchange capac i t y (CEC) on N H 4 + re ten t ion has been a s s o c i a t e d w i th the use of anhydrous N H 3 ( Jackson and C h a n g , 1947; S t a n l e y and S m i t h , 1956; Wahhab et a l . , 1956; M c D o w e l l and S m i t h , 1958; La rsen and Gunary , 1962 and Harmsen and Ko lenb rander , 1965). N H 3 - N l o s s e s f r o m s o i l app l i ed n i t r ogenous fe r t i l i ze rs have been found to be greates t in sandy s o i l s , i n te rmed ia te in s i l t l oam s o i l s and least in c lay s o i l s (S tan ley and S m i t h , 1956; Wahhab et a l . , 1956 and M c D o w e l l and S m i t h , 1958). N H 3 l o s s e s dec rease w i t h i nc reas ing C E C ( M c D o w e l l and S m i t h , 1958; Fenn and K i s s e l , 1976). S o i l and air t empera tu re , s o i l mo i s tu re and N H , l o s s There ex i s t s a d i rect re la t i onsh ip b e t w e e n s o i l and air t empera tu re , s o i l mo i s tu re and a m m o n i a v o l a t i l i z a t i o n (Doak, 1952; V o l k , 1959; Ernst and M a s s e y , 1960; A d r i a n o et a l . , 1971; and Beauchamp et a l . , 1978 and 1982). W a g n e r and S m i t h (1958) de te rm ined vo la t i l i za t i on l o s s e s f r o m urea at tempera tu res of 10 and 2 5 ° C . For the f i rs t two w e e k s af ter add i t i on of u rea , l o s s e s w e r e higher at 2 5 ° C , af ter that more N H 3 w a s los t f r o m the s o i l at 1 0 ° C . The l o w e r tempera ture w a s thought to inhibi t n i t r i f i ca t i on and ma in ta in a higher N H 3 concen t ra t i on in the s o i l ove r a long pe r i od o f t i m e . A d r i a n o et a l . (1971) measured higher N l o s s e s at 2 5 ° C than at 10°C f r o m an app l i ed f a e c e s - u r i n e mixture hav ing mo is tu re l eve l s of 60 or 90%. They ind ica ted that tempera tu re and mo i s tu re a f f e c t N H 3 v o l a t i l i z a t i o n because of their 21 e f f ec t on the evapo ra t i on of wa te r and m ic rob ia l a c t i v i t y . Higher N H 3 v o l a t i l i z a t i o n has been found under f avou rab le e v a p o r a t i v e c o n d i t i o n s (El l iot et a l . , 1971; Lueb et a l . , 1974 and S tewa r t , 1970). A s ev idence that N H 3 e v o l u t i o n is s o i l tempera ture dependent , E l l i o t et a l . (1971) repor ted that much more N H 3 e v o l v e d f r o m a f e e d l o t in the spr ing than w in te r . M c G a r i t y and Rajara tnam (1973), D e n m e a d et a l . (1974), Beauchamp et a l . (1978, 1982) and Harper et a l . , (1983) o b s e r v e d diurnal pa t terns in N H 3 f lux f r o m app l i ed sheep ur ine, sheep grazed pas tu re , s e w a g e s ludge and l iqu id da i ry cat t le manure and urea r e s p e c t i v e l y . Beauchamp et a l . (1978, 1982) ind ica ted that the diurnal pat tern o f the N H 3 f lux w a s ve ry c l o s e l y re la ted to aer ia l tempera ture w i th its m a x i m a occur r ing shor t l y af ter m idday and m i n i m a dur ing the ear ly m o r n i n g hours . They s u g g e s t e d that the concen t ra t i on of a m m o n i a c a l N and its part ia l p ressure inc reased in the aqueous phase dur ing the late morn ing hours due to the evapo ra t i on of dew wate r wh i ch enhanced the l o s s of N H 3 . M a x i m u m l o s s occu r red dur ing m i d d a y , a f ter wh i ch ve ry l i t t le a m m o n i a c a l N w a s ava i lab le fo r v o l a t i l i z a t i o n because the dec rease in temperature resu l ted in l ower water vapour p ressure de f i c i t in the a tmosphe re and reduced e v a p o r a t i o n rate. Later , d e w accumu la ted in the manure layer and e f f e c t i v e l y d i lu ted the a m m o n i a c a l N c o n c e n t r a t i o n . The s a m e authors ind ica ted that magni tude of the f lux dec reased w i t h t i m e , i nc reased w i th tempera tu re and w a s s u p p r e s s e d by ra in fa l l as e v i d e n c e d in F i g . 3 taken f r o m their wo rk . Harper et a l . (1983) o b s e r v e d the h ighest co r re l a t i on of a m m o n i a f lux w i th s o i l su r face tempera tu re , f o l l o w e d in d e s c e n d i n g order by w i n d s p e e d and evapo t ransp i ra t i on dur ing the 22 A M M O N I A F L U X F R O M L IQUID D A I R Y C A T T L E M A N U R E ( B e a u c h a m p et a l . , 1 9 7 8 ) N H , V O L A T I L I Z A T I O N M A Y , 1976 0 T I M E : DATE ; 12 0 12 0 12 0 12 0 12 0 12 0 12 0 12 0 3 4 5 6 7 8 9 10 (Figure 3) 23 s u m m e r s e a s o n . For the rema inder of the year the h ighest co r re la t i on w a s w i t h evapo t ransp i ra t i on f o l l o w e d by so i l tempera ture and w i n d s p e e d . S o i l mo is tu re may have p o s i t i v e or nega t i ve e f f e c t s on N H 3 v o l a t i l i z a t i o n depend ing on the t ype o f the mater ia l added in the s o i l . It m a y enhance v o l a t i l i z a t i o n by t ranspor t ing the d i s s o l v e d N H 3 to the s o i l su r face (Stan ley and S m i t h , 1956; Denmead et a l . , 1976 and 1978) or d e p r e s s it by inc reas ing the e f f e c t i v e n e s s of s o i l i nco rpo ra t i on w h e n l iqu id a m m o n i a or an ima l w a s t e in the f o r m o f s lu r ry is added to the s o i l (Fenn and K i s s e l , 1976). Harper et a l . (1983) o b s e r v e d three pat terns of f lux dens i t y in re la t i on to su r face s o i l wa te r content and ra i n f a l l . N H 3 e f f l ux i nc reased to high rates when the s o i l w a s we t but i n c r e a s e d s l o w l y to modera te l eve l s when urea w a s app l ied to a dry s o i l su r f ace because of i n c o m p l e t e urea h y d r o l y s i s . The inc idence and amount of ra in fa l l a f ter the onset of large f lux dens i t i e s s t r ong l y i n f l u e n c e d to ta l N H 3 l o s s to the a tmosphe re . Ra in fa l l o f about 5 m m or mo re subs tan t i a l l y reduced N H 3 e f f l ux and the dura t ion of the large e f f l ux p e r i o d s c o r r e s p o n d e d to the number of r a i n l ess days af ter urea a p p l i c a t i o n . It may be c o n c l u d e d f r o m the a b o v e d i s c u s s i o n that the f a c t o r s m o s t h igh ly a s s o c i a t e d w i th m a x i m u m N H 3 e f f l ux are in te r re la ted through their dependence on the d r i v i ng f o r c e o f so la r ene rgy . P r e s e n c e of f ree C a C O , and N H , l o s s The e f f e c t o f s o i l C a C 0 3 content on N H 3 vo l a t i l i za t i on has gene ra l l y been c o n s i d e r e d o n l y as a s o i l pH bu f fe r . H o w e v e r , s tud ies done f r o m 1913 to 1946 by Du tch , Ge rman and Dan ish researchers s u g g e s t e d an add i t iona l i n f l uence of C a C 0 3 on N H 3 v o l a t i l i z a t i o n 24 (Harmsen and Ko lenbrander , 1965). M o r e recen t l y , Vo l k (1961) no ted greater N H 3 - N l o s s e s f r o m ( N H 4 ) 2 S 0 4 than f r o m N H 4 N 0 3 where both were su r face app l ied to heav i l y l imed grass s o d s . Fenn and K i s s e l (1973, 1974) and Fenn (1975) have demons t ra ted the ex i s tence o f a c h e m i c a l m e c h a n i s m , f i rs t s u g g e s t e d by Te rman and Hunt (1964) w h i c h is g i ven b e l o w : X ( N H 4 ) Y + N C a C 0 3 - — ^ N ( N H 4 ) 2 C 0 3 + Ca Y Z (s) N X _ where Y = an ion a s s o c i a t e d w i th N H 4 + ( N O y , ' S 0 4 ~ , C I ) and N , Z and X are dependent on the v a l e n c e s of the an ion and c a t i o n . A c c o r d i n g to th is m e c h a n i s m C a C 0 3 reac ts w i t h cer ta in a m m o n i u m c o m p o u n d s to p roduce uns tab le ( N H 4 ) 2 C 0 3 and , t he re fo re , i nc reased vo la t i l i za t i on o f N H 3 . T h o s e c o m p o u n d s w h i c h f o r m e d Ca reac t i on p roduc ts of l o w s o l u b i l i t y los t the greatest amount of N H 3 . ( N H 4 ) 2 S 0 4 + C a C 0 3 ^ C a 2 + + 2 0 H " + C a S 0 4 + N H 4 H C 0 3 2 N H 4 H C 0 3 2 N H 3 + 2 C 0 2 + 2 H 2 0 These ear l ie r resu l ts s u g g e s t e d that the quant i ty of C a C 0 3 cou l d a f fec t the rate and extent of ( N H 4 ) 2 C 0 3 f o r m a t i o n . Fenn and K i s s e l (1975) f r o m a labora to ry s tudy repor ted that N H 3 l o s s e s f r o m su r face app l ied ( N H 4 ) 2 S 0 4 i nc reased rap id ly up to s o i l C a C 0 3 content of 6.1%. N H 3 l o s s i nc reased s l i gh t l y when the C a C 0 3 con ten t of the s o i l i nc reased f r o m 6.1 to 9.7%. N H 3 l o s s d id not inc rease b e y o n d th is leve l o f s o i l C a C 0 3 con ten t . N H 4 N 0 3 reached m a x i m u m N H 3 l o s s at 1.3% s o i l C a C 0 3 and 110 kg N H 4 + - N h a - 1 , w i th l owe r but s t i l l i nc reas ing l o s s e s o f N H 3 - N at 6.1% s o i l C a C 0 3 and 550 kg N H 4 + - N h a 1 . A c i d i t y of the a m m o n i u m c o m p o u n d s caused a reduc t i on in f i na l s o i l pH at l o w C a C 0 3 l e ve l s and high N H 4 + - N app l i ca t i on r a t e s ; but at 6.1% C a C 0 3 and a b o v e , the pH va lues rema ined at 7 .5-7 .6 . The e f f e c t o f s o i l pH on N H 3 - N l o s s e s 25 w a s greater fo r N H 4 N 0 3 than for ( N H 4 ) 2 S 0 4 . Leaching loss of N The leach ing of nut r ients • is a harmfu l p h e n o m e n o n wh ich causes f i nanc ia l l o s s e s to agr icu l ture and m a y cause env i ronmen ta l po l l u t i on . S e v e r a l s o i l and c l i m a t i c f a c t o r s and cul tural p rac t i ces may a f fec t N m o v e m e n t in the s o i l . The degree of N m o b i l i t y in a po rous med ium l ike s o i l is s t rong l y dependent upon the f o r m in wh i ch it is p resen t , because of the p resence of nega t i ve l y and p o s i t i v e l y charged s u r f a c e s . Hence , the fa te of n i t rogenous w a s t e s app l i ed to . agr icu l tura l land w i l l be con t ro l l ed to a large extent by the b i o c h e m i c a l t r a n s f o r m a t i o n s they w i l l undergo in the s o i l env i r onmen t . R e v i e w s of these t r a n s f o r m a t i o n s have been car r ied out by a large number of w o r k e r s (Gasse r , 1964; B a r t h o l o m e w and C la rk , 1965; A l l i s o n , 1966; S t e v e n s o n and W a g n e r , 1970; B roadben t , 1973). The N H 4 + ion because of i ts capac i t y fo r adso rp t i on on to the nega t i ve l y charged s i t es o f c lay m ine ra l s and o rgan ic pa r t i c les genera l l y exh ib i ts l i t t le m o b i l i t y in s o i l s . In a w e l l aerated s o i l env i ronmen t , N H 4 4 c o m p o u n d s are read i l y c o n v e r t e d to N G y by n i t r i f y i ng bac te r ia . N G y ions cons t i tu te an in te rmed ia ry s ta te in this t r a n s f o r m a t i o n , but they have a very t rans ient ex i s tence in s o i l s and w i l l not be further c o n s i d e r e d . Because of i ts ex t reme l o c a t i o n s at the end of the m ic rob ia l ox i da t i on cha in , at the top o f the s o l u b i l i t y sca le and at the b o t t o m of the sca le of a f f i n i t y fo r c l a y p a r t i c l e s , N 0 3 " is o f g reates t impor tance f r o m a ground water po l l u t i on s tandpo in t . N G y can be w e a k l y adso rbed by s e s q u i o x i d e s w h e n the s o i l pH is 6 or b e l o w . A n exper iment on red s u b s o i l s in the Sou theas te rn U.S. s h o w e d a d s o r p t i o n o f N G y and CI" to be s im i l a r and c o n s i d e r a b l y sma l l e r than a d s o r p t i o n of S G y 2 (Thomas , 1970). 26 C a s e s tud ies of N c o n t a m i n a t i o n of ground w a t e r s are ex t reme ly abundant in the l i terature. E x t e n s i v e w e l l water s u r v e y s in the cent ra l Un i t ed S ta tes in par t icu lar (e.g. I l l i no is , K a n s a s , M i n n e s o t a , M i s s o u r i , N e b r a s k a , T e x a s ) have revea led large pe rcen tages of s a m p l e s app roach ing or e x c e e d i n g r e c o m m e n d e d l im i t s fo r N G y and N 0 2 " (Todd and M c N u l t y , 1976). The m e t h e m o g l o b i n e m i a haza rd , a s s o c i a t e d w i t h N 0 3 ~ and N 0 3 " in d r ink ing wa te r w a s d i s c u s s e d by B a i l e y (1966), Lee (1970) and W i n t o n (1970). When it accumu la tes in s o i l s , N O , - can a l so lead to t o x i c i t y hazards f o r p lan ts and ca t t le . A c c o r d i n g to Mar r i o t and Bart le t t (1975), f o rage con ta i n i ng 0.2% of N 0 3 - - N shou ld make up on l y part o f the ca t t le ra t i on , w h i l e i nges t i on o f mater ia l con ta in ing ove r 0.4% may resul t in N 0 3 ~ p o i s o n i n g . In m o s t c a s e s , agr icu l ture w a s iden t i f i ed as the ma in N 0 3 -con t r ibu to r due to an ima l w a s t e s and fe r t i l i ze rs as w e l l as to the e c o l o g i c a l changes brought on by the p lough (Krei ler and J o n e s , 1974). Ko lenbrander (1969) a n a l y z e d a ' large number of l y s i m e t e r t es t s repo r ted in the l i terature. A l l his resu l ts app ly to leach ing f r o m an a p p r o x i m a t e l y 1 m thick layer of s o i l , chem ica l fe r t i l i ze r be ing used e x c l u s i v e l y in each c a s e . Leach ing of N w a s found to be d i rec t l y p ropo r t i ona l to the amount o f dra inage wa te r in the range of 0 to about 600 m m y r - 1 . On cu l t i va ted land (sandy s o i l ) wh i ch had not been fe r t i l i zed w i t h n i t rogen fo r a number o f y e a r s , the l o s s w a s about 45 kg N h a - 1 y r 1 at 250 m m dra inage wa te r . The a p p l i c a t i o n of an o p t i m u m d o s e of c h e m i c a l fe r t i l i ze r i nc reased th is l o s s by about 14% of the fe r t i l i ze r app l i ed . The heav ier the s o i l , the less the leach ing of N. J a a k k o l a (1984), f r o m a f i e l d t r ia l on a c lay s o i l , r epo r ted 1-38% leach ing l o s s e s o f app l i ed n i t rogen w i t h a c o r r e s p o n d i n g wa te r d i scharge o f 65 to 255 m m through the subd ra i ns . H ighest leach ing l o s s w a s f o u n d to be c a u s e d by a p rev ious 27 f a l l o w . The s a m e author a l so repor ted 1-4% l o s s of the N used in cerea l p roduc t i on if app l ied in the spr ing c o m p a r e d to 20% f r o m the fa l l a p p l i c a t i o n . L i t t le i n f o r m a t i o n is ava i lab le on the leach ing of N f r o m f a r m y a r d manure . To eva lua te th i s , Ko lenbrander (1978) made seve ra l a s s u m p t i o n s and ca l cu la ted the percen tage of the N that w i l l be los t by leach ing f r o m an imal manure app l i ed ei ther in the sp r ing or fa l l on arab le land . The degree of leach ing to be expec ted on the b a s i s of his ca l cu l a t i on is s h o w n in Tab le 5. Un l i ke arable land , g rass l and has a vege ta t i ve c o v e r throughout the year capab le of tak ing up n i t rogen as long as the tempera ture is above 6 - 7 ° C . A c c o r d i n g to tes ts by P f a f f (1963), ove r 90% of the minera l N present in the s o i l dur ing the cou rse of a year is taken up, whe reas the f igure for ce rea l s is less than 50%. Leach ing l o s s e s are genera l l y c o r r e s p o n d i n g l y s m a l l . W i l l i a m s and J a c k s o n (1976) c o n s i d e r e d that the l o s s e s on l y b e c a m e s ign i f i can t w h e n mo re N w a s added than requ i red by the crop fo r dry mat ter p roduc t i on . Ko lenbrander (1973) m e n t i o n e d an average l o s s o f 3 kg N h a - 1 y r 1 fo r un fe r t i l i zed land , plus a l o s s of 1-2% of the c h e m i c a l fe r t i l i ze r N app l i ed . These resu l ts we re suppor ted by those of G a r w o o d and T y s o n (1973), in so far as the amoun ts app l ied we re b e l o w 250 kg N h a - 1 annum- 1 . O w e n and Bar rac lough (1983) repor ted 2, 11 and 17% l o s s e s of N app l ied as N H 4 N 0 3 due to leach ing f r o m g rass land that r e c e i v e d 250 , 500 and 900 kg h a - 1 o f N r e s p e c t i v e l y . G a r w o o d and T y s o n (1973), f r o m l y s i m e t e r s t u d i e s , g raph ica l l y represen ted the re la t i onsh ip be tween N l o s s and N app l i ca t i on under g rass land wh ich is represen ted in F i g . 4 . The leach ing l o s s w a s neg l i g ib le as long as the rate of N app l i ca t i on f r o m c h e m i c a l f e r t i l i ze r or fa rm yard manure d id not e x c e e d 350 kg h a - 1 y r _ 1 , but sharp ly i nc reased a b o v e th is Table 5. Percentage of nitrogen lost by leaching from animal manure on arable land (equilibrium condition). Kolenbrander, 1978. Type of waste Time of application Spring Autumn Cattle slurry 16 30 Pig slurry 13 30 Poultry slurry 8 31 Calf slurry 5 " 31 Liquid manure 2 32 N I T R O G E N L O S S E S O N G R A S S L A N D V S A N N U A L Q U A N T I T Y O F C H E M I C A L F E R T I L I Z E R N I T R O G E N A P P L I E D ( G a r w o o d S T y s o n , 1 9 7 3 ) 2 0 0 o <D 100 X o < U J —1 0 2 0 0 4 0 0 6 0 0 N A P P L I C A T I O N ( k g / h a / y e a r ) 3 0 M A R C H 1970 — 29 MARCH 1971 , - 2 8 0 mm DRAINAGE WATER (LYSIMETER) 29 M A R C H 1971 - 20 M A R C H 1972 , ~ 2 7 0 m m DRAINAGE WATER (LYSIMETER) H U P S E L E B E E K ( C A T C H M E N T A R E A ) (Figure 4) 30 rate. S t e e n v o o r d e n and O o s t e r o m (1977), f r o m a f i e l d exper iment on a sandy s o i l (peaty sand 0 - 2 0 c m , humus r ich sand 2 0 - 3 0 c m , h u m u s - p o o r sand >30 c m ) r ece i v i ng 150 kg inorgan ic fe r t i l i ze r N h a - 1 or 280 and 560 kg h a - 1 o f N in the f o r m of manure , d id not reco rd a large d i f f e rence in N G y concen t ra t i on b e l o w 60 cm depth . Mineral izat ion of slurry N The s o i l nutr ient that p lants require in greates t quant i ty is n i t r ogen . N i t rogen is a s s i m i l a t e d a l m o s t ent i re ly in the inorgan ic s ta te , as N 0 3 ~ or N H y . H o w e v e r , the bulk of the n i t rogenous mate r ia l s f ound in s o i l or added in the f o r m of plant res idues or an imal w a s t e s is usua l l y o rgan ic and , hence , unava i l ab le . The c o n v e r s i o n of th is o rgan i ca l l y bound N into inorgan ic f o r m s and its f l o w into the agr icu l tura l s y s t e m may i m p r o v e so i l fe r t i l i t y and bene f i t c rop p r o d u c t i o n . Changes in the me thods of l i v e s t o c k rear ing have led to the hand l ing of an imal w a s t e s as s lur ry rather than the t rad i t iona l f a r m y a r d manure . S lu r r i es are bu l ky , he te rogeneous ma te r i a l s , o f var iab le c o m p o s i t i o n and are c o n s i d e r e d as l o w grade f e r t i l i ze r s . The to ta l plant nutr ient content is usua l l y on l y 10% of that o f m o s t inorgan ic f e r t i l i ze rs (Pratt et a l . , 1976). H o w e v e r , their n i t rogen con ten ts have d rawn par t icu lar a t ten t ion because o f the impor tance o f c rop r e s p o n s e to th is e lement and the r i s k s o f N 0 3 -po l l u t i on o f su r f ace and ground wa te rs if e x c e s s i v e a p p l i c a t i o n s are u s e d . S lu r r i es can be c o n s i d e r e d as a mix ture o f f a e c e s and ur ine , p lus sma l l e r amoun ts of other o rgan ic ma te r ia l s such as w a s t e d f e e d and bedd ing , w i t h va ry i ng amoun ts of add i t i ona l wa te r . S o u r c e s and amount of wa te r added va r ies w i th the c o n d i t i o n o f c o l l e c t i o n . A s v o i d e d by the an ima ls the N in the f a e c e s and urine is a l m o s t en t i re l y in o rgan ic f o r m s 31 but urea and s o m e lab i le o rgan ic c o m p o u n d s are rap id ly c o n v e r t e d to N H 4 \ There is c o n s i d e r a b l e va r i a t i on in both the c o m p o s i t i o n and the p ropo r t i on of N in the inorgan ic f o r m . U s u a l l y about half o f the to ta l N is present as N H , * , the other inorgan ic f o r m s genera l l y be ing absent (Evans et a l . , 1978; M i n i s t r y o f Ag r i cu l t u re , F i she r i es and F o o d (M.A.F.F. , 1976). A large f rac t i on o f the to ta l N is present as organ ic f o r m s of va ry i ng res i s tance to m i c r o b i a l d e c o m p o s i t i o n and it is impor tant to measure the con t r i bu t i on o f th is f r a c t i o n to the p o o l o f plant ava i l ab le N in the. f i r s t and subsequent yea rs af ter a p p l i c a t i o n . The n i t rogenous c o m p o u n d s present in the s o i l o rgan ic f r ac t i on pe rs i s t f o r l ong pe r i ods in nature, the res i s tance to at tack be ing s o apprec iab le that on l y 1-3% of the N rese rvo i r o f the s o i l is m ine ra l i zed in each g row ing s e a s o n (Bremner , 1967). M c C a l l a et a l . (1977) sugges ted that the o rgan ic f r ac t i on of an ima l w a s t e c o n s i s t s ma in l y of t w o f o r m s : 1. P ro te i ns that have res i s t ed an ima l d i ges t i on and are . more or l ess c o m b i n e d w i th l idnin or l i g n i n - l i k e s u b s t a n c e s . 2 . Dead and l i v ing m ic rob ia l c e l l s f r o m the in tes t ina l t ract . The re la t i ve amoun ts o f these t w o f r a c t i o n s are not k n o w n and may be expec ted to va ry w i t h the age and diet of an imal and p o s s i b l y w i t h s t o rage . In par t i cu la r , d i f f e r e n c e s may be expec ted be tween the s lur ry f r o m ruminant and n o n - r u m i n a n t a n i m a l s . V e r y d i f fe ren t ra tes o f d e c o m p o s i t i o n may be e x p e c t e d f r o m the t w o f r a c t i o n s . Ma te r ia l that has res i s t ed d i g e s t i o n by ruminant an ima l s is l i ke ly to be ve ry res is tan t to further d e c o m p o s i t i o n in the s o i l . 32 N in the s lur ry can be present in three f o r m s (S lu i j smans and Ko lenb rander , 1977; and Bhat et a l . , 1980) n a m e l y inorgan ic N, o rgan ic N m ine ra l i zab le in the year of a p p l i c a t i o n , and res is tant o rgan ic N w h i c h m ine ra l i zes in subsequent y e a r s . L im i t ed research conce rn i ng m ine ra l i za t i on o f s w i n e s lur ry N conduc ted under c o n t r o l l e d env i ronmen t has been repor ted in the l i terature. Resu l t s of such s tud ies can not be ex t rapo la ted to f i e l d s i tua t ions but p rov ide an impor tant c lue to ind ica te what might happen in the f i e l d under s im i l a r c o n d i t i o n s . In terpretat ion of resu l ts of many o f these s tud ies has been d i f f i cu l t as no d i s t i n c t i on has been made be tween o rgan ic and inorgan ic N in i t ia l l y present in the s lur ry and no measurement has been made of N l o s s e s through v o l a t i l i z a t i o n and deni t r i f i ca t ion ( M a s s et a l . , 1973; C o o p e r , 1975). G e r m o n et a l . (1979) f a i l ed to reco rd m ine ra l i za t i on of any s i gn i f i can t amount o f p ig s lur ry o rgan ic N f r o m an incubat ion s tudy car r ied out ove r a raoge o f t empera tu res . F l o w e r s and A r n o l d (1983) ind ica ted i m m o b i l i z a t i o n of 40% o f the s lur ry N H y N w i thou t subsequent m ine ra l i za t i on of the i m m o b i l i z e d or s lu r ry o rgan ic N w h e n incubated ove r a range o f tempera tu res and mo is tu re con ten ts . On the other hand on l y 25% of the to ta l s w i n e s lur ry N has been found to be res is tan t to d e c o m p o s i t i o n under ex tens i ve ae rob i c d i g e s t i o n (Loynachan et a l . , 1976). Su t ton (1981) a s s u m e d that 35% of the s lur ry o rgan ic N cou ld be ava i l ab le dur ing the year of a p p l i c a t i o n , but th is w a s not suppo r ted by any pub l i shed f i e l d or l abo ra to ry e v i d e n c e . T ie t jen (1977) s ta ted that l i t t le i n f o r m a t i o n on the annual rate of b i o l o g i c a l decay of the o rgan ic f r ac t i on f r o m s w i n e s lur ry is ava i l ab le and no p r e d i c t i o n w i t h cer ta in ty can be g i ven about the ava i l ab i l i t y o f the o rgan ic bound nut r ien ts . 33 M i n e r a l i z a t i o n is a b i o l o g i c a l p r o c e s s and is car r ied out by a va r ie ty of m i c r o f l o r a . A c t i v i t y of the d i ve r se groups of m i c r o o r g a n i s m s is a f f e c t e d by d i f fe ren t env i ronmen ta l f a c t o r s . A s d i ve rse groups of o r g a n i s m s are i n v o l v e d in the m ine ra l i za t i on of n i t rogen the pecu l ia r i t i es of the habitat do not c o m p l e t e l y e l im ina te m ine ra l i za t i on in arable land as long as m ic rob ia l p ro l i f e ra t i on is p o s s i b l e , but on the other hand the rate is marked ly a f f e c t e d by the env i ronment (A lexander , 1977). A d i s c u s s i o n of s o m e o f the impor tant f a c t o r s a f f e c t i n g m ine ra l i za t i on w i l l f o l l o w . Fac to rs a f fect ing mineral ization of N Tempera tu re and m ine ra l i za t i on Tempera tu re is one of the m o s t impor tant env i ronmen ta l f a c t o r s k n o w n to a f fec t the g rowth of m i c r o o r g a n i s m s and the b i o l o g i c a l ac t i v i t y o f s o i l s . N u m e r o u s s tud ies have s h o w n that m i c r o b i a l ac t i v i t i es in s o i l are s t imu la ted by i nc reas ing the tempera ture (A lexander , 1965). The o p t i m u m cons tan t tempera ture fo r a m m o n i f i ca t i on and n i t r i f i ca t i on is b e t w e e n 25 and 35 °C (A lexander , 1965; J u s t i c e and S m i t h , 1962). M i n e r a l i z a t i o n of the o rgan ic c o m p l e x e s takes p lace ve ry s l o w l y at 2 ° C w i t h no inc rease in N H / or N O / when the s o i l is f r ozen (A lexander , 1977). S i n c e m o s t s o i l b i o l o g i c a l research on temperature e f f e c t s has been car r ied out us ing cons tan t tempera ture c o n d i t i o n s , ve ry l i t t le is k n o w n about the re la t i ve e f f e c t o f c y c l i c a l as o p p o s e d to cons tan t t empera tu res . The rate of m i c rob ia l g row th at cons tan t tempera tu re is c o n s i d e r a b l y greater than at f l uc tua t ing t empera tu res , par t i cu la r l y i f the amp l i tude of f l uc tua t ion exceeds 10°C ( J e n s e n , 1969; J e n s e n and R e y n o l d s , 1971; S m i t h , 1964; and H o w e l l et a l . , 1971). H o w e v e r s o m e 34 repor ts tend to con t rad ic t th is re la t i onsh ip . Bu rgess and G r i f f i n (1968) c l a i m e d that tempera ture f l uc tua t ion per se d o e s not a f fec t the rate of fungal g row th , and P o w e r s et a l . (1965) repor ted that bac te r ia g rew fas te r under c y c l i c a l 5 - 2 7 ? C than at mean cons tan t tempera ture of 16°C. F e w i nves t i ga to rs have s tud ied the in f luence of d iurnal tempera ture f l uc tua t i ons on s o i l m i c r o b i a l a c t i v i t y . W h e n unamended s o i l w a s incubated at f l uc tua t ing l o w tempera tu res the v iab le count of m i c r o o r g a n i s m s dec l i ned sharp ly (B iederbeck and C a m p b e l l , 1971). These de t r imenta l e f f e c t s we re g rea t l y reduced w h e n the s o i l w a s amended w i th N H y - N or pep tone (Campbe l l et a l . , 1972). The rate of n i t r i f i ca t i on w a s a l so s i g n i f i c a n t l y l ower w i t h the f l uc tua t ing than w i t h the c o r r e s p o n d i n g cons tan t mean temperature (Campbe l l et a l . , 1971, 1973; C o o k , 1952). In con t ras t , it has been repor ted that d iurnal tempera tu re f l uc tua t i ons b e l o w 15.5°C t e m p o r a r i l y caused more n i t r i f i ca t i on than d id the c o r r e s p o n d i n g mean cons tan t tempera ture (Freder ick,1956) . A n o t h e r overs igh t in th is area of research is the lack of a t ten t ion g i ven to the p reced ing tempera ture on s o i l b i o l o g i c a l ac t i v i t y measu red at subsequen t l y d i f fe ren t tempera tu res . U s i n g three d i f fe ren t cons tan t tempera tu res (5, 16, 2 7 ° C ) , Chandra (1962) s h o w e d that n i t r i f i ca t i on in a l oam s o i l w a s c o n s i d e r a b l y l owe r when the incubat ion tempera tu re w a s sh i f t ed f r o m s u b o p t i m a l to op t ima l than v i c e v e r s a . R e c e n t l y it w a s e m p h a s i z e d that the rate o f N t r a n s f o r m a t i o n under a g i ven tempera tu re c o n d i t i o n w a s a f unc t i on of the p reced ing tempera tu re reg ime (Campbe l l and B iede rbeck , 1972). These w o r k e r s f ound that a m m o n i f i c a t i o n at T 18/7 (in each 24 h pe r i od the s a m p l e s 35 we re ma in ta ined at 18 and 7 ° C fo r 9 h each w i t h t rans i t i on pe r i ods of 3 h) f o l l o w i n g T 27 /16 (s imu la t ing S e p t e m b e r t empera tu res ) w a s much greater than dur ing the s a m e T 18/7 w h e n f o l l o w i n g T 13/2 (s imula t ing M a y tempera tu res) . They h y p o t h e s i z e d that at o p t i m u m tempera tu res p roduc t i on of m i c r o b i a l b i o m a s s w a s h igh , but w i th the onset of sudden un favourab le tempera tu res there w a s in i t ia l l y a large k i l l wh i ch p r o v i d e d c o n s i d e r a b l e amoun ts of read i l y ava i l ab le N subs t ra te f o r subsequent a m m o n i f i ca t ion and n i t r i f i ca t i on as the su rv i v i ng o r g a n i s m s adapted to the new temperature r e g i m e . B iede rbeck and C a m p b e l l (1973) c o n f i r m e d the above h y p o t h e s i s in another s tudy and a l so repor ted that the va l i d i t y of th is p h e n o m e n o n w a s suppo r ted by f i e l d data (4 yea rs ) that s h o w e d the onset of the f i rs t c o l d spe l l each fa l l and late f r o s t s in sp r ing resu l ted in sudden f l ushes in N O y N p r o d u c t i o n . S o i l M o i s t u r e and N M i n e r a l i z a t i o n Bo th ae rob ic and anaerob i c o r g a n i s m s are i n v o l v e d in a m m o n i f i ca t i on . A s a resul t o rgan ic n i t rogen is m ine ra l i zed at modera te or at e x c e s s i v e l y high m o i s t u r e l eve l s (A lexande r , 1977). N H 4 + is f o r m e d s l o w l y at wa te r con ten ts s l i gh t l y b e l o w the permanent w i l t i n g pe rcen tage , but i m p r o v i n g the mo is tu re s ta tus s t imu la tes m i n e r a l i z a t i o n . In ar id or s e m i a r i d reg ions and in c l i m a t i c zones hav ing wet and dry c y c l e s , the onse t of ra in fa l l is t y p i c a l l y a s s o c i a t e d w i t h a rap id in i t ia t ion of m i n e r a l i z a t i o n . A l t hough s o i l s d i f f e r in their p rec i se o p t i m u m mo is tu re v a l u e s , the o p t i m u m fo r m ine ra l i za t i on genera l l y f a l l s be tween 50 and 75% of the wa te r ho ld ing c a p a c i t y (A lexande r , 1977). A m m o n i f i ca t i on is not e l im ina ted by s o i l s u b m e r g e n c e , and the p r o c e s s is rap id in we t paddy f i e l d s , where 0 2 36 leve l is qui te l o w . A s a ru le , s o i l s ac t i ve in aerob ic m ine ra l i za t i on a l so f o r m N H 4 + read i l y in the absence of 0 2 , and those s l o w in these p r o c e s s e s in aera ted c o n d i t i o n s l i k e w i s e generate N H 4 4 s l o w l y under a n a e r o b i o s i s (Waring and Bremner ,1964) . N i t r i f i ca t i on on the other hand is ve ry much s e n s i t i v e to the p resence or absence of 0 2 as N H 4 + is c o n v e r t e d to N G y on l y in w e l l aera ted habi ta ts (A lexander , 1977). S o i l wa te r that is held at 1 m (98 kPa) of t e n s i o n is c o n s i d e r e d to be o p t i m u m for n i t r i f i ca t i on (Fitts et a l . , 1955). We t t i ng and d ry ing - f reez ing and thaw ing and N m ine ra l i za t i on S o m e unexp la ined change occu rs when s o i l s b e c o m e dry and then we t aga in . W h e n p r e v i o u s l y dry s o i l s are r e m o i s t e n e d the m ine ra l i za t i on rates are greater than if they we re kept con t i nuous l y w e t . If a number of such d ry ing and we t t i ng c y c l e s occu r , c o n s i d e r a b l e quant i t ies of the organ ic n i t rogen may be degraded to the inorgan ic f o r m al though the rate of the p r o c e s s dec l i nes in the later c y c l e s . Fur the rmore , the longer the dry p e r i o d , genera l l y the greater is the amount of inorgan ic n i t rogen re l eased dur ing the subsequent wet phase . The d ry ing - w e t t i n g c y c l e may make i n a c c e s s i b l e subs t ra tes more e a s i l y ava i lab le to the m i c r o b i a l c o m m u n i t y or the d ry ing may cause ce l l d i s i n t e g r a t i o n , h o w e v e r , none of the exp lana t ions fo r th is a n o m a l o u s f l ush of m i c r o b i a l d e v e l o p m e n t has c o n v i n c i n g suppor t ing ev idence (A lexander , 1977). B i rch (1960) and S t e v e n s o n (1956) ind ica ted that under natural c o n d i t i o n s , f requent we t t i ng and d ry ing p roduced e a s i l y m ine ra l i zab le N subs t ra te , the p roduc t i on of wh i ch is m in ima l under cons tan t mo i s tu re cond i t i ons such as those used in the incuba t ion s t u d i e s . W e t t i n g and d ry ing apparen t l y accoun t fo r 7 0 - 9 0 % o f the N 0 3 - - N p roduced in the 0 -2 .5 c m s e c t i o n o f the s o i l ove r a 37 g row ing s e a s o n (Campbe l l et a l . , 1974). Frequent c y c l e s of f r eez ing f o l l o w e d by t h a w i n g , much as d ry ing f o l l o w e d by w e t t i n g , i nc reases exchangeab le N H / but not N G y (Gasser , 1958; and H i n m a n , 1970). G a s s e r (1958) fa i l ed to o b s e r v e any p o s i t i v e e f f ec t o f s ing le f reez ing pre t rea tment on n i t rogen m ine ra l i za t i on dur ing subsequent i ncuba t ion . H o w e v e r , Mack (1963) repor ted a sharp inc rease in minera l n i t rogen when s o i l w a s f r o z e n in l iqu id n i t rogen and then incuba ted . The favou rab le e f f e c t o f f reez ing and thaw ing f o l l o w e d by incubat ion on minera l N con ten t w a s o b s e r v e d by R o s s et a l . (1978) and on exchangab le N H / - N but not N O y content in s te r i l e so i l by C a m p b e l l et a l . (1971). C / N ra t io and N m ine ra l i za t i on The rate at w h i c h n i t rogen b e c o m e s ava i lab le to the plant w h e n organ ic res idues are added to the s o i l is gove rned by the p ropo r t i ons in wh i ch C and N are present in the added ma te r i a l s . In order fo r the o rgan ic n i t rogen to be m ine ra l i zed the o rgan ic r es i dues added to the s o i l shou ld have a des i rab le C / N ra t io . Because dur ing the course o f m ine ra l i za t i on on ly mater ia l w i t h a C / N ra t io of 20;1 or l o w e r genera l l y can d i rec t l y p r o v i d e minera l n i t r ogen ; mater ia l w i t h higher C / N rat io in i t i a l l y a l l o w s on l y the l ibera t ion o f C G y al l m ine ra l i zed n i t rogen be ing i m m e d i a t e l y bound in the p r o t o p l a s m of the d e v e l o p i n g m i c r o b e s . A lag p e r i o d , t he re fo re , must be expec ted unt i l the C / N ra t io is na r rowed to a p p r o x i m a t e l y 2 0 : 1 . Th i s w h o l e c o m p l e x p h e n o m e n o n is b a s e d on t w o s u p p o s i t i o n s : 1. dur ing the m ic rob ia l d e c o m p o s i t i o n of o rgan ic mat ter at least 1.5 to 2.5% N must be present in that mat ter to guarantee g o o d g rowth of the m i c r o b e s w i thou t net i m m o b i l i z a t i o n ; and 38 2. in the long run N content of the d e c o m p o s i n g mater ia l tends to approach that of the p r o t o p l a s m of the m i c r o b e s . D. Rate o f slurry appl icat ion In order to arr ive at a su i tab le fe r t i l i ze r app l i ca t i on rate one has to d i s t i ngu i sh be tween m a x i m u m p ro f i t ab le y i e l d and m a x i m u m p o s s i b l e y i e l d . In mos t c a s e s the ob jec t i ve is to make the m a x i m u m pro f i t f r o m the resou rces ava i l ab le . M a x i m u m y i e l d is not the s a m e as m a x i m u m p ro f i t . If m a x i m u m y i e l d is the o b j e c t i v e , fe r t i l i ze r w i l l have to be app l ied to the point where the app l i ca t i on of add i t i ona l f e r t i l i ze r w o u l d resul t in no add i t iona l y i e l d . The on ly t ime that the m a x i m u m y i e l d w o u l d resul t in m a x i m u m pro f i t is w h e n fe r t i l i ze r p r i ces are nil i.e. fe r t i l i ze r is f r ee . T o ca lcu la te the m a x i m u m pro f i t po in t , the do l la r va lue of the c rop must be c o m p a r e d to the cos t o f the inputs used to p roduce the c r o p . To de termine the mos t p ro f i t ab le rate of fe r t i l i ze r a p p l i c a t i o n , one must k n o w ; ' 1. The p h y s i c a l output (i.e. y i e l d ) that resu l ts f r o m d i f fe ren t ra tes of fe r t i l i ze r a p p l i c a t i o n . 2. The expec ted pr ice of the c rop be ing g rown 3. The cos t o f fe r t i l i ze r be ing u s e d . In dea l ing w i th o rgan ic fe r t i l i ze rs l ike an ima l w a s t e s the m o s t impor tan t f ac to r that has to be taken into c o n s i d e r a t i o n in de te rm in ing a p p l i c a t i o n rate is the c o s t o f app l i ca t i on . B e c a u s e o f the l o w concen t ra t i on of the nutr ients and bu lky nature of the m a t e r i a l s , a large v o l u m e has to be app l i ed to ob ta in the s a m e amount o f nut r ients w h e n c o m p a r e d w i th inorgan ic fe r t i l i ze r . A f rac t i on of the plant nutr ients present in the s lur ry is not read i l y ava i l ab l e . Their ava i l ab i l i t y is de te rm ined great ly by seve ra l 39 env i r onmen ta l and management f a c t o r s . T h e r e f o r e , in de te rm in ing s lur ry app l i ca t i on rate, in add i t i on to the c rop ' s requ i rement the f o l l o w i n g f ac to r s have to be taken into c o n s i d e r a t i o n as w e l l . They a re ; 1. F ie ld t opog raphy 2. C l i m a t i c reg ions 3. S o i l t ype 4. T y p e of the o rgan ic w a s t e s and its chem ica l c o m p o s i t i o n 5. M e t h o d o f app l i ca t i on 6. I r r igat ion p rac t i ces and ground and su r face wa te r fea tures o f the app l i ca t i on s i t e . Basis of determining appl icat ion rate The ma in c rop fe r t i l i t y requ i rements are N , P , K and S . N is o f t en the nutr ient that l im i t s g rowth and is c o n v e r t e d f r o m o rgan ic c o m p o u n d s to N H 4 + and N G y w h i c h can be c o n v e r t e d to N 2 0 , N 2 or back to organ ic c o m p o u n d s through m i c r o b i a l t r a n s f o r m a t i o n s . S o m e of these f o r m s are re la t i ve l y inso lub le in wa te r and o thers are h ighly s o l u b l e , s o m e exis t as gases or are read i l y v o l a t i l i z e d . On the other hand, e x c e s s i v e N app l i ca t i on can a d v e r s e l y a f f ec t agr icu l tura l c r o p s . It may cause lodg ing of c e r e a l s , reduc t ion of dry mat ter and s ta rch content of p o t a t o e s , reduc t ion of sugar con ten t and ju ice pur i ty of s u g a r b e e t s , and ni t rate accumu la t i on in v e g e t a b l e s (Cremer , 1977) or may po l lu te su r face and ground wa te r . The re l a t i ve l y large quant i ty o f N in the s lur ry and i ts po ten t ia l de t r imenta l e f f e c t s on the env i ronmen t ca l l fo r s p e c i a l a t ten t ion to its use as the b a s i s f o r de te rm in ing app l i ca t i on ra tes . W h e n N is used as a bas i s fo r de te rm in ing app l i ca t i on ra tes , a k n o w l e d g e of the amount o f o rgan ic N that 40 can be m ine ra l i zed f r o m s lur r ies of v a r y i n g c o m p o s i t i o n under d i f fe ren t env i r onmen ta l cond i t i ons dur ing the year of app l i ca t i on and a l so in subsequent yea rs p l ays an impor tant ro le (Powers et a l . , 1975). Pratt et a l . (1976) d e v e l o p e d a decay se r i es approach fo r dai ry cat t le manure wh i ch can have i m p l i c a t i o n s not on l y in t e rms of manure app l i ca t i on ra tes re la t i ve to c rop n e e d s , but a l so fo r p red ic t i ng N G y leach ing to g round w a t e r s . It can a l s o be used to ca lcu la te the e f f e c t s of va r ious managemen t p rac t i ces on N m ine ra l i za t i on . Pe rhaps , because o f a lack of such i n f o r m a t i o n , app l i ca t i on rates based on a decay se r i es approach for s w i n e s lu r ry have not been d o c u m e n t e d in the l i terature. M c A l l i s t e r (1966) c o m p a r e d s w i n e s lur ry w i th v a r i o u s inorgan ic f e r t i l i ze rs on the bas i s of to ta l N con ten t . The y i e l d r e s p o n s e to s lurry N w a s app rox ima te l y 2 /3 of that of a m m o n i u m su lphate . The s a m e author (1970) f r o m 13 bar ley expe r imen ts car r ied out over a p e r i o d of f i v e yea rs c o m p a r i n g a m m o n i u m su lphate or urea and so lub le s lu r ry N s h o w e d that both y i e l d and N uptake r e s p o n s e s to s o l u b l e N in s lur ry w e r e equ iva len t to those o f N app l i ed as a m m o n i u m su lphate or urea. The so lub le N f r ac t i on w a s ex t rac ted by shak ing the s lu r ry w i th c o l d 0.1 N HCI over a pe r i od of 24 h, a p rocedure s u g g e s t e d by H o y l e and M a t t i n g l y (1954). The so lub le N f r ac t i on has been found to be ve ry s im i l a r to the N H y - N conten t o f the s lur ry ( M c A l l i s t e r , 1970), r ep resen ted about 66% o f the to ta l N and w a s ava i l ab le dur ing the year of a p p l i c a t i o n (Ber ryman, 1970; Tunney , 1977; and S u t t o n , 1981). 41 E. D i s t r i b u t i o n o f s l u r r y N f o l l o w i n g a p p l i c a t i o n A c o n s i d e r a b l e amount of s lu r ry N can be present as N H 4 + - N depend ing on its s to rage and hand l ing . The re fo re , when in jec ted , its concen t ra t i on can be high w i th in the zone of app l i ca t i on if not d i s p e r s e d . Th is is a l so true of the sa l t s present in the s lu r ry . L o c a l i z e d concen t ra t i on of N H 4 + or sa l t s or both can have de t r imenta l e f f e c t s on plant g r o w t h , e s p e c i a l l y ge rm ina t i on . The d is t r i bu t ion of s lurry N , sho r t l y a f ter in jec t ion cou ld be of paramount impor tance fo r s u c c e s s f u l c rop g r o w t h . No i n fo rma t i on is ava i l ab le on the d i s t r i bu t ion of s lu r ry N subsequent to in jec t ion into the s o i l . M c i n t o s h and Freder ick (1958) and M c D o w e l l and S m i t h (1958) h o w e v e r , have repor ted that N H 4 + had m o v e d 7.5 c m la tera l ly f r o m the po in t o f in jec t ion af ter one week f o l l o w i n g anhydrous a m m o n i a t rea tment . The s a m e authors ind ica ted that the s o i l tex ture , m o i s t u r e , depth and spac ing of app l i ca t i on p lay a key ro le in the m o v e m e n t and l o s s e s of N H 4 + - N f r o m the s o i l . They repor ted reduced m o v e m e n t and l o s s e s o f N H 4 + as the s o i l texture changed f r o m sand and s i l t l oam to c l a y , spac ing of app l i ca t i on d e c r e a s e d f r o m 100 c m to 40 cm and depth o f app l i ca t i on i nc reased f r o m 7.5 c m to 15 c m . F. C r o p r e s p o n s e t o s l u r r y N Land app l i ca t i on of an ima l w a s t e s and r e c y c l i n g of nut r ients through the s o i l plant c o m p l e x has been a c o m m o n l y accep ted me thod of d i s p o s a l . M o s t research i nves t i ga t i ng the e f f ec t o f w a s t e app l i ca t i ons on c rop land has deal t w i th ca t t le or pou l t r y w a s t e s (Powers et a l . , 1975). L i t t le research has been c o n d u c t e d d o c u m e n t i n g c rop r e s p o n s e s resu l t i ng f r o m s w i n e s lurry a p p l i c a t i o n s . 42 Crop y i e l d and qua l i ty can o f ten be de te rm ined by the amount of s lu r ry app l ied and its ava i l ab le N , sal t and Cu c o n t e n t s . G o o d r i c h et a l . , (1973) and Hanson et a l . , (1974) f r o m a t w o year f i e l d exper imen t in wh i ch 318 , 224 and 448 t ha-> y r 1 o f s lur ry (wet we igh t b a s i s con ta in ing 2 -2 .4% dry mat ter ) we re added r e s p e c t i v e l y d id not r eco rd any adve rse e f f ec t of app l i ca t i on rates on corn y i e l d s . The amount of N that w a s added f r o m these rates has not been ind ica ted b y , any o f the au thors . Su t ton et a l . , (1978) f r o m s lur ry app l i ca t i ons o f 4 5 , 90 and 134 t h a 1 (1 .8 -3% dry mat ter ) r eco rded y i e l d i nc reases up to a rate o f 90 t h a - 1 (which supp l i ed 250 kg h a - 1 of N) and then l eve l l i ng o f f . Tunney (1975) f r o m a se r i es of expe r imen ts in w h i c h the r e s p o n s e o f d i f f e ren t g rass s p e c i e s to s w i n e s lur ry and c h e m i c a l fe r t i l i ze r were t e s t e d , s ta ted that " s w i n e s lur ry of k n o w n c o m p o s i t i o n can be used to rep lace c h e m i c a l f e r t i l i z e r " because none of the s p e c i e s tes ted we re par t i cu la r l y w e l l su i ted or unsu i ted fo r use w i th s w i n e s lu r r y . Lanza (1977) f r o m expe r imen ts car r ied out ove r a pe r i od of f i v e yea rs ind ica ted that f o rage c r o p s , pa r t i cu la r l y annual rye g r a s s , ma ize (green fo rage and s i l age c r o p s ) , f odder so rghum and w in te r ce rea l f o rage c r o p s (bar ley , rye and o a t s ) have r e s p o n d e d to s lur ry a p p l i c a t i o n . The p o s i t i v e e f f ec t of sw ine s lu r ry on f o rage p roduc t i on w a s a t t r ibuted to its d i lu te s ta te and neutral r e a c t i o n . Tunney (1975) a l so ind ica ted that at an equal rate of N , sw ine s lu r ry gave c o n s i s t e n t l y bet ter g rass dry mat ter y i e l d s than cat t le s lu r ry . Th is w a s thought to be due in part to the higher ava i l ab i l i t y o f N f r o m s w i n e s lu r r y . M o r e o v e r , ca t t le s lu r ry might have an a d v e r s e phys i ca l and c h e m i c a l e f f e c t on g rass g row th because it has been no ted that higher ra tes o f cat t le s lur ry f o r m a coa t i ng on the g rass su r face wh i ch might last f o r seve ra l w e e k s under dry wea ther c o n d i t i o n s . It is l i ke l y that th is coa t 43 of s lur ry reduces the l ight ava i l ab le to the g rass fo r p h o t o s y n t h e s i s . S w i n e s lu r ry , because of its granular nature, in c o m p a r i s o n to the f i b rous nature of s lur ry f r o m cat t le fed on hay or s i l a g e , d o e s not f o r m a dense coa t ing on the grass su r f ace . S u p p l e m e n t a r y Cu used in the p ig ra t ions has been a matter of conce rn fo r i ts e f fec t on s o i l and c rop qua l i t y . Ko rnegay et a l . (1974) repor ted high concen t ra t i ons of Cu in co rn leaves f r o m an app l i ca t i on of 36 t h a 1 the f i rs t year , and 29 t h a - 1 the s e c o n d year o f s w i n e s lur ry (conta in ing 22 percent dry mat te r ) f r o m the p igs f e d high Cu d ie ts (250-370 ppm Cu). Su t ton et a l . (1983) on the other hand d id not reco rd any a c c u m u l a t i o n of Cu in the co rn t i s s u e f r o m app l i ca t i ons of 90 , 180 or 270 t h a - 1 o f sw ine s lur ry (3.2-5.2% dry mat te r ) f r o m p igs f e d 125 - 250 ppm C u . G . S l u r r y I n j e c t o r - i t s p o s s i b l e b e n e f i c i a l e f f e c t s o n s o i l p r o p e r t i e s a n d c r o p y i e l d The e f f i c i e n c y of water and nutr ient uptake f r o m s o i l by p lan ts depends on the root concen t ra t i on in the zone of ex t rac t i on . R o o t s g r o w d o w n w a r d due to - a geo t rop i c r e s p o n s e unti l impedence f o r c e s exceed geo t rop i c r e s p o n s e . There fo re , s o i l c o n d i t i o n s wh i ch impede plant root g rowth a f f ec t the s ize o f the roo t i ng v o l u m e and al ter the e f f i c i e n c y of nutr ient and wa te r ex t rac t i on . S o i l c o n d i t i o n s wh i ch impede root g rowth have been measu red as s o i l dens i t y (Ve ihmeye r et a l . , 1948; Z i m m e r m a n et a l . , 1961) and s o i l s t rength (Tay lor and Burnet t , 1964; T a y l o r and Rat l i f f , 1969; and S o a n e and P i d g e o n , 1975). In genera l , high s o i l s t rength or dens i t y r e f l e c t s a c o m p a c t e d cond i t i on or a reduced s o i l p o r o s i t y , a l though the re la t i onsh ip of s t rength to dens i t y va r i es w i th d i f f e ren t s o i l t y p e s 44 (Por tas , 1968; S o a n e and P i d g e o n , 1975). C o m p a c t i o n p roduced p r imar i l y by t i l l age equ ipmen t g i ves r i se to the f o r m a t i o n o f t i l l age pans or p lough pans . T i l l age pans are charac te r i zed by high dens i t y and l o w p o r o s i t y . These may resul t in pond ing f r o m dec reased water pe rmeab i l i t y and e thy lene f o r m a t i o n dur ing i nc reased a n a e r o b i o s i s . The t i l l age or p lough pans can be b roken d o w n by s u b - s o i l i n g or deeper p l ough ing . In the recent yea rs the H o w a r d Ro tava to r C o m p a n y L i m i t e d of Grea t Br i ta in has c o m e up w i t h a new type of imp lemen t fo r deep p lough ing ca l l ed the p a r a p l o w . The s lur ry in jec tor used in the present research has s o m e s i m i l a r i t y to the p a r a p l o w . S i n c e no re fe rence on the e f fec t o f the in jec tor on s o i l p roper t i es and c rop y i e l d cou ld be ob ta ined in the l i te ra ture, a d i s c u s s i o n on the e f f e c t o f p a r a p l o w on s o i l p rope r t i es and crop y i e l d w i l l f o l l o w . Deep p lough ing in c lay s o i l s and other s o i l s w i t h p lough pans reduces s o i l dens i t y and s t reng th , i nc reases the v o l u m e and number o f large p o r e s , resu l t i ng in i m p r o v e d root d e v e l o p m e n t , ae ra t i on , wa te r m o v e m e n t and re ten t ion and s o i l tempera tu re . The s i ze of the c rop y i e l d r esponse depends on the degree of c o m p a c t i o n of the s o i l , the t i l l age opera t ion used and subsequent t ra f f i c ( S p o o r , 1982; Karg in and D a n i l o v , 1982; F l o y d , 1984). B ra im et a l . (1984) in a l o n g - t e r m cu l t i va t i on exper iment on a s a n d y c l ay l oam s o i l in w h i c h bar ley w a s g r o w n each y e a r , c o m p a r e d m o u l d b o a r d p lough ing , s h a l l o w t ine cu l t i va t i on and d i rect d r i l l i ng . T o a l l ev ia te c o m p a c t i o n w h i c h b e c a m e ev ident on the d i rec t d r i l l ed t rea tment , the pa rap low w a s used in al l t rea tments to a depth of 35 c m . P a r a p l o w dec reased s o i l s t rength and bulk dens i t y o f the s o i l . Th is e f f ec t w a s e s p e c i a l l y p r o n o u n c e d in the s u b s o i l be tween 2 0 - 3 5 c m . The p a r a p l o w 45 i m p r o v e d su r face dra inage on uncu l t i va ted land p reven t ing sur face pond ing f r o m heavy ra in . P a r a p l o w i n g i nc reased grain y i e l d by 12%. The r e s p o n s e of the crop to cu l t i va t i on by the p a r a p l o w w a s greates t on the mou ldboa rd and l o n g - t e r m d i r e c t - d r i l l e d s y s t e m s . The dec rease in s o i l s t rength caused by the pa rap low resu l ted in more rap id penet ra t ion of r o o t s in each ho r i zon of the p r o f i l e . There w a s no s i gn i f i can t e f f e c t on shoo t dry mat ter up to an thes is but, at harves t , bar ley on land t reated w i t h the p a r a p l o w had more ears w i t h more gra ins per ear. III. S U M M A R Y O F T H E L I T E R A T U R E R E V I E W A b o u t 6 m i l l i o n wet tonnes of an ima l manure is p roduced in Br i t i sh C o l u m b i a , 9% of wh i ch c o m e s f r o m s w i n e p roduc t i on s y s t e m s (Barber, 1978). A n i m a l manures have been r e c o g n i z e d as a nutr ient sou rce for the p roduc t i on of c rops (Mutlak et a l . , 1975; Su t ton et a l . , 1978; R o b i n s o n and B e a u c h a m p , 1982; Beauchamp , 1983; and Wh i te and S a f l e y , 1984). Manure not on l y p r o v i d e s plant nutr ients but a l s o i m p r o v e s p h y s i c a l and c h e m i c a l p roper t i es of the s o i l . Improved p h y s i c a l p roper t ies such as aggregate s tab i l i t y ( E l s o n , 1943), w a t e r - h o l d i n g c a p a c i t y and reduced e v a p o r a t i o n rate (Unger and S t e w a r t , 1974), wa te r i n f i l t ra t ion rate (Mazurak et a l . , 1955; S w a d e r et a l . , 1972; Mathers et a l . , 1977) we re reco rded by these authors f r o m s o i l r e c e i v i n g an imal manure . A d a m o n (1980) and Lund and D o s s (1980) repor ted higher ava i l ab i l i t y o f P, K, Ca and M g w h e n manure w a s used as a s o u r c e of these nutr ients c o m p a r e d to inorgan ic f e r t i l i ze r s . Manure can i m p r o v e organ ic mat ter con ten t o f the s o i l as w e l l (Ke tcheson and Beauchamp,1978) . The po ten t ia l fe r t i l i ze r va lue o f s w i n e s lur ry can vary c o n s i d e r a b l y depend ing on its nutr ient and dry mat ter con ten t . Fac to rs such as c o m p o s i t i o n of the ra t ion f e d , t y p e s o f handl ing and s to rage s y s t e m s , amount of f e e d and wa te r s p i l l a g e , age and type of an ima l and c l i m a t i c c o n d i t i o n s m a y in f luence the nutr ient c o m p o s i t i o n of the s lu r ry . S w i n e s lur ry is c o n s i d e r e d as a sou rce of N fo r plant use . N in the s lu r ry occu rs in t w o f o r m s - o rgan ic and ino rgan ic . Inorganic N (espec ia l l y NH„ + ) represen ts about 1/2 of the t o ta l . A s i gn i f i can t amount o f th is N can be los t depend ing on handl ing and s to rage s y s t e m s . V o l a t i l i z a t i o n of N H 3 is c o n s i d e r e d to be the major m e c h a n i s m o f N l o s s f r o m the s w i n e s lu r ry . S e v e r a l s o i l (pH, texture, C E C , tempera tu re and mo is tu re con ten t , p resence 46 47 o f f ree C a C 0 3 ) , s lur ry ( N H 4 - N con ten t , pH), management (app l i ca t ion me thod and rate) and env i ronmen ta l f a c t o r s (part ial p ressure of N H 3 in the ai r , air tempera tu re ) a f f ec t N H 3 v o l a t i l i z a t i o n l o s s . A v a i l a b i l i t y o f N f r o m the s lurry o rgan ic f r ac t i on is de te rm ined by the amount m i n e r a l i z e d . Fac to rs such as temperature and mo is tu re content o f the s o i l , w e t / d r y and f r e e z e / t h a w c y c l e s and C / N rat io o f the s lu r ry have been s h o w n to a f f ec t the m ine ra l i za t i on p r o c e s s . N conten t of the s lur ry has been used as a b a s i s for de te rm in ing app l i ca t i on ra tes . R e c o m m e n d a t i o n s based on N content o f the s lur ry shou ld take into c o n s i d e r a t i o n the cos t o f a p p l i c a t i o n , N requ i rement of the c rop to p roduce a p ro f i t ab le y i e l d , f r ac t i on of the o rgan ic N that w i l l be m ine ra l i zed and l o s s e s due to N H 3 v o l a t i l i z a t i o n f r o m d i f fe ren t t reatment s y s t e m s . G e n e r a l l y , s lu r ry app l i ca t i on rates that w i l l supp ly nutr ients in amoun ts equal to c rop u t i l i za t ion are r e c o m m e n d e d . H o w e v e r , because o f the uncer ta in ty in de te rm in ing actual nutr ient ava i l ab i l i t y ( resul t ing e s p e c i a l l y f r o m the lack o f a k n o w l e d g e of N m ine ra l i za t i on ) , c rop p roducers w h o are a im ing fo r top y i e l d s have been hes i tant to re ly s o l e l y on an imal manure as a nutr ient sou rce for c rop p r o d u c t i o n . Fa rmers o f t en app ly ei ther c o m m e r c i a l f e r t i l i ze rs in add i t i on to s lur ry or e x c e s s i v e amoun ts of s lu r ry as a s a f e t y f a c t o r , w h i c h resu l ts in nutr ient app l i ca t i on in e x c e s s of c rop u t i l i za t i on . In a d d i t i o n , f o r many in tens i ve l i ves tock o p e r a t i o n s , s lu r ry app l i ca t i on in e x c e s s of c rop u t i l i za t ion is o f ten n e c e s s i t a t e d by land unava i l ab i l i t y . High s lur ry app l i ca t i on rates cou ld po ten t ia l l y reduce the qua l i t y of g round and su r face water (Evans et a l . , 1984; and Wh i te and S a f l e y , 1984) and qua l i ty and y i e l d o f c rop (Tunney, 1975). C o n t a m i n a t i o n o f g round wa te r w i th N G y and N G y is of p r ime conce rn to the f a rm ing c o m m u n i t i e s . The p resence o f high l eve l s o f these inorgan ic c o m p o u n d s in 48 ground wa te r has resu l ted in m e t h e m o g l o b i n e m i a in b o t t l e - f e d in fan ts and p o i s o n i n g o f f a rm a n i m a l s . S i m i l a r c rop y i e l ds cou ld resul t w h e n s lurry of k n o w n c o m p o s i t i o n or c o m m e r c i a l N is used as a s o u r c e of N (Tunney, 1975). The s a m e author a l so ind ica ted that at an equal rate of N , s w i n e s lu r ry gave bet ter dry mat ter y i e l d s than the cat t le s lu r r y . Higher ava i l ab i l i t y of N f r o m s w i n e s lur ry and adverse p h y s i c a l and chem ica l e f f e c t s of ca t t le s lu r ry we re thought to be r e s p o n s i b l e . The amount of N l o s s e s f r o m the s lur ry can be g rea t l y i n f l uenced by the m e t h o d of s lur ry a p p l i c a t i o n . Inject ing s lur ry can s i g n i f i c a n t l y dec rease N l o s s e s c o m p a r e d to the b roadcas t m e t h o d . The in jec t ion p r o c e s s cou ld a l so i m p r o v e s o i l p h y s i c a l c o n d i t i o n s for bet ter c rop g r o w t h . F rom a su rvey of the l i terature it b e c o m e s ev iden t that the i n f o rma t i on on the a v a i l a b i l i t y , t r a n s f o r m a t i o n and d is t r i bu t ion of N in the s o i l f o l l o w i n g in jec t ion and b roadcas t p lus i nco rpo ra t i on me thods o f manure app l i ca t i on is ve r y l im i t ed . Higher gra in p roduc t i on f r o m the in jec t ion as o p p o s e d to the b roadcas t p lus i nco rpo ra t i on m e t h o d o f s lu r ry app l i ca t i on has been a t t r ibuted to the c o n s e r v a t i o n of s lu r ry N fo r the in jec t ion t rea tment . N o men t i on has been made as to h o w the in jec t ion app l i ca t i on me thod c o n s e r v e s N. V o l a t i l i z a t i o n of N H 3 is o b v i o u s l y neg l i g i b l e fo r the in jec t ion t rea tment but is there anyth ing e l se? Ano the r conce rn c o u l d be the c o m p a c t i o n of the f ine tex tured s o i l w h e n s lur ry is b roadcas t e s p e c i a l l y on a m o i s t s o i l (Beauchamp, 1983). In the a b s e n c e of a w e a l t h o f i n f o r m a t i o n , seve ra l h y p o t h e s e s w i l l be made as to h o w the m e t h o d o f app l i ca t i on c o u l d a f f e c t ava i l ab i l i t y , c o n s e r v a t i o n and d i s t r i bu t i on o f s o i l and s lurry N ; 1. The in jec t ion app l i ca t i on me thod w i l l resu l t in higher concen t ra t i on of N w i th in the zone o f app l i ca t i on 49 c o m p a r e d to the b roadcas t p lus i nco rpo ra t i on method 2. The in jec t ion app l i ca t i on me thod w i l l resul t in greater m o v e m e n t of N into the l ower depths of the s o i l as c o m p a r e d to the b roadcas t p lus i nco rpo ra t i on me thod o f app l i ca t i on 3. The in jec t ion app l i ca t i on me thod w i l l imp rove s o i l phys i ca l c o n d i t i o n and a l so w i l l resul t in more N ava i lab le fo r c rop uptake IV. M A T E R I A L S A N D M E T H O D S A . T h e s o i l The expe r imen ts we re conduc ted in 1981, 1982 and 1983 on the Barry Baehr Farm l oca ted on 232nd S t ree t , L a n g l e y , 60 km east o f V a n c o u v e r , B.C. The s i te is o w n e d by the c r o w n and managed by Br i t i sh C o l u m b i a M i n i s t r y of Ag r i cu l t u re and F o o d ( B C M A F ) . The s o i l o f the exper imen ta l s i te w a s Ber ry s i l t l o a m , c l a s s i f i e d as G l e y e d P o d z o l i c G ray Luv i so l (Aqua l f i c Hap lo r t hod , U S D A ) . It d e v e l o p e d f r o m m o d e r a t e l y to f ine tex tu red , s tone f r ee , mar ine s e d i m e n t s and is i m p e r f e c t l y d ra ined ( < 0.02 cm Iv 1 , W a l m s l e y et. a l , 1980). It is m o d e r a t e l y pe rv i ous (0.3-1.0 c m Iv 1 ) in the upper 75 c m but b e c o m e s s l o w l y pe rv i ous (0.02-0.1 c m f r 1 ) at depths b e l o w about 75 c m . The s l o w pe rmeab i l i t y is re la ted to greater c lay con ten ts in the subsu r face h o r i z o n s . D e s c r i p t i o n s of the s o i l p ro f i l e and s o m e of the p h y s i c a l and c h e m i c a l p roper t i es are g i ven in append i ces 1 and 2 r e s p e c t i v e l y . A k n o w n h i s to ry o f past management p rac t i ces is unava i l ab le , h o w e v e r , i n f o r m a t i o n gathered ve rba l l y f r o m the ne ighbour ing f a rmers s u g g e s t s that the s tudy area w a s under rough pasture fo r the last s e v e n yea rs and has been g razed regu la r l y . The p resence of a dere l ic t da i ry barn a l s o s u g g e s t s that the exper imen ta l s i te m a y have r e c e i v e d heavy manure app l i ca t i ons in the pas t . A p ic ture taken pr ior to cu l t i va t i on in 1981 (Figure 5) i l l us t ra tes the la test c rop be ing g r o w n . B. T h e s l u r r y The s lu r ry fo r the exper iment c a m e f r o m the Caro l i ne F a r m s . The f a rm is s i tua ted at 224th S t ree t , Lang ley and opera ted by Mr . Ralph J e s i a k . Ca ro l i ne Fa rms has a s w i n e popu la t i on of 1200 g r o w e r s , 340 weane rs and 50 51 52 300 s o w s and s lur ry s to rage capac i t y fo r three mon ths . On the f a r m , s lur ry is f i rs t c o l l e c t e d fo r one month in f i ve ind iv idua l ba rns , al l of wh i ch have b e l o w s l o t t ed f l o o r s to rage p i t s . Four of these s to rage p i ts 1.2 m x 2.4 m x 15 m, the f i f t h one be ing 2.4 m x 2.4 m x 24m. A f t e r one m o n t h , s lu r ry f r o m each barn is pumped (using a 10 HP pump w i th a 10 c m d iameter out let p ipe) to a 18 m x 9 m x 3.6 m c o v e r e d , conc re te l ined anaerob ic main s to rage pit w h i c h can a c c o m o d a t e three months c o l l e c t i o n . The dry mat ter and N conten t o f the s lur ry are p resen ted in Tab le 6. A n i m a l s w e r e f e d the s a m e rat ion each year . The t y p e o f the rat ion supp l i ed is g i ven in A p p e n d i x 3. Each year app rox ima te l y one w e e k pr ior to s lur ry app l i ca t i on the pit w a s ag i ta ted us ing a hydrau l ic p o w e r e d ag i ta tor (shown in F igure 6) fo r at least an hour fo r thorough m ix i ng . S lu r r y s a m p l e s were then c o l l e c t e d f r o m the four co rne rs and cent re o f the pit us ing an emp ty paint can a t tached to a s t r i ng . In each l oca t i on a set o f three 1 L s a m p l e s o f w e l l m i x e d s lur ry w a s c o l l e c t e d . T o reduce the p o s s i b i l i t y of c h e m i c a l change , the s a m p l e s we re s t o red in t igh t ly capped po l y thene bo t t l es to w h i c h 2 ml_ o f concen t ra ted H 2 S 0 4 (per l i t re of s lur ry ) had been added . They we re then put in a coo le r fo r t ranspor t into the labora to ry and s to red at 2 ° C . The s a m p l e s we re a n a l y s e d fo r to ta l Kje ldahl and N H / - N and the resu l ts used in ca l cu la t i ng s lur ry requ i red per p lot f o r the severa l rates used in the s tudy . On the day of f i e l d a p p l i c a t i o n , the s lurry w a s tho rough ly m i x e d f o l l o w i n g the m e t h o d d e s c r i b e d ear l ie r . The w e l l m i x e d s lu r ry w a s then pumped into the tank o f the app l i ca to r us ing a vacuum pressure pump (1.4 kg c r r r 2 ) . A 1 L s a m p l e w a s c o l l e c t e d f r o m each load (using an e m p t y paint can) o f the app l i ca to r tank and w a s hand led and a n a l y s e d in a manner s i m i l a r to that s ta ted ear l ie r . The resu l ts were used to ca l cu la te the Table 6. Composition of Liquid Swine Slurry Used in the Experiment Analyses 1981 1982 1983 pH 6.5 6.5 6.5 Dry matter 3.30 (7.42)* 4.98 (10.42) 3.61 (5.90) Kjeldahl-N 0.41 (2.17) 0.42 (19.64) 0.36 (2.86) NH^ -N 0.26 (0) 0.27 (25.88) 0.25 (12.33) * Figure within the parentheses indicates coefficient of variation. 54 AGITATOR USED IN MIXING THE SLURRY (Figure 6) 55 actual amount of N app l i ed . Dry mat ter content of the s lurry w a s de te rm ined by d ry ing a 100 mL s u b s a m p l e in an o v e n at 65 ± 2 ° C fo r 72 h. C . Inorganic fer t i l izers Each year pr ior to p lan t ing , s o i l s a m p l e s we re taken f r o m the exper imen ta l s i t e by the fa rmer and sent to the s o i l t es t i ng labora to ry to measure P and K content fo r de te rm in ing fe r t i l i ze r requ i remen ts . P and K fe r t i l i ze rs w e r e b roadcas t and ha r rowed in be fo re s e e d i n g . In a d d i t i o n , s tar ter N w a s banded 5 c m b e l o w and to the s ide of the s e e d each year dur ing p lan t i ng . Rates of inorgan ic f e r t i l i ze r app l i ca t i on used in d i f f e ren t yea rs are g i ven in Tab le 7. D. Herbic ides In order to insure adequate c rop g rowth every e f fo r t w a s made to con t ro l w e e d s . The w e e d p r o b l e m -was more p ronounced in 1981 and 1983 than in 1982. The p lo t s we re ro to t i l l ed and s p r a y e d w i th at raz ine (9 kg ha- 1 ) in 1981 and on ly s p r a y e d in 1982 and 1983 (4.5 kg h a - 1 y r - 1 ) . E. Field methods Bu l l ey and Cappe lae re (1978) r e c o m m e n d e d that a s o i l in the L o w e r Fraser V a l l e y w i t h l i t t le or no g rowth l im i ta t i on requ i res about 300 kg h a - 1 of s w i n e s lu r ry N in the s o i l fo r a y i e l d of 20 t h a - 1 o f s i l age c o r n . Each year three s w i n e s lur ry ra tes , inc lud ing the r e c o m m e n d e d and a con t ro l w e r e used in this s tudy . In 1981 the s lu r ry app l i ca t i on inc luded the r e c o m m e n d e d rate and half and t w i c e the r e c o m m e n d e d rate. In 1982 and 1983 the m a x i m u m rate o f s lur ry app l i ca t i on w a s reduced to a p p r o x i m a t e l y Table 7. Rates of Inorganic F e r t i l i z e r Applied-Year N P 20 5 K 20 ! kg ha" 1  1981 18 182 80 1982 25 112 145 1983 40 179 202 57 1.5 x r e c o m m e n d e d rate, as the corn y i e l d w a s reduced at that rate. The s w i n e s lur ry w a s either b roadcas t or in jec ted to a depth of 0.3 m us ing a B ig A W a s t e A p p l i c a t o r (manufac tured by R icke l Manu fac tu r i ng Co rp . , S a l i n a , U S A and s h o w n in F ig . 7) w i th four in jec t ion shanks s p a c e d at 0.6 m in te rva ls . The eight t rea tments we re app l i ed to 48.7 m x 4.8 m p lo t s ar ranged in a randomized c o m p l e t e b lock des ign w i th three r ep l i ca tes . To a s s e s s the p h y s i c a l e f fec t o f the in jec t ion p r o c e s s , in jec t ion shanks were drawn through a set o f con t ro l in jec ted p l o t s w i thou t a p p l y i n g s lu r ry or wa te r . F . Cal ibrat ion o f the equipment and slurry appl icat ion The amount of s lur ry to be app l i ed per p lo t fo r three d i f fe ren t s lur ry app l i ca t i on rates w a s ca l cu la ted b a s e d on the s lur ry to ta l N , the c rop requ i rement , the so i l res idua l N conten t and the s ize of the p lo t . On the day of a p p l i c a t i o n , the B ig A W a s t e A p p l i c a t o r w i th a k n o w n v o l u m e of s lu r ry (8,000 L) in i ts tank w a s run on an area ou ts ide the exper imen ta l p l o t s . The ent i re v o l u m e of s lur ry w a s e m p t i e d running at a k n o w n speed w i th k n o w n out let open ings . The area w a s then measu red and the s lur ry app l i ed (L ha- 1 ) ca l cu la ted . Th is p rocedure w a s repeated seve ra l t i m e s unti l a su i tab le s p e e d and out let open ings w e r e es tab l i shed to supp l y the p rede te rm ined quant i ty of w a s t e . Each y e a r , the equ ipment ca l i b ra t i on w a s done fo r the r e c o m m e n d e d rate f i r s t . S i n c e the l ower rate w a s 1/2 the r e c o m m e n d e d rate, the app l i ca to r w a s run t w i c e as fas t to d i s p e n s e 1/2 the r e c o m m e n d e d ra te . In 1981, the m a x i m u m s lur ry app l i ca t i on rate w a s t w i c e the r e c o m m e n d e d rate. T o d i s p e n s e the requi red amoun t , the s p e e d o f the app l i ca to r w a s cut d o w n to hal f . In 1982 and 1983 the equ ipment w a s sepa ra te l y ca l i b ra ted (in a 58 (Figure 7) 59 w a y d e s c r i b e d ear l ie r ) fo r the 1.5 x the r e c o m m e n d e d rate. In the three years of the s tudy , s lur ry w a s app l ied in the s e c o n d half o f M a y . In 1981 the s lu r ry w a s d i s k e d in a day later whereas in 1982 and 1983 it w a s d i s k e d in three days later. G . W e a t h e r c o n d i t i o n b e t w e e n s l u r r y a p p l i c a t i o n , i n c o r p o r a t i o n a n d s e e d i n g o f c o r n Dates of s lu r ry a p p l i c a t i o n , i nco rpo ra t i on and s o m e s o i l and c l i m a t i c pa ramete rs measu red on the day of app l i ca t i on are p resen ted in Tab le 8. There w a s no rain on the day of s lu r ry app l i ca t i on in 1981, w h e r e a s , 2.8 and 2.0 m m rain fe l l on that day in 1982 and 1983 r e s p e c t i v e l y . Wea the r w a s r e l a t i ve l y dry be tween s lur ry app l i ca t i on and i nco rpo ra t i on in 1981 and 1983 c o m p a r e d to 1982. Th is resu l ted f r o m higher average da i l y tempera tu res (Table 8) and no ra in fa l l dur ing that p e r i o d . Wea the r c o n d i t i o n in 1982 w a s c o m p a r a t i v e l y m i l d fo r the same pe r i od as 1 m m rain f e l l the day af ter s lu r ry app l i ca t i on and a l so the average da i l y tempera tu res w e r e l o w as w e l l (Table 8). S lu r ry app l i ca t i on rates and the amount of N H 4 + and to ta l N app l i ed are g i ven in Tab le 9. S i l age corn fZea<*mays L.) c v . "Dekalb 24 ' w a s s e e d e d perpend icu la r to the long ax is o f the p l o t s in 0.8 m r o w s p a c i n g w i th an average popu la t i on o f 100,000 p lan ts h a - 1 . In 1981, p lan t ing w a s done t w o days af ter s lu r ry app l i ca t i on whe reas in 1982 and 1983 it w a s done s e v e n and eight days later r e s p e c t i v e l y . Table 8. Spring Weather Condition During 1981, 1982 and 1983 at the Experimental S i t e . A i r Percent Temperature A i r A i r S o i l moisture Date of Date of Weather on °C Temperature Temperature (0 - 15 cm) Slurry Slurry the day of (Max., Min. °C °C on the day of Date of Year A p p l i c a t i o n Incorporation A p p l i c a t i o n and Average one day l a t e r two days l a t e r A p p l i c a t i o n Planting Sunny Max. 18.0 Max. 19.5 1981 May 26 May 27 and Aver. 13.5 Aver. 13.0 43 May 28 dry. Min. 8.5 Min. 6.5 (No rain) Occasional Max. 21.5 Max. 14.5 Max. 16.0 1982 May 21 May 24 showers. Aver. 14.8 Aver. 11.0 Aver. 9.8 26 May 28 (2.8 mm rain) Min. 8.0 Min. 7.5 Min. 3.5 Cloudy with Max. 12.0 Max. 17.5 Max. 18.5 1983 May 17 May 20 sunny Aver. 10.0 Aver. 13.5 Aver. 13.0 44 May 25 breaks Min. 8.5 Min. 9.5 Min. 7.5 (2.0 mm rain) Table 9. Rate of Application SWINE SLURRY NH4-N TOTAL N 1981 1982 1983 1981 1982 1983 1981 1982 1983 t ha - 1_ -1 0 0 0 0 0 0 0 0 0 42 37 45 110 99 113 173 157 163 78 80 86 206 212 215 321 336 309 - 127 120 - 340 299 - 538 430 158 - - 418 - - 653 - -62 H. Soi l sampling Each year , af ter a l l o w i n g an 8.2 m buf fer at bo th e n d s , the p lo t s w e r e further s u b d i v i d e d into four 7.6 m x 4.8 m s u b p l o t s , each con ta in ing ten corn r o w s and . separa ted by a 0.6 m bu f fe r . On each s a m p l i n g o c c a s i o n a subp lo t w a s r a n d o m l y s e l e c t e d w i thou t rep lacemen t and used fo r both s o i l and plant s a m p l i n g . In 1982 and 1983, dur ing the g r o w i n g s e a s o n , at a p p r o x i m a t e l y one month i n te rva l s , s o i l s a m p l e s we re taken f r o m th is p lo t f o l l o w i n g a s y s t e m a t i c pat tern at depths of 0 - 1 5 , 1 5 - 3 0 , 3 0 - 6 0 and 6 0 - 9 0 c m w i th a 2.5 c m d iameter O a k f i e l d p robe . The 6 0 - 9 0 c m s a m p l e s c o n s i s t e d of a c o m p o s i t e of four c o r e s per p lot wh i l e c o m p o s i t e s a m p l e s fo r the other depths had t w e l v e c o r e s each . S a m p l e s w e r e ob ta ined by s y s t e m a t i c a l l y p roceed ing a long the long axis (7.6 m) of each subp lo t , 1.5 m f r o m each corner (Figure 8). A t t hose four po in t s three co res we re c o l l e c t e d (the f i rs t one at 75 c m and the s e c o n d and the third each at 45 c m in terva ls f r o m one another) on a l ine perpend icu la r to the d i rec t i on o f s lu r ry t rea tment . The center co re o f each set o f three w a s s a m p l e d to 90 c m . Dur ing s lur ry a p p l i c a t i o n , the B ig A w a s t e app l i ca to r p robab ly d id not run on a st ra ight l ine a long the long axis of the p lo t and may have m o v e d by ± 1 5 c m on the short ax i s . The above s a m p l i n g in terva ls w e r e des igna ted s o that no more than one co re w o u l d be taken f r o m the center of an in jec t ion z o n e . A t the t ime of s a m p l i n g it w a s in tended to p r o c e e d I. 5 m a long the long ax is in order to loca te the f i rs t s a m p l i n g spo t . But if the des i red length of 1.5 m w o u l d hit a corn r o w a 30 c m sh i f t a long the long ax is w a s made to a v o i d it. C o l l e c t e d s o i l s a m p l e s w e r e p laced in a por tab le c o o l e r fo r t ranspor t to the l abo ra to ry , where they we re s t o red at 2 ° C . The s a m p l e s we re w e l l m i xed w i t h i n the p l as t i c bags by gen t l y p r e s s i n g the c o r e s be tween the f i nge rs and w e r e ex t rac ted w i th in a day or S O I L S A M P L I N G P L A N D i r e c t i o n s o f S e e d i n g a n d S l u r r y T r e a t m e n t 4.8 m C O R N R O W S 75 ,45 45 cm t 80 cm 45 45 75cm 7.6 m X H H 1.5 m I I 2 3 4 5 6 7 8 8 I N J E C T I O N Z O N E S (Figure 8) 64 t w o af ter c o l l e c t i o n . Bulk dens i t i e s of the s o i l fo r four d i f fe ren t s a m p l i n g depths w e r e de te rm ined us ing the core me thod of B lake (1965). I. Locat ing in ject ion zones In 1982, in an area o f a p lot that w a s not used in s o i l and plant s a m p l i n g , four in jec t ion z o n e s each 3.04 m long we re marked w i th bur ied me ta l l i c rods each a t tached to co l ou red s t r ing i m m e d i a t e l y f o l l o w i n g the app l i ca t i on of 120 t h a - 1 s lu r ry . A f t e r the f i e l d had been h a r r o w e d , each in jec t ion zone w a s l oca ted w i th the help of the c o l o u r e d s t r i ngs . S o i l s a m p l e s w e r e taken o n e , t w o , three, four and eight w e e k s f o l l o w i n g s lur ry app l i ca t i on f r o m the 0 - 2 0 , 2 0 - 4 0 , and 4 0 - 6 0 c m dep ths . A t each date one s a m p l i n g l o c a t i o n a long the long axis of each in jec t ion zone w a s random ly s e l e c t e d w i thou t rep lacemen t and at each po in t four se ts of s a m p l e s w e r e c o l l e c t e d us ing a 2.5 c m O a k f i e l d probe f r o m 0, 10, 20 and 30 c m apart on a l ine perpend icu la r to the d i rec t i on of s lu r ry a p p l i c a t i o n . J . Plant sampling On each plant s a m p l i n g date (a day f o l l o w i n g each s o i l s a m p l i n g date) two c rop s a m p l e s each c o n s i s t i n g o f one 1 m length o f r o w (conta in ing 10 p lan ts ) we re c o l l e c t e d f r o m each p lo t . R o w s f i v e and s e v e n of the s a m e subp lo t w e r e genera l l y used fo r the pu rpose of s a m p l i n g . To ta l above ground plant f r esh we igh t s w e r e de te rm ined in the f i e l d us ing a f i e l d s c a l e and three p lan ts r a n d o m l y s e l e c t e d fo r m o i s t u r e , dry matter and to ta l N d e t e r m i n a t i o n s . P lant and s o i l s a m p l e s w e r e c o l l e c t e d acco rd i ng to p lan fo r the yea rs 1982 and 1983 but not fo r 1981 because o f the poor c l i m a t i c c o n d i t i o n s w h i c h res t r i c ted plant g row th dur ing the ear ly part o f the g r o w i n g s e a s o n . 65 In order to i nves t iga te c rop root r e s p o n s e to the app l i ed s lurry N, t renches in a con t ro l and a t reated (160 or 120 t h a - 1 i n jec ted) p lot we re opened in 1981 and 1982 af ter the p lants es tab l i shed brace roo ts and v isua l o b s e r v a t i o n s w e r e m a d e . K. Laboratory methods Fresh s o i l ( I0g) w a s s u b s a m p l e d and ex t rac ted w i th 2N KCI (100 mL) and the f i l t ra te w a s c o l l e c t e d fo r N H 4 + and N G y - N a n a l y s e s . Separa te 10g s u b s a m p l e s were o v e n dr ied ( 1 0 5 ° C , 24 h) fo r g rav ime t r i c mo is tu re de te rm ina t i ons to conver t the N data to a dry we igh t b a s i s . The N H 4 + - N of the s lur ry s a m p l e s w a s ex t rac ted w i t h 0.1N HCI, us ing a 1:10 s lur ry to extractant rat io f o l l o w i n g Byrne and P o w e r (1974). Chopped plant s a m p l e s were dr ied at 6 5 ° C for 120 h and ground in a s ta i n l ess s tee l W i l e y m i l l . S lu r r y , s o i l and ground plant s a m p l e s w e r e d iges ted for to ta l Kje ldahl N (TKN) inc lud ing N G y and N G y f o l l o w i n g the me thod of B remner (1965). C o n c e n t r a t i o n s of N H 4 + and N 0 3 - N in the s a m p l e s were de te rm ined us ing the A u t o a n a l y z e r II (Techn icon A u t o a n a l y z e r II M e t h o d o l o g y 1972). To ta l C of the s lur ry s a m p l e s w a s de te rm ined us ing a L e c o induc t ion fu rnace , o rgan ic mat ter o f the so i l by the W a l k l e y - B lack we t ox i da t i on m e t h o d ^ ( A l l i s o n , 1965) and so i l pH in 0.01 M C a C I 2 ( s o i h s o l u t i o n rat io 1:2). L. Stat is t ical analyses A n a l y s i s of va r iance w a s used in tes t i ng the e f f e c t s of s lu r ry rates and a p p l i c a t i o n me thods on y i e l d of co rn dry mat ter and N uptake. Trend c o m p a r i s o n s o f rate and rate x m e t h o d in te rac t ions w e r e p e r f o r m e d us ing s ing le degree o f f r e e d o m tes ts fo r l inear and curv i l inear e f f e c t s . 66 In 1981 plant a n a l y s i s , rates and me thods we re ar ranged f a c t o r i a l l y in a r a n d o m i z e d c o m p l e t e b lock d e s i g n w i t h three b l o c k s and t w o s u b s a m p l e s (Table 10). In the 1982 and 1983 plant a n a l y s i s da ta , s u c c e s s i v e samp l i ng dates we re c o n s i d e r e d as a subp lo t e f f e c t in a sp l i t p lo t des ign w i t h rates and me thods as w h o l e p lo t s in a r a n d o m i z e d b lock des ign w i th t w o s u b s a m p l e s (Table 10). A n a l y s i s of var iance w a s a l s o p e r f o r m e d to test the e f f e c t s of s lu r ry app l i ca t i on ra tes , m e t h o d s and date and depth o f s o i l s a m p l i n g on the d i s t r i bu t i on o f N H y and N O y - N in the s o i l . In teract ions s tud ied are ind ica ted in Tab le 10. The f i rs t s o i l s a m p l e in 1981 w a s c o l l e c t e d f r o m a s ing le dep th , t he re fo re , f o r that date on l y rates and me thods we re ar ranged as a fac to r i a l exper iment in three r a n d o m i z e d c o m p l e t e b l o c k s . In the s e c o n d and the third s o i l s a m p l i n g da tes in 1981 and al l data in the 1982 and 1983 e x p e r i m e n t s , the s o i l s a m p l i n g depths w e r e c o n s i d e r e d as a subp lo t e f f e c t , and dates as subsubp lo t s in a s p l i t - s p l i t p lo t d e s i g n . Rate and m e t h o d c o m b i n a t i o n s were a n a l y z e d as w h o l e p l o t s in a r andom ized c o m p l e t e b lock des ign w i th three b l o c k s (Table 10). A least square r e g r e s s i o n and a co r re l a t i on a n a l y s e s f o l l o w i n g L i t t le and H i l l s (1978) w e r e p e r f o r m e d to s tudy the re la t i onsh ip be tween N uptake and N app l i ed and N uptake and dry mat te r y i e l d . Table 10. Partitioning of BUB of squares and degrees of freedom for plant and soil for 1981, 1982 and 1983. Plant Plant Soil Soil Soli 81 82/83 81 81 82/83 dl d2/3 Block - b - 3 3 3 3 3 Rate - r - 4 4 4 4 4 Method - • 2 2 2 2 2 Depth - c - 1 1 1 4 4 Date - d - 1 3 1 2 3 Samples - a - 2 2 1 1 1 Anova df Block n-1 2 2 2 2 2 Rate r-1 3 3 3 3 3 Method n-1 1 1 1 1 1 Rate x Method (r-l)(«-l) 3 3 3 3 3 Error (1) (n-D(rm-l) 14 14 14 14 14 Depth c-1 0 0 0 3 3 Depth x Rate ( c - D ( r - l ) 0 0 0 9 9 Depth x Method ( c - D ( m - l ) 0 0 0 3 3 Depth x Rate x Method ( c - l ) ( r - l ) ( m - l ) 0 0 0 9 9 Error (2) rm(n-l)(c-l) 0 0 0 48 48 Date d-1 0 2 0 1 4 Date x Rate (d - D(r-i) 0 6 0 3 12 Date x Method ( d - l ) ( m - l ) 0 2 0 1 4 Date x Rate x Method ( d - l ) ( r - l ) ( m - l ) 0 6 0 3 12 Date x Depth (d-l)(c-l) 0 0 0 3 12 Date x Depth x Rate (d-l)(c-l)(r-i) 0 0 0 36 Date x Depth x Method (d-l)(c-l)(m-l) 0 0 0 3 12 Date x Depth x Rate x Method ( d - l ) ( c - l ) ( r - l ) ( m - l ) 0 0 0 9 36 Error (3) rmc(n-l)(d-l) 0 32 0 64 256 Sub-samples nrmd(s-l) 24 72 0 0 0 Total nrmds-1 47 143 23 47 119 V . R E S U L T S AND DISCUSSION A . Co rn yield S i x ind iv idua l measu remen ts we re made to de te rm ine the va r iab i l i t y in co rn dry matter y i e l d s at any par t icu lar date and fo r any par t icu lar rate and me thod of s lu r ry a p p l i c a t i o n . In gene ra l , fo r both the m e t h o d s of s lur ry a p p l i c a t i o n , va r iab i l i t y in y i e l d m e a s u r e m e n t s were higher f o r the con t ro l and for the 40 t h a - 1 ra tes , as c o m p a r e d to the 80 and the 160 or 120 t h a - 1 rates (Table 11). I r respect ive of the method o f a p p l i c a t i o n , higher va r iab i l i t y in y i e l d s were reco rded for ear l ier plant ha rves t i ng pe r i ods c o m p a r e d to the later date (maturat ion) . But in a l m o s t a l l c a s e s , y i e l d s we re more var iab le when s lur ry w a s b roadcas t c o m p a r e d to the in jec t ion app l i ca t i on (Table 11). Y i e l d va r iab i l i t y fo r the ear ly plant harves t ing da tes and lower s lur ry app l i ca t i on rates cou ld resul t f r o m t w o d i f fe ren t f a c t o r s . F i r s t , when very l i t t le s lur ry is app l i ed to the s o i l ( espec ia l l y in jec ted) , perhaps it c o m e s in con tac t w i t h a re la t i ve l y s m a l l v o l u m e o f the s o i l as c o m p a r e d to the m o d e r a t e l y higher app l i ca t i on ra tes . Th i s c o u l d resul t in greater va r iab i l i t y in the d i s t r i bu t ion of plant nutr ients (eg. n i t rogen) . Th is may be true fo r the b roadcas t t reatment as w e l l , because s lu r ry c o m e s in con tac t on l y w i th the su r face f e w c m of the s o i l . S e c o n d , because of the re l a t i ve l y s m a l l roo t ing s y s t e m at an ear ly s tage of g r o w t h , p lan ts exp lore a c o m p a r a t i v e l y s m a l l v o l u m e of the s o i l fo r nut r ients . Greater va r iab i l i t y in nutr ient uptake cou ld resul t e s p e c i a l l y if there is an uneven d i s t r i bu t i on of the s a m e in the so i l and s o m e plant g rowth o c c u r s in the p r o x i m i t y of the concen t ra ted area. Th is may resul t in var iab le plant g r o w t h . No exp lana t ion can be g i ven for the ove ra l l t rend in higher va r i ab i l i t y in dry mat ter p roduc t i on wh i ch is 68 Table 11. Coefficient of variation in corn dry matter yield and N uptake at different sampling dates for the slurry application rates used in 1981, 1982 and 1983. Slurry applied (t ha - 1) 0 40 80 160 or 120 Dry Dry Dry Dry Method of Time after matter N matter N matter N matter N Year Application Planting (mo) yield uptake yield uptake C.V. yield V uptake ' yield uptake 1981 Broadcast Injection 4 23.0 22.8 30.8 22.8 21.7 21.4 13.5 24.5 , to 15.1 7.4 15.8 12.2 9.4 6.2 11.8 14.1 Broadcast o 10.5 11.3 13.2 13.6 7.6 9.9 8.2 11.9 Injection Z 11.7 10.7 9.0 9.2 10.4 9.9 10.9 10.6 1982 Broadcast Injection 3 9.4 9.6 16.2 24.0 9.8 5.6 24.6 20.7 8.9 4.0 16.0 8.5 7.3 6.4 19.6 13.0 Broadcast / . 1.9 10.3 2.4 12.9 4.4 10.0 5.7 12.2 Injection 4.9 14.1 9.6 19.6 3.3 5.6 4.5 7.1 Broadcast o 13.8 17.5 • 18.4 8.4 14.7 13.0 16.7 17.7 Injection / 7.7 15.6 16.5 20.4 13.5 22.0 16.3 11.5 1983 Broadcast Injection 3 19.7 16.2 19.3 22.7 20.6 6.1 44.0 15.8 8.7 6.6 8.8 13.2 13.7 9.6 13.7 6.8 Broadcast A 7.4 9.1 7.0 14.6 9.2 10.9 3.8 7.8 Injection 4 7.0 5.7 5.7 7.1 11.3 13.7 2.5 5.7 70 a s s o c i a t e d w i t h the b roadcas t as o p p o s e d to the in jec t ion me thod of s lurry a p p l i c a t i o n . The lower y i e l d va r i ab i l i t y a s s o c i a t e d w i t h the in jec t ion app l i ca t i on cou ld resul t in a re la t i ve l y higher dry matter p roduc t i on fo r this me thod as c o m p a r e d to the b roadcas t a p p l i c a t i o n . Y i e l d va r iab i l i t y at matura t ion ranged f r o m 6 - 2 3 % (1981, Tab le 11) as c o m p a r e d to 2 - 1 0 % (1982) and 3 - 1 1 % (1983). Greater va r i ab i l i t y in y i e l d s in 1981 cou ld result f r o m the fact that the exper imen ta l s i te w a s f i rs t p loughed out of s o d in that year resu l t i ng in a ve ry rough s e e d b e d . Because of the rough seed b e d , s lur ry app l i ca t i on (espec ia l l y fo r the b roadcas t t rea tmen t ) cou ld be more uneven resu l t i ng in var iab le d i s t r i bu t i on o f nut r ients such as n i t rogen . Uneven d i s t r i bu t i on of nut r ients cou ld have resu l ted in d i f fe ren t ia l ava i l ab i l i t y thereby resu l t ing in more var iab le plant g row th . A d d i t i o n of sw ine s lur ry us ing t w o d i f fe ren t m e t h o d s o f app l i ca t i on resu l ted in higher corn y i e l d s when c o m p a r e d w i th the c o n t r o l (Table 12). The in jec t ion app l i ca t i on me thod inc reased co rn y i e l d s w h e n c o m p a r e d to the b roadcas t m e t h o d . For all y e a r s , co rn y i e l d s i nc reased w i th the app l i ca t i on rates o f up to 80 t h a - 1 . Curv i l i nea r a n a l y s i s p e r f o r m e d on the data s h o w e d s ign i f i can t l inear and quadrat ic e f f e c t s of rates on y i e l d s in al l the years (Tables 13 and 14). In 1981 a s t rong quadrat ic y i e l d t rend resu l ted f r o m a dec rease in y i e l d f r o m the 160 t h a - 1 rate app l i ed in that year (Figure 9 , Tab le 12). The quadrat ic e f fec t w a s subs tan t i a l l y weake r in 1982 and 1983 w h e n the m a x i m u m app l i ca t i on w a s reduced to 120 t h a - 1 (Figure 9). K lausner and Gues t (1981); Beauchamp (1983) repo r ted higher corn y i e l d w h e n the s a m e rate of manure w a s in jec ted as c o m p a r e d to b roadcas t . Su t t on et a l . (1978) repor ted a l m o s t s im i l a r co rn y i e l d s f r o m s w i n e s lur ry app l i ca t i on rates of 90 and 134 t h a - 1 . The i r N app l i ca t i ons f r o m the t w o rates w e r e s l i gh t l y l owe r than the N supp l i ed by the Table 12. Silage Corn Dry Matter Yield 1981 1982 1983 1981 - 1982 1983 Swine Slurry Rate Broadcast Injected Broadcast Injected Broadcast Injected ^ 0 0 0 6.3 7.1 17.7 18.4 13.2 14.5 42 37 45 8.4 9.8 19.0 19.6 15.7 17.1 78 80 86 10.6 12.9 22.4 24.8 19.8 21.0 - 127 120 - - 22.4 23.3 18.0 20.4 158 - - 7.9 9.2 - - - -AVERAGE 8.3 9.8 20.4 21.5 16.7 18.3 Table 13. Calculated F-values for Measured Crop Responses and Mean Square Error Terms (1981). F-Ratio Calculated F--Values Source DF Denominator Dry Matter Yields N-Uptake N-Concentration Block (B) 2 Experr 16.67** 21.84** 0.55 Rate (R) 3 Experr 30.54** 48.87** 16.92** Method (M) 1 Experr 15.25** 38.93** 9.58** R X M 3 Experr 0.72 3.96 3.90* Experr 14 Error 35.19** 1.93 0.72 Curvilinear Analysis (Trend Analysis) R-Linear 10.90** 53.32** 50.68** R-Quadratic 75.17** 84.44** 4.06E-3 . R-Deviation8 5.56* 8.85* 8.49E-2 R*M Linear 0.15 6.03* 9.83** R*M Quadratic 1.72 3.93 0.15 R*M Deviations 0.29 1.94 1.69 Mean Square Values Calculated Mean Square Terms Experimental Error 1.74 223 8.80E-3 Error 4.93E-2 115 1.22E-2 *, ** Significant at 5% and 1% level respectively. Table 14. Calculated F-values for Measured Crop Responses and Mean Square Error Terms (1982, 1983). Calculated F-Values Source DF F-Ratio Dry Matter Yields N Uptake N Concentration Denominator 1982 1983 1982 1983 1982 1983 Block (B) 2 B X RM 4.48* 1.53 18.34** 5.48* 17.98** 5.16* Rate (R) 3 B X RM 199.94** 152.35** 234.25** 285.32** 176.67** 106.47** Method (M) 1 B X RM 49.34** 43.43** 78.48** 61.51** 56.25** 11.48** R X M 3 B X RM 7.29** 0.49 7.19** 0.94 6.73** 2.29 B X RM 14 Experr 0.73 1.05 0.62 1.15 0.53 1.05 Date (D) 2 Experr 4164.10** 1399.60** 132.77** 240.95** 1202.50** 393.31** D X R 6 Experr 15.77** 4.52** 4.43** 4.67** 3.90* 5.32* D X M 2 Experr 2.33 4.46* 1.17 5.46** 0.79 0.13 D X RM 6 Experr 0.38 0.39 0.36 0.48 0.94 0.75 Experr 32 Error 0.82 0.56 2.16** 0.50 2.50** 1.03 Curvilinear Analysis (Trend Analysis) R-Linear 352.65** 298.38** 485.05** 577.07** 440.27** 187.81** R-Quadratic 179.76** 113.35** 167.87** 261.35** 74.61** 115.85** R-Deviations 67.41** 45.33** 48.83** 17.53** 15.14** 15.76** R X M Linear 2.63 1.09E-3 8.73* 1.56 9.60** 0.32 R X M Quadratic 14.13** 4.05E-1 2.21 0.96 5.70* 0.18 R X M Deviations 5.13* 1.05 10.63** 0.29 4.91* 6.40 Mean Square Values Calculated Mean Square Terms Experimental Error 7.32E-1 1.17 620.66 250.04 2.53E-2 1.75E-: Error 8.91E-1 2.09 287.49 500.59 1.01E-2 1.70E-: , **Signifleant at 5% and 1% level respectively. 74 E F F E C T OF SWINE S L U R R Y APPLICATION R A T E ON S I L A G E C O R N DRY M A T T E R Y I E L D 25-— 20 >-or Ld >-or o 15 10 o- - -o BROADCAST • • INJECTION 1981 1982 1983 40 80 120 0 40 80 120 40 80 160 0 A P P L I C A T I O N R A T E (t ho*') (Figure 9) 75 c o m p a r a b l e ra tes of 80 and 120 t h a - 1 , and much lower than that of 160 t h a - 1 used in the present s tudy . A v e r a g e d ove r the t w o me thods of a p p l i c a t i o n , dry mat ter y i e l d w a s 9 t h a - 1 in the f i rs t year as c o m p a r e d to 21 t h a - 1 in the s e c o n d and 17 t h a - 1 the th i rd year . Th is y i e l d va r ia t ion a m o n g y e a r s w a s p r imar i l y due to the d i f fe ren t weather (espec ia l l y ra in fa l l ) in each year (Table 15). A v e r a g e m a x i m u m and m i n i m u m air tempera tu res ove r the g r o w i n g s e a s o n fo r the f i r s t , s e c o n d and th i rd yea rs w e r e 19.5 and 1 0 ° C ; 21 and 1 1 ° C ; and 20 and 10°C r e s p e c t i v e l y . The quant i ty of ra in fa l l and its d i s t r i bu t ion pat tern fo r the three yea rs we re quite d i f fe ren t . The 1981 g row ing s e a s o n had a to ta l ra in fa l l o f 492 m m , 20 and 42% of w h i c h f e l l in M a y and J u n e ; the 1982 g row ing s e a s o n had a tota l ra in fa l l o f 250 m m , 38 and 20% of wh i ch fe l l in J u l y and A u g u s t , the rest more or l ess equa l l y d is t r ibu ted ove r the other mon ths of the g r o w i n g s e a s o n . The 1983 g r o w i n g s e a s o n had a to ta l ra in fa l l of 406 m m , 47% of w h i c h fe l l be tween the s e c o n d week in June and the s e c o n d week in J u l y . The later hal f o f J u l y and Augus t we re re la t i ve l y dry in that yea r . Due to high ra in fa l l and l o w tempera tu res at the beg inn ing of the 1981 g r o w i n g s e a s o n (June average m a x i m u m and m i n i m u m tempera tu res 16.4 and 8 .5°C) c o m p a r e d to 1982 (22.7 and 10.5°C) and 1983 (19.2 and 10.0°C) fo r the s a m e p e r i o d , co rn p lan ts f a i l ed to e s t a b l i s h p rope r l y . R e l a t i v e l y c o l d s o i l , and perhaps an anaerob i c s o i l env i ronmen t m a y have c a u s e d an ear ly s e a s o n g rowth shock to co rn p lan ts caus ing them to turn y e l l o w i s h . Th is w a s f o l l o w e d by re la t i ve l y w a r m , dry c o n d i t i o n s in A u g u s t . One other r eason fo r the re l a t i ve l y poo r c rop y i e l d in the s a m e year e s p e c i a l l y fo r the 160 t h a - 1 rate c o u l d be the shor t gap b e t w e e n . s lu r ry app l i ca t i on and seed ing (Table 8). The high N H 4 + and sa l t con ten t of the s lur ry c o u l d have a d v e r s e l y a f f e c t e d the s e e d g e r m i n a t i o n . Table 15. Growing season weekly average maximum and minimum air temperatures and total r a i n f a l l (1 May - 30 September, 1981, 1982 and 1983). 1981 1982 1983 Week Max. °C Min. °C Total ppt Max.°C Min. °C Total ppt Max.°C Min. °C Total ppt mm mm mm 1 12.5 5.4 37.4 14.6 4.6 7.2 15.1 7.2 ' 32.6 2 15.1 6.4 18.0 15.6 6.1 10.4 16.6 5.1 32.6 *3 16.2 7.4 12.8 17.0 6.9 12.6 18.6 7.9 2.2 **4 19.8 9.2 31.8 21.3 7.0 2.8 24.0 11.4 1.8 5 16.5 8.4 46.0 15.9 7.6 4.8 18.6 1 0 * 1 6.2 6 15.8 8.6 88.2 24.5 10.1 0.0 19.9 10.2 18.2 7 14.1 8.1 61.0 27.4 12.1 0.0 18.2 9.1 42.8 8 19.3 8.9 12.0 22.9 12.2 31.4 20.2 10.8 3.0 9 22.0 10.3 18.2 18.1 11.0 60.0 19.7 10.3 17.2 10 19.6 9.9 7.4 22.4 10.1 22.2 18.1 11.6 109.8 11 20.4 12.7 30.8 19.1 12.1 6.2 23.7 11.1 0.8 12 23.4 12.9 9.0 24.3 11.9 5.6 22.3 10.0 7.0 13 23.9 11.0 0.0 21.3 11.4 3.4 24.1 11.6 3.6 14 27.4 14.7 0.0 20.4 10.9 32.0 22.6 12.6 9.6 15 23.6 12.6 0.0 24.2 11.2 0.0 24.3 9.8 0.0 16 21.0 10.9 27.0 23.2 11.9 7.6 21.7 12.3 37.4 17 22.2 10.8 1.6 22.7 12.1 12.4 18.4 11.3 38.4 18 22.7 9.7 0.6 22.5 9.4 24.8 17.7 7.8 22.8 19 19.4 10.1 24.6 21.8 9.6 0.0 19.9 6.2 7.4 20 15.2 6.6 66.0 17.6 7.5 6.2 17.0 6.2 12.4 X=49.5 X=9.7 E=492.4 X=20.8 X=9.8 E=249.6 X= =20.0 X=9.6 E=405.8 •Slurry applied 1982 and 1983 **Slurry applied 1981. 77 No adve rse e f f ec t of 120 t h a - 1 used in 1982 and 1983 w a s ind ica ted f r o m the plant popu la t i on coun ts taken in those y e a r s . Su t ton et a l . (1978) d id not record any adve rse e f f ec t f r o m s w i n e s lurry app l i ca t i on rates of 90 and 134 t h a - 1 on seed ge rm ina t i on and , t he re fo re , on plant p o p u l a t i o n . In each s a m p l i n g pe r i od (both in 1982 and 1983), the rate of dry matter a c c u m u l a t i o n averaged fo r the t w o me thods of app l i ca t i on s h o w e d a dec l ine for the con t ro l and the 40 t h a - 1 rate be tween three and four mon ths . But dry mat ter accumu la ted at a l m o s t the s a m e rate f o r the 80 and 120 t h a - 1 rates (Table 16 a and b) f o r the same p e r i o d . In 1982 N d e f i c i e n c y s y m p t o m s occu r red in the con t ro l p l o t s , and in 1983 in the con t ro l and the p lo t s r ece i v i ng the 40 t h a - 1 rate dur ing th is t i m e . Th is resul t c l ea r l y ind ica ted that the c rops w e r e not equa l l y bene f i t t ed by al l the ra tes , and that the dec rease in the rate of dry mat ter a c c u m u l a t i o n fo r the con t ro l and the 40 t h a - 1 rate resu l ted p r imar i l y f r o m a d e f i c i e n c y o f N . Because of a poo r g r o w i n g s e a s o n in 1981, plant s a m p l e s w e r e taken on l y at the f i n a l . ha rves t , t he re fo re , no such C o m p a r i s o n w a s made fo r that year . B. Injection method e f fec t on corn yield C o r n dry mat ter y i e l d w a s 1.38 t h a - 1 y r 1 higher fo r the in jec t ion than the b roadcas t app l i ca t i on m e t h o d when averaged a c r o s s the yea rs and al l app l i ca t i on ra tes . W h e n ave raged a c r o s s the yea rs f o r the 80 t h a 1 ra te , y i e l d w a s 2.0 t h a - 1 y r 1 h igher w h e n s lur ry w a s in jec ted than b roadcas t (Table 12). Su t t on et a l . (1982) and S a f l e y et a l . (1981) repor ted that ove r a three year pe r iod co rn y i e l d f r o m p lo t s rece i v i ng in jec ted manure ave raged 2.1 t h a - 1 and 1.0 t h a - 1 r e s p e c t i v e l y y e a r - 1 more than the p l o t s r e c e i v i n g b roadcas t manure . H o w e v e r , the N app l i ca t i on rates of Su t ton et Table 16.a. Dry matter yield at different sampling dates after planting (1982). Rate of Slurry Application t ha" 1 One month Two months Three months Four months Dry matter yield t hp- 1 Dry matter yield + ha" 1 Dry matter yield h Via" 1 Dry matter yield r h a - 1 Broadcast Injection Broadcast Injection Broadcast Injection Broadcast Injection 0 X = 0.13 ± 0.06 X 3.9 4.0 3.95 X 11.5 11.6 11.55 X 17.7 18.4 18.05 40 4.7 5.0 4.85 12.5 . 13.5 13.00 19.0 19.6 19.30 80 5.4 6.4 5.90 14.5 16.5 15.50 22.4 24.8 23.60 120 5.1 5.4 5.25 ... . . . . 14.1 15.0 14.55 22.4 23.3 22.85 Table 16.b. Dry matter yields at different sampling dates after planting (1983). Rate of Slurry Application t h a - 1 One month Two months Three months Four months Dry matter yield f ha~ l Dry matter yield Dry matter yield ^ ho- 1 Dry matter yield Broadcast Injection Broadcast Injection Broadcast Injection Broadcast Injection 0 X - 0.12 ± 0.04 X 3.9 4.4 4.15 X 9.4 11.1 10.25 X 13.2 14.5 13.85 t 40 4.4 4.9 4.65 11.7 12.3 12.00 15.7 17.1 16.40 80 7.0 8.0 7.50 14.5 16.3 15.4 19.9 21.0 20.45 120 6.8 6.9 6.85 13.9 15.1 14.5 18.0 20.4 19.20 CO 80 a l . (1982) we re c o n s i d e r a b l y higher (428, 643 and 857 kg ha- 1 ) and those of S a f l e y et a l . (1981) were s l i gh t l y l owe r (168, 336 kg ha- 1 ) than the rates used in this s tudy . W i th in year and app l i ca t i on m e t h o d , and w i th in year and app l i ca t i on rate, there we re s t a t i s t i c a l l y s i gn i f i can t d i f f e r e n c e s (Tables 13 and 14) in co rn y i e l d a s s o c i a t e d w i t h app l i ca t i on rates and m e t h o d s . In al l the y e a r s , ra tes had greater e f f e c t on co rn y i e l d than the app l i ca t i on m e t h o d s . But fo r the s a m e rate or even when no s lu r ry w a s a p p l i e d , the in jec t ion app l i ca t i on me thod resu l ted in higher corn y i e l d than the b roadcas t m e t h o d . Out of three year ' s of expe r imen t , on l y in 1982 there w a s rate x me thod in te rac t ion (Table 14). Th is i nd ica ted that the e f f e c t o f rate w a s dependent on the m e t h o d of app l i ca t i on in that year o n l y . In al l the y e a r s , me thod in i t se l f had an e f f e c t on corn dry mat ter p r o d u c t i o n . C o r n dry matter y i e l d s we re 0.8 (1981); 0.7 (1982) and 1.3 (1983) t h a - 1 h igher fo r the in jec t ion con t ro l c o m p a r e d to the b roadcas t con t ro l t rea tment . Th is p o s i t i v e e f f e c t o f the in jec t ion app l i ca t i on me thod cou ld have resu l ted f r o m the i m p r o v e d s o i l p h y s i c a l c o n d i t i o n s , greater s o i l N m ine ra l i za t i on and c o n s e r v a t i o n of s lu r ry N resu l t ing in higher c rop N up take . C . Crop N uptake L ike dry mat ter y i e l d s , c rop N uptake data we re a l so ob ta ined f r o m s ix ind iv idua l m e a s u r e m e n t s . Va r i ab i l i t y in N uptake m e a s u r e m e n t s we re higher fo r the c o n t r o l and fo r the 40 t h a - 1 ra tes c o m p a r e d to the 80 and the 160 or 120 t h a " 1 rates (Table 11). Higher va r i ab i l i t i es w e r e r eco rded at an ear ly s tage of plant g row th than at matur i ty and , in gene ra l , higher va r i ab i l i t i es w e r e a s s o c i a t e d w i th the b roadcas t than the in jec t ion me thod of app l i ca t i on (Table 11). P o s s i b l e exp lana t i ons fo r these va r i ab i l i t i e s have been ind ica ted ear l ie r in the c rop y i e l d s e c t i o n . 81 In all the y e a r s , s lur ry app l i ca t i on rate had s i gn i f i can t l inear and quadrat ic e f f e c t s on c rop N uptake. The quadrat ic e f f e c t w a s much more p ronounced re la t i ve to the l inear e f f e c t in 1981 w h e r e a s in 1982 and 1983 the l inear e f f e c t w a s much more p rominen t (Tables 13 and 14). In al l the y e a r s , c rop N uptake and s lurry N r e c o v e r y i nc reased up to the 80 t h a - 1 rate and then d ropped o f f (Tables 17A and 17B). The drop in N uptake f r o m the h ighest rate each year resu l ted ma in l y because y i e l d s w e r e reduced at that rate (Table 17A). The in jec t ion m e t h o d resu l ted in higher N uptake than the c o m p a r a b l e quant i ty b roadcas t or w h e n no s lur ry w a s app l i ed (Table 17A) . Higher N uptake f o r m the in jec t ion t reatment resu l ted f r o m both high plant dry matter p roduc t i on and N c o n c e n t r a t i o n (Tables 12 and 18). P lacemen t and concen t ra t i on of s lu r ry at depth of 30 c m in the roo t zone may have po ten t i a l l y i nc reased the ava i l ab i l i t y o f N in the s o i l f o r plant use , thereby caus ing a d i f f e rence in N uptake by the c rop or in jec t ion i tse l f may have i m p r o v e d the s o i l ' s p h y s i c a l c o n d i t i o n , e s p e c i a l l y ae ra t i on , resu l t ing in more s o i l N m ine ra l i za t i on and thereby lead ing to the greater plant g row th and N uptake. N H 4 + - N in the s lur ry p laced d i rec t l y in to the s o i l by in jec t ion c o u l d have reduced N H 3 v o l a t i l i z a t i o n l o s s e s and i nc reased the N ava i l ab le fo r p lan ts re la t i ve to the b roadcas t and i nco rpo ra t i on m e t h o d . K lausner and Gues t (1981) and Su t ton et a l . (1982) repor ted higher N uptake in co rn f r o m in jec ted da i ry manure and s w i n e s lu r r y , r e s p e c t i v e l y , w h e n c o m p a r e d w i t h b roadcas t app l i ca t i on of the s a m e ma te r i a l s . The b e n e f i c i a l e f f e c t s o f deep p lough ing on c rop y i e l d w e r e ind ica ted by B ra im et a l . (1984). The m a x i m u m plant r e c o v e r y o f s lur ry N and the greater inc rease in N uptake by the co rn c rop ove r the con t ro l w e r e a s s o c i a t e d w i th the in jec ted 80 t h a - 1 rate (Tables 17B and 19). In 1982, 4 5 % of the s lur ry N Table 17A. Crop N uptake (1981, 1982 and 1983). Time After Application Application Method 1981 treatment (t ha - i) 0 40 80 160 1982 treatment (t ha - 1) 40 80 120 1983 treatment (t ha"') 40 80 120 Month 4 * Broadcast Injection Broadcast Injection Broadcast Injection Broadcast Injection kg ha" 1 71 98 125 102 79 116 171 136 kg ha - 1 kg h a - 1 Average - 5 ± 1.9 Z * * X * * Z * * Z * * 77 66 105 62 139 60 133 56 87 60 112 62 159 54 161 59 90 77 135 80 187 81 170 71 107 73 151 84 236 80 221 81 117 169 232 239 146 180 296 272 Average - 5 ± 2.1 Z * * Z * * X * * X * * 47 51 73 54 126 65 118 64 54 49 94 53 137 60 130 59 57 62 124 91 176 91 161 88 72 65 137 78 201 88 189 86 92 136 193 183 111 176 229 220 •Final harvest. ••Percent of the total uptake. Table 17B. Percent recovery of slurry N (1981, 1982 and 1983). Time Application 1981 1982 1983 After Method treatment (t h a - 1 ) treatment (t ha treatment (t h a _ i ) Ap p l i c a t i o n 0 40 80 160 0 40 80 120 0 40 80 120 Month o Broadcast - - - - 18 18 10 - 16 26 16 L Injection - - - - 16 21 14 - 24 27 18 o Broadcast - - - 29 29 15 - 41 38 24 J I n j e c t i o n - - - 28 38 21 - 40 42 27 Broadcast 16 17 5 - 33 34 23 _ 27 33 21 4* Injection 21 29 9 - 22 45 23 **" 40 38 25 Percent recovery of s l u r r y N calculated as: (N uptake from the treatment - N uptake from the c o n t r o l ) TKN applied from the treatment Table 18. Plant N concentration and coefficient of variation at different sampling periods for the several rates of slurry used in 1981, 1982 and 1983. Slurry application rate (t 80 ha - 1) Time after Method of 0 40 120 or 160 Year planting application N cone C.V. N cone. C.V. N % cone. C.V. N cone. C.V. 1981 4 Broadcast Injection 1.1 1.1 12.6 3.6 1.2 1.2 7.6 9.3 1.2 1.3 6.0 7.6 1.3 1.5 7.1 9.5 O Broadcast 1.9 12.4 2.2 3.1 2.6 4.3 2.6 3.8 Z Injection 2.1 5.6 2.2 4.5 2.7 5.5 3.0 2.6 1982 3 Broadcast Injection 0.8 0.9 22.8 15.4 1.1 1.1 17.8 19.6 1.3 1.4 13.3 6.3 1.2 1.5 14.2 10.2 /. Broadcast 0.7 9.1 0.9 14.6 1.0 7.7 1.1 9.3 Injection 0.8 10.1 0.9 13.2 1.2 5.0 1.2 5.9 o Broadcast 1.2 13.1 1.7 13.6 1.8 5.5 1.7 8.0 L Injection 1.2 9.8 1.9 8.4 1.7 14.7 1.9 11.1 1983 3 Broadcast Injection 0.6 0.7 8.1 19.6 1.0 1.1 26.5 17.1 1.2 1.2 7.4 8.9 1.2 1.3 6.9 4.8 4* Broadcast Injection 0.7 0.8 7.2 6.5 0.9 1.0 12.3 6.8 1.0 1.1 3.9 4.6 1.0 1.1 6.0 4.6 *Final harvest. Table 19. Percent increase i n crop N uptake over the con t r o l for s l u r r y a p p l i c a t i o n rates used i n 1981, 1982 and 1983. Time Method 1981 1982 1983 a f t e r of treatment treatment treatment a p p l i c a t i o n application (t ha" 1) — (t ha" 1) — (t ha" 1) (month) . 40 80 160 40 80 120 40 80 120 9 Broadcast 36 80 73 55 168 151 i. Injection 29 83 85 74 154 140 Broadcast 50 108 89 117 209 182 J Injection 41 121 106 90 179 162 Broadcast 38 76 44 44 98 104 48 110 99 4* Injection 47 116 72 23 102 86 58 106 98 * F i n a l harvest. 86 w a s r e c o v e r e d by the c rop when the a b o v e rate of s lur ry w a s in jec ted as o p p o s e d to 34% w h e n the s a m e rate w a s b roadcas t p lus i nco rpo ra ted (Table 17B). In the same year and fo r the s a m e rate of s lur ry a p p l i c a t i o n , the inc rease in c rop N uptake over the con t ro l amoun ted to 102% for the in jec t ion as c o m p a r e d to 98% fo r the b roadcas t p lus i nco rpo ra t i on app l i ca t i on (Table 19). S i m i l a r resu l ts w e r e o b s e r v e d fo r the 80 t h a - 1 rate in 1983. A c o n s i d e r a b l y greater amount of N uptake occu r red later in the g r o w i n g s e a s o n for the con t ro l than fo r the s lur ry t rea ted p lo t s (Table 17A) . Th is w a s e s p e c i a l l y true in 1983 w h e n s o i l ava i l ab le N w a s the l o w e s t . A s a resul t of l o w ava i lab le N, the s o i l cou ld not keep up w i t h the c rop d e m a n d . A f t e r t w o months in 1982, 159 kg h a - 1 o f N we re taken up by the co rn c rop (an uptake rate of 5 kg h a - 1 o f N d a y - 1 dur ing J u l y ) f r o m the in jec ted 80 t h a - 1 rate as o p p o s e d to 87 kg f r o m the in jec ted con t ro l p l o t s (2.7 kg h a - 1 o f N d a y - 1 dur ing Ju l y ) . C o r r e s p o n d i n g va lues fo r 1983 w e r e 137 and 54 kg h a - 1 o f N r e s p e c t i v e l y . A s w i l l be ev iden t later in the t hes i s (Table 26, p 112) when the supp ly of s o i l ava i l ab le N w a s re l a t i ve l y l o w , the co rn c rop re l ied more heav i l y on s lur ry N . In 1982, af ter t w o mon ths of g row th w h e n the supp l y o f s o i l ava i l ab le N w a s c o m p a r a t i v e l y h igh , 55% of the c rop N w a s supp l i ed by the s o i l as c o m p a r e d to 45% f r o m the s lur ry fo r the 80 t h a - 1 rate. In 1983 when the supp l y o f ava i l ab le s o i l N w a s l o w e r , on l y 39% of the c rop N w a s supp l i ed by the s o i l as c o m p a r e d to 6 1 % f r o m the s lur ry fo r the s a m e rate and fo r the s a m e g row th p e r i o d . It is a l s o in te res t ing to note that by three mon ths 7 3 - 7 7 % of the c rop N uptake had occu r red in the con t ro l p lo t s in 1982 as c o m p a r e d to 6 2 - 6 5 % in 1983. C o r r e s p o n d i n g va lues fo r the 80 t h a - 1 rate we re 8 0 - 8 1 87 and 8 8 - 9 1 % r e s p e c t i v e l y . The co rn c rop demands a large amount of N about one month af ter the date o f p lan t ing fo r s tu rdy s t a l k s , w i d e leaves and rap id dry mat ter p roduc t i on and aga in be tween 1.5-2.5 mon ths months af ter p lant ing fo r t a s s e l i n g , s i l k i ng and fo r high p ro te in gra in (A ld r i ch and L e n g , 1972). T h e r e f o r e , adequate quant i t ies of N must be present in the s o i l one month af ter app l i ca t i on if m a x i m u m g rowth rate and u l t imate dry mat ter y i e l d is to be a c h i e v e d . Each year the 80 t h a - 1 rate p roduced m a x i m u m co rn dry mat ter y i e l d s . In 1982, the corn c rop that resu l ted in m a x i m u m y i e l d con ta ined 296 kg h a - 1 o f N. M o s t of th is N uptake occu r red dur ing i ts ac t i ve pe r i od of g row th dur ing the s e c o n d (5 kg h a - 1 o f N d a y 1 ) and th i rd mon ths (2.6 kg h a 1 o f N day - 1 ) . S o i l and s lur ry o rgan ic N m ine ra l i za t i on data f r o m the in jec ted con t ro l p lo t s in 1982 p resen ted later on in the t hes i s (Table 25 , p 112) sugges t that at t w o mon ths 36 kg h a - ' of N we re m ine ra l i zed (a net m ine ra l i za t i on rate of 1.2 kg h a - 1 o f N day - 1 ) . In add i t i on to the m ine ra l i za t i on of s o i l o rgan ic N , 107 kg of the s lur ry o rgan ic N we re m ine ra l i zed in that year f r o m the 80 t h a - 1 rate dur ing th is p e r i o d . Th is rate, t he re fo re , cou ld meet the c rop ' s demand fo r N dur ing its ac t i ve g rowth p e r i o d . The con t ro l p lo t s and the p lo t s r ece i v i ng 40 t h a - 1 o f s lu r ry on the other hand fa i l ed to meet this high N requ i rement of the c rop and p roduced re l a t i ve l y l ower y i e l d s . M a x i m u m crop N uptake and co rn dry mat ter y i e l d s resu l ted f r o m the 80 t h a - 1 rate in 1983 as w e l l . The higher N uptake f r o m the con t ro l p lo t s later on in the g r o w i n g s e a s o n in both the y e a r s may have resu l ted f r o m s l o w e r m ine ra l i za t i on of s o i l o rgan ic N . P r o p o r t i o n a t e l y greater N uptake by a co rn c rop b e t w e e n 1-3 mon ths f r o m the t reated p l o t s c o m p a r e d to the con t ro l w a s a l s o repo r ted by J o h n s o n (1982). In ject ing 80 t h a - 1 o f s lu r ry in 1982 and 1983 resu l ted in 64 and 36 88 kg h a - 1 more • N uptake by the c r o p , r e s p e c t i v e l y , than b roadcas t i ng the s a m e quant i ty . K lausner and Gues t (1981) reco rded 36 kg h a - 1 greater c rop N uptake when 31 t h a ' 1 of da i ry manure w e r e in jec ted as c o m p a r e d to b r o a d c a s t . A s ind ica ted ear l ie r , s lu r ry app l i ca t i on ra tes had s i gn i f i can t l inear and quadrat ic t rend e f f e c t s on dry mat ter p roduc t i on and N uptake fo r al l the y e a r s . In order to s tudy h o w e f f i c i e n t l y the c rop u t i l i zed s lu r ry N in te rms of dry mat te r p r o d u c t i o n , a co r re l a t i on a n a l y s i s w a s p e r f o r m e d on crop N uptake and dry mat ter y i e l d data (Append ix 4 and A p p e n d i x 4.1). S i m i l a r c o m p a r i s o n s we re d rawn by Keu len and Heems t (1982) in an exper iment where the s o u r c e s of N we re f a r m y a r d manure and c h e m i c a l fe r t i l i ze r . The 1981 g r o w i n g s e a s o n w a s one of the w o r s t on r e c o r d , 1982 one of the best and 1983 in te rmed ia te . The un favou rab le c l ima t i c c o n d i t i o n s of the 1981 g r o w i n g s e a s o n s i g n i f i c a n t l y reduced N uptake and dry mat ter y i e l d s f o r that y e a r . B e c a u s e of th is , a separa te a n a l y s i s w a s car r ied out on the data fo r that par t icu lar yea r . Resu l t s o f the co r re la t i on a n a l y s e s sugges t a h igh ly s i g n i f i c a n t p o s i t i v e co r re la t i on b e t w e e n N uptake and dry matter y i e l d s (Figures 10 and 11). It appears f r o m Figure 10 that N w a s more e f f i c i e n t l y u t i l i zed by the co rn c rop in 1981 as c o m p a r e d to 1982 and 1983. In 1981, f o r each add i t i ona l kg of N uptake o v e r 50 k g , 65 kg of dry mat te r w a s p r o d u c e d . In 1982 and in 1983 for an add i t i ona l kg of N uptake ove r 80 k g , 49 kg dry mat te r w a s p r o d u c e d . T h e s e ind ica ted an e f f i c i e n t use o f N by the co rn c rop in 1981 wh i ch w a s m a s k e d by the l ower N uptake that resu l ted f r o m l o w e r y i e l d . Th is re la t i onsh ip is va l id on l y w i t h i n the l imi t o f the measu remen t of N uptake and dry mat ter y i e l d used in the f i gu re . RELATIONSHIP BETWEEN N UPTAKE AND DRY MATTER YIELD 1981 16.8-j 16 H 15.2 H 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 N UPTAKE (kg ha*1) (Figure 10 ) Q I UJ >-en >-Q RELATIONSHIP BETWEEN N UPTAKE AND DRY MATTER YIELD 1982 and 1983 Y = 9.84 + 0 .049 X SE " 1.22 r = 0.92, P = <.001 13 |A A I 1 1 1 1 1 1 1 1 1 1 1 1 1 80 100 120 140 160 180 200 220 240 260 2 8 0 3 0 0 320 340 360 N UPTAKE (kg ha' 1) (Figure 11) 91 F r o m the re la t ionsh ip be tween N uptake and dry mat ter y i e l d (Figure 11), it can be s e e n that about 310 kg N h a - 1 w a s u t i l i zed by the corn c rop to p roduce a y i e l d of about 25 t h a - 1 in a modera te to exce l len t g row ing s e a s o n . I n fo rma t ion f r o m this resul t may be used in fe r t i l i ze r r e c o m m e n d a t i o n s . If one is in te res ted in ob ta in ing the m a x i m u m y i e l d or a cer ta in pe rcen tage of the m a x i m u m y i e l d , one can f igure out the amount of N that has to be present in the c rop to p roduce that y i e l d under s im i l a r so i l and c l i m a t i c c o n d i t i o n s . T h e r e f o r e , th is re la t ionsh ip is ve ry much usefu l fo r f i e l d use . In order to supp ly the requ i red amount o f N fo r the expec ted y i e l d , k n o w l e d g e of the e f f i c i e n c y of the fe r t i l i ze r t ype in t e rms o f i ts N uptake is essen t i a l s o that the amount of fe r t i l i ze r N that has to be app l i ed can be c a l c u l a t e d . In the present r e s e a r c h , s lur ry app l i ca t i on rate had a s ign i f i can t l inear e f fec t on dry mat ter y i e l d and N uptake up to 80 t h a - 1 . The re fo re , to ind ica te e f f i c i e n c y of s w i n e s lur ry N , a r e g r e s s i o n a n a l y s i s w a s p e r f o r m e d us ing N uptake and N app l i ed data (Append ix 5) fo r the years 1982 and 1983 and the fo r the 40 and 80 t h a - 1 s lu r ry a p p l i c a t i o n s . R e g r e s s i o n a n a l y s i s w a s p e r f o r m e d sepa ra te l y fo r the t w o m e t h o d s . Resu l ts of the a n a l y s e s are p resen ted in F igures 12 & 13. It can be seen f r o m Figure 12 that sw ine s lur ry N w a s 34% e f f i c i en t in t e rms of i ts uptake when it w a s b roadcas t as o p p o s e d to 4 3 % w h e n in jec ted (Figure13). F rom this i n f o r m a t i o n the amount o f s w i n e s lu r ry N that has to be app l ied to supp ly the requ i red amount o f c rop N can be c a l c u l a t e d . On the other hand, i n f o rma t i on f r o m this sor t o f re la t i onsh ip cou ld be taken a s tep f o r w a r d by the g r o w e r s to carry out s o m e c a l c u l a t i o n to ind icate p robab le cos t and pro f i t o f the p roduce . If s w i n e s lur ry is used as a s o i l amendment then the c o s t per unit o f i ts app l i ca t i on and expec ted marke tab le va lue of the RELATIONSHIP BETWEEN N UPTAKE AND TKN BROADCAST 1982 and 1983 3 6 0 - j 3 4 0 -3 2 0 -3 0 0 -2 8 0 -8 0 - 4 1 1 — i 1 1 1 — i — i — i — I — i — I — i 0 40 80 120 160 200 240 280 320 360 400 4 4 0 480 520 N APPLIED (kg ha"1) (Figure 12) RELATIONSHIP BETWEEN N UPTAKE AND TKN INJECTED 1982 and 1983 360-i 0 40 80 120 160 200 240 280 320 360 400 440 480 520 N APPLIED (kg ha' 1) (Figure 13) 94 produce w i l l have to be known to carry out such a c a l c u l a t i o n . There are at least t w o g o o d reasons for p roducers to fe r t i l i ze for the top y i e l d ( C o o k e , 1982). F i rs t , to inc rease fa rmer ' s i n come and the s e c o n d , to i nc rease f o o d p roduc t i on . No f a rm ing enterpr ise can su rv i ve for long un less the p roduce pays fo r al l ove rhead charges and the cos t of inputs . P r e f e r a b l y there shou ld be a surp lus that a l l o w s fa rmers to make further i nves tmen t to imp rove their s y s t e m . F ixed c o s t s of p roduc t i on are the same whether a g o o d or a poo r c rop is g r o w n . The advantage of g row ing higher y i e l d s is that the f i xed cha rges , wh i ch m a y amount to a half or more of to ta l p roduc t i on c o s t s , are sp read ove r larger amount of p roduce s o that i ts unit cos t is r educed . D. Soi l mineral N S o i l m inera l N shor t l y f o l l o w i n g in jec t ion C o n s i d e r a b l e va r iab i l i t y in s o i l m inera l N concen t ra t i on c o u l d resul t e s p e c i a l l y when s lur ry is in jec ted into the s o i l . Th is is because the la tera l and the ve r t i ca l m o v e m e n t of N is g rea t ly i n f l uenced by the s o i l t y p e , c l ima t i c c o n d i t i o n s and by the f o r m of N or h o w it changes w i t h t i m e . If N is concen t ra ted in the zone o f a p p l i c a t i o n , it w i l l have an impac t on plant g r o w t h . Th is is because l o c a l i z e d higher c o n c e n t r a t i o n o f N H 3 may a f fec t seed ge rm ina t i on and the ava i l ab i l i t y o f th is N w i l l be grea t ly de te rm ined by the c rop ' s roo t i ng pat tern and the s p a c i n g b e t w e e n the po in t s of a p p l i c a t i o n . Resu l t s of the exper imen t (Figure 14) fo r the 120 t h a 1 rate of s lu r ry app l i ca t i on s h o w that the lateral and the ve r t i ca l d i s t r i bu t ions of N we re l o c a l i z e d be tween 0 - 3 0 c m ( lateral) and 0 - 4 0 c m (ver t ica l ) z o n e s of the s o i l , r e s p e c t i v e l y , f r o m the point o f i n jec t i on . Four w e e k s af ter s lur ry VERTICAL AND LATERAL N DISTRIBUTION FOLLOWING INJECTION OF 120 t ha" 1 OF SLURRY IN 1982 96 a p p l i c a t i o n , when the c rop w a s beg inn ing to need i ts max imum N s u p p l y , the concen t ra t i on o f N H / + N O y in the 0 - 2 0 c m zone (ver t ica l ) w a s s i m i l a r la tera l ly f r o m 0 - 3 0 c m f r o m the center o f the in jec t ion zone . S u f f i c i e n t d i s p e r s i o n of n i t rogen in the s o i l f r o m sw ine s lur ry in jec t ion w a s ind ica ted by Su t ton et a l . , 1982. In ject ion o f 120 t h a - 1 had l i t t le e f f ec t on minera l N concen t ra t i on b e l o w 40 c m . It a l so appears f r o m the same f igure that the m a x i m u m N concen t ra t i on o f 80 ppm (in the ve r t i ca l 2 0 - 4 0 c m zone ) occu r red in the s o i l f r o m th is rate. S e e d ge rm ina t i on and ear ly roo t g rowth of co rn can be re tarded if the concen t ra t i on of (NH 3 + N H 4 + ) N reaches 944 ppm and c o m p l e t e l y inh ib i ted at a concen t ra t i on of 1628 ppm (Co l l i ve r and W e l c h , 1970). 0 S i n c e the concen t ra t i on of ( N H 4 + + N G y ) N w a s subs tan t i a l l y l owe r than the t ox i c amount i nd i ca ted , it is un l i ke ly that the 120 t h a 1 or the l ower rates used in the- present research had any N H 3 t ox i c i t y e f fec t on s e e d ge rm ina t i on and , t he re fo re , on plant g r o w t h . D i f f e ren t i a l plant g row th cou ld resul t in the event o f an unequal N d i s t r i bu t i on f r o m the in jec t ion t rea tment . Th is is e s p e c i a l l y true fo r the p lants g row ing c l o s e to the in jec t ion zone and cou ld be re f l ec ted in their he igh ts . The in jector used fo r app l y i ng s w i n e s lu r ry had shank s p a c i n g s o f 60 c m . A s no d i f f e rence in plant height w a s e v i d e n c e d in the thes i s r e s e a r c h , p robab l y the shank spac ing used d id not have any adve rse e f f ec t on plant g rowth or on s o i l N d i s t r i bu t i on . M c L e a n and Henry (1982) reco rded unequal height o f a bar ley c rop be tween in jec t ion z o n e s (height d e c r e a s e d as the d i s tance i n c r e a s e d f r o m the center of app l i ca t i on ) in wh i ch s w i n e s lurry w a s in jec ted by shanks s p a c e d 1.0 m apart . Inadequate d i s t r i bu t ion o f the s lur ry N w a s thought to be r e s p o n s i b l e f o r such a var iab le c rop g row th w h i c h 97 resu l ted in a subs tan t ia l dec rease in dry matter y i e l d . S p a c i n g of app l i ca t i on can e s p e c i a l l y l imi t y i e l d of those c rops wh i ch have nar row roo t i ng s y s t e m s . S o i l m inera l N ove r the g r o w i n g s e a s o n S o i l minera l N measu remen ts we re based on three ind iv idua l o b s e r v a t i o n s . Tab le 20 s h o w s a w i d e range of va r i ab i l i t y in s o i l minera l N content data fo r al l the ra tes , da tes , depths and me thods of a p p l i c a t i o n . A s ind ica ted ear l ier (mater ia ls and me thods s e c t i o n ) a p r e - s e t s o i l s a m p l i n g p rocedure w a s used in th is exper iment w i t h the hope o f m i n i m i z i n g these va r i ab i l i t i e s . S i n c e the t rea tment e f f e c t s we re s i gn i f i can t (Table 2 1 , 22), the re la t i ve l y large va r i ab i l i t y d id not a d v e r s e l y e f f ec t the resul t o f th is r esea rch . The e f f e c t s of s lu r ry app l i ca t i on me thods and rates on s o i l m inera l N concen t ra t i ons at 0 - 1 5 , 1 5 - 3 0 , 3 0 - 6 0 and 6 0 - 9 0 c m depths we re c o m p a r e d ove r the ent ire s a m p l i n g pe r i od each year . In al l the y e a r s , app l i ca t i on rates had a greater e f f e c t on changes in s o i l m inera l N concen t ra t i ons than d id s lur ry app l i ca t i on me thods (Table 21 , 22) . The in jec t ion app l i ca t i on me thod a l w a y s resu l ted in greater to ta l quant i t ies of s o i l m inera l N than compa rab le rates b roadcas t (Table 23) . The N H 4 + and N G y - N content o f the s o i l s a m p l e d at d i f fe ren t da tes in 1982 and 1983 have been p resen ted in A p p e n d i x 6. W i th the app l i ca t i on rates used in th is s tudy there were an a c c u m u l a t i o n of m inera l N f r o m the s lur ry t reatment regard less of me thod of a p p l i c a t i o n . The accumu la t i on of m inera l N in the s o i l va r ied depend ing on where the s lur ry w a s in i t i a l l y app l i ed in the s o i l p r o f i l e . The d i s t r i bu t i on pat terns of N f r o m the t w o me thods o f s lu r ry app l i ca t i on w e r e qui te d i f fe ren t . F igures 15 -20 represent minera l N d i s t r i bu t i on Table 20. Percent coefficient of variation In soil mineral N measurements at different sampling dates for the 0, 80 and 120 t ha - 1 rates of slurry used In the experiment in 1982 and 1983. Time Slurry application rate (t ha~ 1) after n Hfl 1?0 Year application Depth Broadcast Injection Broadcast Injection Broadcast Injection (mo) (cm) 0-15 12.8 14.5 10.3 32.0 14.7 44.2 1 15-30 21.5 21.9 12.9 40.5 10.3 30.6 30-60 30.6 15.5 55.9 8.2 58.3 59.0 60-90 27.6 28.9 71.1 37.6 82.2 22.1 0-15 13.4 38.0 18.1 10.7 60.8 24.7 2 15-30 7.3 26.8 16.4 39.1 49.4 40.2 30-60 32.7 75.1 30.4 39.1 25.6 38.5 1982 60-90 64.4 53.8 52.3 55.1 39.7 58.1 0-15 37.1 9.1 34.2 29.5 36.0 100.2 3 15-30 42.8 24.2 15.8 39.5 51.2 51.2 30-60 47.4 62.9 34.6 24.0 27.7 25.5 60-90 57.8 81.6 58.4 53.6 36.5 49.0 0-15 14.2 21.4 11.7 57.9 28.8 32.5 4 15-30 43.6 8.1 21.2 34.2 57.4 64.7 30-60 41.9 23.1 94.0 30.0 1.8 51.4 60-90 5.3 94.8 53.6 47.1 15.6 75.0 0-15 1.5 49.1 12.4 10.7 71.4 42.7 1 15-30 15.5 11.9 29.0 10.5 35.4 21.1 30-60 12.9 23.1 28.5 7.3 38.9 22.0 60-90 21.9 29.5 44.9 25.9 13.2 22.2 0-15 29.4 42.5 32.3 31.5 39.6 55.8 2 15-30 24.4 40.7 8.6 24.3 36.1 15.4 30-60 35.4 34.9 21.7 24.1 19.4 8.7 t Qfll 60-90 32.5 35.6 15.1 30.4 19.4 8.9 1 7 0 J 0-15 22.2 38.3 57.1 3.1 33.4 80.9 3 15-30 110.0 74.3 11.5 12.9 45.8 9.2 30-60 68.1 29.3 1.4 27.9 23.3 35.4 60-90 45.4 2.2 15.9 22.8 49.1 46.7 0-15 10.0 23.2 39.9 27.0 35.2 40.7 4 15-30 20.0 8.8 59.7 39.7 28.0 40.0 30-60 12.9 7.5 41.2 27.3 46.9 33.9 60-90 5.5 5.7 38.6 39.3 46.6 18.5 Table 21. Calculated F values for Soil NH^ and NO3-N Concentrations and Mean Square Error Terms (1981) Calculated F-Values F-Ratio NH^ -N N03-N Source DF Denominator Concentration Concentration Block 2 ER(MR) 0.19 0.33 Method (M) 1 ER(MR) 38.94** 32.42** Rate (R) 2 ER(MR) 41.21** 211.66** M X R 2 ER(MR) 44.34** 5.45* ER(MR) 10 ERR(C) 1.76 0.60 C » depth 3 ERR(C) 54.78** 357.66** C X M 3 ERR(C) 29.13** 36.83** C X R 6 ERR(C) 27.79** 34.92** C X M X R 6 ERR(C) 23.66** 7.91** ERR(C) . 36 ERROR 1.51 0.85 Date = D 1 ERROR 230.78** 307.53** D X M 1 ERROR 102.41** 41.61** D X R 2 ERROR 105.41** 18.31** D X M X R 2 ERROR 88.65** 7.39** D X C 3 ERROR 57.07** 214.07** D X C X M 3 ERROR 34.23** 20.16** D X C X R 6 ERROR 38.05** 24.26** D X C X MR 6 ERROR 30.04** 5.41** Error 48 Mean Square Values Calculated Mean Square Terms ER (MR) 298.63 15.46 ERR (C) 611.01 25.65 ERROR 538.87 29.94 *, ** Significant at 5% and 1% level respectively. 100 Table 22. Calculated F values for Soil NHlt and NO 3-N concentrations and Mean Square Error Terms (1982 and 1983). Calculated F-Values F-Ratio Source DF Denominator NH^ -N Concentration NO 3-N Concentration 1982 1983 1982 1983 Block 2 ER(MR) 3.19E-2 0.12 0.66 10.45** Method (M) 1 ER(MR) 7.44* 21.27** 0.17 6.24* Rate (R) 2 ER(MR) 10.87** 12.37** 26.75** 289.32** M X R 2 ER(MR) 3.39 7.32* 0.11 3.03 ER(MR) 10 ERR(C) 1.93 2.18* 2.42* 0.34 C = depth 3 ERR(C) 32.23** 40.53** 79.53** 51.19** C X M 3 ERR(C) 30.96** 21.35** 31.17** 13.84** C X R 6 ERR(C) 6.46** 7.03** 11.89** 5.36** C X M X R 6 ERR(C) 9.03** 8.21** 8.89** 6.33** ERR(C) 36 ERROR 0.96 1.05 2.08** 1.78** Date = D 4 ERROR 26.91** 60.68** 26.64** 58.95** D X M 4 ERROR 1.83** 17.61** 1.44 4.94** D X- R 8 ERROR 5.48** 5.72** 10.63** 6.38** D X M X R 8 ERROR 0.86 5.81** 0.79** 4.28** D X C 12 ERROR 7.33** 11.07** 17.11** 28.89** D X C X M 12 ERROR 11.46** 8.92** 7.31** 7.49** D X C X R 24 ERROR 2.08** 3.67** 3.21** 4.15** D X C X MR 24 ERROR 3.14** 3.23** 2.08** 3.51** Error 192 Mean Square Values Calculated Mean Square Terms ER (MR) 117.90 12.61 547.47 14.55 ERR (C) 61.23 5.78 225.99 42.48 ERROR 63.73 5.48 108.53 23.80 *, ** Significant at 5% and 1% level respectively. Table 23. So i l mineral nitrogen (Ammonium + Nitrate) before and 1, 2 and 4 months after application of . swine slurry (1981, 1982 and 1983).  Time Manure Treatment (t ha After Soil 0 , 80 120* Application Depth Broadcast Injection Broadcast Injection Broadcast Injection k o h a - 1 . (mo) (cm) 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 0-15 18 16 20 14 17 16 20 14 17 21 26 16 15-30 20 14 16 15 16 16 19 23 17 23 32 20 Before 30-60 43 21 38 22 37 35 42 48 43 57 60 64 60-90 34 18 36 18 37 27 37 41 36 43 44 53 Total 115 69 110 69 107 94 118 126 113 144 162 153 0-15 50 34 54 44 156 105 56 92 214 162 117 86 1 15-30 18 30 18 33 19 40 166 146 28 58 209 181 30-60 21 32 15 37 46 40 28 62 73 62 68 85 60-90 18 28 13 29 33 28 17 43 62 67 34 49 Total 107 124 100 143 254 213 267 343 377 349 428 401 0-15 13 26 20 27 121 67 24 40 138 74 51 50 2 15-30 11 26 12 20 25 59 158 95 58 79 209 171 30-60 16 27 17 23 22 57 98 75 38 51 106 100 60-90 9 15 5 13 12 34 17 39 24 32 28 64 Total 49 94 54 83 181 217 297 249 258 236 394 385 0-15 12 9 15 9 73 16 16 16 77 21 56 28 4 15-30 7 9 8 10 27 19 69 28 51 25 107 146 30-60 9 16 10 16 34 37 79 67 34 60 100 100 60-90 8 13 6 13 11 26 19 42 16 43 13 43 Total 36 47 39 48 145 98 203 153 178 149 276 317 0-15 13 9 14 12 26 22 5 15-30 30-60 60-90 7 7 4 4 6 4 12 16 10 25 33 12 31 25 10 53 55 16 Total 31 23 52 82 92 146 *For 1981 this rate was 160 t ha - 1. 102 pat terns of the 80 t h a 1 rate fo r the years 1982 and 1983. One month af ter s lur ry app l i ca t i on in 1982, 47% o f the minera l N in the b roadcas t t rea tment w a s in the N H 4 4 f o r m , 52% of w h i c h w a s loca ted in the 0 - 1 5 c m zone . In the c a s e of in jec t ion t reatment 6 1 % of the minera l N w a s in N H 4 + f o r m , 76% o f w h i c h w a s present in the 15 -30 c m z o n e . Three mon ths af ter s lu r ry app l i ca t i on the N H / - N concen t ra t i ons we re s im i l a r f o r bo th the me thods whe reas the N 0 3 - N concen t ra t i on in the 15 -30 c m zone w a s three t i m e s higher for the in jec t ion m e t h o d . A s im i l a r t rend fo r the s a m e rate w a s o b s e r v e d in 1983. The d is t r i bu t ion of the N H 4 + and N 0 3 " - N concen t ra t i ons f r o m the 120 t h a - 1 s lur ry t reatment is p resen ted in A p p e n d i x 7. Su t t on et a l . (1978 and 1982) reco rded higher concen t ra t i ons of m inera l N in the 0 - 3 0 and 3 0 - 6 0 c m z o n e , r e s p e c t i v e l y , f r o m b roadcas t and in jec t ion s w i n e s lu r ry t rea tment . The resu l t s o f the present s tudy a l s o sugges t that the N H 4 " - N in the s lur ry w a s more qu ick l y n i t r i f i ed w h e n it w a s b roadcas t as c o m p a r e d to i n jec ted . Vet te r and S t e f f e n s (1978) repor ted higher N 0 3 - N in the 0 - 3 0 c m s e c t i o n o f the s o i l c o m p a r e d to the lower dep ths shor t l y f o l l o w i n g su r face app l i ca t i on of s w i n e s lu r r y . Pe rhaps , because of a re la t i ve l y bet ter aera t ion and w a r m e r c o n d i t i o n o f the su r face s o i l as c o m p a r e d to the s u b s o i l , s lu r ry N H 4 + - N is qu i ck l y c o n v e r t e d to N 0 3 " in that zone . The fas te r n i t r i f i ca t i on of s lu r ry N in the case of the b roadcas t t reatment m a y resul t in s i gn i f i can t l o s s e s of N 0 3 " due to leach ing and /o r den i t r i f i ca t i on because o f the s m a l l c rop d e m a n d at a ve ry ear l y s tage o f i ts d e v e l o p m e n t . A l s o the greater c o n c e n t r a t i o n o f minera l N deeper in the r o o t i n g zone w i th the i n jec t i on t reatment may c o n s e r v e s lu r ry N and resul t in i nc reased plant up take . AMMONIUM AND N I T R A T E N DISTRIBUTION ONE MONTH AFTER APPLICATION - 1982 (80 tha" ' SWINE S L U R R Y ) N H 4 8. N 0 3 N CONC. (ppm) DEPTH (cm) (Figure 15) A M M O N I U M AND" N I T R A T E N D I S T R I B U T I O N T W O M O N T H S A F T E R A P P L I C A T I O N - 1982 ( 8 0 t hcf' SWINE S L U R R Y ) 6 0 -N H 4 a N 0 3 N C O N C . (ppm) 20 40 60 80 100 13-D E P T H (cm) 30-9 0 J -o N H 4 •o N 0 3 • N H 4 — — • N O , B R O A D C A S T I N J E C T E D o (Figure 16) AMMONIUM AND N I T R A T E N DISTRIBUTION THREE MONTHS A F T E R APPLICATION — 1982 (80 tha" ' SWINE S L U R R Y ) N H 4 8 NO3 N CONC. ( p p m ) 0 2 0 4 0 6 0 8 0 100 1 l 1 1 1 D E P T H (cm) 30 -\ 6 0 H -o NH4 -o N 0 3 * • N H 4 • • N 0 3 (Figure 17) } } B R O A D C A S T I N J E C T E D o A M M O N I U M A N D N I T R A T E N D I S T R I B U T I O N O N E MONTH A F T E R A P P L I C A T I O N - 1983 ( 8 0 t h < f ' SWINE S L U R R Y ) N H 4 a N 0 3 N CONC. (ppm) (Figure 18) A M M O N I U M AND N I T R A T E N D I S T R I B U T I O N TWO MONTHS A F T E R APPLICATION - 1983 ( 8 0 t ha" 1 SWINE S L U R R Y ) N H 4 S N 0 3 N CONC. (ppm) 0 10 2 0 30 4 0 50 _ i i i i i > } B R O A D C A S T V INJECTED • • N 0 3 J (Figure 19) A M M O N I U M AND N I T R A T E N D I S T R I B U T I O N T H R E E MONTHS A F T E R A P P L I C A T I O N - 1983 ( 8 0 t h a " ' SWINE S L U R R Y ) DEPTH (cm) 1 5 -3 0 -6 0 -9 0 J N H 4 & N 0 3 N CONC. ( p p m ) 10 20 30 40 50 > U I I I I I I / / / / 61 o N H 4 -j ^ \ BROADCAST ° N 0 3 J * N " 4 ) INJECTED (Figure 20) o CO 109 S o m e of the s lu r ry N f r o m the 120 t h a - 1 rate in jec ted (Table 23) w a s found in the 0 - 1 5 c m zone in 1982 and 1983. Th is ind ica ted either an upward m o v e m e n t of N subsequent to app l i ca t i on had occur red or more l i ke ly that the larger v o l u m e be ing app l i ed at the heavier rate came c l o s e r to the su r face du r ing ' a p p l i c a t i o n . In f ac t , the latter w a s o b s e r v e d in the f i e l d . S i n c e N G y - N conten t of the s lur ry dur ing i ts app l i ca t i on is neg l i g i b l e , any upward m o v e m e n t of N H / - N shor t l y f o l l o w i n g s lur ry app l i ca t i on in a so i l w i th an apprec iab le amount o f c l ay and o rgan ic mat ter conten t d o e s not s e e m reasonab le as w e l l . E. Volat i l izat ion of N due to b roadcas t treatment Very l i t t le N (5 kg ha" 1 ) w a s taken up by the co rn c rop dur ing the f i rs t month o f it 's g rowth for both the in jec t ion and the b roadcas t me thods o f a p p l i c a t i o n . A n y d i f f e rence in s o i l m inera l N content at th is s tage b e t w e e n the t w o me thods of app l i ca t i on cou ld be c o n s i d e r e d to be the N l o s s e s due to v o l a t i l i z a t i o n , if i m m o b i l i z a t i o n is a s s u m e d to be neg l i g i b l e . A m m o n i a v o l a t i l i z a t i o n l o s s e s have been ca l cu la ted fo r the 80 and 120 t h a - 1 ra tes fo r the yea rs 1982 and 1983 (Table 24). In the c a l c u l a t i o n , any i m m o b i l i z a t i o n of s lu r ry N shor t l y f o l l o w i n g app l i ca t i on and it 's subsequent m ine ra l i za t i on dur ing the pe r i od in ques t i on have not been c o n s i d e r e d . To ta l m inera l N conten t of the s o i l ( 0 -15 and 15-30 c m s e c t i o n s ) be fo re s lur ry app l i ca t i on w a s sub t rac ted f r o m the to ta l m inera l N con ten t (same depth) one month af ter app l i ca t i on to ob ta in the minera l N f r o m the t rea tment . D i f f e r e n c e s in N content be tween the in jec t ion and the b roadcas t t rea tments w e r e c o n s i d e r e d to be the N l o s s e s due to v o l a t i l i z a t i o n . Table 24. Mineral N content of the s o i l (0-15 and 15-30 cm) 1 month after 8lurry application and N losses due to broadcast treatment. Time Soil Slurry application rate (t ha" 1) after depth 8 n application (cm) Broadcast Injection Broadcast Injection (month) 1982 1983 1982 1983 1982 1983 1982 1983 (Vo Via - 1) 0-15 17 16 20 14 17 21 26 16 Before 15-30 16 16 19 23 17 23 32 20 Total 33 32 39 37 34 44 58 36 0-15 156 105 56 92 214 162 117 86 l 15-30 19 40 166 146 28 58 209 181 Total 175 145 222 238 242 220 326 267 N from treatment 142 113 183 201 208 176 268 231 N volatilized 41 88 — — 60 55 — — 111 In 1982, v o l a t i l i z a t i o n l o s s e s w e r e higher for the 120 t h a - 1 rate (60 kg ha- 1 ) c o m p a r e d to the 80 t h a - 1 rate (41 kg h a 1 , Tab le 24). Reasons fo r these d i f f e ren t ia l l o s s e s cou ld be the large v o l u m e of s lu r ry f r o m the 120 t h a - 1 rate. Because of the large v o l u m e , s lur ry w a s e x p o s e d to the a tmosphe re for a re l a t i ve l y long pe r i od of t ime be fo re be ing in f i l t ra ted or i nco rpo ra ted into the s o i l as c o m p a r e d to the 80 t h a - 1 rate. S o m e va r ia t i on in resu l ts we're o b s e r v e d b e t w e e n the two rates (88 kg h a - 1 o f N v o l a t i l i z e d fo r the 80 t h a - 1 of s lu r ry app l i ca t i on as c o m p a r e d to 55 kg h a - 1 o f N fo r the 120 t h a - 1 rate) in 1983. Th is cou ld have resu l ted f r o m the fac t that one of the p lo t s r ece i v i ng 80 t h a - 1 o f s lu r ry ( Injected) w a s g i v i ng unexpec ted l y high s o i l minera l N va lues c o m p a r e d to the other p l o t s r e c e i v i n g the s a m e t rea tment . Th is p lot w a s c l o s e to the fa rmer ' s f i e l d w h i c h r e c e i v e d inorgan ic N t reatment and that might have a f f e c t e d th is p lo t . The high N r e c o v e r y va lue fo r th is part icular t rea tment in 1983 m a y have a f f e c t e d the e s t i m a t i o n of v o l a t i l i z a t i o n l o s s e s . F. Mineral izat ion of soi l and slurry organic N Because of the greater uncer ta in ty in the amount o f s lu r ry N that is los t due to v o l a t i l i z a t i o n f r o m the b roadcas t t rea tment , N m ine ra l i za t i on has been ca l cu la ted fo r the in jec t ion t reatment on l y . The amoun ts of N mine ra l i zed dur ing 1982 and 1983 f r o m the s o i l and s lur ry o rgan ic f r ac t i ons f r o m the p l o t s r ece i v i ng d i f fe ren t ra tes o f in jec ted s lu r ry t reatment are s h o w n in Tab le 25 . S o i l minera l N and c rop N content o f the in jec ted c o n t r o l p l o t s have been added together to es t ima te the amount o f N mine ra l i zed f r o m the s o i l o rgan ic p o o l . In ca lcu la t ing the amount of N m ine ra l i zed f r o m the s lu r ry o rgan ic f r a c t i o n t w o a s s u m p t i o n s have been m a d e ; Table 25. Amount of s o i l and slurry organic N mineralized from injection treatment at different sampling periods (1982 and 1983). Time After Application (mo) _ 0 t ha" 1 _ - 80 t kg ha" 1-ha" 1 _ 120 t h a - i -1982 1983 1982 1983 1982 1983 1 105 148 -41 -10 -5 -35 2 141 137 107 38 81 85 4 185 159 106 12 30 79 113-1. T w o percent of s lur ry inorgan ic N w a s lost dur ing in jec t ion t reatment (Su t ton , 1981). 2. • A d d i t i o n s or l o s s e s o f N through any other means (eg. b i o l og i ca l f i x a t i o n , p rec ip i t a t i on ) w e r e cons tan t fo r al l the ra tes . A samp le ca l cu la t i on that has been used to ca lcu la te the amount of N m ine ra l i zed f r o m the s lur ry o rgan ic f r ac t i on us ing the a b o v e a s s u m p t i o n s is s h o w n b e l o w : 80 t h a - 1 ra te. 1982  Init ial T K N app l ied f r o m the above rate = 336 kg h a 1 (Table 9) M ine ra l N in the s lur ry = 212 kg (Table 9) Init ial s o i l m inera l N = 118 kg (Tab le . 23) N H 3 l o ss dur ing in jec t ion = 2% o f 212 = 4 kg A c t u a l A m o u n t o f T K N app l i ed = 336 - 4 = 332 kg h a - 1 A c t u a l A m o u n t o f M inera l N app l i ed = 212 - 4 = 208 kg h a - 1 Organ ic N app l i ed = 124.0 kg h a - 1 A f t e r 1 mon th In ject ion c o n t r o l s o i l m inera l N + C r o p N = 100 + 5 = 105 kg h a 1 (Table 17, 23) T rea ted s o i l m inera l N + c rop N = 267 + 5 = 272 kg h a - 1 (Table 17, 23) M ine ra l N f r o m the t reatment = 272 - 105 = 167 kg h a - 1 Slu r ry supp l i ed 208 kg minera l N Can account fo r 167.0 kg minera l N M ine ra l N unaccoun ted fo r = 41 kg There w a s no i nd i ca t i on of any o rgan ic N m ine ra l i za t i on f r o m the 80 t h a - 1 rate one month af ter a p p l i c a t i o n , in fac t , s o m e i m m o b i l i z a t i o n or l o s s may have occu r red . 114 Changes in the s o i l and s lur ry o rgan ic N ove r the g row ing s e a s o n for the t w o yea rs are s h o w n in Tab le 25. In 1982, 86% of the s lur ry o rgan ic N w a s m ine ra l i zed f r o m the 80 t h a - 1 app l i ca t i on af ter two months c o m p a r e d to 40% in 1983. No subsequent inc rease occu r red ove r the rest of the 1982 or 1983 g row ing s e a s o n s . A p o s s i b l e exp lana t ion fo r this d i f f e rence in ear ly s e a s o n N m ine ra l i za t i on cou ld be that the 1982 g row ing s e a s o n w a s re la t i ve l y wa rmer than 1983 g row ing s e a s o n w i th modera te ra in fa l l wh i ch may have fac i l i t a ted the m ic rob ia l ac t i v i t y resu l t i ng in larger quant i t ies of s lur ry o rgan ic N be ing m i n e r a l i z e d . Heavy rates of a t raz ine app l ied in 1981 and a modera te rate in 1982 may have i nc reased N m ine ra l i za t i on as w e l l (Cerve l l i et a l . 1982). It can a l so be seen f r o m Tab le 25 that at the end of the g row ing s e a s o n 185 kg of s o i l o rgan ic N w a s m ine ra l i zed in the con t ro l p lo t s in 1982 c o m p a r e d to 159 kg in 1983 Th is d i f f e rence in N m ine ra l i za t i on cou ld be due to the fac t that in 1981 the s o d w a s turned under and d id not d e c o m p o s e fu l l y because o f poo r c l i m a t i c c o n d i t i o n s in that yea r . M o s t of the m ine ra l i zab le N in the g rass may have m ine ra l i zed in 1982 because of a much mo re f avou rab le env i ronmen ta l c o n d i t i o n . The expe r imen ta l p lo t s d id not rece i ve any p lough ing in 1983 but had r e c e i v e d c o n s i d e r a b l e ra in fa l l ove rw in te r (Append ix 8). Th is may have resu l ted in sea l i ng and c o m p a c t i o n of the su r face f e w m i l l i m e t e r s of the s o i l and had an adve rse e f f e c t on aera t ion and w a r m i n g . P o o r aera t ion may have resu l ted in den i t r i f i ca t ion and in c o m b i n a t i o n w i th s l o w e r w a r m i n g may have d e c r e a s e d m ine ra l i za t i on . D e c r e a s e d m ine ra l i za t i on may have con t r i bu ted to the l ower minera l N va lues f o l l o w i n g s lur ry app l i ca t i on in 1983 as c o m p a r e d to 1982. L o w e r m ine ra l i za t i on and /o r deni t r i f i ca t ion o f s o m e o f the s o i l m inera l N in 1983 cou ld have con t r ibu ted to the l ower s o i l m inera l N va lue in that year 115 c o m p a r e d to 1982. For al l the s lurry ra tes , m a x i m u m m ine ra l i za t i on of o rgan ic N occu r red t w o mon ths af ter app l i ca t i on (Table 25). S i n c e s ign i f i can t amounts of N we re taken up by the corn c rop dur ing th is pe r i od it cou ld read i l y bene f i t f r o m the s lur ry t rea tment . Tunney (1975) and M c A l l i s t e r (1977) repor ted s i m i l a r c rop y i e l d s when the sou rce of N w a s ei ther s w i n e s lur ry or c o m m e r c i a l f e r t i l i ze r . The p resence of a s i gn i f i can t p ropo r t i on o f s lur ry N in inorgan ic f o r m , and re la t i ve l y quick m ine ra l i za t i on of i ts o rgan ic f r ac t i on w e r e thought to be r e s p o n s i b l e . S o i l p lus c rop N con ten t fo r the in jec t ion m e t h o d w a s higher than fo r the b roadcas t me thod throughout the 1982 and 1983 g row ing s e a s o n s fo r the con t ro l and for al l the s lur ry rates (Table 26). Th is sugges ts higher s o i l N m ine ra l i za t i on and greater s lu r ry N c o n s e r v a t i o n fo r the in jec t ion m e t h o d . In 1982, 32 kg h a - 1 more of s o i l m inera l N w a s present in the in jec ted than the b roadcas t con t ro l p l o t s . S i m i l a r resu l ts we re o b s e r v e d in 1983 as w e l l . Th is bene f i c i a l e f f e c t of in jec t ion t reatment on s o i l N mine ra l i za t i on cou ld have resu l ted f r o m more favou rab le s o i l cond i t i on for the m ine ra l i za t i on p r o c e s s . It can a l so be seen f r o m the s a m e tab le that i r r espec t i ve o f the me thod or rate a greater percen tage (55%) of the c rop N uptake dur ing the s e c o n d month af ter p lan t ing w a s p r o v i d e d by the s o i l in 1982 as c o m p a r e d to the s lur ry t reatment (45%). A t f ina l harvest (4 mon ths later) the con t r i bu t i ons of the s o i l and s lur ry N in plant N nut r i t ion w e r e a l m o s t equa l . In 1983 a greater p ropo r t i on of the c rop N w a s p r o v i d e d by the s lu r ry t reatment c o m p a r e d to s o i l N ove r the ent i re g r o w i n g s e a s o n . Th is e f f e c t w a s mo re p ronounced at t w o months be ing 6 1 % (s lurry) and 39% (so i l ) r e p e c t i v e l y than at f ina l ha rves t . The greater amoun t o f s o i l m inera l N in 1982 (185 kg h a - 1 ) c o m p a r e d to 1983 (159 kg Table 26. Soil + Crop N content at different sampling periods (1982, 1983). Time after Application (months) 1 M a n u r e T r p a f m p n f (r h a - 1 ) .... .... n Hn 19H Broadcast Injection 1982 1983 1982 1983 Broadcast Injection 1982 1983 1982 1983 \rp h a - 1 Broadcast Injection 1982 1983 1982 1983 112 129 105 148 259 218 272 348 382 354 433 406 2 126 141 141 137 (77) (47) (87) (54) 320 343 456 386 (139) (126) (159) (137) 391 354 555 515 (133) (118) (161) (130) % o f Crop N *from s o i l **from slurry treatment 55 37 55 39 45 63 45 61 58 40 54 41 42 60 > 46 58 4 153 139 185 159 (117) (92) (146) (111) 377 291 499 382 (232) (193) (296) (229) 417 332 548 537 (239) (183) (272) (220) % o f Crop N *from s o i l **from slurry treatment 50 48 49 48 50 52 51 52 49 50 54 50 51 50 46 50 Figures within parentheses indicate Crop N uptake. *% of crop N from s o i l = Control Plant N x 100 **% of crop N from treatment = Treated Plant N Treated Plant N - Control Plant N Treated Plant N cn 117 h a 1 ) p robab l y resu l ted in th is d i f f e r e n c e . G . Percent accountable slurry N Percent accoun tab le s lur ry N ove r the ent ire g row ing s e a s o n fo r al l the y e a r s , rates and me thods have been ca lcu la ted f o l l o w i n g the equat ion g i ven b e l o w and is p resen ted in Tab le 27. ( T S M N + T C r N ) - ( C S M N + C C r N ) P A S N = X 100 T K N app l ied (Table 9) Where T S M N =Trea ted s o i l m inera l N (Table 23) T C r N = Trea ted C r o p N (Table 17) CCrn = Con t ro l C rop N (Table 17) C S M N = Con t ro l s o i l m inera l N (Table 23) „ P A S N = Percent accoun tab le s lur ry N In the ca l cu la t i on the amount o f inorgan ic fe r t i l i zer N banded near the c rop r o w over the ent i re exper imenta l area each year (Table 7) has not been taken into c o n s i d e r a t i o n . Th is is because the fe r t i l i ze r N w i l l a f f ec t both the t reated and the con t ro l s o i l and /o r c rop N va lues and , t he re fo re , w i l l not change the percent accoun tab le s lu r ry N . A greater pe rcen tage of the app l i ed N w a s accoun tab le w h e n the s lur ry w a s in jec ted rather than b roadcas t and m a x i m u m N accoun tab le w a s ob ta ined t w o mon ths af ter a p p l i c a t i o n . N r e c o v e r y w a s greatest fo r the in jec ted 80 t h a - 1 rate w h i c h ind ica ted an app rec iab le amount o f N l o s s e s f r o m the 160 (1981) and 120 (1982, 1983) t h a - 1 ra tes . The l o w accoun tab le N va lue in 1981 c o u l d have resu l ted f r o m the p o o r c rop y i e l d and late s o i l s a m p l i n g in that yea r . By the end of the 1982 g row ing s e a s o n 153 and 185 kg h a - 1 o f m inera l N Table 27. Percent accountable s l u r r y N (1981, 1982 and 1983). Time af t e r a p p l i c a t i o n (month) Slurry treatment (t h a - 1 ) Broadcast 80 Injection Broadcast 120 In j e c t i o n 160 Broadcast Injection 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1 2 4 5 — 44 29 — 58 65 — 67 49 23 — — — 50 65 — 94 81 — 94 72 47 — — — 50 53 — 49 50 — 49 45 61 60 77 88 68 88 14 28 119 w e r e r e l eased (0 -90 c m ) f r o m the con t ro l b roadcas t and in jec t ion p lo t s (Table 26) and fo r the 1983 g row ing s e a s o n the c o r r e s p o n d i n g va lues were 139 and 159 kg h a - 1 (Table 26). Th is ind ica ted that the in jec t ion in i tse l f f ac i l i t a t ed m ine ra l i za t i on of o rgan ic N p o s s i b l y through i m p r o v e d s o i l ae ra t ion . Improvemen t of s o i l p h y s i c a l c o n d i t i o n s f r o m deep p l o w i n g of subsu r face c o m p a c t e d s o i l and its bene f i c i a l e f f ec t on c rop g rowth have been repor ted b y . B r a i m et a l . (1984). H. N balance A n n u a l , and overa l l s u m m a r y N ba lance shee ts have been ca l cu la ted fo r the yea rs 1981, 1982 and 1983. In ca l cu la t i ng the amount of N a d d e d , the in i t ia l s o i l minera l N (0 -90 cm) , inorgan ic fe r t i l i ze r N and the s lur ry T K N were added together fo r the t reated p lo t s and in i t ia l s o i l m inera l N (0 -90 c m ) and inorgan ic fe r t i l i ze r N for the con t ro l p l o t s . In ca l cu la t i ng the amount of N that can be accoun ted fo r at the end of the g r o w i n g s e a s o n , the N in the c rop and minera l N present in the s o i l s a m p l e c o l l e c t e d af ter f ina l harves t w e r e added toge ther . The amount of N added w a s sub t rac ted f r o m the amount of N accoun ted for to ob ta in N unaccoun ted fo r . In 1981 amoun ts o f 220 and 144 kg of the added N (Table 28) c o u l d not be accoun ted fo r f o l l o w i n g the 80 t h a - 1 rate b roadcas t and in jec ted , r e s p e c t i v e l y . C o r r e s p o n d i n g va lues fo r the 160 t h a - 1 rate w e r e 535 and 447 kg N. It is ev iden t f r o m the s a m e tab le that the amount o f N unaccoun ted fo r i nc reased w i th the inc rease in N add i t i on and that mo re N w a s unaccoun ted fo r when the s lur ry w a s b roadcas t than when a c o m p a r a b l e rate w a s in jec ted . Greater N l o s s e s f r o m the higher rate and the b roadcas t app l i ca t i on m e t h o d w e r e e v i d e n c e d f r o m percent accoun tab le N c a l c u l a t i o n s as w e l l . B e c a u s e 1981 w a s a poo r g r o w i n g s e a s o n , plant harves t w a s Table 28. Nitrogen Balance - 1981 Experiment. Slurry Appli-cation rate t h a - 1 S o i l Mineral kg ha"' F e r t i l i z e r N kg ha" 1 Slurry TKN kg ha" 1 Total I n i t i a l N kg ha" 1 End of season Crop & S o i l N kg ha" 1 Total N accounted for End of season Crop & S o i l N kg ha"' Total N accounted for N unaccounted for • (N accounted for) - (N added) kg ha"' Broadcast Injection Broadcast Injection Broadcast Broadcast kg ha" 1 i n j e c t i o n Injection kg ha"' Broadcast i n j e c t i o n Crop S o i l Crop S o l i 0 58 58 18 0 76 76 71 31 102 79 23 102 + 26 + 26 80 58 58 18 321 397 397 125 52 177 171 82 253 -220 -144 120 — — — Not applied In 1981 160 58 58 18 653 729 729 102 92 194 136 146 282 -535 -447 121 d e l a y e d that year to p rov ide m a x i m u m t ime for c rop matura t ion and the pos t harves t s o i l s a m p l e w a s c o l l e c t e d in N o v e m b e r . A b o u t 90% o f the s o i l m inera l N w a s present in N C y f o r m at that t i m e . S o i l T K N data (Append ix 9) d id not ind ica te any s i gn i f i can t f r ac t i on of th is N enter ing into the so i l o rgan ic p o o l through m ic rob ia l i m m o b i l i z a t i o n as there w a s no s ign i f i can t d i f f e rence in the T K N va lues o f the s o i l samp le c o l l e c t e d be fo re and at the end o f three years of f i e l d expe r imen t s . A to ta l of 245 m m rain fe l l in Oc tobe r 1981. It c o u l d , t he re fo re , be a s s u m e d that a c o n s i d e r a b l e amount of NO3--N might have been leached b e l o w the s a m p l i n g depth or den i t r i f i ed . S o i l m inera l N va lues fo r the pos t harvest 1981 s a m p l e date were c o n s i d e r a b l y l owe r than those of 1982 and 1983 fo r the s a m e p e r i o d . In 1981, 82 kg N h a - 1 were present in the pos t harvest s o i l s a m p l e that r e c e i v e d in jec ted 80 t h a - 1 o f s w i n e s lur ry (Table 28). C o r r e s p o n d i n g va lues for 1982 and 1983 we re 203 (Table 29) and 153 (Table 30) kg N h a - 1 r e s p e c t i v e l y . In 1982 and 1983 pos t harves t s o i l s a m p l e s w e r e c o l l e c t e d in S e p t e m b e r i m m e d i a t e l y b e f o r e crop ha rves t . L o w e r ra in fa l l and leach ing be tween the c e s s a t i o n of c rop N uptake and the f ina l s o i l s a m p l i n g might have resu l ted in th is d i f f e r e n c e . A g a i n , a poo r c rop y i e l d resu l ted in s i g n i f i c a n t l y l owe r N uptake fo r all the rates and me thods in 1981 (Table 28), c o m p a r e d to 1982 and 1983 (Tables 29 and 30). L o w e r N up take , and p resence of h igher minera l N in s o i l ( espec ia l l y in N 0 3 - f o r m ) m a y have con t r ibu ted to the greater N l o s s e s . There w e r e s i gn i f i can t quant i t ies of res idua l N in the so i l p ro f i l e of the 80 t h a - 1 t rea tment f o l l o w i n g the 1982 and 1983 g r o w i n g s e a s o n s (Table 23). Th is rate p roduced m a x i m u m co rn y i e l d s . It appea red , the re fo re , that , e i ther the c rop d id not require al l the N supp l i ed at that ra te , or that it w a s bene f i t t i ng the c rop in add i t i on to the ava i l ab le N it supp l i ed . Table 29. Nitrogen Balance - 1982 Experiment. Slurry Appli-cation Rate t ha" 1 S o i l Mineral kg ha" 1 F e r t i l i z e r N kg ha"' Slurry TKN kg ha" 1 Total I n i t i a l N kg ha" 1 End of Season Crop & S o i l N kg ha" 1 Total N accounted for End of Season Crop & S o i l N kg ha" 1 Total N accounted for N unaccounted for -(N accounted for) - (N added) kg h a - 1 Broadcast Injection Broadcast Injection Broadcast Broadcast kg ha" 1 Inject ton Injection kg ha"' Broadcast Injection Crop S o i l Crop S o i l 0 115 110 25 0 140 135 117 36 153 146 39 185 + 13 + 50 80 107 118 25 336 468 479 232 145 377 296 203 499 - 91 + 20 120 113 162 25 538 676 725 239 178 417 272 276 548 -259 -177 160 Not applied In 1982 • Table 30. Nitrogen Balance - 1983 Experiment. Slurry Appli-cation rate t ha"' S o i l Mineral kg ha" 1 F e r t i l i z e r N kg ha" 1 Slurry TKN kg ha" 1 Total I n i t i a l N kg ha"' End of Season Crop & S o i l N kg ha" 1 Total N accounted for End of Season Crop & S o i l N kg ha" 1 Total N accounted for N unaccounted for " (N accounted for) - (N added) kg ha Broadcast|Injection Broadcast Injection Broadcast Broadcast kg/ha Injection InJectIon kg/ha Broadcast Injection Crop S o i l Crop S o i l 0 69 40 40 0 109 109 92 47 139 111 48 159 + 30 + 50 80 94 126 40 309 443 475 193 98 291 230 153 383 -152 - 92 120 144 153 40 430 614 623 183 149 332 220 317 537 -282 - 86 CO 124 S lu r r y supp l i ed add i t iona l P and K (Append ix 10) in add i t i on to the amoun ts o f these nutr ients added as fe r t i l i ze r . S lu r ry a l so p r o v i d e d s o m e s e c o n d a r y and t race e l e m e n t s and o rgan ic mat ter . A t the end of the 1982 g r o w i n g s e a s o n 67 and 94% of the app l ied N we re accoun ted fo r w i th the 80 t h a - 1 rate b roadcas t and in jec ted r e s p e c t i v e l y (Table 27). C o r r e s p o n d i n g va lues for the s a m e rate 1983 we re 49 and 72%. The resu l ts sugges t that 3 0 - 5 0 % o f the app l i ed N we re los t dur ing the g r o w i n g s e a s o n when 80 t h a - 1 rate w a s b roadcas t c o m p a r e d to 6 - 2 8 % w h e n in jec ted . Higher N l o s s e s we re r eco rded fo r the b roadcas t 120 t h a 1 ra te. Greater N l oss f r o m the b roadcas t c o m p a r e d to the in jec t ion t reatment ove r the g row ing s e a s o n cou ld resul t ma in l y f r o m the v o l a t i l i z a t i o n o f N H 3 and , leach ing and or deni t r i f i ca t i on of N 0 3 ~ . Qu ick c o n v e r s i o n of N H 4 + to N O f in the c a s e of the b roadcas t t reatment ( ind ica ted ear l ie r ) cou ld fac i l i t a te th is l o s s in the a b s e n c e of greater c rop demand ve ry ear l y in the g r o w i n g s e a s o n (0-1 mon th af ter seed ing ) . In ject ing s w i n e s lur ry as o p p o s e d to b r o a d c a s t i n g resu l ted in greater amoun ts o f c a r r y - o v e r N f r o m one s e a s o n to another and m i n i m i z e d N l o s s e s . In 1981 and 1982, 2 and 16% of the app l i ed IM w e r e ca r r ied ove rw in te r w h e n 80 t h a - 1 o f s w i n e s lur ry we re i n jec ted . C o r r e s p o n d i n g va lues fo r the b roadcas t t rea tment w e r e 0 and 7% (Table 31). L o w e r c a r r y - o v e r N va lues in 1981 resu l ted f r o m the greater N l o s s pr ior to the f i na l s a m p l i n g in that year c o m p a r e d to 1982. W h e n 80 t h a - 1 o f s w i n e s lu r ry w e r e b roadcas t in 1981 and 1982, 100 and 77%, r e s p e c t i v e l y , we re los t o v e r w i n t e r . C o r r e s p o n d i n g va lues fo r the in jec t ion t reatment fo r the s a m e rate w e r e 86 and 65%. A b o u t 8 0 - 9 0 % of the res idua l m inera l N w a s present in the f o r m of N 0 3 ~ at the end of each g r o w i n g s e a s o n . The expe r imen ta l s i te r ece i ved 1400 m m rain be tween O c t o b e r 1981 to A p r i l Table 31. Carry-over N and Overwinter N Losses (1981, 1982 and 1983). Slurry application rate Method of application Time of N measurement and amount present In the s o i l Changes in N over control (Residual N) Time of N measurement and amount present in the s o i l Changes Carry-over Overwinter in N over control (Carry-over N) N as % of the applied N N loss kg ha - 1 % of the residual N (t ha" 1) F a l l 1981 kg ha -1 Spring 1982 kg ha - 1 Broadcast Injected 31 23 115 110 80 Broadcast Injected 52 82 21 59 107 118 -8 +8 0 2 29 51 100 86 160 Broadcast Injected 92 146 61 123 113 162 -2 +52 0 8 63 71 100 58 F a l l 1982 Spring 1983 0 Broadcast 36 — 69 — — — — Injected 39 — 69 — - — - — — 80 Broadcast 145 109 94 25 7 84 77 Injected 203 164 126 57 16 107 65 120 Broadcast 178 142 144 75 13 67 47 Injected 276 237 153 84 15 153 64 Overwinter N loss = Residual N - Carry-over N. 126 1982 and 1174 m m fo r the s a m e pe r i od in 1982 and 1983 (Append ix 8). S i n c e add i t i on of s w i n e s lur ry d id not s i g n i f i c a n t l y inc rease the s o i l o rgan ic N p o o l dur ing the cou rse of the exper imen t (Append i x 9), leach ing of N O j - cou ld be thought to be the major m e c h a n i s m o f these N l o s s e s . In ject ing 80 and 120 t h a " 1 o f s lu r ry in the sp r ing of 1982 resu l ted in ca r ry ing ove r of 57 (16%) and 84 kg (15%) of the app l i ed N r e s p e c t i v e l y to the 1983 g r o w i n g s e a s o n (Table 31). C o r r e s p o n d i n g va lues for the b roadcas t t rea tment we re 25 (7%) and 75 kg N (13%). There w a s a s i gn i f i can t e f f e c t o f rate on minera l N conten t of the s o i l fo r the f i r s t s a m p l i n g date in 1983. Th is ind ica ted that the amount N car r ied over i nc reased w i th the inc rease in app l i ca t i on rate. M o s t of th is res idua l N w a s present in the 3 0 - 6 0 and 6 0 - 9 0 c m z o n e s of the s o i l p r o f i l e (Table 23). T h e r e f o r e , the ava i l ab i l i t y o f th is N w i l l ve ry much depend on the roo t i ng pat tern of o f the c rop to be g r o w n . F r o m the resu l ts of th is research m o s t o f the c o m roo ts w e r e f ound to be a c t i v e l y a b s o r b i n g mo is tu re and nutr ients f r o m the 0 - 4 5 c m dep th . In the event of a shor tage of mo is tu re or nut r ien ts , co rn roo ts have the po ten t ia l to acqu i re them f r o m deeper dep ths . The to ta l amount of N app l i ed in the s lur ry ove r the ent i re exper imen ta l pe r i od f r o m the 80 , 120 and 160 t h a - 1 r a tes , i ts r emova l in p lan ts and a c c u m u l a t i o n in s o i l , and l o s s f r o m the s y s t e m are s h o w n in Tab le 32 and s o m e of the c a l c u l a t i o n s i n v o l v e d are g i ven b e l o w : 1. N app l ied as s lur ry = ZSIu r ry T K N app l i ed each year 2. N r e m o v e d in c r o p s = L ( N in the t reated c r o p s - N in the con t ro l c rops at the end o f each g r o w i n g s e a s o n ) 3. N rema in ing in the s o i l = Z S o i l m inera l N at the end o f each g r o w i n g s e a s o n Table 32. N-balance after slurry application for 3 years. Addition and Losses Slurry Rate ; 80 t h a - 1 Broadcast Injection Slurry Rate 120 or 160 t h a - 1 Broadcast Injection Applied as slurry 966 (Amount of N kg ha - 1) 966 1621 1621 Removed in crops (- N in the Controls) 270 361 244 292 Remaining in the s o i l (end of the growing seasons) 295(31) 438(45) 419(26) 739(46) Total N accounted for 565 799 663 1031 Total loss from the system over the growing seasons 401 Annual loss over the growing season 134 167 56 958 319 590 197 Figures within the parentheses are percent of the applied N in the s o i l . 128 4. To ta l N accoun ted for = N r e m o v e d in c rops + N rema in ing in the s o i l 5. To ta l l o s s f r o m the s y s t e m = L S I u r r y N app l ied - To ta l N accoun ted for 6. Annua l l oss = To ta l l o s s f r o m the . s y s t e m / N o . of s e a s o n s The amount of N rema in ing in the s o i l w a s l ower when s lur ry w a s b roadcas t rather than in jec ted . A n n u a l l y 134 kg h a - 1 o f N were los t dur ing the g r o w i n g s e a s o n when 80 t h a " 1 of s lu r ry we re b roadcas t c o m p a r e d to 56 kg when the same rate w a s in jec ted (Table 32). The greater N l o s s e s f r o m the b roadcas t s lur ry might have resu l ted f r o m the vo l a t i l i za t i on of N H 3 . V o l a t i l i z a t i o n and i m m o b i l i z a t i o n are thought be the major m e c h a n i s m s of N l o s s e s dur ing the g r o w i n g s e a s o n . Ove rw in te r N l o s s e s , on the other hand, we re higher fo r the in jec t ion me thod c o m p a r e d to the b roadcas t me thod because s i g n i f i c a n t l y higher amoun ts o f res idua l N rema ined in the s o i l f r o m that me thod (Table 31). In 1981, 51 kg h a 1 o f N we re los t ove rw in te r w h e n 80 t ha1 were in jec ted as o p p o s e d to 29 kg when b roadcas t . C o r r e s p o n d i n g va lues fo r 1982 w e r e 107 and 84 kg h a - 1 r e s p e c t i v e l y fo r the s a m e quant i ty (Table 31). Ove rw in te r N l o s s va lues were l ower in 1981 c o m p a r e d to that of 1982 because of the late pos t harvest s o i l s a m p l i n g in that year . S i g n i f i c a n t N 0 3 - leach ing l o s s e s p robab l y occu r red pr ior to s o i l s a m p l i n g , thereby lower ove rw in te r N l o s s e s were measu red . F r o m the d i s c u s s i o n s o far , it is ev ident that more N w a s present in the 15 -30 c m s e c t i o n of the s o i l w h e n s lur ry w a s in jec ted as o p p o s e d to the 0 - 1 5 c m when b r o a d c a s t . A b o u t 70% of the N that w a s car r ied over f r o m one g r o w i n g s e a s o n to the next w a s f o u n d to be present at lower s o i l dep ths (30 -60 and 6 0 - 9 0 cm) . I n fo rmat ion on the d i s t r i bu t i on pat tern 129 o f the corn roo ts cou ld shed s o m e l ight on h o w it 's g rowth is a f f e c t e d by the N concen t ra t i on and it 's l oca t i on in the s o i l p r o f i l e . I. R o o t r e s p o n s e t o s l u r r y N a p p l i c a t i o n Crop root r e s p o n s e to s lur ry N cou ld d i f f e r if the in jec t ion app l i ca t i on m e t h o d resu l ted in i nc reased concen t ra t i on of plant nutr ients w i th in the zone o f t rea tment . The d i s t r i bu t i on pat tern of the corn r oo t s o b s e r v e d in the present s tudy i m m e d i a t e l y af ter es tab l i shmen t of brace r oo t s (around 45 d a y s f r o m the date of p lan t ing) f r o m the p lo t s rece i v i ng 0, 160 t h a - 1 (1981) . and 0, 120 t h a - 1 (1982) ra tes d id not ind icate any d i f f e r e n c e in r e s p o n s e due to d i f fe ren t t r ea tmen ts . Th is cou ld sugges t that f r o m the rates a p p l i e d , su f f i c i en t a c c u m u l a t i o n of the plant nutr ients or t ox i c c o n d i t i o n s d id not occur w i th in the zone of in jec t ion app l i ca t i on s u f f i c i e n t l y to cause a d i f f e r e n c e in root r e s p o n s e . V I . SUMMARY AND CONCLUSIONS S i l a g e co rn dry matter y i e l d s inc reased in r e s p o n s e to s w i n e s lur ry app l i ca t i on rates of up to 80 t h a - 1 in 1981, 1982 and 1983. H o w e v e r , in 1981 the 160 t ha~' s lur ry rate s i g n i f i c a n t l y dec reased y i e l d s . M a x i m u m dry mat ter y i e l d s of 13.0 (1981), 24.8 (1982) and 21.0 t h a - 1 (1983) occu r red w h e n app rox ima te l y 80 t h a - 1 o f s w i n e s lur ry w i th a c o r r e s p o n d i n g to ta l s lu r ry N app l i ca t i on averag ing 320 kg h a - 1 were in jec ted . The in jec t ion app l i ca t i on me thod a l w a y s resu l ted in greater to ta l quant i t ies of s o i l m inera l N than the compa rab le rate b roadcas t . In the case of i n jec t ion t reatment re la t i ve ly more N w a s present in the 15 -30 c m s e c t i o n o f the s o i l as o p p o s e d to the 0 - 1 5 c m for the b roadcas t a p p l i c a t i o n . The in jec t ion app l i ca t i on me thod a l so inh ib i ted ear ly s e a s o n n i t r i f i ca t i on of s lu r ry N. Inject ing 80 t h a - 1 o f s lu r ry resu l ted in 1 9 - 3 7 % higher c rop N uptake ove r the s a m e quant i ty b roadcas t . A m a x i m u m quant i ty of N equ iva len t to 4 5 % o f the app l i ed s lur ry N w a s r e c o v e r e d by the corn c rop when the 80 t h a ' 1 rate w a s in jec ted as o p p o s e d to 34% w h e n the s a m e rate w a s b roadcas t . In add i t i on , the in jec t ion p r o c e s s appeared to inc rease the m ine ra l i za t i on of s o i l o rgan ic N . M a x i m u m rate of r e c o v e r y of s lu r ry N occu r red at t w o months af ter app l i ca t i on and a l w a y s w a s a s s o c i a t e d w i t h the 80 t h a - 1 rate in jec ted . Var iab le amoun ts of s lu r ry o rgan ic N were m ine ra l i zed ove r the g r o w i n g s e a s o n each yea r , p robab l y depend ing on the weather c o n d i t i o n s ( espec ia l l y tempera tu re and mo is tu re ) . B e t w e e n 4 0 - 8 6 % of the s lur ry o rgan ic N w a s m ine ra l i zed w h e n 80 t h a - 1 w e r e in jected as c o m p a r e d to 4 1 - 6 5 % f r o m the 120 t h a 1 rate. M a x i m u m net N m ine ra l i za t i on occu r red dur ing the s e c o n d mon th af ter s lur ry app l i ca t i on and w a s a l w a y s a s s o c i a t e d w i t h the 130 131 80 t h a - 1 ra te. Each year , ove r the g row ing s e a s o n on ly 6 - 2 8 % of the app l ied s lur ry T K N w a s los t dur ing the g row ing s e a s o n when 80 t h a - 1 of s lur ry we re in jec ted c o m p a r e d to 3 0 - 5 0 % when the s a m e amount w a s b r o a d c a s t . A s i gn i f i can t f r ac t i on of th is N l o s s fo r the b roadcas t t reatment p robab l y occu r red w i th in one month af ter a p p l i c a t i o n . Th is is because 1 9 - 4 1 % o f the s lur ry minera l N w a s v o l a t i l i z e d f r o m the 80 t h a " 1 rate b roadcas t dur ing that p e r i o d . In ject ion c o n s e r v e d s lur ry N , p robab ly through m i n i m i z i n g v o l a t i l i z a t i o n l o s s e s . S l o w e r n i t r i f i ca t i on rates reco rded f o l l o w i n g s lu r ry in jec t ion may have a l so inh ib i ted leach ing or den i t r i f i ca t i on l o s s e s . B e t w e e n 6 4 - 8 6 % of the res idua l minera l N in the s o i l f r o m the s lur ry t reatment w a s los t ove rw in te r when 80 t h a - 1 of s lu r ry we re in jec ted c o m p a r e d to 7 7 - 1 0 0 % w h e n the s a m e amount w a s b roadcas t . A b o u t 8 0 - 9 0 % of the fa l l res idua l s o i l m inera l N occu r red as N 0 3 - each year . There w a s no ind ica t ion of any o f the app l i ed s lur ry N enter ing into the s o i l o rgan ic p o o l . The exper imen ta l s i te r ece i ved 1400 m m p rec ip i t a t i on be tween Oc tobe r 1981 to A p r i l 1982 and 1174 m m be tween O c t o b e r 1982 to A p r i l 1983. T h e r e f o r e , leach ing of N 0 3 ~ w a s thought to be the major m e c h a n i s m of ove rw in te r N l o s s e s . The m e t h o d and the amount of s lur ry app l i ca t i on in f l uenced the quant i ty of the res idua l N that w a s car r ied ove r f r o m one g r o w i n g s e a s o n to the next . B e t w e e n 2 - 1 6 % o f the app l i ed N w a s car r ied over when 80 t h a - 1 o f s lu r ry w e r e in jec ted c o m p a r e d to 0 - 7 % when the s a m e amount w a s b r o a d c a s t . The c o r r e s p o n d i n g va lues for the 120 t h a - 1 rate w a s 8 - 1 5 and 0 - 1 3 % r e s p e c t i v e l y . In no c a s e d id the amount of N car r ied ove r e x c e e d 16% of that a p p l i e d . 132 A n amount of 120 t h a - 1 o f s lu r ry in jec ted to a depth o f 30 c m d id not have any N H 3 t o x i c i t y e f f e c t on seed ge rm ina t i on . Four w e e k s af ter a p p l i c a t i o n of th is ra te, the concen t ra t i on of N H 4 + + N 0 3 - " n the 0 - 2 0 c m s e c t i o n o f the s o i l w a s s i m i l a r la te ra l l y f r o m 0 -30 c m f r o m the center of the in jec t ion zone . A t depths b e l o w 40 c m , th is rate had ve ry l i t t le e f f ec t on minera l N c o n c e n t r a t i o n . The in jec t ion m e t h o d of app l i ca t i on is r e c o m m e n d e d fo r s lur ry w h e n e v e r it is used in c rop p r o d u c t i o n . Th is is because the in jec t ion m e t h o d m i n i m i z e s v o l a t i l i z a t i o n l o s s e s and resu l ts in mo re N ava i lab le f o r c rop uptake. T o produce about 25 t h a - ' dry mat te r , around 310 kg h a - 1 of N w e r e requ i red by the co rn c rop in the present r esea rch . T o meet th is requ i rement a p p r o x i m a t e l y 300 kg h a 1 o f s lu r ry T K N had to be app l ied on top of 150 kg h a - 1 o f N supp l i ed b y the s o i l . If a s o i l supp l i ed more or l e s s N than in th is s t u d y , s lu r ry N app l i ca t i on rate w o u l d have to be ad jus ted up or d o w n . Dur ing ad jus tment , about 25% more s lur ry N has to be a d d e d , if b roadcas t p lus i nco rpo ra t i on me thod is used as o p p o s e d to i n j ec t i on . Th is is because N uptake e f f i c i e n c i e s w e r e 34 and 43%, r e s p e c t i v e l y , fo r the b roadcas t and the in jec t ion m e t h o d s . Resu l t s of the present research d id not ind ica te any d i f f e rence in roo t r e s p o n s e due to s lu r ry in jec t ion c o m p a r e d to the c o n t r o l . M o r e research shou ld be car r ied out to unders tand the e f f e c t s o f i n jec t ion on s o i l p h y s i c a l p rope r t i es and c rop y i e l d s . VII . L I T E R A T U R E C I T E D A d r i a n o , D.C., P.F. Pratt and S . E . B i s h o p . 1971. 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Va r i a t i ons be tween f a r m s in N , P , K, M g and dry mat ter c o m p o s i t i o n o f ca t t le , p ig and pou l t ry manures . Irish J . A g r . R e s . 14 (1); 7 1 - 7 9 . Turner , D.O. 1975. On the f a rm de te rm ina t ion of an ima l w a s t e s d i s p o s a l rates fo r c rop p r o d u c t i o n . M a n a g i n g L i v e s t o c k W a s t e s . The p r o c . o f the 3rd Int. S y m p . of l i ves tock w a s t e s , A S A E , Pub . P r o c . 275 , pp . 5 8 7 - 5 9 0 . Unger , P.W. and B.A.. S t e w a r t . 1974. Feed lo t w a s t e e f f e c t on s o i l c o n d i t i o n s and wa te r e v a p o r a t i o n . S o i l S c i . S o c . A m . P r o c . J . 38 : 954-957.-V a l l i s , I., L .A . Harper , V.R. C a t c h p o o l e and K.L. W e i e r . 1982. V o l a t i l i z a t i o n o f a m m o n i a f r o m urine pa tches in a sub t rop ica l pas tu re . A u s t . J . A g r i c . R e s . 33 : 9 7 - 1 0 7 . V a n d e r h o l m , D.H. 1975. Nutr ient l o s s e s f r o m l i v e s t o c k w a s t e dur ing s to rage t reatment and hand l ing , pp . 2 8 2 - 2 8 5 . In: Manag ing L i v e s t o c k W a s t e . 158 P r o c . Int. S y m p . L i v e s t o c k w a s t e s , Urbana C h a m p a i g n , III., 2 1 - 2 4 A p r i l , 1975. A m . S o c . A g r i c . Eng . , S t . J o s e p h , M i c h i g a n . Van K l e e c k , R .J . and P.D.A. J o h n s o n . 1982. Urban in f luence on L i v e s t o c k W a s t e M a n a g e m e n t . Manure Hand l i ng , S to r age and A p p l i c a t i o n S y s t e m s . Paper p resen ted at the s u m m e r mee t i ng of the C S A E , C S A , and C S A S he ld at the U n i v e r s i t y of B r i t i sh C o l u m b i a , V a n c o u v e r , Canada on J u l y 13, 1982. V e i h m e y e r , F .G. and A . H . H e n d r i c k s o n . 1948. S o i l dens i t y and root pene t ra t i on . S o i l S c i . 65 : 4 8 7 - 4 9 3 . Ve t te r , H. and S t e f f e n s , G . 1978. The e f f ec t of n i t rogen in p ig s lu r r y , sp read out at d i f fe ren t app l i ca t i on t i m e s . In: J .K . G a s s e r (ed.) M o d e l l i n g N f r o m the W a s t e , pp . 4 4 - 6 1 . V o l k , G . M . 1959. V o l a t i l e l o s s e s of a m m o n i a f o l l o w i n g su r face a p p l i c a t i o n of urea to turf or bare s o i l s . A g r o n . J . 5 1 : 7 4 6 - 7 4 9 . V o l k , G . M . 1961. G a s e o u s l o s s of a m m o n i a f r o m sur face app l i ed n i t r ogenous f e r t i l i z e r s . J . A g r i c . F o o d C h e m . 9; 2 8 0 - 2 8 3 . W a g n e r , G.H. and G.E. S m i t h . 1958. N i t r ogen l o s s e s f r o m s o i l s f e r t i l i zed w i t h d i f fe ren t n i t rogen ca r r i e rs . S o i l S c i . 8 5 ; 125 -129 . W a h h a b , A . , M . S . Randhawa and S . Q . A l a m . 1956. L o s s o f a m m o n i a f r o m a m m o n i u m su l fa te under d i f f e ren t c o n d i t i o n s w h e n app l i ed to s o i l s . 159 S o i l S c i . 84 : 2 4 9 - 2 5 5 . W a l m s l e y , M „ G . U t z i g , T. V o i d , D. M o o n and J . V . Be rneve ld 1980. D e s c r i b i n g e c o s y s t e m s in the f i e l d s . Techn i ca l Paper 2. Br i t i sh C o l u m b i a M i n i s t r y of Env i rnment Resou rce A n a l y s i s B ranch , pp. 4 7 - 4 8 . W a r i n g , S . A . and J . M . Bremner . 1964. A m m o n i u m p roduc t i on in so i l under w a t e r l o g g e d c o n d i t i o n s as an index of n i t rogen ava i l ab i l i t y . Nature . 2 0 1 : 9 5 1 - 9 5 2 . W a t k i n s , S .H. , R.F. S t r a n d , D.S. Debe l l and J . E s c h , J r . 1972. Fac to rs in f l uenc ing a m m o n i a l o s s e s f r o m urea app l i ed to no r thwes te rn fo res t s o i l s . S o i l S c i . S o c . A m . J . 36 : 3 5 4 - 3 5 7 . Webbev , L.R. and T .H. Lane. 1969. The n i t rogen p r o b l e m in the land d i s p o s a l o f l iqu id manure . A n i m a l w a s t e managemen t . Co rne l l U n i v e r s i t y C o n f . on Ag r i cu l t u ra l W a s t e M a n a g e m e n t , pp . 1 2 4 - 1 3 0 . W h i t e , R.K. and L . M . S a l f l e y . 1984. O p t i m u m land u t i l i za t i on of manure . T r a n s a c t i o n s o f the A S A E , 27(2): 5 2 0 - 5 2 4 . W i l l i a m s , T .E. and M.V. J a c k s o n . 1976. The r e c o v e r y of fe r t i l i ze r n i t rogen in herbage and s o i l . U.K. M i n i s t r y of Ag r i cu l t u re F i she r i es and F o o d , T e c h . B u l l . 3 2 ; 1 4 5 - 1 5 2 . W i n t o n , E.F. 1970. The heal th e f f e c t s of n i t ra tes in wa te r In: Ni t ra te and wa te r s u p p l y : S o u r c e and c o n t r o l . P r o c . T w e l f t h . San i t a r y Eng in . Con f . , 160 Urbana , II. Z i m m e r m a n , R.P. and L.T. Ka rdos . 1961. E f f ec t of bulk dens i t y on root g row th . S o i l S c i . 9 1 - 9 2 : 2 8 0 - 2 8 8 . 161 Appendix 1. F i e l d d e s c r i p t i o n of the s o i l used In the study. S o i l c l a s s i f i c a t i o n : Gleyed Podzollc Gray L u v l s o l , Can. (Aqualfic Haplorthod, U.S.) Location: Langley 232nd Street, 60 km east of Vancouver, B.C. Horizon Depth Description (cm) Ap 0-20 Dark brown (7.5 YR 3.0/2.0, m); s i l t loam; moderate medium subangular blocky; f r i a b l e ; abundant roots; abrupt boundary to: Bf 20-32 Dark gray (7.5 YR 4.0/4.0, m); s i l t loam; moderate medium subangular blocky; f r i a b l e ; few fi n e faint mottles; abundant roots; clear boundary to: Bmgj 32-47 Dark yellowish brown (10.0 YR 4.0/4.0, m); s l l t y clay; moderate medium to coarse subangular blocky; firm; common medium d i s t i n c t 7.5 YR 5.0/7.0 mottles; abundant roots; c l e a r boundary to: Aeg 47-62 Grayish brown (2.5 Y 5.0/2.0, m); s l l t y clay; moderate medium to coarse subangular blocky; firm; common medium d i s t i n c t 7.5 YR 7.0/6.0 mottles; p l e n t i f u l roots; clear boundary to: Btgl 62-77 Gray (5.0 Y 5.0/1.0, m); heavy clay; moderate to strong coarse prismatic; firm; common medium prominent 7.5 YR 5.0/7.0 mottles; few; gradual boundary to: Btg2 77-98 Gray (5.0 Y 5.0/1.0, a); heavy clay; moderate to strong coarse prismatic; very firm; common medium prominent 5.0 YR 2.0/2.0 mottles; gradual boundary to: BC 98-117 Dark grayish brown (2.5 Y 4.0/2..0, m); s l l t y clay; moderate to strong medium to coarse angular blocky pseudo; common medium d i s t i n c t 10.0 YR 4.0/4.0 mottles; d i f f u s e boundary to: Cg 117+ Dark grayish brown (2.5 Y 4.0/2.0, m); s i l t y clay; moderate to strong medium to coarse angular blocky pseudo; common medium d i s t i n c t 10.0 YR 4.0/4.0 mottles. Appendix 2. Selected physical and chemical properties of soils used in thesis research, 1981-1983. Texture Depth cm Sand S i l t % -Clay Bulk density kg m"^  Exch. Na Exch. K - me.g" Exch. Ca -100 Exch. Mg CEC pH7 Total Total C N % C/N ratio pH CaCl 2 S i l t y , clay loam 0-15 6 60 34 922 0.19 0.16 6.47 0.81 30.3 4.8 0.45 10.6 4.5 Silty, clay loam 15-30 6 58 36 990 0.14 0.13 2.26 0.76 25.2 3.1 0.34 9.1 4.6 Sil t y clay 30-60 2 51 47 1400 0.41 0.24 5.75 7.40 34.4 0.5 0.17 2.9 5.0 Heavy clay 60-90 1 39 60 1250 1.35 0.40 13.0 17.10 40.6 0.3 0.08 3.7 5.4 Appendix 3. Ratio 16% SOW RATION R E G I S T R A T I O N N O . : 23739 G U A R A N T E E D A N A L Y S I S : M i n . C r u d e P r o t e i n . . M i n . C r u d e F » t M i l . C r u d e F i b r e . . . S a i l ( a c t u a l ) C a l c i u m ( a c t u a l ) — P h o s p h o r u s ( a c t u a l ) M i n . V i t a m i n A M m V i t a m i n D M i n . V i t a m i n E Z i n c ( a c t u a l ) . . . T h e i n g r e d i e n t s u s e d i n t h i s f e e d i r e t h o s e n a m e d i n t h e C e r t i f i c a t e o f R e g i s t r a t i o n . T h i s f e e d c o n t a i n s a d d e d s V . l e n i u m a t 100 m g / t o n r . *. D I R E C T I O N S F O R U S B : F e e d a a t h e s o l e r a t i o n . C A U T I O N : O v e r d o s e s o f S e l e n i u m a r e t o x i c . D i r e c t i o n s f o r u s e m u s t b e c a r e f u l l y f o l l o w e d . 16% W> 6% 0.5% 0.8% 0.6% 8.000 I . U . / k g 1.325 I . U . / k g ...20 l . U . / k g 0.01% W A L L b R E D E K O P F E E D S L T D . B o x 333. 3067 T u r n e r R o a d . A b b o l s f o r d . B . C . Telephone- MfMKSl o r M0-06U supplied to the animals (1981, 1982 and 1983) 16% HOG GROWER R E G I S T R A T I O N N O . : 23740 G U A R A N T E E D A N A L Y S I S : M i n . C r u d e P r o t e i n 16% M i n . C r u d e F a t 3% M a x . C r u d e F i b r e 6% S a l t ( a c t u a l ) 05% C a l c i u m ( a c t u a l ) 0.8% P h o s p h o r u s ( a c t u a l ) 0.6% M i n . V i t a m i n A 8.000 I . U . / k g M i n V i t a m i n D BOO I . U . / k g M i n . V i t a m i n E £0 I . U . / k g Z i n c ( a c t u a l ) 0.01% T h e i n g r e d i e n t s u s e d i n thiB f e e d a r e t h o s e n a m e d i n t h e C e r t i f i c a t e o f R e g i s t r a t i o n . T h i s f e e d c o n t a i n s a d d e d a e l e n U u n a t 100 m g / t o n n e . D I R E C T I O N S F O R U S E : F e e d a s t h e s o l e r a t i o n f r o m 25 k g b o d y w e i g b t t o m a r k e t i n g . C A U T I O N : O v e r d o s e s o f S e l e n i u m a r e t o x i c . D i r e c t i o n s f o r u s e m u s t b e c a r e f u l l y f o l l o w e d . 18% MEDICATED PIG WEANER M E D I C A T E D W I T H : T y l o a i n p h o s p h a t e a t 0.0044% a n d F u r a z o l i d o n e a t 0.022% a a a n a i d i n t h e p r e v e n t i o n o f b a c t e r i a l e n t e r i t i s i n s t a r t e r p i g s a s s o c i a t e d w i t h s w i n e d y s e n t e r y a n d E s c h e r i c h i a coil i n f e c t i o n s s e n s i t i v e t o t y l o e i n a n d / o r f u r a z o l i d o n e . R E G I S T R A T I O N N O . : 20033 G U A R A N T E E D A N A L Y S I S : M i n . C r u d e P r o t e i n 18% M i n . C r u d e F a t 3.5% M a x . C r u d e F i b r e 6.0% S a l t ( a c t u a l ) 0.5% C a l c i u m ( a c t u a l ) 1.0% P h o s p h o r u s ( a c t u a l ) 0.75% M i n . V i t a m i n A 8,000 I . U . / k g M i n . V i t a m i n D B O O I . U . / k g M i n V i t a m i n E 20 I . U . / k g Z i n c ( a c t u a l ) 0.010% T h e i n g r e d i e n t s u s e d i n t h i s f e e d a r e t h o s e n a m e d i n t h e C e r t i f i c a t e o f R e g i s t r a t i o n . T h i s f e e d c o n t a i n s a d d e d s e l e n i u m a t 100 m g / t o n n e . D I R E C T I O N S F O R U S E : 9 e d a s t h e s o l e r a t i o n f o r 21 d a y a t o p i g s in t h e 10-20 k g . ' / e w e i g h t r a n g e . W A R N I N G : 1. T r e a t e d a n i m a l s m u s t n o t b e s l a u g h t e r e d f o r u s e i n f o o d f o r a t l e a s t f i v e d a y s a f t e r t h e l a t e s t t r e a t m e n t w i t h t h i s d r u g . C A U T I O N S : 1. T h i s f e e d i s t o b e f e d t o s t a r t e r pigs o n l y . 2. O v e r d o s e s o f S e l e n i u m a r e t o x i c . D i r e c t i o n s f o r use m u s t b e c a r e f u l l y f o l l o w e d . Telephone: 8M-4861 or 6MMMIS Telephone. 85H-4861 or K30-081I Appendix 4. Crop N uptake and dry matter yiel d (1981) Method Broadcast Injection Rep. I 0 40 80 160 DMY* H0«* DOT j(U DMY _N0 DMY JJO 8 96 11 US 13 147 8 103 9 101 12 149 14 194 9 143 Rep.II .Slurry application rate (t h a - 1 ) -0 40 80 160 Rep.Ill DMY NU DMT Nil DMY _N0 DMY _NU 6 66 8 93 9 111 9 112 6 73 10 109 13 159 10 147 0 40 80 160 DMY NU DMY NU DMY HO DMY NO 5 50 7 87 10 115 7 89 6 63 8 91 12 159 9 119 •Dry natter yi e l d In t h a - 1 . **N uptake In kg ha -> Appendix 4.1. Crop N uptake and dry matter y i e l d (1982 and 1983). Rep. I Rep.II Rep.Ill S l n r r v A n n l l r j i H on rate It h«-0 40 80 120 0 40 30 120 0 40 80 120 Year Method DMY* NU" DMY NU DMY NU DMY NU DMY NU DMY NU DMY NU DMY NU DMY NU DMY NU DMY NU DMY NU Broadcast 17 no 19 149 22 243 21 216 18 124 19 166 22 203 " 23 241 18 113 19 192 23 249 22 261 1982 Injection 18 129 20 157 24 284 22 255 19 141 19 171 25 291 24 278 19 167 20 210 25 312 23 184 Broadcast 14 97 IS 151 21 211 19 199 13 84 16 135 19 191 18 174 13 93 14 124 17 174 18 176 1983 Injection 15 no 18 186 23 247 20 223 14 113 17 181 20 207 20 209 14 111 17 161 20 235 21 229 *Dry matter y i e l d In t ha . **N uptake In kg h a - 1 . 166 Appendix 5. Crop N uptake and TKN applied (Broadcast and Injected) 1982 and 1983. T r i -\ a n A N Year applied N uptake N uptake (kg ha" 1) Rep. I Rep. II Rep. I l l Rep. I Rep. II Rep. I l l kg-ha - 1 0 110 124 113 129 141 167 1982 157 149 166 192 157 171 210 336 243 203 249 284 291 312 0 97 84 93 110 113 111 1983 163 151 135 124 186 181 161 309 211 191 174 247 207 235 Appendix 6. S o l i N H i , and N O 3 - N content before and 1, 2 and 4 months after application of swine slurry (1982 and 1983). Tine S o l i After Depth Application Honth (c«) 0-15 Before 15-30 30-60 60-90 Total 0-15 15-30 1 30-60 60-90 Total 0-15 15-30 2 30-60 60-90 Total 0-15 15-30 4 30-60 60-90 Total Broadcast Injection 1982 Kh\ NO 3 kg ha" 5.3 6.6 8.3 5.7 1983 N H \ NO 3 1982 N H i , NO 3 1983 NHt, N O 3 12.9 13.7 34.9 27.9 5.1 5.6 8.1 7.1 10.9 8.2 13.0 10.4 6.8 6.2 10.6 10.3 13.1 10.2 27.1 25.6 4.4 6.1 9.0 7.2 9.9 8.8 13.5 10.3 25.7 89.4 25.9 42.5 33.9 76.0 26.7 42.5 11.6 38.3 8.1 5.7 11.8 12.1 12.8 8.0 13.0 11.4 6.5 13.1 26.1 11.8 17.6 4.8 18.8 8.6 14.7 9.1 42.6 9.7 34.4 13.0 10.0 23.1 6.4 13.0 24.3 4.1 13.5 15.9 41.5 64.6 46.3 77.2 34.3 66.1 46.2 97.7 4.7 7.9 3.5 7.8 4.9 11.2 3.3 5.5 3.6 3.5 2.7 0.9 22.9 22.6 24.4 14.1 6.0 2.1 3.2 1.2 14.0 6.5 20.2 9.8 4.5 15.6 14.0 6.4 16.4 3.7 2.6 10.2 16.4 32.4 10.7 84.0 12.5 41.5 20.0 62.4 7.2 4.4 5.1 1.5 7.7 1.7 6.4 1.1 2.8 2.7 2.7 0.9 6.6 6.7 13.0 12.2 4.1 3.8 8.8 5.0 10.6 2.8 3.3 2.7 0.9 2.6 0.5 1.3 7.3 7.1 13.3 11.8 26.4 8.7 9.1 37.9 21.7 15.3 9.4 39.5 .Manure Treatment (t h a - 1 ) 80 Broadcast 1982 1983 . kg ha" ln j e c t l o n 1982 1983 NHt, N 0 3 Nn\ NO 3 NH„ NO 3 NH„ N 0 3 6.8 9.8 4.6 5.7 10.0 4.1 11.5 25.4 7.1 12.8 23.9 6.3 11.5 11.8 27.1 20.3 9.1 7.8 12.4 11.1 10.5 3.6 10.8 11.3 6.9 15.8 29.8 8.1 40.0 25.8 8.0 33.2 36.8 69.1 22.1 70.7 40.4 77.4 26.6 99.8 61.6 94.4 8.7 6.5 12.0 7.7 28.9 17.4 11.7 21.7 10.9 9.4 95.9 12.4 31.9 124.7 28.3 16.8 18.3 9.1 43.7 29.8 62.6 40.8 58.8 87.3 11.4 14.8 47.5 8.1 11.5 31.7 118.7 134.7 37.5 174.4 163.0 104.0 114.9 229.1 10.9 101.I 14.4 3.5 22.4 4.4 3.2 19.8 5.4 1.8 10.2 3.4 52.8 4.4 20.0 5.5 34.1 54.8 47.7 110.0 18.3 76.6 31.6 14.8 83.1 5.6 69.8 30.9 1.6 15.2 5.1 34.1 120 Broadcast 19.4 153.5 27.6 170.1 68.5 228.3 34.5 214.6 9.5 63.9 2.8 6.5 21.7 2.6 9.3 24.6 4.4 3.9 6.8 1.7 3.2 16.1 31.9 24.2 4.8 10.6 11.6 8.9 31.5 1.9 14.4 58.1 2.2 26.1 66.9 3.6 63.2 10.0 3.4 38.5 29.2 62.1 11.5 85.4 35.9 166.5 11.1142.2 1982 N H i , N O 3 5.4 11.6 3.9 12.6 9.3 33.3 7.0 28.5 • kg ha Injectlon 1983 m ^ NO, 8.8 12.7 5.0 18.4 8.1 48.7 7.6 35.0 1982 N H i , 11.8 16.9 23.6 15.7 NO 3 14.6 14.7 36.5 28.4 1983 N H i , N O , 4.1 12.1 4.1 15.6 8.9 55.4 6.7 46.5 25.6 86.0 29.5 114.8 68.0 94.2 23.8 129.6 61.0 153.3 7.5 20.7 30.0 42.8 23.6 37.9 15.6 146.7 25.5 12.2 46.2 148.6 19.0 42.6 20.7 20.1 47.1 10.1 91.1 35.7 50.2 60.5 74.8 106.3 47.8 23.4 61.2 23.9 11.4 37.2 122.4 254.7 66.9 282.6 204.9 223.3 145.3 254.9 11.4 126.2 3.7 11.8 45.8 5.4 8.1 30.3 4.5 4.1 20.0 3.4 70.4 10.2 40.4 3.8 46.6 73.5 56.4 152.5 68.0 102.5 46.8 17.7 88.1 22.6 77.0 28.4 2.5 25.5 4.3 59.3 35.4 222.3 17.0 219.1 86.8 306.5 98.7 285.4 6.2 70.9 3.6 4.7 46.0 3.0 8.4 25.7 4.4 6.0 9.7 3.4 17.2 22.3 55.7 39.3 6.0 22.0 30.1 5.2 50.1 3.4 24.5 85.6 20.8 125.9 69.7 9.7 9.9 7.3 2.5 40.8 25.3 152.3 14.4 134.5 63.3 212.7 36.4 201.1 C D Appendix 7. Concentration of NHi,* and NO3--N after 120 t h a - 1 swine slurry application (1982, 1983). Tlae after application (month) Depth (cm) 1 a a7 NH4-N (ppm) N03-N (ppm) Broadcast Injection Broadcast Injection NHH-N (ppm) ... N0j-N (ppm) . Broadcast Injection Broadcast Injection 1 0-15 15-30 30-60 60-90 44.11 18.47 110.22 65.66 5.06 100.07 13.99 40.67 7.22 4.92 10.20 11.35 6.29 2.68 10.15 6.37 7.92 18.42 74.33 25.83 4.58 28.25 17.00 40.08 3.50 4.33 7.75 11.33 3.92 2.25 9.17 7.33 2 0-15 15-30 30-60 60-90 8.23 7.37 91.24 29.23 7.96 7.99 30.85 102.73 1.94 4.21 7.22 20.97 1.10 0.99 5.34 6.81 1.83 1.83 34.50 22.67 1.92 24.33 26.17 36.50 0.83 4.17 8.67 14.17 0.67 0.83 5.50 11.33 3 0-15 15-30 30-60 60-90 6.82 6.30 83.67 49.16 3.24 11.31 21.09 74.27 2.77 4.45 9.10 18.41 2.50 2.82 7.64 8.23 2.58 2.50 21.33 13.58 1.67 2.25 24.17 24.67 1.00 6.83 14.17 21.17 0.83 0.67 8.50 13.67 169 Appendix 8. Weekly r a i n f a l l received by the experimental site for the period October 1981 to April 1982 and October 1982 to April 1983. Rainfall for the period Rainfall for the period Week October 1981 - Apr i l 1982 October 1982 - April 1983 (mm) (mm) 1 108.6 29.8 2 15.4 0.4 3 2.4 49.4 4 118.8 38.8 5 2.2 53.8 6 86.4 38.4 7 107.2 34.0 8 37.0 77.2 9 50.4 77.8 10 71.8 49.4 11 50.0 44.8 12 39.2 5.6 13 0 125.6 14 37.8 49.0 15 92.2 32.3 16 100.6 28.2 17 5.6 12.6 18 159.4 59.0 19 73.6 84.2 20 39.8 35.4 21 21 21.4 22 40.8 61.4 23 0 9.0 24 30.2 54.2 25 47.2 35.2 26 39.4 26.0 27 5.4 23.2 28 15.8 17.8 Total 1398.2 1173.8 Appendix 9. Some selected s o i l TKN and organic N data before and at the end of the three years of s l u r r y a p p l i c a t i o n . S l u r r y Slurry TKN Rep. I _ TKN (ke h a - 1 ) _ Rep. II Time applied applied Depth (t ha" 1) (kg ha" 1) (cm) X 0-15 3518 4532 5547 Before . . 15-30 3173 3426 3679 s l u r r y 30-60 1487 1715 1944 app l i c a t i o n 69-90 814 775 737 Total 8992 10448 11907 Organic N 8882 10337 11792 0-15 4589 4531 4474 f\ n 15-30 3299 3792 4286 u u 30-60 1493 1915 2338 60-90 1009 1049 1090 • To t a l 10390 11287 12188 Organic N 10343 11241 12140 Aft e r 0-15 4931 4888 4845 three years , 15-30 3270 3839 4408 of s l u r r y 30-60 1373 1673 1973 appli c a t i o n 60-90 928 928 929 To t a l 10502 11328 12155 Organic N 10404 11203 12002 0-15 4859 5094 5330 15-30 3230 3859 4489 405 1621 30-60 1480 1748 2017 60-90 949 979 1009 Tot a l 10518 11680 12845 Organic N 10369 11448 12528 171 Appendix 10. Concentration of P and K in swine slurry used in the experiment. Analyses 1981 1982 1983 7. P 0.16 (17.12)* 0.14 (21.42) 0.15 (18.13) K 0.12 (1.89) 0.13 (13.43) 0.12 (6.75) * Figures within the parentheses indicate coefficient of variation. 

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