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The effects of a single biosolids application on soil physical properties in three forage production… Wallace, Brian Mark 2007

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T H E E F F E C T S O F A S I N G L E B I O S O L I D S A P P L I C A T I O N O N S O I L P H Y S I C A L P R O P E R T I E S I N T H R E E F O R A G E P R O D U C T I O N S Y S T E M S I N T H E S O U T H E R N I N T E R I O R O F B R I T I S H C O L U M B I A b y B R I A N M A R K W A L L A C E B . S c . (Agroeco logy) , The U n i v e r s i t y o f B r i t i s h C o l u m b i a , 2005 A T H E S I S S U B M I T T E D I N P A R T I A L F U L F I L L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F M A S T E R O F S C I E N C E i n T H E F A C U L T Y O F G R A D U A T E S T U D I E S ( S o i l Science) / T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A June 2007 © B r i a n M a r k Wal l ace , 2007 ABSTRACT The Greater V a n c o u v e r Reg iona l Dis t r ic t applies about 15,000 d ry tonnes o f b ioso l ids per year to var ious types o f land i n B r i t i s h C o l u m b i a ( B C ) i n an effort to divert b ioso l ids from landf i l l ing , incinerat ion, and ocean disposal . T h e effects o f b ioso l ids (20, and 60 M g ha" 1) and chemica l fert i l izer on aggregate stabil i ty, bu lk density, aeration porosi ty, total C and N o f stable aggregates, and the hydro lys i s o f f luorescein diacetate ( F D A ) i n aggregates > 2 m m were investigated five years after so i l appl icat ion i n three c o m m o n forage product ion systems (crested wheatgrass = C W , native range = N R , and irr igated alfalfa = I A ) i n the southern interior o f B C . A t each o f the three sites, the experiment was la id out i n 2001 i n a randomized b lock design w i t h four treatments replicated over four b locks . S o i l samples were col lected dur ing spring, summer, and fal l 2005 and 2006. A t the C W site, b iosol ids at 60 M g ha" 1 increased the stabil i ty and propor t ion o f so i l aggregates > 1 m m , the concentration o f C and N i n aggregates, and the hydro lys i s o f F D A . O n the N R site, there were no differences i n the mean weight diameter ( M W D ) or the propor t ion o f stable aggregates > 1 m m from either b ioso l ids rates, yet together the b ioso l ids treatments were greater from the control or fert i l izer treatments dur ing every sample per iod i n 2006. B i o s o l i d s appl ied at 20 M g ha" 1 s ignif icant ly increased total C and N o f stable aggregates and reduced b u l k density relative to a l l other treatments. A t the I A site, b ioso l ids appl ied at 60 M g ha" 1 decreased bu lk density i n 2005 and 2006, relative to the control and the fert i l izer treatment decreased aeration porosi ty and the concentrat ion o f C i n aggregates. O u r data showed that, l and appl ied b ioso l ids to these c o m m o n forage product ion systems i n the southern interior o f B C enhanced aggregate stabil i ty and total C o f stable aggregates. The majori ty o f improvements to so i l properties at the C W and I A sites came f rom b ioso l ids appl ied at 60 M g ha" w h i l e the greatest improvements to so i l properties at the N R site were f rom the 20 M g ha" 1 bioso l ids treatment. T h i s is thought to be due to greater site p roduc t iv i ty (above and be low ground) f rom the 60 M g ha" 1 treatment at the C W and I A sites, as compared to the N R site where the 20 M g ha" 1 b iosol ids treatment decreased bu lk density and increased the concentration o f C and N among stable aggregates, relative to a l l other treatments. TABLE OF CONTENTS ABSTRACT ii TABLE OF CONTENTS . iii LIST OF TABLES v LIST OF FIGURES vi LIST OF ABBREVIATIONS viii ACKNOWLEDGEMENTS ix CO-AUTHORSHIP STATEMENT x Chapter 1: General Introduction 1 1.1 Background on biosolids 1 1.1.1 Chemical and biological properties of biosolids 2 1.2 Land application of G V R D biosolids 4 1.2.1 Issues associated with biosolids land applications 5 1.4 Forage production systems in B C 7 1.5 Aggregate stability 8 1.6 Soil properties following biosolids application :.. 10 1.7 Objectives 13 1.8 References 14 Chapter 2: Effects of biosolids on soil physical properties in a crested wheatgrass pasture in the southern interior of British Columbia 18 2.1 Introduction 18 2.2 Material and Methods 20 2.2.1 Site Description 20 2.2.2 Soil Properties 23 2.2.3 Statistical Analysis 26 2.3 Results and Discussion , 26 2.3.1 Soil Bulk Density and Aeration Porosity 26 2.3.2 Aggregate Stability 27 2.3.3 Total Carbon and Nitrogen of Soil Aggregates 32 2.3.4 Hydrolysis of Fluorescein Diacetate 35 2.4 Conclusions 37 2.5 References ; .38 Chapter 3: Effects of biosolids on soil physical properties in native grasslands in the southern interior of British Columbia 42 3.1 Introduction 42 3.2 Material and Methods 44 3.2.1 Site Description : 44 3.2.2 Soil Properties 46 3.2.3 Statistical Analysis 48 3.3 Results and Discussion 49 3.3.1 Bulk Density 49 3.3.2 Aggregate stability 50 3.3.3 Total Carbon and Nitrogen of Soil Aggregates r 54 3.3.4 Hydrolysis of Fluorescein Diacetate 57 3.4 Conclusions 59 3.5 References 59 Chapter 4: Effects of biosolids on soil physical properties in a stand of irrigated alfalfa in the southern interior of British Columbia 62 4.1 Introduction 62 4.2 Material and Methods 64 4.2.1. Site Description : ; 64 4.2.2 Soil Properties • --65 4.2.3 Statistical Analysis -68 4.3 Results and Discussion 69 4.3.1 Bulk Density and Aeration Porosity 69 4.3.2 Aggregate stability- 70 4.3.3 Total Carbon and Nitrogen of Soil Aggregates 73 4.3.4 Hydrolysis of Fluorescein Diacetate 76 4.4 Conclusions 77 4.5 References • -. • 77 Chapter 5: General Summary 80 APPENDICES 82 Appendix 1 - British Columbia's trace element concentrations for Class A and B biosolids 82 Appendix 2 - Particle size analysis by block from the crested wheatgrass, native range, and irrigated alfalfa sites 83 Appendix 3a - A N O V A tables for the aggregate stability data 84 Appendix 3b - A N O V A tables for the bulk density and aeration porosity data : 87 Appendix 3c - A N O V A tables for the aggregate associated C, N and C : N data 88 Appendix 3d - A N O V A tables for the F D A data 89 Appendix 4 - Total soil C and N from 2002 to 2004 in bulk soil 90 Appendix 5 - Experimental layouts at the Ashcroft ranch 91 i v LIST OF TABLES Table 2.1 - S o i l bu lk densi ty and aeration poros i ty i n M a y 2005 and 2006 27 Table 3.1 - S o i l bu lk density ob four treatments i n M a y 2005 ...49 Table 4.1 - S o i l bu lk density and aeration poros i ty i n M a y 2005 and 2006. 70 v LIST OF FIGURES Figure 2.1 - C l ima te and weather at the Ashcrof t R a n c h , B C 22 F igure 2.2 - The mean weight diameter ( M W D ) and water content o f so i l aggregates dur ing the 2005 and 2006 crested wheatgrass g r o w i n g seasons 29 F igure 2.3 - F rac t ion o f total s o i l sample present i n four aggregate s ize classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2005 crested wheatgrass g r o w i n g season 31 F igure 2.4 - F rac t ion o f total so i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2006 crested wheatgrass g r o w i n g season 32 F igure 2.5 - C a r b o n concentration o f aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) at the crested wheatgrass site dur ing summer 2005 33 F igure 2.6 - N i t rogen concentration o f aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) at the crested wheatgrass site dur ing summer 2005 34 F igure 2.7 - T h e C : N ratio o f aggregates i n size classes (2-6, 1-2, and 0.25-1 m m ) at the crested wheatgrass site dur ing summer 2005 35 F igure 2.8 - T h e hydro lys i s o f f luorescein diacetate ( F D A ) i n the 2-6 m m aggregate size class i n June 2006 at the crested wheatgrass site 36 F igure 2.9 - T h e relationship o f f luorescein diacetate ( F D A ) act iv i ty and aggregate mean weight diameter ( M W D ) from s o i l sampled M a y 31 , 2006 at the crested wheatgrass site '. 37 F igure 3.1 - C l i m a t e and weather at the Ashcrof t R a n c h , B C 45 F igure 3.2 - T h e mean weight diameter ( M W D ) and water content o f s o i l aggregates dur ing 2005 and 2006 g r o w i n g seasons at the native range 51 F igure 3.3 - F rac t ion o f total so i l sample present i n four aggregate s ize classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2005 g r o w i n g season at the native range 52 F igure 3.4 - F rac t ion o f total so i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2006 g r o w i n g season at the native range 54 F igure 3.5 - C a r b o n concentrat ion o f stable aggregates i n three s ize classes (2-6, 1-2, and 0.25-1 m m ) from so i l sampled on June 16, 2005 from the native range 55 F igure 3.6 - N i t r o g e n concentration o f stable aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) from s o i l sampled o n June 16, 2005 at the native range 56 v i Figure 3.7 - The C : N ratio o f stable aggregates i n three size classes from so i l sampled o n June 16, 2005 f rom the native range 57 F igure 3.8 - The hydro lys i s o f f luorescein diacetate ( F D A ) i n the 2-6 m m aggregate size class i n June 2006 at the native range 58 F igure 4.1 - The mean weight diameter ( M W D ) and water content o f so i l aggregates dur ing 2005 and 2006 g rowing seasons at the irrigated alfalfa site 71 F igu re 4.2 - F rac t ion o f total s o i l sample present i n four aggregate s ize classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2005 g r o w i n g season at the irr igated alfalfa site 72 F igure 4.3 - F rac t ion o f total so i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2006 g r o w i n g season at the irr igated alfalfa site 73 F igure 4.4 - C a r b o n concentration o f stable aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) f rom s o i l sampled o n June 16, 2005 f rom the irrigated alfalfa site 74 F igure 4.5 - N i t r o g e n concentration o f stable aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) from so i l sampled on June 16, 2005 at the irrigated alfalfa site. 75 F igure 4.6 - The C : N ratio o f stable aggregates i n three size classes f rom so i l sampled on June 16 2005 at the irrigated alfalfa site 76 F igure 4.7 - T h e hydro lys i s o f f luorescein diacetate ( F D A ) i n the 2-6 m m aggregate size class i n June 2006 from the irrigated alfalfa site '. 77 v n LIST OF ABBREVIATIONS BC - Brit ish Columbia CW - Crested Wheatgrass FDA - Fluorescein Diacetate GVRD - Greater Vancouver Regional District HEPH - Heavy Extractable Petroleum Hydrocarbons IA - Irrigated Al fa l fa iPOM - Intra-Aggregate Particulate Organic Matter LSD - Least Significance Difference MPN - Most Probable Number MWD - Mean Weight Diameter NR - Native Range OMRR - Organic Mater Recycl ing Regulation TKN - Total K j eldahl Nitrogen WWTP - Waste Water Treatment Plant ACKNOWLEDGEMENTS Firs t and foremost, I w o u l d l ike to thank m y supervisor M a j a K r z i c for her cont inual encouragement, guidance and support throughout m y undergraduate and graduate studies dur ing the last s ix years. Wi thou t her encouragement to enrol into a pedo logy course and attend an annual meet ing for P R S S S I w o u l d not be do ing what I am today. I w o u l d also l ike to thank T o m Forge for his excellent guidance and leadership dur ing m y research. H i s c r i t i ca l th ink ing and general enthusiasm about the research gave me the confidence and resources to f o l l o w through w i t h the w o r k smoothly. The guidance and support I 've received f rom m y commit tee members, A r t B o m k e and Suzanne S i m a r d as professors and mentors has been first class. I w o u l d l i ke to thank A r t B o m k e for be ing i n his office the day I strolled through the hal ls o f the agricul tural sciences b u i l d i n g seven years ago, and for every other day he 's been there since then. I w o u l d l ike to thank a l l o f m y so i l student colleagues w h o together have been a tremendous group o f people to study, work , and p lay w i th . The assistance o f D a v i d Poon , G o r d o n L e e , X i a o W u , Shaobing Y u , A n d y Jakoy, B a l i n t H e i l , S i m o n Zhao , Shannon R i p l e y i n the f ie ld and laboratory is appreciated. W i l l A r n u p ' s incredible dedicat ion as a research assistant was greatly appreciated. I w o u l d also l ike to thank the Greater V a n c o u v e r R e g i o n a l Dis t r i c t and Agr i cu l tu re and A g r i - F o o d Canada for the funding and support o f the project. F i n a l l y , I w o u l d l ike to thank m y fami ly for a l l their support dur ing these m a n y years I have been at U B C . Spec i f i ca l ly , I thank m y parents for cont inual ly encouraging me to pursue m y studies and their relentless support. i x CO-AUTHORSHIP STATEMENT Chapter 2: I was responsible for the experimental design, data co l lec t ion , a l l statistical analyses, and w r i t i n g the manuscript . M a j a K r z i c , T o m Forge , K l a a s Broe r sma and R e g N e w m a n contr ibuted to the experimental design, the choice o f statistical tests and to the interpretation and presentation o f the manuscript . Chapter 3: I was responsible for the experimental design, data co l lec t ion , a l l statistical analyses, and w r i t i n g the manuscript . M a j a K r z i c , T o m Forge , R e g N e w m a n , and K l a a s Broe r sma contributed to the experimental design, the choice o f statistical tests and to the interpretation and presentation o f the manuscript. Chapter 4: I was responsible for the experimental design, data co l lec t ion , a l l statistical analyses, and w r i t i n g the manuscript . M a j a K r z i c , T o m Forge , K l a a s B r o e r s m a and R e g N e w m a n contributed to the experimental design, the choice o f statistical tests and to the interpretation and presentation o f the manuscript . \ Chapter 1: General Introduction 1.1 B a c k g r o u n d o n b ioso l ids The Greater V a n c o u v e r Reg iona l Dis t r ic t ( G V R D ) has f ive wastewater treatment plants ( W W T P s ) , serv ic ing over 1 m i l l i o n people, that process about 1.2 m i l l i o n litres o f wastewater every day to produce over 15,000 dry tonnes o f Class A and B b ioso l ids per year ( G V R D , 2005). In compar ison, the Greater Toronto A r e a has a popula t ion that is over 5 m i l l i o n people and produces 65,000 dry tonnes per year f rom its four W W T P s (Toronto, 2004). In total, Canada produces about 0.5 x 1 0 6 M g yr" 1 (dry weight) o f b iosol ids , as compared to over ten times that amount i n the U n i t e d States (Cogger et a l , 2006). The level o f treatment to the separated solids varies f rom mun ic ipa l i t y to munic ipa l i ty . P r i m a r y wastewater treatment a l lows sol ids to settle to the bo t tom or float to the top o f a settling pond where mater ial is then removed from the water (Jensen, 1993). Secondary wastewater treatment involves adding floes o f bacteria to the solids that w i l l improve the rate i n w h i c h the sol ids are b roken d o w n and s tabi l ized dur ing digest ion or compost ing . So l i d s are digested aerobical ly or anaerobical ly at mesophi l i c (~ 3 5 ° C ) or thermophi l ic (~ 5 5 ° C ) temperatures that stabilizes organic matter and nutrients w h i l e reducing pathogens and bacteria. Other secondary treatments invo lve increasing the p H that w i l l precipitate most trace metals and reduces odours caused b y N and S compounds . In Canada, p r o v i n c i a l environment and agriculture minis t r ies l i m i t b iosol ids applications o n the basis o f so i l metal l imi ts , b iosol ids concentrations, and cumula t ive load ing o f metals i n the so i l . In B r i t i s h C o l u m b i a ( B C ) , b ioso l ids are defined b y the Organic Mat te r R e c y c l i n g Regu la t ion ( O M R R ) as "s tab i l ized m u n i c i p a l sewage sludge result ing f rom a m u n i c i p a l waste water treatment process or septage treatment process w h i c h has been suff ic ient ly treated to reduce 1 pathogen densities and vector attraction to a l l ow the sludge to be benef ic ia l ly recyc led i n accordance w i t h the requirements o f this regula t ion" ( O M R R , 2002). B i o s o l i d s are analyzed regular ly for pathogen, nutrient, and trace metal content that determine their sui tabi l i ty for land appl icat ion. C lass A b ioso l ids are defined as materials w i t h a fecal c o l i f o r m count be low 1000 M P N (most probable number) /gram dry weight and trace element concentrations b e l o w guidelines set out i n the O M R R ( A p p e n d i x 1). B i o s o l i d s that meet these strict cr i ter ia for Class A b ioso l ids are suitable for agricultural use and can be used wi thout permit ; however land appl ica t ion plans completed b y a registered Profess ional A g r o l o g i s t are required. C lass B b ioso l ids is defined as material w i t h a fecal co l i f o rm count above 1000 M P N / g ram dry weight and trace elements concentrations that meet the standards o f the O M R R ( A p p e n d i x 1). L a n d appl ica t ion o f b ioso l ids has been a research focus for over three decades and continues to be an area o f intense invest igat ion (Cogger et a l . , 2006) The Greater V a n c o u v e r R e g i o n a l Dis t r ic t ( G V R D ) manages the product ion and dis t r ibut ion o f b ioso l ids through the Nut r i fo r Program. The largest treatment plant, located on A n n a c i s Island, uses secondary b iosol ids treatment b y anaerobic thermophi l ic digest ion and is dewatered b y centrifuge. Anae rob ic thermophi l ic digest ion raises the temperature o f wastewater sol ids to 5 5 ° C for 28 days necessary to k i l l pathogens dangerous to human health. A n n a c i s Island W W T P services around 1 m i l l i o n residents to produce more than 8 0 % o f a l l b ioso l ids i n the ( G V R D . 1.1.1 Chemical and biological properties of biosolids The phys ica l and chemica l characteristics o f b ioso l ids produced b y W W T P s u l t imate ly depend o n the treatment processes, age o f material , and the source o f the wastewater. Wastewaters f rom commerc ia l and industr ial areas that are processed a long w i t h residential waste 2 have a high likelihood of having elevated concentrations of organic compounds and trace metals in their biosolids. Wastewaters from industrial areas are strictly monitored to reduce trace metal contents in biosolids. The metals in biosolids can also come from the water supply pipes themselves (GVRD, 1999) including copper and lead pipes used in aging infrastructure. Natural sources of trace metals include rainfall, soils, and dust being flushed into stormwater runoff catchments that empty into the sewage system. For example, hydrocarbons and metals accumulate in wastewater when run-off from roadways and rooftops brings engine fluid, tar, and metals into the sewer system. Drinking water retrieved from belpwground sources is often alkaline, while drinking water from aboveground reservoirs is often acidic. Acidic water running through copper pipes will increase the copper concentration in wastewater, which in turn increases the copper concentration in biosolids. Biosolids with copper concentrations above 1000 mg/kg represent drinking water from an aboveground or acidic water source (GVRD, 1999). A study carried out by the GVRD found that about 50% of copper and 5% of iron in local biosolids originated from the drinking water (GVRD, 1999). The detection of fecal coliform bacteria (such as Escherichia coli) identifies fecal contamination from warm-blooded animals including humans (USEPA, 1995). Fecal coliforms are not necessarily a dangerous group of organisms to humans but are useful indicator species. Higher levels of these organisms indicate a greater likelihood to find pathogenic organisms as well. Fecal coliforms are easily cultured in the laboratory and are found in the digestive systems of all mammals. Fecal coliforms present in biosolids will help determine the class of biosolids produced. For example, class A biosolids requires the count to be below 1000 MPN/g, while class B requires a bacteria count below 2,000,000 MPN/g (Appendix 1). Class A biosolids used in the Ashcroft Ranch Fertilization Study were received from the Annacis Island WWTP in 2001. Total N and P contents of Class A biosolids were 45,033 mg T K N * kg" 1 and 29,992 m g P kg" 1 o n a dry weight basis. A d d i t i o n a l studies w i t h the same material measured the ava i lab i l i ty o f N i n the laboratory and f ie ld settings reported values o f 3 4 % and 17.5%, respectively, ( S y l v i s , 2001). 1.2 L a n d appl icat ion o f G V R D b ioso l ids A p p r o x i m a t e l y 7 0 % o f the annual b iosol ids product ion f rom the G V R D is recyc led back to the land, w h i l e the remainder is land dr ied and stored o n site for future r ecyc l i ng (Duynstee and Lee , 2000). R e c y c l e d b ioso l ids accounted for 5 7 % o f b ioso l ids produced i n 2002, 8 4 % i n 2003, 68%> i n 2004, and 7 0 % i n 2005. The fluctuations are dependent on the number o f land reclamat ion and ranch fer t i l izat ion projects go ing on i n the province . Current ly , no b ioso l ids are recyc led w i t h i n the G V R D itself. One o f the future goals for the Nut r i fo r P rogram is to market their product as an amendment and fert i l izer for g o l f courses and sports fields and potent ial ly for the use i n landscaping and home gardens ( G V R D , 2002-2004) . : B i o s o l i d s have successfully been used i n various mine reclamat ion projects i n B C i l lustrat ing a significant capabi l i ty for so i l b u i l d i n g o n heav i ly disturbed sites (Duynstee, 2001). T h i s type o f land appl ica t ion is presently responsible for r e cyc l i ng o f almost a l l G V R D b ioso l ids i n the province . The H i g h l a n d V a l l e y Copper M i n e near L o g a n L a k e , B C has been i n operation for 40 years. A b o u t 1/3 o f the 6,000 hectares o f l and that have been disturbed b y m i n i n g has been revegetated w i t h grasses, legumes, shrubs, and trees f o l l o w i n g b ioso l ids appl ica t ion at this site (Duynstee, 2001). Ano the r extensive reclamat ion project i n B C us ing b ioso l ids is at Cons t ruc t ion Aggregates L t d . i n Sechelt , B C ( V a n H a m et a l . , 2000). T h i s is Canada ' s largest sand and gravel process ing faci l i ty . B i o s o l i d s f rom the Gibsons and Sechelt W W T P s a long w i t h pulp sludge from H o w e Sound P u l p and Paper L t d . are combined and appl ied to a l l o w vegetation establishment * TKN = Total Kjeldahl Nitrogen 4 and growth on s tockpi led overburden. Th i s partnership has resulted i n the development o f a regional organic residuals r ecyc l ing program w i t h l oca l munic ipa l i t i es and industry. The partnership was able to rehabilitate this site that produces 3 m i l l i o n tonnes o f sand and gravel per year. M i n i n g operations throughout the province are or w i l l be i n need o f remediat ion at some t ime i n the future and b ioso l ids cou ld successfully be used to a l l o w vegetative biomass product ion over mine tai l ings at these sites. 1.2.1 Issues associated with biosolids land applications S o i l amendments, i nc lud ing b iosol ids , are k n o w n to improve var ious aspects o f so i l qual i ty b y increasing nutrient and water ho ld ing capacities (Zebarth et a l . , 1999). In contrast to inorganic fertil izers, b ioso l ids have h i g h organic matter content and can be used as a s low release source o f N and P (Mar t inez et a l . , 2003). O n the other hand, b ioso l ids can contain a variety o f heavy metals, organic compounds , and pathogens that cou ld be dangerous to environmental and human health. A n i m a l manures are k n o w n to contain a l l o f the same pathogens, metals, and organic compounds as those found i n b iosol ids ( O ' C o n n o r et a l . , 2005), yet the two organic amendments are regulated and managed i n different ways . Me ta l s i n b iosol ids are considered potent ial ly hazardous because they can accumulate i n so i l through repeated applications ( G V R D , 1999). O f the trace metals present i n b ioso l ids , C d poses the greatest long-term threat to human health due to b ioaccumula t ion i n the food chain ( W E R F , 1993). There is also a threat to graz ing animals due to elevated C u and NO3 levels i n forage from heavy b ioso l ids applications (Zebarth et a l . , 2000). In a lkal ine soi ls i n particular, b ioso l ids use i n alfalfa (Medicago sativa L . ) product ion c o u l d cause a r isk to ruminant animals due to molybdenos is i f the C u : M o i n the an imal ' s diet falls b e l o w 2 (Stehouwer and M a c n e a l , 2004). F i n a l l y , decreases i n overa l l m i c r o b i a l b iomass w h i l e causing a shift i n c o m m u n i t y 5 structure f o l l o w i n g b ioso l ids applications i n Co lo rado are reported and par t ia l ly expla ined b y elevated concentrations o f heavy metals, such as C u and Z n ( S u l l i v a n et a l . , 2006). The ava i lab i l i ty o f heavy metals i n soils is dependent o n specific environmental condit ions (i.e., precipi tat ion, so i l p H , so i l part icle dis tr ibut ion, so i l minera logy) and interpretation o f any environmental r isks should be done o n a site-by-site basis. In a semiar id reg ion o f Spa in , M a r t i n e z et a l . (2003) found no increase i n so i l concentrations o f D T P A -extractable C d , C r , P b , or N i three years f o l l o w i n g the one t ime appl ica t ion o f b ioso l ids at 0 to 120 M g ha" 1. In the same study, C u and Z n concentrations i n soils increased after two years from b ioso l ids appl ied at 80 and 120 M g ha" 1 , but were o n l y s igni f icant ly elevated after three years f rom the 120 M g ha" 1 rate. Calcareous soi ls , h igh so i l p H , and l o w annual precipi ta t ion contributed to the lack o f any significant differences found b y M a r t i n e z et a l . (2003). Recent ly , the fate o f organic contaminants (i.e., vola t i le organics, P C B s , dioxins/furans) found i n b ioso l ids have been analysed over a s ix -month per iod at the f ive W W T P s i n the G V R D (Br ight and H e a l y , 2003). Organic compounds found i n b ioso l ids inc luded p-cresol , phenol , phenanthrene, pyrene, naphthalene, and heavy extractable petroleum hydrocarbons ( H E P H s ) . W i t h the except ion o f the H E P H s , no organic contaminants pose a significant environmental r isk w h e n b ioso l ids are occas iona l ly appl ied and m i x e d w i t h the so i l . A n extensive rev iew o f the fate o f l and appl ied wastes b y Overcash et a l . (2005) reveals that the fate o f wastes conta ining new anthropogenic chemicals (i.e., pharmaceuticals, antibiotics, surfactants, cosmetics , estrogenic compounds) i n fu l l scale land appl icat ion systems is not fu l ly understood and requires more research ( X i a et a l . , 2005). 6 1.4 Forage product ion systems i n B C Grasslands occupy about 1.3 m i l l i o n ha i n B C representing o n l y 1% o f the total land area, but are important for late-fall , winter, and ear ly-spring graz ing ( W i k e e m et a l . , 1993). The majori ty o f grasslands i n B C are located i n va l leys and a long rivers i n the southern and central interior, Ca r iboo C h i l c o t i n , and Peace R i v e r regions. The Bunchgrass b iogeoc l imat ic zone comprises about 300, 000 ha i n the southern interior o f B C and general ly occurs at elevations between 300 and 1000 m above sea leve l (S t i l l et a l . , 1994). The highest elevations i n this zone occur m a i n l y o n the bot tom edge o f the Ponderosa P ine b iogeoc l imat ic zone, w h i l e lower elevations are dominated b y a m i x o f grassland vegetation inc lud ing b luebunch wheatgrass {Pseudoroegneria spicata (Pursh) Scr ibn . & Smith) , needle-and-thread grass (Stipa comata T r i n . & Rupr . ) , c o m m o n rabbitbrush {Chrysothamnus spp.), and b i g sagebrush {Artemisia tridentata N u t t ) . Grasslands i n this zone are used as graz ing land for the beef cattle industry and prov ide habitat for over 3 0 % o f threatened and endangered species i n the p rov ince (Grasslands Conserva t ion C o u n c i l o f B C , 2004). In the southern interior o f B C , cattle w i l l generally f o l l o w an al t i tudinal migra t ion that begins at l o w elevations close to feeding grounds i n the winter and ear ly spr ing and then gradual ly moves into the Interior Douglas - f i r or Ponderosa P ine b iogeoc l imat ic zones as the snow melts ( W i k e e m et a l . , 1993). D u r i n g winter months, cattle depend on a m i x o f grass and legume hay that are produced i n the summer months. The product ion o f alfalfa {Medicago sativa L . ) is important i n areas that have adequate access ibi l i ty to i r r igat ion. A p p r o x i m a t e l y 4 0 % o f the annual forage requirement is g rown on about 1.5 m i l l i o n ha o f private rangeland and irr igated pasture ( W i k e e m et a l . , 1993). The majori ty o f grasslands i n B C and N o r t h A m e r i c a i n general, have been modi f i ed f rom their potential natural commun i ty b y either grazing, fire,, in t roduct ion o f non-native species, and 7 mechanica l cul t ivat ion. S ince the late 1930s, about 45,000 ha o f grasslands i n B C have been seeded to introduced species such as crested wheatgrass (Agropyron cristatum ( L . ) Gaertn.). Throughout the southern interior o f B C , the seeding was done as part o f the s o i l conservat ion program carried out to improve degraded land o n abandoned farmland and overgrazed rangeland. Crested wheatgrass is characterized b y early spring biomass product ion and good regrowth i n the fa l l after summer drought condi t ions. 1.5 Aggregate stabil i ty S o i l structure (i.e., arrangement o f p r imary s o i l particles into secondary particles or aggregates) p lays an important role i n the phys i ca l protection o f so i l organic matter b y con t ro l l ing m i c r o b i a l access to substrates (E l l i o t and C o l e m a n , 1988; van V e e n and K u i k m a n , 1990). T i s d a l l and Oades (1982) introduced the aggregate hierarchy concept where different b i n d i n g agents (transient, temporary, and persistent) sequential ly inf luence aggregation at different s ize fractions; p r imary particles (< 20 um) , microaggregates ( 2 0 -2 5 0 um), and macroaggregates (> 250 (am). Microaggregates are thought to be bound together b y persistent b i n d i n g agents (humif ied organic matter and polyvalent metal cat ion complexes) , oxides , and h i g h l y disordered aluminosi l icates . Microaggregates are bound together into macroaggregates b y temporary (roots and fungal hyphae) and transient b ind ing agents (plant and m i c r o b i a l der ived polysaccharides) . Oades (1984) modi f i ed this m o d e l after considerat ion that roots and fungal hyphae (temporary b i n d i n g agents) w i l l not persist due to re la t ive ly qu ick decompos i t ion leaving s tabi l ized, organo-mineral fragments (microaggregates) f rom the turnover and b reakdown o f macroaggregates. S i x et a l . (2000) re-addressed the aggregate formation m o d e l and conducted several experiments to elucidate this theory. Macroaggregates are formed around fresh residue that 8 becomes coarse intra-aggregate particulate organic matter ( i P O M ) . The new C source for microbes stabil izes the i P O M due to various by-products o f m i c r o b i a l act ivi ty . Coarse i P O M is b roken-down into fine i P O M upon u t i l i za t ion o f a l l avai lable C sources that inc lude the b i n d i n g agents used to encrust the coarse i P O M creating h i g h l y stable microaggregates. The format ion o f microaggregates is then control led b y the turnover t ime o f macroaggregates, and the degree o f b i o l o g i c a l ac t iv i ty w i t h i n the macroaggregates. The microaggregate is then phys i ca l l y protected f rom other s o i l organisms creating a stable microaggregate and storing C un t i l the microaggregate particle is dispersed w h i c h is estimated to take over 50 years (Carter, 1996). I f the turnover t ime is too rapid , or m i c r o b i a l ac t iv i ty is reduced b y unfavourable condi t ions, then microaggregates w i l l not have enough t ime to stabil ize, and the protect ion o f so i l organic matter w i l l not occur. The most c o n v i n c i n g quantitative evidence supporting the m o d e l that microaggregates are spawned f rom macroaggregates came from Anger s et a l . (1997) where , 3 C and 1 5 N - l a b e l e d wheat straw was traced dur ing decomposi t ion . The 1 3 C and 1 5 N accumulated i n macroaggregates, and then were redistributed i n microaggregates. The modi f i ca t ion changed the w a y w e v i e w C sequestration and so i l organic matter cycles . The process is m u c h more dynamic than the or ig ina l step-by-step hierarchy m o d e l proposed b y T i s d a l l and Oades (1982). The interpretation o f aggregate size data and their degree o f s tabi l izat ion should reflect the idea that large aggregates are not necessari ly the most stable or the last step o f aggregation. The influence o f fungal organisms o n aggregation has been studied extensively due to intimate and v i s ib l e relationship between m y c e l i a and minera l particles. R i l l i g and M u m m e y (2006) rev iewed mycor rh i zas ' effect on so i l structure that suggested that fungi had a m u c h bigger role not o n l y at the macroaggregate leve l (T i sda l l and Oades, 1982) but also o n microaggregate format ion and s tabi l izat ion processes as w e l l . Recent ly , most studies i n v o l v i n g mycor rh izae and 9 so i l structure have focused on an extracellular g lycoprote in ca l led g l o m a l i n produced b y arbuscular mycor rh izae fungi. W r i g h t and U p a d h y a y a (1998) were first to l i n k aggregate s tabi l i ty and the presence o f g loma l in , w h i l e other authors have also concluded that aggregate stabil i ty has increased w i t h the presence o f arbuscular mycorrh izae fungi as demonstrated b y the concentrat ion o f g l o m a l i n i n soils ( M i l l e r and Jastrow, 2000). The influence o f g l o m a l i n i n the format ion o f stable aggregates was examined by W r i g h t (2000) us ing an indirect immunofluorescence approach. G l o m a l i n was o n l y detected b y indirect immunofluorescence w h e n it was n e w l y s loughed o f f from young hyphae, w h i l e older hyphae d i d not have any signs o f g l o m a l i n us ing this technique. G l o m a l i n m a y ind i rec t ly help i n so i l aggregate s tabi l izat ion. The author suggested that g l o m a l i n provided a protective and nurtur ing b i o f i l m for s o i l organisms a id ing i n aggregate stabil i ty. A l t h o u g h the role o f arbuscular mycor rh izae fungi i n s o i l aggregation has been extensively investigated, there has been l imi ted informat ion on impacts o f ectomycorrhizae. Presumably , the connect ion is not be ing made because the major i ty o f research o n phys ica l properties is done i n agricul tural contexts where ectomycorrhizae abundance is l imi ted . R i l l i g and M u m m e y (2006) suggested that ectomycorrhizae most l i k e l y p lays substantial roles i n aggregation i n non-agricul tural ecosystems, s imi la r to that o f their arbuscular mycor rh izae counterpart. 1.6 S o i l properties f o l l o w i n g b ioso l ids appl icat ion Range land appl ica t ion o f b ioso l ids can provide benefit i n terms o f increased yields for as l ong as f ive years due to an increased supply o f nutrients, and i m p r o v e d s o i l water h o l d i n g capaci ty ( M c D o u g a l l et a l . , 2002). F o r grass-legume m i x e d stands i n the southern interior o f B C that are expected to y i e l d 10 -12 M g ha" 1 per year the N requirement i s 3 1 0 - 3 6 0 k g N ha" 1 10 ( M c D o u g a l l et a l . , 2002). B i o s o l i d s appl icat ion rates o f 15 - 25 M g ha" 1 w o u l d satisfy the crop N requirements o f grass-legume m i x e d stands i n the southern interior o f B C . H o w e v e r , re la t ively litt le is k n o w n o f the long-term fate o f b io so l i d s -C and b i o s o l i d s - N after it is appl ied to so i l i n f ie ld settings, especia l ly typ ica l forage product ion systems o f the southern interior o f B C . Information is also l a ck ing on the extent to w h i c h b ioso l ids stimulate so i l b io log i ca l ac t iv i ty o f a type conducive to the aggregate formation and related changes i n so i l phys i ca l properties. N e i l s e n et a l . (2003) observed greater wet aggregate stabil i ty, water -holding capacity, and inf i l t ra t ion i n orchard so i l i n the southern Okanagan.to w h i c h 90 M g ha" 1 o f b ioso l ids had been surface-applied. The increase i n s o i l C and N associated w i t h b ioso l ids amendments to crested wheatgrass persisted through at least three fu l l g rowing seasons after b ioso l ids appl icat ion (Forge et a l . , i n preperation). That indicated that b i o s o l i d s - C was either re la t ive ly resistant to m i c r o b i a l attack, or the increased root -C inputs and m i c r o b i a l ac t iv i ty that occur i n b ioso l ids -amended so i l were conducive to the sequestration o f m i c r o b i o l o g i c a l l y processed C into protected aggregates. A single b ioso l ids appl icat ion to a semi-ar id grassland i n Co lo rado caused a shift i n so i l m i c r o b i a l and plant commun i ty structure relative to the control and reduced fungal biomass w i t h increasing appl ica t ion rates ( S u l l i v a n et a l . , 2006). S i m i l a r l y , fungal species d ivers i ty was reduced f rom h igh b ioso l ids appl ica t ion (90 M g ha" 1) i n a degraded semiar id rangeland i n N e w M e x i c o 12 months after appl icat ion, but overa l l fungal b iomass increased w i t h increasing b ioso l ids appl icat ion rates (Dennis and Fresquez, 1989). A f ie ld study b y K l a d i v k o and N e l s o n (1979) investigated effects o f a s ingle b ioso l ids appl ica t ion at 56 M g ha" 1 and different methods o f incorporat ion (i.e., ro to t i l l , d isk, surface-applied) o n so i l properties. S o i l organic C and cat ion exchange capaci ty were s ignif icant ly different f rom the control 12 months after appl icat ion w h e n b ioso l ids were rotot i l led to 0 - 15 c m depth on ly . Increases i n aeration poros i ty due to b iosol ids appl ica t ion were found i n plots 12 11 months after be ing surface appl ied or d i sked (0 - 5 c m depth). B u l k density was decreased 12 months after appl ica t ion i n a l l incorporat ion treatments. F i n a l l y , aggregate stabili ty, expressed as the mean weight diameter ( M W D ) , was s ignif icant ly increased four months after b ioso l ids appl icat ion i n a l l incorporat ion treatments; however , differences among treatments were not observed 12 months after appl icat ion. La rge quantities (72 M g ha"1) o f sludge (biosolids) were appl ied to smal l plots (7.2 m 2 ) annual ly for eight years at the O x f o r d Tract f ie ld plots, Be rke ley , C a l i f o r n i a (Glauser et a l . , 1988). Aggregate stabil i ty was measured once at the end o f the study compar ing results f rom b ioso l ids treated plots to non-treated plots (control). The propor t ion o f stable aggregates f o l l o w i n g wet s iev ing was increased from 4 5 % o n the control to 8 5 % o n the treated plots. In a study f rom V a l e n c i a , Spa in , three rates o f two different sewage sludges corresponding to 400, 800, and 1200 k g o f N ha" 1 were compared to a minera l fert i l izer treatment (500 k g N ha" 1) and a non-fer t i l ized control plot. N o differences i n so i l properties (i.e., aggregate stabili ty, m i c r o b i a l b iomass , enzymatic act ivi ty) were found among the treatments ( A l b i a c h et a l . , 2001). A study f rom central Greece evaluated the effects o f b iosol ids . appl ica t ion o n aggregate s tabi l i ty at four different rates (0, 10, 30, and 50 dry M g ha"1) where the stabil i ty o f so i l aggregates was s ignif icant ly i m p r o v e d relative to the control i n the 50 M g ha" 1 treatment o n l y (Tsadilas et a l . , 2005). N i t rogen is t yp i ca l l y the nutrient that controls b ioso l ids appl ica t ion rates. A p p l i c a t i o n rates are based o n an estimate o f crop N requirements and b ioso l ids N avai labi l i ty . Est imat ions o f b ioso l ids N ava i lab i l i ty are based on the concentrat ion o f N i n b ioso l ids , fer t i l izat ion his tory o f the site, method o f appl ica t ion and incorporat ion ( N loss through vola t i l iza t ion) , and effective precipi ta t ion. It is acceptable to exceed the one-year crop N requirement i n areas that have l o w annual precipi ta t ion and little potential o f nitrate leaching, as found i n the southern interior o f B C . Generally, a limited amount of N is available to forage when biosolids are left on the soil surface following application. Site selection is important and areas that are in poor condition due to an invasion of weeds and other non-native species is not recommended (McDougal l et al., 2002). Native grasslands, crested wheatgrass pastures, and irrigated alfalfa are three common forage production systems of the southern interior of B C . Biosolids application may lead to increased nutrient availability and/or improved soil physical properties on those forage production systems. Specific site conditions (i.e., site fertility, water availability) can affect the rate at which biosolids w i l l be decomposed. This in turn w i l l affect the availability nutrients to soil organisms that could lead to changes in soil quality parameters, in particular soil physical properties. Biosolids application rates are determined in these systems by the crop N requirement and the biosolids N availability, yet improvements to physical properties are mainly associated with the additions of organic matter. It is unclear what effect biosolids application wi l l have on soil quality parameters in these three adjacent forage production systems five years following a single biosolids application. 1.7 Objectives Objective no. 1: Determine the effects of biosolids application on soil physical properties including; the stability of soil aggregates, bulk density, and aeration porosity. Hypothesis to be tested: Biosolids application w i l l improve stability of soil aggregates, increase aeration porosity, and reduce soil bulk density relative to control and fertilized treatments. 13 Objective no. 2: Evaluate the dis tr ibut ion o f so i l total C and N among aggregate size fractions for biosol ids-amended, fer t i l ized, and non-amended so i l . Hypothesis to be tested: B i o s o l i d s appl icat ion w i l l increase C and N concentrations found w i t h i n stable so i l aggregates relative to fer t i l ized and non-amended so i l . Objective no. 3: Determine the hydro lys i s o f f luorescein diacetate ( F D A ) (an indicator o f m i c r o b i a l act ivi ty) i n so i l aggregates > 2 m m from biosol ids-amended, fer t i l ized, and non-amended so i l . Hypothesis to be tested: B i o s o l i d s appl ica t ion w i l l increase F D A hydro lys i s i n so i l aggregates > 2 m m relative to the fer t i l ized and non-amended soils . 1.8 References A l b i a c h , R . , R . Canet, F . Pomares, and F . Ingelmo. 2001 . Organic matter components, aggregate stabi l i ty and b i o l o g i c a l ac t iv i ty i n a hort icul tural so i l fer t i l ized w i t h different rates o f two sewage sludges dur ing ten years. Bioresource Techno logy 77:109-114. Anger s , D . A . , S. Recous , and C . A i t a . 1997. Fate o f carbon and ni t rogen i n water-stable aggregates dur ing decompos i t ion o f 1 3 C 1 5 N - l a b e l l e d wheat straw i n situ. European Journa l o f S o i l Science 48 :295-300 . Br igh t , D A . , and N . Hea ley . 2003. Contaminant r isks f rom b ioso l ids l and appl icat ion: Contemporary organic contaminant levels i n digested sewage sludge f rom five treatment plants i n Greater Vancouve r , B r i t i s h C o l u m b i a . Env i ronmenta l P o l l u t i o n 126:39-49. Carter, M . R . , . 1996. A n a l y s i s o f so i l organic matter storage i n agroecosystems. In: Carter, M . R . , , Stewart, B . A . (Eds.) , Structure and Organic Mat te r Storage i n A g r i c u l t u r a l So i l s . C R C - L e w i s , B o c a Ra ton , F L , pp. 3 - 1 1 . Cogger , C . G . , T A . Forge , and G . H . N e i l s e n . 2006. B i o s o l i d s r ecyc l ing : ni trogen management and s o i l ecology. Canad ian Journal o f S o i l Science 86 :613-620 . Denn i s , G . I . , and P . R . Fresquez. 1989. The so i l m i c r o b i a l c o m m u n i t y i n a sewage-sludge-amended semi-ar id grassland. B i o l o g y and Fer t i l i ty o f So i l s 7 :310-317 . 14 Duynstee, T. and K. Lee. 2000. A decade of biosolids recycling at the Greater Vancouver Regional District. G V R D -Nutrifor Program publication. Available at: http://wvv^v.nutrifor.com/pdfs/hvc_biosolidsrecprogram.pdf Duynstee, T. 2001. Highland valley copper biosolids reclamation program (1996-2000). G V R D -Nutrifor Program publication. Available at: http://www.nutrifor.com/pdfs/hvc_biosolidsrecprogram.pdf Elliott, E.T., and D.C. Coleman. 1988. Let the soil work for us. Ecological Bulletins 39:23- 32. Glauser, R., H.E. Dormer, and E.A. Paul. 1988. Soil Aggregate stability as a function of particle size in sludge treated soils. Soil Science 146:37- 43. Grasslands Conservation Council of British Columbia. 2004. B C grasslands mapping project: a conservation risk assessment. Final Report. Grassland Conservations Society of B C , Kamloops, BC. 109 pp. Available at: http://ww.bcgrasslands.Org/SiteCM/U/D/D51D823AC0A09A05.pdf G V R D . 1999. Recycling biosolids to the soil; Trace metals. Technical bulletin prepared by the G V R D to provide B.C. medical and environmental health officers with information about biosolids. Report No. 2. Available at: http://www.gvrd.bc.ca/nutrifor/publication.htm G V R D . 2002 - 2005. Biosolids recycling program annual report. Greater Vancouver Regional District, Burnaby, BC. Available at: http://www.gvrd.bc.ca/nutrifor/publication.htm Jensen, R. 1993. Research encourages biosolids reuse. Environmental Protection 4:14-18. Kladivko, E.J., and D.W. Nelson. 1979. Changes in soil properties from application of anaerobic sludge. Journal of the water pollution control federation 51:325-332. McDougall, R., Van Ham, M.D. , and Douglas, M.J . 2002. Best Management Practices Guidelines for the Land Application of Managed Organic Matter in British Columbia. Martinez, F., G. Cuevas, R. Calvo, and I. Walter. 2003. Biowaste effects on soil and native plants in a semiarid ecosystem. Journal of Environmental Quality 32:472-^179. Miller, R . M . and J.D. Jastrow. 2000. Mycorrhizal fungi influence soil structure. In: Y . Kapulnik and D.D. Douds (Eds.) Arbuscular mycorrhizae: Molecular biology and physiology. Kluwer Academic Press, Dordrecht, The Netherlands, pp. 3-18. Neilsen, G.H., E.J. Hogue, T. Forge, and D. Neilsen. 2003. Surface application of mulches and biosolids affect orchard soil properties after 7 years. Canadian Journal of Soil Science 83:131— 137. Oades, J .M. 1984. Soil organic matter and structural stability; mechanisms and implications for management. Plant and Soil. 76:319-337. 15 O ' C o n n o r , G . A . , H . A . E l l i o t , N . T . Basta , R . K . Bas t ian , G . M . P i e r z y n s k i , R . C . S ims , and J . E . Smi th , Jr. 2005. Sustainable land appl icat ion: an overv iew. Journal o f Env i ronmen ta l Qua l i t y 34 :7 -17 . O M R R . 2002. Organic matter r e cyc l i ng regulat ion [online]. Waste management act and health act, B . C . R e g . 18/2002 O . C . M i n i s t r y o f Water , L a n d and A i r P o l l u t i o n . Government o f B . C . A v a i l a b l e f rom ht tp : / /www.qp.gov.bc .ca /s ta t reg/ reg/E/EnvMgmt/18_2002.htm Overcash , M . , R . C . S ims , J . L . S ims , and J . K . C . N i e m a n . 2005. B e n e f i c i a l reuse and sustainabili ty: the fate o f organic compounds i n land appl ied waste. Journal o f Env i ronmen ta l Qua l i t y 34 :29 -41 . R i l l i g , M . C . and D . L . M u m m e y . 2006. Tans ley rev iew; M y c o r r h i z a s and s o i l structure. N e w Phyto logis t 171:41-53 . S i x , J . , E . T . E l l i o t , and K . Paustian. 2000. S o i l macroaggregate turnover and microaggregate formation: a mechan i sm for C sequestration under no-t i l lage agriculture. S o i l B i o l o g y and B i o c h e m i s t r y 32 :2099-2103 . Stehouwer, R . C , E . M a c n e a l . 2004. Effect o f a lkal ine-s tabi l ized b ioso l ids on alfalfa m o l y b d e n u m and copper content. Journal o f Env i ronmenta l Qua l i t y 33 :133-140 . S u l l i v a n , T . S . , M . E . Stromberger, and M . W . Paschke. 2006. Para l l e l shifts i n plant and so i l m i c r o b i a l communi t ies i n response to b ioso l ids i n ' a s emi -a r i d grassland. S o i l B i o l o g y and B i o c h e m i s t r y 38 :449-459 . S t i l l , G . , A . M a c K i n n o n , and R . P landen (eds.). 1994. Forest, range and recreation resource analysis. B . C . M i n i s t r y o f Forests, V i c t o r i a , B . C . S y l v i s . 2001 . B i o s o l i d s minera l iza t ion rates. Labora tory and f ie ld studies: Phases 1 & 2. Prepared for the G V R D b y S y l v i s Env i ronmenta l . A v a i l a b l e at: ht tp: / /www.gvrd.bc.ca/nutr i for /publicat ion.htm. T i s d a l l , J . M . and J . M . Oades. 1982. Organic matter and water-stable aggregates i n soi ls . Journal o f S o i l Science 33 :41-163 . Toronto. 2004. C i t y o f Toronto B i o s o l i d s and residuals master p lan ; Execu t ive summary. Prepared for the c i ty o f Toronto b y K M K consultants l imi t ed i n associat ion w i t h B l a c k and V e a t c h Canada. A v a i l a b l e at: ht tp: / /www.toronto.ca/wes/ techservices/ involved/wws/biosol ids/pdf/2004-09-6_execut ive.pdf . Tsadi las , C D . , I . K . M i t s i o s , and E . G o l i a . 2005. Influence o f b ioso l ids appl ica t ion on some so i l phys i ca l properties. Communica t ions i n S o i l Science and Plant A n a l y s i s 36 :709-716 . U S E P A . 1995. U . S . Env i ronmen ta l Protect ion A g e n c y . Off ice o f Wastewater Management . A guide to the B i o s o l i d s R i s k Assessments for the E P A Part 503 R u l e . E P A / 8 3 2 / R - 9 3 - 0 0 5 . 145pp. A v a i l a b l e at: h t tp : / /www.epa.gov/owm/mtb/biosol ids /503rule / index.htm 16 V a n H a m , M . , K . L e e , and B . M c L e a n . 2000. P i t to park: gravel m ine reclamat ion us ing b iosol ids . In: P l ann ing for E n d L a n d Uses i n M i n e Rec l ama t ion - Proceedings o f the Twen ty -fourth A n n u a l B r i t i s h C o l u m b i a M i n e Rec lama t ion S y m p o s i u m , W i l l i a m s L a k e , B C . pp. 3 8 - 51 . A v a i l a b l e at: ht tp: / /www.gvrd.bc.ca/nutr ifor/pdfs/Pit toPark. v a n V e e n , J . A . and P . J . K u i k m a n . 1990. S o i l structural aspects o f decompos i t ion o f organic matter b y microbes . B iogeochemis t ry 11:213-233. W E R F . 1993. Water Env i ronmenta l Research Foundat ion . Documents on long-term experience o f b ioso l ids land appl icat ion programs. Project 91- ISP-4 . 120pp. A v a i l a b l e at: h t tp : / /www.wer f .us /Col lec t ion^ ioso l ids_char t . c fm W i k e e m , B . M . , A . M c l e a n , A . Bawtree , and D . Quin to . 1993. A n ove rv iew o f the forage resource and beef product ion on c r o w n land i n B r i t i s h C o l u m b i a . Canad ian Journal o f A n i m a l Science 73 :779-794 . Wr igh t , S. F . and A . Upadhyaya . 1998. A survey o f soi ls for aggregate s tabi l i ty and g loma l in , a g lycopro te in produced b y hyphae o f arbuscular myco r rh i za l fungi. Plant and S o i l 198:97-107. Wr igh t , S .F . 2000. A fluorescent ant ibody assay for hyphas and g l o m a l i n f rom arbuscular m y c o r r h i z a l fungi. Plant and S o i l 226 :171-177 . X i a , K . , A . Bhandar i , K . Das , G . P i l l a r . 2005. Occurrence and fate o f pharmaceuticals and personal care products ( P P C P s ) i n B i o s o l i d s . Journal o f Env i ronmen ta l Q u a l i t y 34 :91-104 . Zebarth, B . J . , G . H . N e i l s e n , E . Hogue , and D . N e i l s e n . 1999. Influence o f organic waste amendments o n selected so i l phys ica l and chemica l properties. Canad ian Journal o f S o i l Science 79 :501-504 . Zebarth, B . J . , R . M c D o u g a l l , G . N e i l s e n , and D . Ne i l s en . 2000. A v a i l a b i l i t y o f ni trogen from m u n i c i p a l b ioso l ids for dry land forage grass. Canad ian Journal o f Plant Science 80 :575-582 . , 17 Chapter 2: Effects of biosolids on soil physical properties in a crested wheatgrass pasture in the southern interior of British Columbia1 2.1 Introduction B i o s o l i d s are the residual solids o f m u n i c i p a l wastewater treatment that meet regulatory requirements for land appl icat ion. Treatment invo lves phys i ca l separation o f solids f rom wastewater, fo l lowed b y secondary treatment b y h igh temperature digest ion to reduce vector attraction and pathogens, degrade organic matter, and dewatered b y centrifuge to facilitate hand l ing and transport. B i o s o l i d s are c lass i f ied as class A or B depending o n the leve l o f pathogen reduction. In 2005, the Greater V a n c o u v e r R e g i o n a l Dis t r ic t ( G V R D ) appl ied about 15,000 dry tonnes o f b ioso l ids to various types o f lands i n B r i t i s h C o l u m b i a ( B C ) . The largest users o f G V R D b ioso l ids are m i n e rec lamat ion projects (78%), w h i l e a m u c h smal ler p ropor t ion o f b ioso l ids (10%) is used for fer t i l izat ion o f rangeland and pasture soils . S ince the late 1930s, about 45,000 ha o f grasslands i n the southern interior o f B C have been re-seeded w i t h crested wheatgrass (Agropyron cristatum ( L . ) Gaertn.) , an introduced grass species f rom Siber ia . The seeding was done to improve degraded land o n abandoned farmland and overgrazed rangeland ( W i k e e m et a l . , 1993). Crested wheatgrass has the advantage o f early spring growth due to more efficient N use as compared to native grasses ( S m o l i a k and Dormaar , 1985; B o x , 1986; Dormaar et a l . , 1995). B i o s o l i d s are re la t ive ly rich i n N as w e l l as other nutrients such as P , S, C a , and M g (Cogger et a l . , 2006) and are k n o w n to improve the p roduc t iv i ty o f crested wheatgrass (van R y s w y k et a l . , 1993). 1 N O T E : A vers ion o f this chapter w i l l be submitted for publ ica t ion . B M W a l l a c e , M K r z i c , T A Forge , K Broe r sma , and R F N e w m a n . Effects o f b ioso l ids on so i l phys i ca l properties i n a crested wheatgrass pasture i n the southern interior o f B r i t i s h C o l u m b i a . 18 The appl icat ion o f b ioso l ids to rangelands and pastures increases so i l organic matter that c o u l d potent ia l ly sequester C and improve phys i ca l and chemica l aspects o f so i l qual i ty (Ne i l sen et a l . , 2003). The previous study b y Forge et a l . (unpublished data) has shown that the increase i n s o i l total C and N associated w i t h b ioso l ids amendments to crested wheatgrass pastures i n the southern interior o f B C persisted through at least three fu l l g rowing seasons. T h i s was an ind ica t ion that b io so l i d s -C is re la t ively resistant to m i c r o b i a l attack or that the improved s o i l nutr i t ion has led to increased plant product iv i ty and increased returns o f organic matter to the so i l . Increased b i o l o g i c a l ac t iv i ty i n b iosol ids-amended so i l (Forge et a l . , i n preparation) m a y enhance aggregate stabil i ty, w h i c h has been noted as an important indicator o f ecosystem health and so i l qual i ty ( B i r d et a l . , 2002; H a m e l , 1996; H e r r i c k et a l . , 2002; Jeffries et a l . , 2003). Aggregate s tabi l i ty measurements i nvo lve the determination o f aggregate-size dis tr ibut ion. The parameter c o m m o n l y used to describe aggregate stabil i ty is mean weight diameter ( M W D ) . The effect o f organic amendments, i nc lud ing b ioso l ids , on s o i l phys i ca l properties depends o n the rate o f decomposi t ion , quantity appl ied, and method o f s o i l incorporat ion (Kha lee l , 1981). A n increase i n water infi l t rat ion, aggregate s tabi l i ty (expressed as M W D ) , water -holding capacity, and cat ion exchange capaci ty was observed i n coarse textured so i l i n orchards i n the southern interior o f B C where two applications o f 45 M g b ioso l ids ha" 1 had been surface-applied over seven years (Ne i l sen et a l . , 2003). S i m i l a r l y , K l a d i v k o and N e l s o n (1979) reported greater aggregate size and stabili ty, aeration poros i ty (macropores), and a decrease i n b u l k density one year after the surface appl icat ion o f b ioso l ids at 56 M g ha" 1 to a silt l o a m so i l i n Indiana. S o i l fert i l i ty and C sequestration can be improved i n B C rangelands through a better understanding o f the effects o f b iosol ids appl icat ion o n aggregate s tabi l i ty and other so i l phys ica l properties. 19 The main objective of this study was to determine the effects of biosolids on soil physical properties (stability of soil aggregates, bulk density, and aeration porosity) in a crested wheatgrass pasture in the southern interior of BC. The hypotheses were that biosolids application improves the stability of soil aggregates, increases aeration porosity, and reduces soil bulk density relative to control and chemically fertilized plots. The additional objectives were to (i) determine the distribution of soil total C and N among stable aggregate size fractions and (ii) to determine the hydrolysis of fluorescein diacetate (FDA), an indicator of microbial activity, in aggregates larger than 2 mm among biosolids-amended, fertilized, and non-amended soil. The hypotheses associated with these objectives were that biosolids application would increase F D A hydrolysis activity and the soil total C and N in stable aggregates relative to control and chemically fertilized treatments. 2.2 Material and Methods 2.2.1 Site Description The study was conducted on an existing long-term experiment (established in 2001) maintained by Agriculture and Agri-Food Canada. The study site is located at the Ashcroft Ranch, B C (50°40'N, 121°21'W; elevation 258 m), 10 km south of Cache Creek, BC. The soil is a silt loam Orthic Brown Chernozem developed from surficial deposits in colluvial fans and fluvial gravels covered with a thin veneer of aeolian material (Young et al., 1992). Soil on the study site have a pH of 8.5, 38% sand, 51%. silt, and 11%. clay, varying amounts of coarse fragments (1- 44%. by vol.), and a saturated electrical conductivity of 0.4 dS m"1. In the late 1970s, the site was broadcast seeded to crested wheatgrass at 22.4 kg ha"1 following disking. 20 Crested wheatgrass is s t i l l the dominant grass species at the site, compet ing w e l l against weeds and natural vegetation. The region is characterized b y a semi- to sub-arid c l imate regime w i t h hot, d ry summers and moderately c o l d winters , often w i t h litt le snowfa l l (Lavender et a., 1990). Ave rage annual air temperature i n this reg ion is 8 . 9 °C , w h i l e average J u l y temperature is 2 2 ° C . The number o f frost-free days averages 143 i n the va l l ey bot tom w i t h an average number o f 2539 g r o w i n g degree-days. A n n u a l precipi ta t ion is 243 m m w i t h the majori ty o f the ra infa l l be ing received dur ing M a y to September (89 m m ) , w h i l e the average snowfa l l is 142 c m ( Y o u n g et a l . , 1992). Precipi ta t ion and air temperatures recorded at the site dur ing the 2005 and 2006 study years deviated f rom the long-term averages (F ig . 2.1). A i r temperatures i n J u l y o f both study years were 2 ° C above normal . T h i s was coupled w i t h l o w precipi tat ion, w h i c h was about 25 m m lower than the 1971-2000 J u l y average. O n the other hand, i n June 2005 precipi ta t ion was near ly 30 m m greater than the 1971-2000 June average for this region. 21 Jan Feb March April May June July Aug Sep Oct Nov Dec Figure 2.1 - C l i m a t e and weather at the Ashcrof t R a n c h , B C i n (a) 2005 and (b) 2006. In fa l l o f 2001 , the experiment was l a id out i n a randomized complete b l o c k design w i t h four treatments i n each o f four b locks . Treatments were: (1) no b ioso l ids and no fert i l izer appl ica t ion (control) , (2) N + P fert i l izer (300 k g N + 400 k g P ha" 1 as a mix ture o f a m m o n i u m phosphate and urea) (ferti l izer), (3) b ioso l ids appl icat ion at 20 dry M g ha" 1 (B io -20) and (4) b ioso l ids appl ica t ion at 60 dry M g ha" 1 (B io -60) . The fert i l izer appl ica t ion rate was determined to provide s imi la r first-year potent ia l ly avai lable N (300 k g N ha" 1) and total P (400 k g P ha"1) as i n the B i o - 2 0 treatment. A l l treatments were appl ied to the s o i l surface wi thout subsequent incorporat ion. Plots were 10 m w i d e and var ied i n length f rom 90 to 140 m due. to uneven fence l ines. The study area was fenced w i t h 1.5 m - h i g h barbed w i r e to exclude spring graz ing b y cattle. Prev ious research at the same study site (Forge et a l . , prog, rep.) measured total so i l C and N between 2002 and 2004 f o l l o w i n g b iosol ids appl ica t ion i n fa l l 2001 . B o t h so i l C and N 22 increased w i t h increasing rates o f b ioso l ids appl icat ion ( A p p e n d i x 4). In fa l l 2002, 2003 and 2004, so i l organic C and total N at the 0-15 c m depth were s igni f icant ly greater (P < 0.05) o n the 60 M g ha" 1 b ioso l ids treatment relative to the control . S o i l N was also s ignif icant ly greater o n 60 M g ha" 1 b ioso l ids treatment relative to the control i n spring 2003. 2.2.2 Soil Properties Aeration Porosity and Bulk Density S o i l aeration poros i ty and bu lk density were determined on undisturbed so i l core samples. S o i l cores were taken f rom 0-7.5 c m depth on M a y 12, 2005 and o n M a y 31 , 2006 w i t h a double-cyl inder , drop-hammer sampler and a 7.5-cm-diameter b y 7.5-cm-deep core. Three samples were taken per transect running through the midd le o f each plot. Samples were wrapped i n plast ic and stored i n the refrigerator at 4 ° C un t i l analysis. S o i l cores were weighed , and then progress ively saturated i n a container w i t h tap water for an average o f 20 hours. Af t e r saturation, the cores were we ighed and p laced on a tension table (Danie l son and Sutherland, 1986), w h i c h contained a tension m e d i u m o f s i l i con carbide sand (grit 400). Ae ra t i on porosi ty , w h i c h corresponds to the v o l u m e o f so i l pores w i t h a diameter >50 u m , was determined o n a water tension table adjusted to -6 k P a o f matric potential for a per iod o f 20 hours. Wate r - f i l l ed pore-space was calculated f rom the mass /volume o f water that was retained i n the so i l at -6 k P a , relative to the total so i l vo lume . The cores were then dr ied for 24 hours at 1 0 5 ° C . S o i l bu lk densi ty was determined as the mass o f dry s o i l per unit v o l u m e o f f ield-moist so i l (B lake and Hartge, 1986). Coarse fragments (diameter >2 m m ) w i t h i n the sample were screened out and weighed . V o l u m e o f minera l coarse fragments was determined f rom dry mass, assuming a part icle density o f 2.65 M g m" 3 . B u l k densities o f minera l so i l samples were calculated as the mass o f dry, coarse fragment-23 free soil per volume of field-moist soil, where volume was also calculated on a coarse fragment-free basis. Aggregate Stability Samples for aggregate stability determination were collected on May 12 (Spring), June 16 (Summer), and October 10 (Fall) of 2005 and on May 31 (Spring), July 10 (Summer), and October 6 (Fall) of 2006. Two composite soil samples were taken per plot. Each composite sample consisted of five individual samples taken every 5 m along a transect running through the middle of each plot. The only exception was the first sampling period (May 12, 2005), when one composite sample consisting of 10 individual soil samples was taken. Samples were collected with a hand trowel at 0-5 cm depth. Since biosolids were surface applied to an established grass sward, an effort was made to sample from the mineral layer and any organic matter, including biosolids, was scraped away before sampling. Samples were transported to the laboratory in closed plastic containers to prevent crushing, and stored in the refrigerator at 4°C until analysis. Aggregate stability was assessed using a variation of the wet sieving method (Nimmo and Perkins, 2002). Field moist samples were first passed through a 6-mm sieve and collected on a 2-mm sieve. The pre-sieved 2-6 mm moist sample (of about 10 g) was placed on top of a nest of sieves with openings of 2, 1, and 0.25 mm, and wetted in a humidifier for 1 hour to minimize disruption caused by air trapping. This was performed immediately before wet sieving. Wet sieving was performed for 10 minutes in a motor-driven mechanical device with a vertical stroke of 2.5 cm at a rate of 30 strokes per minute. The motion of the system had both a vertical stroke and an oscillating action through an angle of 30°. After the sieves were removed from the water, the material retained on each sieve was oven dried at 60°C for 24 hours, weighed, and the mass from each size fraction was expressed as a percentage of the total soil mass. The results for 24 aggregate stabil i ty were expressed as the mean weight diameter ( M W D ) , w h i c h represents the summat ion across size fractions o f the product o f the mean diameter o f each size fraction (Di) and 4 the propor t ion o f the sample weight occurr ing i n that size fraction (W,) ( M W D = J]WiD.). 1=1 Correct ions were made for minera l particles retained o n each sieve to a v o i d biased interpretations o f water stable aggregates. Total C and N of SoU Aggregates Tota l so i l C and N were determined on aggregates col lected dur ing June 16, 2005 sampl ing. Aggregates i n the 2-6, 1-2, and 0.25-1 m m size fractions f o l l o w i n g 2005 wet -s iev ing were saved, oven dr ied at 6 0 ° C for 24 hours, and analyzed for total C and N b y dry combus t ion (Ne l son and Sommers , 1982) us ing the L E C O C N S - 2 0 0 0 automated analyzer (Leco Corp . , St. Joseph, M I ) . Hydrolysis of Fluorescein Diacetate The compound fluorescein diacetate (3', 6 ' -d iacetyl f luorescein [ F D A ] ) is hyd ro lyzed b y esterases, proteases, and lipases i n plant, fungal, and bacterial cel ls and is indica t ive o f so i l m i c r o b i a l ac t iv i ty (Schnurer and R o s s w a l l , 1982). The fluorescent product o f this reaction (fluorescein) f o l l o w i n g an incubat ion per iod is e l iminated f rom the c e l l and can be quantif ied b y V i s i b l e Spectrophotometer (Pye U n i c a m , SP6-350) b y measur ing fluorescence at 490 n m . H y d r o l y s i s analysis f o l l owed the procedure as proposed b y Green et a l . (2006) where 0.75 g o f f ie ld mois t so i l was p laced i n a flask, 50 m L o f 60 m M sod ium phosphate buffer ( p H 7.6), and 0.50 m L o f 4.9 r n M F D A substrate solut ion were added. The flask was c losed w i t h a stopper, swi r l ed for a few seconds, and p laced i n a water bath incubator for 3 h at 3 7 ° C . Quant i f ica t ion o f 25 m g fluorescein k g " so i l 3 h r " was done b y compar ing the absorbance to a standard curve made w i t h a stock solu t ion o f f luorescein. Sample co l lec t ion for this analysis was done on M a y 31 , 2006. T w o composi te samples consisted o f f ive i nd iv idua l samples taken every 5 m along a transect running through the m i d d l e o f each plot. F i e l d mois t samples were first s ieved through a 6-mra sieve and then through a 2-m m sieve. A sub-sample o f 10-15 g o f 2 - 6 m m aggregates f rom each composi te sample was stored and kept refrigerated at 4 ° C unt i l analysis. 2.2.3 Statistical Analysis Aggregate stabil i ty and C and N data were analyzed as a randomized , complete b l o c k design w i t h four replications. The so i l bu lk density and aeration poros i ty data were analyzed as a randomized , complete b l o c k design w i t h four replicat ions and three subsamples per plot . The F D A hydro lys i s data was analyzed as a randomized, complete b l o c k design w i t h four replicat ions and two subsamples per plot . The S A S general l inear m o d e l procedure was used ( S A S Institute Inc., 2003). Probabi l i t ies and F values obtained b y the A N O V A are tabulated i n A p p e n d i x 3. F o l l o w i n g a significant F-test, differences between treatment means were evaluated us ing Scheffe 's mul t ip le compar i son test. Resul ts were considered signif icant at P < 0.05. 2.3 Resul ts and D i s c u s s i o n 2.3.1 Soil Bulk Density and Aeration Porosity S o i l b u l k density was not affected b y fert i l izer and b ioso l ids applications (Table 2.1). A rev iew b y C l a p p et a l . (1986) reported a general trend o f decreasing s o i l bu lk density w i t h increasing rates o f b ioso l ids appl icat ion o n 17 different soi ls . In m y study, the lack o f treatment effect o n s o i l bu lk density was most l i k e l y due to a large var ia t ion i n texture among the study 26 b locks (sand fraction ranged from 46 to 5 5 % b y v o l . for b locks 3 and 4, respect ively) . T h i s i n turn led to a re la t ively large var ia t ion i n so i l bu lk density (from 1.14 to 1.33 M g m" 3 ) . B u l k density values were s imi la r to those b y K r z i c et a l . (2000) from a study conducted on crested wheatgrass sites located about 20 k m east o f m y study site and o n the same so i l type. Ae ra t i on poros i ty was not s ignif icant ly affected b y fert i l izer or b ioso l ids applicat ions (Table 2.1). A l imi t ed number o f studies evaluated impacts o f b ioso l ids o n aeration porosi ty. F o r example, K l a d i v k o and N e l s o n (1979) observed a 2 7 % increase i n aeration poros i ty one year f o l l o w i n g surface appl ica t ion o f b iosol ids at 56 M g ha" 1 to a silt l o a m so i l i n Indiana. Table 2.1 - S o i l b u l k density and aeration poros i ty on four study treatments i n M a y 2005 and 2006 o n the crested wheatgrass site. 3 3 3 B u l k density ( M g m" ) Ae ra t i on porosi ty (m m" ) Treatments 2005 2006 2006 . C o n t r o l 1.33a 1.24a 0.20a Fer t i l i zer 1.34a 1.24a 0.16a B i o - 2 0 1.27a 1.18a 0.19a B i o - 6 0 1.21a 1.19a 0.19a P 0.150 0.630 0.310 Z S E 0.041 0.041 0.014 Z SE = Standard error of the mean (« =12) P O . 0 5 2.3.2 Aggregate Stability D u r i n g a l l three sampl ing periods i n 2005 and summer 2006, aggregate M W D was s igni f icant ly greater (P < 0.05) i n the B i o - 6 0 than i n the control and fert i l izer treatments (F ig . 2.2). Genera l ly , b ioso l ids appl ied at 60 M g ha" 1 produced about 5 0 % more large aggregates (>2 m m ) than the control and fert i l izer treatments i n both 2005 and 2006 ( F i g . 2.3). M e a n weight diameter i n the B i o - 2 0 treatment was statistically different f rom the control or ferti l izer treatments at two o f the s ix sampl ing periods. S i m i l a r l y , K l a d i v k o and N e l s o n (1979) reported 27 that b ioso l ids surface-applied at 56 M g ha" rate to a silt l o a m s o i l i n Indiana increased M W D b y 5 0 % relative to the control a year after appl icat ion. In our study, M W D was general ly greater at sampl ing t imes w h e n s o i l water content was l o w . F o r example, i n the unusual ly dry M a y 2005 (F ig . 2.1a) h igh M W D was observed, f o l l owed b y l o w overa l l M W D i n June 2005, after an unusual ly h igh amount o f ra infa l l . A s imi la r relationship was observed i n 2006 w i t h the greatest M W D values came f rom samples taken i n J u l y when the so i l was driest (F ig . 2.1b). Decreases i n M W D associated w i t h the increases i n water content were reported prev ious ly (Haynes and Swif t , 1990; Anger s , 1992; H e r m a w a n and B o m k e , 1996; K r z i c et a l . , 2000). Haynes and Swif t (1990) reported an increase i n M W D w i t h decreasing water content i n permanent pasture soils i n N e w Zealand, w h i l e soi ls under pasture/arable c ropp ing rotations showed a decrease i n the M W D w i t h decreasing water content. H e r m a w a n and B o m k e (1997) reported that when s lak ing o f aggregates was not prevented pr ior to wet -s iev ing analysis a posi t ive relationship between M W D and water content was found. Aggregates w h e n pre-wetted pr ior to analysis, as i n our study, showed a negative relationship between s o i l water content and M W D . Based on these f indings, c ropp ing his tory at the site (permanent pasture) and methodology used i n the analysis (s laking prevented) c o u l d expla in the temporal var ia t ion found, i n this study. 28 Spring Summer Fall Spring Summer Fall Figure 2.2 - The mean weight diameter ( M W D ) (a, b) and water content (c, d) o f so i l aggregates dur ing the 2005 and 2006 crested wheatgrass g rowing seasons. E r ro r bars represent the standard error o f the mean ( « = 4 ) . Bars w i t h the same letter w i t h i n sampl ing t imes are not s ignif icant ly different (P > 0.05). The fraction o f so i l i n the largest aggregate size class (2-6 m m ) general ly exhibi ted a s imi la r trend as the M W D , be ing s ignif icant ly greater i n the B i o - 6 0 treatment than i n the control and ferti l izer treatments (Figs. 2.3a and 2.4a). Increases i n the size and propor t ion o f stable aggregates from b ioso l ids appl icat ion m a y be attributed to increased plant and mic rob i a l ac t iv i ty associated w i t h i m p r o v e d s o i l nutr i t ion (Haynes and Swif t , 1990; Ange r s and G i r o u x , 1996; Puget et a l . , 1995). Aggrega t ion is improved because o f the numerous compounds produced w i t h i n the rhizosphere (i.e., root exudates, m ic rob i a l gums) that act as b i n d i n g agents among p r imary so i l particles. In 2005, the proport ion o f stable aggregates i n the largest size class observed i n the control decreased from 4 7 % i n the spring to 6% i n the fa l l . T h i s is most l i k e l y 29 due to an increase o f s o i l water content (Figure 2.2). A s imi la r effect was seen i n 2006 for the largest aggregate size class, but it occurred dur ing different sampl ing periods perhaps due to a different precipi ta t ion dis t r ibut ion relative to the 2005 g r o w i n g season. In both years, less than 1 5 % o f the total so i l f rom a l l treatments was i n the 1-2 m m aggregate size class (Figs . 2.3b and 2.4b). S i m i l a r proportions o f aggregates were found i n this size class i n other studies carr ied out i n grasslands i n the southern interior o f B C (Broersma et a l . , 2000; K r z i c et a l . , 2000). Aggregates o f this size d i d not seem to exhibi t the same seasonal fluctuations as 2 - 6 m m size class. Gup ta and G e r m i d a (1988) evaluated bacterial and fungal contributions to m i c r o b i a l b iomass C across various aggregate s ize classes at a native grassland i n southern Saskatchewan. T h e y found that 0.5-1 m m aggregates contained four times more fungal biomass than aggregates > 1 m m . The authors suggested that aggregates > 1 m m had greater amount o f temporary b i n d i n g agents (i.e., polysaccharides and fine roots that were more susceptible to mineral iza t ion) , w h i l e aggregates < 1 m m were s tabi l ized b y more permanent b i n d i n g agents, such as hyphae. 30 Figure 2.3 - F rac t ion o f total so i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2005 crested wheatgrass g r o w i n g season. E r ro r bars represent standard error o f the mean (n-4). Bars w i t h the same letter w i t h i n sampl ing t imes are not different (P > 0.05). In summer o f 2005 and 2006, the untreated control had 25 -34% higher propor t ion o f the 0.25-1 m m aggregates relative to a l l other treatments (Figs. 2.3c and 2.4c). The Bio-20 . treatment had the smallest propor t ion (19 - 21%) o f aggregates i n the smallest size class (0.25-1 m m ) . The aggregate size class <0.25 m m , that represents the propor t ion o f so i l that passes through the smallest sieve used, was the most dominant aggregate class on the control and fert i l izer treatments for both years o f this study (Figs. 2 .3d and 2.4d). There were no differences i n the aggregate size class <0.25 m m between fert i l izer and control treatments. The fact that the B i o - 2 0 and B i o - 6 0 treatments had predominant ly large aggregates (>1 m m ) , w h i l e the control and fert i l izer treatments were determined b y aggregates < 1 m m indicates that b ioso l ids appl ica t ion m a y have helped the s tabi l izat ion o f aggregates w i t h diameters larger than 1 m m . T h i s i n turn means that b ioso l ids appl icat ion m a y have improved aggregate stabil i ty. The B i o - 6 0 treatment, w h i c h is three times higher than the typ ica l appl ica t ion rate for pastures i n the interior o f B C , general ly resulted i n the greatest M W D and largest propor t ion o f aggregates > 1 m m . Increases i n so i l C due to appl ica t ion o f var ious organic amendments were observed to affect s o i l phys i ca l properties (Clapp et a l . , 1986; A l b i a c h et a l . , 2001 ; N e i l s e n et a l . , 2003). It is important to note; however , that improvements to aggregate s tabi l i ty and infi l t rat ion rates have o n l y been observed i n studies where b ioso l ids were appl ied i n excess o f guidelines based on metal load ing l imi t s or agronomic considerations ( A l b i a c h et a l . , 2001 ; C l a p p et a l . , 1986; N e i l s e n e t a l . , 2003; K h a l e e l et a l . , 1981). 31 Spring Summer Fall Spring Summer Fall Figure 2.4 - F rac t ion o f total so i l sample present i n four aggregate s ize classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2006 crested wheatgrass g r o w i n g season. E r r o r bars represent standard error o f the mean ( « = 4 ) . Bars w i t h the same letter w i t h i n sampl ing times are not different (P > 0.05). 2.3.3 Total Carbon and Nitrogen of Soil Aggregates O v e r a l l , C and N concentrations were greater i n larger aggregate size fractions. The B i o -60 treatment increased C concentration o f stable aggregates relat ive to control and fert i l izer treatments ( F i g . 2.5); the B i o - 2 0 treatment was intermediate. There were no differences between control and fert i l izer treatments. The B i o - 6 0 treatment resulted i n 9 0 % greater C than i n the B i o -20 i n the 1-2 m m size fraction, w h i l e the 0.25-1 m m fraction had C concentrat ion that was 6 8 % greater relative to the B i o - 2 0 b ioso l ids rate. C lass A b ioso l ids are c o m m o n l y appl ied i n accordance w i t h N ava i lab i l i ty and crop N requirements. In the southern interior o f B C , this results i n an applicat ions rate o f about 20 M g ha" 1 ( M c D o u g a l l et a l . , 2002). Organic matter additions from b ioso l ids appl ied at 20 M g ha" 1 is 32 estimated to raise the so i l C content f rom an in i t i a l 25 g kg" 1 to 25.6 g kg" 1 (0-30 c m depth) w h e n a conservative 3 0 % minera l iza t ion rate o f total C i n the first year f o l l o w i n g appl icat ion is used. The predicted increase i n total C from bu lk so i l is considerably lower than the increase observed i n stable aggregates i n our study. Stable aggregates contained greater total C (Figure 2.5) than bu lk so i l ( A p p e n d i x 4) and c o u l d lead to C sequestration at this site through cont inued protection o f C w i t h i n stable aggregates. 120 o CD c o 00 -t—• c CD o c o o O 100 A 80 A 60 40 20 A • Control I Fertilizer ~~9 Bio-20 I777I Bio-60 Aggregate Size Classes (mm) Figure 2.5 - C a r b o n concentration o f aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) at the crested wheatgrass site dur ing summer 2005. E r r o r bars represent standard error o f the mean (n=4). Ba r s w i t h the same letter w i t h i n size classes are not s ignif icant ly different (P > 0.05). B i o s o l i d s rate o f 60 M g ha" 1 s ignif icant ly increased the N concentration i n a l l aggregate size classes relative to a l l other treatments ( F i g . 2.6). The N concentrat ion was two times greater i n B i o - 6 0 than i n other treatments. Three other treatments resulted i n the same N concentration i n a l l size classes. Greater total N i n stable aggregates from biosol ids-amended so i l , four years after 33 appl ica t ion suggests that N is s l o w l y be ing minera l i zed over t ime and not a l l at once. Th i s is i n agreement w i t h Zebar th et a l . (2000) w h o estimated that dur ing the first, second, and th i rd year f o l l o w i n g b ioso l ids appl icat ion on pastures i n the central interior o f B C that 25, 10, and 5%, respect ively o f the total N w i l l be avai lable to forage crops. U p o n aggregate breakdown, occ luded N and C from aggregates cou ld be minera l i zed into available forms. 12 2-6 1-2 0.25-1 Aggregate Size Classes (mm) Figure 2.6 - N i t rogen concentration o f aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) at the crested wheatgrass site dur ing summer 2005. Er ro r bars represent standard error o f the mean (n-4). Ba r s w i t h the same letter w i t h i n size classes are not s igni f icant ly different (P > 0.05). The C : N ratios were s imi la r for a l l treatments and size fractions except for the B i o - 6 0 treatment, w h i c h had lower C : N ratios (F ig . 2.7). The C : N o f b ioso l ids t yp i ca l ly is w i t h i n 8 to 10 (Cogger et a l . , 2006); whereas the C : N o f so i l sampled i n 2004 at 0-15 c m depth at this site was 14.5 ( A p p e n d i x 3). It w o u l d seem that a l l treatments except for the B i o - 6 0 had reached a steady state value where C and N were l i k e l y be ing minera l i zed at s imi la r rates. The narrow C : N ratio 34 (o f about 11) on B i o - 6 0 treatment i n a l l aggregate s ize classes indicates that b ioso l ids amended so i l c o u l d s t i l l potent ial ly release/mineralize addit ional N and approach a steady state. o 20 15 10 5 H Control Ferti l izer Bio-20 I7771 Bio-60 2-6 1-2 0.25-1 Aggregate S ize C lasses (mm) Figure 2.7 - The C : N ratio o f aggregates i n size classes (2-6, 1-2, and 0.25-1 m m ) at the crested wheatgrass site dur ing summer 2005. E r ro r bars represent standard error o f the mean (n=4). Bars w i t h the same letter w i t h i n size classes are not s ignif icant ly different (P > 0.05). 2.3.4 Hydrolysis of Fluorescein Diacetate Fluoresce in diacetate ( F D A ) is hyd ro lyzed b y a number o f different m i c r o b i a l endocel lular enzymes such as, proteases, lipases, and esterases (Green et a l . , 2006) .The hydro lys i s o f F D A is an indicator o f overa l l m i c r o b i a l ac t iv i ty and has been correlated w i t h direct v i sua l measurements o f m i c r o b i a l b iomass (Swischer and C a r r o l l , 1980). The greatest F D A hydro lys i s ac t iv i ty (F ig . 2.8) was measured i n so i l from the B i o - 6 0 treatment (212 m g fluorescein g"1 so i l 3 hr" 1), and there were no differences among other treatments ( F D A hydro lys i s rates ranged from 163 to 187 m g g"1 3 hr" 1). These data are consistent w i t h the tendency for C and N concentrations, representing greater potential m i c r o b i a l substrate, 35 to be greater i n the 60 M g ha" 1 treatment. Forge et a l . ( in preparation) found that bacterial feeding nematode populat ions and the d ivers i ty and intensity o f E c o L o g substrate u t i l i za t ion were elevated i n 60 and 20 M g ha" ! treatments i n the same study. In a B i o l o g EcoP la t e substrate u t i l i za t ion study b y S u l l i v a n et a l . (2006), carr ied out o n a sandy l o a m so i l f rom Colo rado , b ioso l ids (0 to 30 M g ha"1) amended so i l exhibi ted a greater and faster u t i l i za t ion o f avai lable substrates. W h i t e et a l . (1997) reported an increase i n fungal act ivi ty , relative to the control , f rom b ioso l ids appl ied at 45 and 90 M g ha" 1 to a semiar id rangeland i n N e w M e x i c o . 250 -T ~ 200 -sz CO o J° 150-'co _ % 100 -1_ O __ E 50 -0 --Control Fertilizer Bio-20 Bio-60 Figure.2 .8 - The hydro lys i s o f f luorescein diacetate ( F D A ) i n the 2-6 m m aggregate size class i n June 2006 at the crested wheatgrass site. E r r o r bars represent standard error o f the mean ( « = 8 ) . Bars w i t h the same letter among treatments are not s ignif icant ly different (P> 0.05). Aggregate formation has been shown to be enhanced b y so i l b i o l o g i c a l act ivi ty , and it was hypothesized that F D A hydro lys i s ac t iv i ty w o u l d be correlated w i t h aggregate stabili ty. A weak pos i t ive relationship (r 2 = 0.4) between the hydro lys i s o f F D A and the M W D was found ( F i g . 2.9). The relationship improves to an r 2 value o f 0.63 w h e n the two grey h ighl ighted points ( F i g . 2.9) are treated as outliers. 36 2.2 2.0 A 1.8 A y = 7.98x-0.18 r 2 = 0.41** n=16 0.8 120 140 160 180 200 220 240 FDA Hydrolysis (kg-1 soil" 1 soil 3 hr"') Figure 2.9 - The relat ionship o f f luorescein diacetate ( F D A ) ac t iv i ty and aggregate mean weight diameter ( M W D ) f rom so i l sampled M a y 31 , 2006 at the crested wheatgrass site. 2.4 Conc lus ions F i v e years after a single, surface appl icat ion o f b ioso l ids at 60 M g ha" 1, greater stabil i ty o f s o i l aggregates (both M W D and largest propor t ion o f aggregates > 1 m m ) , the concentration o f C and N w i t h i n aggregates, and the hydro lys i s o f F D A were observed relat ive to the 20 M g ha" 1, ferti l izer, and control treatments. B i o s o l i d s appl ied at 20 M g ha" 1 tended to increase aggregate stabili ty, as compared to the control , but significant differences i n aggregate stabil i ty were observed o n l y at two out o f s ix sampl ing periods. Signif icant differences i n so i l bu lk density and aeration poros i ty were not detected among treatments. A p p l i c a t i o n o f chemica l fertilizers had no effect o n so i l phys i ca l properties as compared to the control and 20 M g ha" 1 treatments. 37 Data f rom this study indicates that m u n i c i p a l b ioso l ids can improve o f so i l properties (e.g., aggregate stabil i ty and total C and N o f aggregates) o n crested wheatgrass pastures i n the southern interior o f B C . A p p l i c a t i o n rates are determined m a i n l y b y N content o f b iosol ids , yet caut ion s t i l l needs to be exercised due to h igh concentrations o f P , and trace metals i n b ioso l ids that m a y reduce on so i l qual i ty and species compos i t ion . 2.5 References A l b i a c h , R . , R . Canet, F . Pomares, and F . Ingelmo. 2001 . Organic matter components, aggregate stabi l i ty and b i o l o g i c a l ac t iv i ty i n a hort icul tural s o i l fer t i l ized w i t h different rates o f two sewage sludges dur ing ten years. Bioresource Techno logy 77 :109-114 . Anger s , D . A . 1992. Changes i n s o i l aggregation and organic carbon under corn and alfalfa. S o i l Science Soc ie ty o f A m e r i c a Journal 56 :1244-1249 . Anger s , D . A . and M . G i r o u x . 1996. Recen t ly deposited organic matter i n so i l water-stable aggregates. S o i l Science Socie ty o f A m e r i c a Journal 60 :1547-1551 . B i r d , S . B . , J . E . He r r i ck , M . M . Wander , and S .F . Wr igh t . 2002. Spat ia l heterogeneity o f aggregate stabil i ty and s o i l carbon i n semi-ar id rangeland. Env i ronmen ta l P o l l u t i o n 116:445—455. B i t tman , S., T . A . Forge , and C . G . K o w a l e n k o . 2005. Responses o f the bacterial and fungal b iomass i n a grassland s o i l to mul t i -year applications o f da i ry manure s lurry and ferti l izer. S o i l B i o l o g y & B i o c h e m i s t r y 37 :613-623 . B l a k e , G . R . , and K . H . Hartge. 1986. B u l k density. Pages 363 -375 i n A . K l u t e (ed.) Me thods o f so i l analysis. Part 1. 2nd ed. A g r o n o m y M o n o g r a p h 9. A S A - S S S A , M a d i s o n , W I . B o x , T . W . 1986. Crested wheatgrass: its values, problems and myths; where n o w ? Pages 3 4 3 -345 In K . L . Johnston, ed. Crested wheatgrass: its values, problems and myths . S y m p o s i u m proceedings. U t a h State Un ive r s i ty , L o g a n , U T . Broe r sma , K . , M . K r z i c , D . J . Thompson , and A . A . B o m k e . 2000. S o i l and vegetation o f ungrazed crested wheatgrass and native rangelands. Canad ian Journal o f S o i l Science 80 :411-417 . C l a p p , C . E . , S. A . Stark, D . E . C l a y , and W . E . Larson . 1986. Sewage sludge organic matter and so i l properties. In Y . C h e n and Y . A v n i m e l e c h (eds). The role o f organic matter i n modern agriculture, (pp. 209 -253 ) . Mar t inus N i j h o f f Publ ishers , Bos ton , Massachusetts . Cogger , C . G . , T . A . Forge , and G . H . Ne i l s en . 2006. B i o s o l i d s r ecyc l ing : ni t rogen management and s o i l ecology. Canad ian Journal o f S o i l Science 86 :613-620 . 38 Danie l son , R . E . and P . L . Sutherland. 1986. Porosi ty . Pages 4 4 3 - 462 i n A . K l u t e , ed. Me thods o f so i l analysis. Part 1. 2nd ed. A g r o n o m y M o n o g r a p h 9. A S A - S S S A , M a d i s o n , W L Dormaar , J .F . , M . A . Nae th , W . D . W i l l m s , and D . S . Ghanasyk. 1995. Effect o f native prairie, crested wheatgrass (Agropyron cristatum (L . ) Gaertn.) and Russ i an w i l d r y e (Elymus junceus Fisch . ) o n so i l chemica l properties. Journal o f Range Management 48 :258 -263 . Green, V . S . , D . E . Stott, and M . D i a c k . 2006. A s s a y for f luorescein diacetate hydro ly t ic act ivi ty: op t imiza t ion for so i l samples. S o i l B i o l o g y and B iochemis t ry 38 :693 -701 . Gupta , V . , and J.J . Ge rmida . 1988. Di s t r ibu t ion o f m i c r o b i a l b iomass and its ac t iv i ty i n different so i l aggregate size classes as affected b y cul t ivat ion. S o i l B i o l o g y and B i o c h e m i s t r y 20 :777-786 . H a m e l , C . 1996. Prospects and problems pertaining to the management o f arbuscular mycor rh izae i n agriculture. Agr icu l tu re Ecosys tems and Envi ronment 60 :197-210 . Haynes , R . J . , and R . S . Swift . 1990. S tabi l i ty o f s o i l aggregates i n relat ion to organic constituents and so i l water content. Journal o f S o i l Science 4 1 : 7 3 - 8 3 . H e r m a w a n , B . and A . A . B o m k e . 1996. Aggrega t ion o f degraded l o w l a n d so i l dur ing restoration w i t h different c ropp ing and drainage regimes. S o i l Techno logy 9 :239-250 . H e r m a w a n , B . and A . A . B o m k e . 1997. Effects o f winter cover crops and successive spr ing t i l lage o n so i l aggregation. S o i l and T i l l age Research 44 :109-120 . Her r i ck , J . E . , J .R . B r o w n , A . J . Tuge l , P . L . Shaver, and K . M . Havs tad . 2002. A p p l i c a t i o n o f so i l qual i ty to moni to r ing and management: Paradigms f rom rangeland ecology. Journal o f A g r o n o m y 9 4 : 3 - 1 1 . Jeffries, P . , S. G i a n i n a z z i , S. Perotto, K . Turnau, and J . M . Barea . 2003 . T h e contr ibut ion o f arbuscular m y c o r r h i z a l fungi i n sustainable maintenance o f plant health and s o i l fertili ty. B i o l o g y and Fer t i l i ty o f So i l s 37 :1 -16 . K h a l e e l , R . , K . R . R e d d y , and M . R . Overcash . 1981. Changes i n so i l phys i ca l properties due to organic waste applicat ions: A rev iew. Journal o f Env i ronmen ta l Q u a l i t y 10 :133-141 . K l a d i v k o , E . J . , and D . W . N e l s o n . 1979. Changes i n so i l properties f rom appl ica t ion o f anaerobic sludge. Journal o f the Water P o l l u t i o n C o n t r o l Federat ion 51 :325-332 . K r z i c , M . , K . Broe r sma , D . J . Thompson , and A . A . B o m k e . 2000. S o i l properties and species d ivers i ty o f grazed crested wheatgrass and native rangelands. Journal o f Range Management 53 :353-358 . Lavender , D . P . , R . Par ish , C M . Johnson, G . M o n t g o m e r y , A . V y s o , R A . W i l l i s , and D . W i n s t o n . 1990. Regenerat ing B r i t i s h C o l u m b i a ' s forests. U n i v e r s i t y o f B r i t i s h C o l u m b i a Press, Vancouve r , B C . 39 M c D o u g a l l , R . , V a n H a m , M . D . , and Douglas , M J . 2002. Best Management Practices Guide l ines for the L a n d A p p l i c a t i o n o f M a n a g e d Organic Mat te r i n B r i t i s h C o l u m b i a . N e i l s e n , G . H . , E . J . Hogue , T . Forge , and D . N e i l s e n . 2003. Surface appl ica t ion o f mulches and b ioso l ids affect orchard s o i l properties after 7 years. Canad ian Journal o f S o i l Science 8 3 : 1 3 1 -137. N e l s o n , D . S . and L . E . Sommers . 1982. To ta l carbon, organic carbon, and organic matter. Pages 5 3 9 - 5 7 9 i n A . L . Page, R . H . M i l l e r , and D . R . Keeney , ed. Me thods o f so i l analysis. Part 2. 2nd ed. A g r o n o m y M o n o g r a p h 9. A S A - S S S A , M a d i s o n , W I . N i m m o , J . R . and K . S . Perkins . 2002. Aggregate stabil i ty and size dis tr ibut ion. Pages 317-328 i n J . H . Dane and G . C . T o p p (eds.) Me thods o f S o i l A n a l y s i s . Part 4: P h y s i c a l Methods . S S S A B o o k Series 5, M a d i s o n , W I . Puget, P . , C . Chenu , and J . Balesdent. 1995. To ta l and young organic matter distributions i n aggregates o f s i l ty cul t ivated soils . European Journal o f S o i l Science 46 :449-459 . S A S Institute Inc. 2003. S A S / S T A T user 's guide. V e r s i o n 6, 4th ed., V o l . 2 . S A S Inst. Inc., C a r y , N . C . Schniirer , J . , and T . R o s s w a l l . 1982. F luoresce in diacetate hydro lys i s as a measure o f total m i c r o b i a l ac t iv i ty i n so i l and litter. A p p l i e d Env i ronmenta l M i c r o b i o l o g y 43 :1256 -1261 . S m o l i a k , S. and J .F . Dormaar . 1985. P roduc t iv i ty o f Russ i an w i l d r y e and crested wheatgrass and their effect on prair ie soi ls . Journal o f Range management 38 :403-405 . S u l l i v a n , T . S . , M . E . Stromberger, and M . W . Paschke. 2006. Para l l e l shifts i n plant and so i l m i c r o b i a l communi t ies i n response to b ioso l ids i n a s e m i - a r i d grassland. S o i l B i o l o g y and B i o c h e m i s t r y 38:449^159. Swischer , R . and C . C a r r o l l . 1980. F luoresce in diacetate hydro lys i s as an estimator o f m i c r o b i a l b iomass on coniferous needle surfaces. M i c r o b i a l E c o l o g y 6 :217-226 . van R y s w y k , A . L . , B . M . W i k e e m , R . F . N e w m a n , and K . Broe r sma . 1991. N i t rogen fer t i l izat ion o f grass and forested rangelands o f southern Interior B r i t i s h C o l u m b i a , Canada: evaluat ion o f y i e l d response. Four th International Range land Congress , M o n t p e l l i e r / F r a n c e . Whi t e , C , S. L o f t i n , and R . A g u i l a r . 1997. A p p l i c a t i o n o f b ioso l ids to degraded semiar id rangeland: N ine -yea r responses. Journal o f Env i ronmenta l Qua l i t y 26 :1663-1671 . W i k e e m , B . M . , A . M c l e a n , A . Bawtree , and D . Quin ton . 1993. A n ove rv i ew o f the forage resource and beef product ion on c r o w n land i n B r i t i s h C o l u m b i a . Canad ian Journal o f A n i m a l Science 73 :779-794 . 40 Y o u n g , G . , M . A . Fenger, and F L A : Lut tmerd ing . 1992. So i l s o f the Ashcrof t M a p A r e a . M O E Techn ica l Repor t 23 / B C S o i l Survey Report N o . 26, Integrated Management B r a n c h , V i c t o r i a B C . Zebarth, B . J . , R . M c D o u g a l l , G . N e i l s e n , and D . Ne i l s en . 2000. A v a i l a b i l i t y o f ni t rogen f rom m u n i c i p a l b ioso l ids for dry land forage grass. Canad ian Journal o f Plant Science 80 :575-582 . 41 Chapter 3: Effects of biosolids on soil physical properties in native grasslands in the southern interior of British Columbia2 3.1 Introduction B i o s o l i d s are the residual sol ids f rom m u n i c i p a l wastewater treatment facil i t ies that meet regulatory requirements for land appl icat ion. The sol ids are s tabi l ized b y h i g h temperature digest ion to reduce vector attraction and pathogens, degrade organic matter, and dewatered to facilitate handl ing and transport. Canada produces about 0.5 x 10 6 M g yr" 1 (dry weight) o f b ioso l ids , as compared to over ten t imes that amount i n the U n i t e d States (Cogger et a l . , 2006). In 2005, the Greater V a n c o u v e r Reg iona l Dis t r ic t ( G V R D ) appl ied about 15,000 dry tonnes o f b ioso l ids to various types o f l and i n B r i t i s h C o l u m b i a ( B C ) . T h e largest users o f G V R D b ioso l ids are mine rec lamat ion projects (78%), w h i l e a m u c h smaller propor t ion o f b ioso l ids (10%>) is used for fer t i l izat ion o f rangeland soils . A s pub l i c op in ion and legis la t ion that discourage the disposal o f organic materials into landfi l ls increases i n many munic ipa l i t ies , pressure to use b ioso l ids as a fert i l izer/organic amendment for agricul tural p roduct ion w i l l also increase. P roduc t iv i ty o f semiar id grasslands is t yp i ca l ly l imi t ed b y l o w nutrient ava i lab i l i ty and moisture def ic iency (Dennis and Fresquez, 1989). B i o s o l i d s are k n o w n to be h igh i n organic matter, avai lable N and other nutrients. W h e n appl ied to the s o i l surface b ioso l ids can act as m u l c h effect ively reducing so i l evaporation i m p r o v i n g degraded rangelands i n semiar id regions ( L o f t i n and A g u i l a r , 1994). Range land restoration programs us ing b ioso l ids have typ i ca l ly been N O T E : A vers ion o f this chapter w i l l be submitted for publ ica t ion . B M W a l l a c e , M K r z i c , T A Forge , R F N e w m a n , and K Broersma. Effects o f b ioso l ids on s o i l phys ica l properties i n native grasslands i n the southern interior o f B r i t i s h C o l u m b i a . 42 app ly ing h igh quantities (> 50 M g ha"1) to the s o i l surface ( A g u i l a r et a l . , 1994; Fresquez et a l . , -1990; Mof fe t et a l . , 2005) and excess N cou ld cause economic loss through crop damage, disease, and y i e l d loss (Cogger et a l . , 2006). A l imi t ed number o f studies have examined so i l phys ica l properties f o l l o w i n g a single appl icat ion o f b ioso l ids at rates intended for agricultural product ion (< 20 M g ha" 1) (Cogger et a l . , 2006). A g u i l a r et a l . (1994) studied the effects o f a single appl ica t ion o f b ioso l ids at 23 to 90 M g ha"1 to a degraded semiar id rangeland i n N e w M e x i c o . The author reported that a l l b ioso l ids treatments s ignif icant ly increased blue grama (Bouteloua gracilis ( H b k ) Lag . ) cover and biomass w h i l e reducing species richness and divers i ty relative to non-amended plots . A n increase i n water inf i l t ra t ion, aggregate stabil i ty, water-holding capacity, and cat ion exchange capaci ty was observed i n coarse textured so i l i n orchards i n the southern interior o f B C where two applications o f 45 M g b ioso l ids ha" 1 had been surface-applied over seven years (Ne i l s en et a l . , 2003). K l a d i v k o and N e l s o n (1979) reported greater aggregate size and stabil i ty, aeration porosi ty (macropores), and a decrease i n bu lk density one year after the surface appl ica t ion o f b ioso l ids at 56 M g ha"'to a silt l oam so i l i n Indiana. Improved phys i ca l and chemica fcond i t ions m a y have a posi t ive impact o n s o i l organisms and ul t imate ly aggregate stabil i ty, w h i c h has been noted as an important indicator o f ecosystem health and so i l qual i ty ( B i r d et a l . , 2002; H a m e l , 1996; H e r r i c k et a l . , 2002; Jeffries et a l . , 2003). The m a i n objective o f this study was to determine the effects o f b ioso l ids on the stabil i ty o f s o i l aggregates and b u l k density i n native grasslands i n the southern interior o f B C . The hypotheses were that b ioso l ids appl icat ion improves the stabil i ty o f so i l aggregates and reduces s o i l bu lk density relative to untreated and fer t i l ized plots. The addi t ional objectives were to (i) determine the dis tr ibut ion o f total s o i l C and N among aggregate size fractions and ( i i ) and to determine the hydro lys i s o f f luorescein diacetate ( F D A ) (an indicator o f m i c r o b i a l act ivi ty) i n 43 aggregates > 2 m m from biosol ids-amended, fer t i l ized, and non-amended so i l . The hypotheses associated w i t h these objectives were that b ioso l ids appl ica t ion w o u l d increase F D A hydro lys i s ac t iv i ty and total so i l C and N i n stable aggregates relative to the control and fer t i l ized treatments. 3.2 M a t e r i a l and Me thods 3.2.1 Site Description The study was conducted on the exis t ing long-term experiment (established i n 2001) mainta ined b y Agr i cu l tu re and A g r i - F o o d Canada. The study site is located at the Ashcrof t R a n c h , B C ( 5 0 ° 4 0 ' N , 1 2 1 ° 2 1 ' W ; elevat ion 258 m) , 10 k m south o f Cache Creek, B C . The so i l is a s i l t l oam Or th ic B r o w n C h e r n o z e m developed f rom surf ic ia l deposits i n c o l l u v i a l fans and f luv ia l gravels covered w i t h a th in veneer o f aeol ian material ( Y o u n g et a l , 1992): The s o i l on the study site has a p H o f 8.1, 3 6 % sand, 53% silt , and 1 1 % clay, va ry ing amounts o f coarse fragments (1 - 5 0 % b y vo l . ) , and a saturated electr ical conduct iv i ty o f 0.46 dS m" 1 . Vegeta t ion was dominated b y b i g sagebrush (Artemisia tridentata Nut t . ) , cheatgrass (Bromus tectorum), needle-and-thread grass (Stipa comata T r i n . & Rupr . ) , alfalfa (Medicago sativa L . ) , and to a lesser extent b luebunch wheatgrass (Pseudoroegneria spicata (Pursh) Sc r ibn . & Smith) . The site is considered to be i n poor health because o f the foraging qual i ty o f the avai lable vegetation. T h e reg ion i s characterized b y a semi - to sub-arid c l imate reg ime w i t h hot, d ry summers and moderately c o l d winters , often w i t h l i t t le snowfa l l (Lavender et a l . , 1990). Ave rage annual air temperature i n this region is 8 . 9 °C , w h i l e average J u l y temperature is 2 2 ° C . The number o f frost-free days averages 143 i n the va l l ey bot tom w i t h an average number o f 2539 g r o w i n g degree-days. A n n u a l precipi ta t ion is 243 m m ; majori ty o f ra infa l l is rece ived dur ing M a y to September (89 m m ) ; and the average snowfa l l is 142 c m ( Y o u n g et a l . , 1992). 44 . Prec ip i ta t ion and air temperatures recorded at the site i n 2005 and 2006 d i d not c lose ly f o l l o w long-term averages ( F i g . 3.1). A i r temperatures i n J u l y o f both study years were 2 ° C above normal . T h i s was coupled w i t h extreme water deficiencies (about 25 m m lower than the long-term average). Al te rna t ive ly , nearly 30 m m o f extra precipi ta t ion was received dur ing the month o f June i n 2005, w h i c h delayed the first harvest o f an adjacent alfalfa f ie ld past the point o f p r ime maturi ty as indicated b y the heavy f lower set. c o Q. O O Q. E a> CO ro i > ro _>. .c c o Jan Feb March April May June July Aug Sep Oct Nov • Dec Figure 3.1 - C l i m a t e and weather at the Ashcrof t R a n c h , B C i n (a) 2005 and (b) 2006. In fa l l o f 2001 , the experiment was l a id out i n a randomized complete b l o c k design w i t h four treatments i n each o f four b locks . Treatments used i n this study were: (1) no b ioso l ids and no fert i l izer appl ica t ion (Cont ro l ) , (2) N + P fert i l izer (300 k g N + 400 k g P ha" 1 as a mixture o f a m m o n i u m phosphate and urea) appl icat ion (Fer t i l izer) , (3) b ioso l ids appl ica t ion at 20 dry M g 45 ha" 1 (B io -20 ) and (4) b ioso l ids appl icat ion at 60 dry M g ha" 1 (B io -60 ) . The fert i l izer appl ica t ion rate was determined to p rov ide s imi la r first-year potent ia l ly avai lable N (300 k g N ha" 1) and total P (400 k g P ha" 1) as i n the B i o - 2 0 treatment. A l l treatments were appl ied to the s o i l surface wi thout subsequent incorporat ion. Plots were 16 m w i d e and var ied i n length from 100 to 200 m due to uneven fence l ines. The study area was fenced w i t h 1.5 m - h i g h barbed w i r e to exclude spring graz ing b y cattle. 3.2.2 Soil Properties Bulk Density B u l k density was determined us ing the core method (B lake and Hartge, 1986). S o i l cores were taken from 0-7.5 c m depth o n M a y 13, 2005 w i t h a double-cyl inder , drop-hammer sampler and a 7.5-cm-diameter b y 7.5-cm-deep core. Three samples were taken per transect running through the midd le o f each plot. S o i l bu lk density was determined as the mass o f dry so i l per unit v o l u m e o f f ie ld-moist so i l . Coarse fragments (diameter >2 m m ) w i t h i n the sample were screened out and weighed . V o l u m e o f minera l coarse fragments was determined f rom dry mass, assuming a particle density o f 2.65 M g m" 3 . B u l k densities o f minera l s o i l samples were calculated as the mass o f dry, coarse fragment-free s o i l per vo lume o f f ield-moist so i l , where volume" was also calculated o n a coarse fragment-free basis. Aggregate Stability. Samples for aggregate s tabi l i ty determination were col lected o n M a y 13 (Spring) , June 28 (Summer) , and October 10 (Fal l ) o f 2005 and o n M a y 31 (Spring) , J u l y 10 (Summer) , and October 6 (Fal l ) o f 2006. T w o composi te so i l samples were taken per plot . E a c h composi te sample consisted o f five i nd iv idua l samples taken every 5 m a long a transect running through the m i d d l e o f each plot. Samples were col lected w i t h a hand t rowel at 0-5 c m depth. Since b ioso l ids 46 were surface appl ied i n order to m i n i m i z e disturbance to native vegetation, an effort was made to sample f rom the minera l layer and any organic matter, i nc lud ing b ioso l ids , was scraped away before sampl ing . Samples were transported to the laboratory i n c losed, plast ic containers, and stored i n the refrigerator at 4 ° C un t i l analysis. Aggregate stabil i ty was assessed us ing a var ia t ion o f the wet s iev ing method ( N i m m o and Perkins , 2002). F i e l d mois t samples were first passed through a 6 - m m sieve and col lected o n a 2-m m sieve. The pre-sieved 2-6 m m mois t sample (o f about 10 g) was p laced on top o f a nest o f sieves w i t h openings o f 2, 1, and 0.25 m m , and wetted i n a humid i f ie r for 1 hour to m i n i m i z e disrupt ion caused b y air trapping. T h i s was performed immedia te ly before wet s ieving. W e t s iev ing was performed for 10 minutes i n a motor-dr iven mechanica l device w i t h a ver t ica l stroke o f 2.5 c m at a rate o f 30 strokes per minute. The m o t i o n o f the system had both a ver t ical stroke and an osc i l la t ing action through an angle o f 3 0 ° . A f t e r the sieves were r emoved f rom the water, the material retained on each sieve was oven dr ied at 6 0 ° C for 24 hours, we ighed , and the mass f rom each size fraction was expressed as a percentage o f the total s o i l mass. The results for aggregate stabil i ty were expressed as the mean weight diameter ( M W D ) , w h i c h represents the summat ion across size fractions o f the product o f the mean diameter o f each size fraction (£),•) and 4 ' the propor t ion o f the sample weight occur r ing i n that size fraction (W,) (MWD = ^WiDi). Correct ions were made for minera l particles retained o n each sieve to a v o i d biased interpretations o f water stable aggregates. Total C and N of Soil Aggregates Tota l so i l C and N were determined o n aggregates col lected dur ing June 16, 2005 sampl ing . Aggregates i n the 2-6; 1-2, and 0.25-1 m m size fractions f o l l o w i n g wet -s iev ing were saved, oven dr ied at 6 0 ° C for 24 hours, and then analyzed for total C and N b y dry combus t ion 47 (Ne l son and Sommers , 1982) us ing the L E C O C N S - 2 0 0 0 automated analyzer (Leco Corp . , St. Joseph, M I ) . Hydrolysis of Fluorescein Diacetate T h e compound fluorescein diacetate (3', 6 ' -d iacetyl f luorescein [ F D A ] ) is h y d r o l y z e d b y esterases, proteases, and lipases i n plant, fungal, and bacterial cel ls and is indica t ive o f s o i l m i c r o b i a l ac t iv i ty (Schniirer and R o s s w a l l , 1982). The fluorescent product o f this reaction (fluorescein) f o l l o w i n g an incubat ion per iod is e l iminated from the c e l l and can be quantif ied b y V i s i b l e Spectrophotometer (Pye U n i c a m , SP6-350) b y measur ing fluorescence at 490 n m . H y d r o l y s i s analysis fo l lowed the procedure as proposed b y Green et a l . (2006) where 0.75 g o f f ie ld mois t s o i l was p laced i n a flask, 50 m L o f 60 m M sod ium phosphate buffer ( p H 7.6), and 0.50 m L o f 4.9 m M F D A substrate solu t ion were added. The flask was c losed w i t h a stopper, swi r l ed for a few seconds, and placed i n a water bath incubator for 3 h at 3 7 ° C . Quant i f ica t ion o f m g f luorescein k g s o i l 3 h r w a s done b y compar ing the absorbance to a standard curve made w i t h a stock solu t ion o f fluorescein. Sample co l lec t ion for this analysis was done o n M a y 31 , 2006. T w o composi te samples consisted o f f ive i nd iv idua l samples taken every 5 m a long a transect running through the midd le o f each plot . F i e l d mois t samples were first s ieved through a 6 - m m sieve and then through a 2-m m sieve. A sub-sample o f 10-15 g o f 2 to 6 m m aggregates f rom each composi te sample was stored and kept refrigerated at 4 ° C unt i l analysis. 3.2.3 Statistical Analysis S o i l bu lk density data were analyzed as a randomized , complete b l o c k design w i t h four replicat ions and three subsamples per plot. Aggregate stabil i ty and F D A hydro lys i s data were analyzed as a randomized, complete b l o c k design w i t h four repl icat ions and two subsamples per 48 plot. Ca rbon and N concentration w i t h i n stable aggregates was analyzed as a randomized , complete b l o c k design w i t h four replications. The S A S general l inear m o d e l procedure was used ( S A S Institute Inc., 2003). Probabi l i t ies and F values obtained b y the A N O V A are tabulated i n A p p e n d i x 3. F o l l o w i n g a significant F-test, differences between treatment means were evaluated us ing F i sher ' s protected least significant difference ( L S D ) and considered significant at P < 0.1. 3.3 Resul ts and D i s c u s s i o n 3.3.1 Bulk Density S o i l b u l k density was s ignif icant ly lower (P < 0.1) i n the B i o - 2 0 treatment as compared to the control and B i o - 6 0 treatments (Table 3.1), w h i l e the fert i l izer treatment was intermediate. N o differences were found f rom the B i o - 6 0 treatment, w h i c h is contrary to results rev iewed b y C l a p p et a l . (1986) w h o found a general trend o f decreasing bu lk density o n 17 different soils w i t h increasing rates o f b ioso l ids appl icat ion. In addit ion, Tsadi las et a l . (2005) found that b iosol ids appl ica t ion at 50 M g ha" 1 rate decreased so i l bu lk density i n a c l ay l o a m f rom 1.41 ( in control) to 1.27 M g m" i n a study carried out i n a Medi ter ranean c l imate i n central Greece. Table 3.1 - S o i l bu lk density o n four treatments i n M a y 2005, o n the native range site. B u l k density ( M g m" 3) Treatments Con t ro l 1.25a Fer t i l i zer 1.16ba B i o - 2 0 1.07b B i o - 6 0 1.20a P 0.053 Z L S D 0.104 ZLSD= Least significant difference (n = 12) P < 0.1 49 3.3.2 Aggregate stability D u r i n g a l l three sampl ing periods i n 2006, the M W D i n both b ioso l ids treatments was s ignif icant ly greater (P < 0.1) ( F i g . 3.3) relative to control and fert i l izer treatments, yet no differences were detected i n 2005 ( F i g . 3.2). There were no differences between b ioso l ids rates dur ing any sampl ing per iod . The M W D from the fert i l izer treatment was the smallest, as compared to a l l other treatments, dur ing summer and fal l s ampl ing periods i n 2006. B i o l o g i c a l ac t iv i ty m a y have been reduced from the fert i l izer treatment, w h i c h i n turn led to a reduct ion i n aggregation. D u r i n g spr ing sampl ing i n 2006, s o i l water content f rom the B i o - 6 0 treatment was greater (P < 0.1) relat ive f rom the control . The M W D was general ly observed to increase at sampl ing t imes w i t h l o w so i l water content. F o r example, i n the unusual ly dry M a y 2005 (F ig . 3.1a) h i g h M W D was observed, f o l l owed b y l o w overa l l M W D i n June 2005 after an unusual ly h i g h amount o f ra infal l . A s imi la r relat ionship was observed i n 2006; the greatest M W D values came from samples taken i n J u l y w h e n the so i l was the driest (F ig . 3.1b). Decreases i n M W D w i t h increasing water content were reported i n numerous studies (Angers , 1992; Haynes and Swif t , 1990; H e r m a w a n and B o m k e , 1996; K r z i c et a l . , 2000). 50 Figure 3.2 - T h e mean weight diameter ( M W D ) (a, b) and water content (c, d) o f so i l aggregates dur ing 2005 and 2006 g rowing seasons at the native range. E r ro r bars represent the standard error o f the mean ( « = 8 ) . Ba r s w i t h the same letter w i t h i n sampl ing t imes are not s ignif icant ly different ( P > 0 . 1 ) . The largest aggregate size class ( 2 - 6 m m ) general ly exhib i ted a s imi l a r trend as the M W D , be ing the greatest on b ioso l ids treatments (Figs. 3.3a and 3.4a); however , no significant differences were reported i n 2005. D u r i n g spr ing and summer sampl ing i n 2006, the 2 - 6 m m aggregates were s imi la r i n fert i l izer and control treatments. The two b ioso l ids treatments exhibi ted a greater propor t ion o f aggregates i n the 2 - 6 m m size fraction relative to the ferti l izer treatment. In both years, less than 10% o f the total so i l was measured i n the 1 - 2 m m aggregate size class (Figs . 3.3b and 3.4b). S i m i l a r proportions o f aggregates were found from this size class i n other studies also carr ied out o n native grasslands i n the southern interior o f B C (Broersma et a l . , 2000; K r z i c et a l . , 2000). The ferti l izer treatment s ignif icant ly (P > 0.1) lowered the propor t ion o f 51 1-2 m m stable aggregates relative to the control dur ing summer and fa l l sampl ing periods i n 2006. C5> CD o TO O £= O U—i o 03 Spring Summer Spring Summer Fall Figure 3.3 - F rac t ion o f total s o i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2005 g r o w i n g season at the native range. E r ro r bars represent standard error o f the mean ( « = 8 ) . Bars w i t h the same letter w i t h i n sampl ing t imes are not different (P > 0.1). The smallest (0.25-1 m m ) aggregate size fraction was s imi l a r on a l l four treatments throughout 2005 ( F i g . 3.3c). The propor t ion o f 0.25 to 1 m m aggregates were about 2 5 % lower i n b ioso l ids amended treatments relat ive to the cont ro l and fer t i l izer treatments dur ing spr ing and summer sampl ing i n 2006 ( F i g . 3.4c). Anger s (1992) reported that an increase i n aggregates > 1 m m was at the expense o f aggregates < 1 m m , w h i c h w o u l d seem to suggest that there is a m a x i m u m aggregating potential distributed between a l l aggregate size fractions rather than proport ions o f aggregates increasing among a l l fractions at the same t ime. Al te rna t ive ly , aggregates > 1 m m from the control were not as stable as those found i n s o i l where b ioso l ids 52 were appl ied and large aggregates broke d o w n into smaller aggregates, thus increasing the propor t ion o f so i l i n the smallest size fraction. B o t h o f these mechanisms c o u l d exp la in the greater dis t r ibut ion o f aggregates w i t h diameters > 1 m m from bioso l ids amended treatments relative to the control . In 2006, the fert i l izer treatment had 0.33 and 0.71 k g kg" 1 o f the total so i l pass through the smallest sieve, as measured i n the smallest size fraction < 0.25 m m , dur ing summer and fa l l sampl ing , respectively. B o t h b ioso l ids treatments had 0.18 and 0.5 k g kg" 1 o f the total so i l pass through the smallest sieve i n summer and fa l l sampl ing , respectively. Organic matter additions from the b ioso l ids appl icat ion have improved the stabil i ty o f s o i l aggregates, as compared to the fert i l izer treatment. The addi t ion o f N i n chemica l fertilizers is k n o w n to stimulate plant and m i c r o b i a l communi t ies i n semiar id ecosystems. T h i s cou ld lead to a substantial reduct ion o f indigenous s o i l organic C that is be ing minera l i zed b y increased b i o l o g i c a l ac t iv i ty (Whi te et a l . , 1997). T h i s is par t icular ly true when chemica l fertil izers are appl ied wi thout any organic amendment. A s a result, noticeable reductions i n aggregate s tabi l i ty c o u l d occur due to the minera l iza t ion o f indigenous s o i l organic C . 53 Spring Summer Fall Spring Summer Fall Figure 3.4 - F rac t ion o f total so i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2006 g r o w i n g season at the native range. E r ro r bars represent standard error o f the mean (n=8). Bars w i t h the same letter w i t h i n sampl ing t imes are not different (P > 0.1). 3.3.3 Total Carbon and Nitrogen of Soil Aggregates The C and N concentrations i n the largest aggregate size fraction ( 2 - 6 m m ) were highest i n the B i o - 2 0 treatment (Figs . 3.5 and 3.6) even though differences i n C concentrat ion among the study treatments were not statistically significant. W h i t e et a l . (1997) suggested that any significant increase i n so i l organic C w o u l d not be detectable for a m i n i m u m o f three to four years. A d d i t i o n a l l y , vegetation i n native rangelands from arid and semiar id regions is characterized as be ing heterogeneous and the dis t r ibut ion o f s o i l organic C and N is often h igh ly correlated w i t h vegetation patterns ( A l b i a c h et a l . , 2001 ; B i r d et a l . , 2002) m a k i n g it inherently diff icul t to achieve statistical s ignif icance. Ca rbon concentration o f 1 - 2 m m aggregates was the greatest i n the B i o - 2 0 treatment (F ig . 3.5). The increase i n C from the B i o - 2 0 treatment c o u l d also exp la in the decrease i n bu lk 54 density (Table 3.1) from this treatment. The smallest aggregate size fraction (0.25 - 1 m m ) had the lowest concentration i n the control , w h i l e C concentrations f rom this size fraction from a l l other treatments were s imi lar . E leva ted concentration o f so i l organic C i n stable aggregates and i n bu lk so i l (Forge et a l . , unpubl ished data, A p p e n d i x 3) from the B i o - 2 0 treatment w o u l d seem to suggest an increase i n b i o l o g i c a l ac t iv i ty above or be low ground relative to the B i o - 6 0 treatment even four years f o l l o w i n g appl icat ion. F i v e years f o l l o w i n g the appl icat ion o f b ioso l ids to a degraded rangeland i n N e w M e x i c o organic matter concentrations i n so i l were highest f rom 45 M g ha" 1 as compared to an appl ica t ion that was 0.5 and 2 t imes that amount (Fresquez et a l . , 1991). 140 120 ° 100 'a> 3 80 c o I 60 c CD o o o O 40 20 A i ^ H Control I I Fertilizer H I Bio-20 I777I Bio-60 2-6 1-2 0.25-1 Aggregate Size Classes (mm) Figure 3.5 - C a r b o n concentration o f stable aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) from so i l sampled on June 16, 2005 from the native range. E r ro r bars represent standard error o f the mean (n=4). Bars w i t h the same letter w i t h i n size classes are not different (P > 0.1). The concentration o f N i n a l l size classes from the B i o - 2 0 treatment was s ignif icant ly greater (P < 0.1) relative to the control (F ig . 3.6). The N concentrations i n 0.25 - 1.00 m m 55 aggregates from both b ioso l ids treatments were s imi lar , w h i l e N concentrat ion i n this aggregate size class from the control and ferti l izer treatments were s imi la r to each other. Prev ious research o f Forge et a l . (unpubl ished data, A p p e n d i x 3) showed a s imi la r trend i n bu lk so i l C and N i n 2004 as observed i n stable aggregates. H i g h e r concentrations o f C and N were found at lower appl icat ion rates (B io -20 ) as compared to the B i o - 6 0 treatment. T h i s is also i n agreement w i t h the findings o f Den i s and Fresquez (1989) w h o reported that so i l total and avai lable N stopped increasing w h e n b ioso l ids were appl ied i n excess o f 20 to 40 M g ha" 1 . 12 10 o .2 6 -4—* CO X— CD I 4 o o 2 A • Control ZD Fertilizer iSII Bio-20 r777i Bio-60 2-6 1-2 0.25-1 Aggregate Size Classes (mm) Figure 3.6 - N i t r o g e n concentration o f stable aggregates i n three size classes (2-6, 1-2, and 0.25-1 m m ) from so i l sampled on June 16, 2005 at the native range. E r r o r bars represent standard error o f the mean (n=4). Ba r s w i t h the same letter w i t h i n s ize classes are not different (P > 0.1). A l t h o u g h several C and N concentration differences were observed among study treatments and aggregate size fractions the o n l y clear change i n C : N ratio were observed i n 2 - 6 m m aggregates. W h e n b ioso l ids were appl ied at 60 M g ha" 1 aggregates had a narrower C : N ratio than aggregates from the fert i l izer treatment. It is not comple te ly clear w h y the C : N ratio o f the 56 largest aggregates i n the ferti l izer treatment w o u l d be s ignif icant ly greater (P < 0.1) relative to the B i o - 6 0 treatment. Poss ib ly , aggregates from the B i o - 6 0 treatment contain unminera l ized b ioso l ids because the C : N ratio o f b ioso l ids is m u c h narrower than that o f native so i l at this site. The ferti l izer treatment had a greater concentrations o f C i n aggregates, but a s imi la r concentration o f N , as compared to the control . 20 Aggregate Size Classes (mm) Figure 3.7 - The C : N ratio o f stable aggregates i n three size classes f rom so i l sampled on June 16, 2005 from the native range. Er ro r bars represent standard error o f the mean (n=4). Bars w i t h the same letter w i t h i n s ize classes are not different (P > 0.1). 3.3.4 Hydrolysis of Fluorescein Diacetate Fluoresce in diacetate ( F D A ) is hydro lyzed b y a number o f different m i c r o b i a l endocel lular enzymes such as, proteases, lipases, and esterases (Green et a l . , 2006). The hydrolys is o f F D A is an indicator o f overa l l m i c r o b i a l ac t iv i ty and has been correlated w i t h direct v i sua l measurements o f m i c r o b i a l ce l l mass (Swischer and C a r r o l l , 1980). 57 There were no differences i n the concentration o f f luorescein produced from the hydro lys i s o f F D A ( F i g . 3.8). Some o f the largest aggregates observed dur ing this study were from the native range site, as compared to the crested wheatgrass and irrigated alfalfa sites. These large aggregates o n the native range site w o u l d have the potential to store a greater propor t ion o f protected aggregate C and N . W h e n aggregates where crushed before F D A analysis greater substrate w o u l d be avai lable to the so i l m ic rob i a l c o m m u n i t y dur ing incubat ion. The greatest hysrolys is activit ies were also measured at this site, yet there were no statistical differences among treatments. Denn i s and Fresquez (1989) reported increased so i l bacterial , fungal, and a m m o n i u m ox id i ze r populat ions two years f o l l o w i n g surface appl ica t ion o f increasing b iosol ids at 22.5, 45 , and 90 M g ha" i n a semiar id grassland i n N e w M e x i c o . Converse ly , S u l l i v a n et a l . (2006) found a decrease i n the E L - F A M E b iomarker for arbuscular m y c o r r h i z a l fungi f rom the one t ime appl icat ion o f increasing rates o f b ioso l ids i n a semi-ar id rangeland o f Co lo rado . Control Fertilizer Bio-20 Bio-60 Figure 3.8 - T h e hydro lys i s o f f luorescein diacetate ( F D A ) i n the 2-6 m m aggregate size class i n June 2006 at the native range. E r ro r bars represent standard error o f the mean ( « = 8 ) . 58 3.4 Conc lus ions F i v e years after a single surface appl icat ion o f b ioso l ids at 20 M g ha" 1, greater aggregate stabil i ty ( M W D and the propor t ion o f aggregates > 1 m m ) , C and N concentrations o f stable aggregates, and so i l bu lk density were observed relative to the untreated control and chemica l fert i l izer treatments. A p p l i c a t i o n o f b ioso l ids at 60 M g ha" 1 d i d not lead to any measurable increases i n so i l properties relative to the 20 M g ha" 1 rate. A p p l i c a t i o n o f chemica l fertil izers had no effect on s o i l phys ica l properties as compared to the control . 3.5 References A g u i l a r , R . , S .R. L o f t i n , and P . R . Fresquez. 1994. Range land restoration w i t h treated m u n i c i p a l sewage sludge.. P . 2 1 1 - 2 2 0 . In C E . C l a p p et a l . (eds.) Sewage sludge: L a n d u t i l iza t ion and the environment. S S S A , M a d i s o n , W I . A l b i a c h , R . , R . Canet, F . Pomares, and F . Ingelmo. 2001 . Organic matter components, aggregate stabi l i ty and b i o l o g i c a l ac t iv i ty i n a hort icul tural s o i l fer t i l ized w i t h different rates o f two sewage sludges dur ing ten years. Bioresource Techno logy 77 :109-114 . Anger s , D . A . 1992. Changes i n so i l aggregation and organic carbon under corn and alfalfa. S o i l Science Soc ie ty o f A m e r i c a Journal 56 :1244-1249 . B i r d , S . B . , J . E . Her r i ck , M . M . Wander , and S .F . Wr igh t . 2002. Spat ia l heterogeneity o f aggregate stabil i ty and s o i l carbon i n semi-ar id rangeland. Env i ronmen ta l P o l l u t i o n 116:445—455. B l a k e , G . R . , and K . H . Hartge. 1986. B u l k density. Pages 363 -375 i n A . K l u t e (ed.) Me thods o f so i l analysis. Part 1. 2nd ed. A g r o n o m y M o n o g r a p h 9. A S A - S S S A , M a d i s o n , W I . Broersma , K . , M . K r z i c , D . J . Thompson , and A . A . B o m k e . 2000. S o i l and vegetation o f ungrazed crested wheatgrass and native rangelands. Canad ian Journal o f S o i l Science 80 :411-417 . C l a p p , C . E . , S. A . Stark, D . E . C l a y , and W . E . Larson . 1986. Sewage sludge organic matter and s o i l properties. In Y . C h e n and Y . A v n i m e l e c h (eds). The role o f organic matter i n modern agriculture, (pp. 209 - 253). Mar t inus N i j h o € Publishers , Bos ton , Massachusetts . Cogger , C . G . , T . A . Forge , and G . H . N e i l s e n . 2006. B i o s o l i d s r ecyc l ing : ni t rogen management and so i l ecology. Canad ian Journal o f S o i l Science 86 :613-620 . Denn i s , G . L . , and P . R . Fresquez. 1989. The so i l m i c r o b i a l c o m m u n i t y i n a sewage-sludge-amended semi-ar id grassland. B i o l o g y and Fer t i l i ty o f So i l s 7 :310-317 . 59 Fresquez, P . R . , R . A g u i l a r , R . E . Francis , and E . F . A l d o n . 1991. H e a v y metal uptake b y blue grama g r o w i n g i n a degraded semiar id so i l amended w i t h sewage sludge. Journal o f Water A i r and S o i l P o l l u t i o n 57-58 :903-912 . Fresquez, P . R . , R . E . Francis , and G . L . Denn i s . 1990. Sewage sludge effects o n s o i l and plant qual i ty i n a degraded, semiar id grassland. Journal o f Env i ronmen ta l Qua l i t y 19:324-329. Green , V . S . , D . E . Stott, and M . D i a c k . 2006. A s s a y for f luorescein diacetate hydro ly t i c act ivi ty: op t imiza t ion for so i l samples. S o i l B i o l o g y and B i o c h e m i s t r y 38 :693 -701 . H a m e l , C . 1996. Prospects and problems pertaining to the management o f arbuscular mycor rh izae i n agriculture. Agr i cu l tu re Ecosys tems and Env i ronment 60 :197-210 . Haynes , R . J . , and R . S . Swif t . 1990. S tabi l i ty o f s o i l aggregates i n relat ion to organic constituents and s o i l water content. Journal o f S o i l Science 4 1 : 7 3 - 8 3 . H e r m a w a n , B . and A . A . B o m k e . 1996. Aggrega t ion o f degraded l o w l a n d s o i l dur ing restoration w i t h different c ropp ing and drainage regimes. S o i l Techno logy 9 :239-250 . Her r i ck , J . E . , J .R . B r o w n , A . J . T u g e l , P . L . Shaver, and K . M . Havs tad . 2002. A p p l i c a t i o n o f so i l qual i ty to moni to r ing and management: Paradigms f rom rangeland ecology. Journal o f A g r o n o m y 9 4 : 3 - 1 1 . Jeffries, P . , S. G i a n i n a z z i , S. Perotto, K . Turnau, and J . M . Barea . 2003 . The contr ibut ion o f arbuscular m y c o r r h i z a l fungi i n sustainable maintenance o f plant health and so i l fertili ty. B i o l o g y and Fer t i l i ty o f So i l s 37 :1 -16 . K h a l e e l , R . , K . R . Reddy , and M . R . Overcash . 1981. Changes i n so i l phys i ca l properties due to organic waste applicat ions: A review. Journal o f Env i ronmen ta l Qua l i t y 10 :133-141 . K l a d i v k o , E . J . , and D . W . N e l s o n . 1979. Changes i n so i l properties f rom appl icat ion o f anaerobic sludge. Journal o f the water po l lu t ion control federation 51 :325-332 . K r z i c , M . , K . Broersma , D . J . Thompson , and A . A . B o m k e . 2000. S o i l properties and species d ivers i ty o f grazed crested wheatgrass and native rangelands. Journal o f Range Management 53 :353-358 . Lavender , D . P . , R . Par ish , C M . Johnson, G . M o n t g o m e r y , A . V y s o , R A . W i l l i s , and D . W i n s t o n . 1990. Regenerat ing B r i t i s h C o l u m b i a ' s forests. U n i v e r s i t y o f B r i t i s h C o l u m b i a Press, Vancouve r , B C . L o f t i n , S . R and R . A g u i l a r . 1994. Semia r id rangeland response to m u n i c i p a l sewage sludge: plant g rowth and litter decomposi t ion . P . 2 2 1 - 2 2 9 . In C E . C l a p p et a l . (eds.) Sewage sludge: L a n d u t i l i za t ion and the environment. S S S A , M a d i s o n , W L 60 Moffe t , C . A . , R . E . Zar tman, D . B . Wester , and R E . Sosebee. 2005. Surface B i o s o l i d s A p p l i c a t i o n : Effects o n infi l t rat ion, erosion, and s o i l organic carbon i n Chihuahuan Desert grasslands and shrublands. Journal o f Env i ronmenta l Quality 34:299—311. N e i l s e n , G . H . , E . J . Hogue , T . Forge , and D . N e i l s e n . 2003. Surface appl ica t ion o f mulches and b ioso l ids affect orchard so i l properties after 7 years. Canad ian Journal o f S o i l Science 8 3 : 1 3 1 -137. ' N e l s o n , D . S . and L . E . Sommers . 1982. To ta l carbon, organic carbon, and organic matter. Pages 5 3 9 - 5 7 9 i n A . L . Page, R . H . M i l l e r , and D . R . Keeney , ed. Me thods o f so i l analysis. Part 2. 2nd ed. A g r o n o m y M o n o g r a p h 9. A S A - S S S A , M a d i s o n , W I . N i m m o , J .R . and K . S . Perkins . 2002. Aggregate stabil i ty and size dis tr ibut ion. Pages 3 1 7 - 328 In J . H . Dane and G . C . T o p p (Eds.) Me thods o f S o i l A n a l y s i s . Part 4: P h y s i c a l Methods . S S S A B o o k Series 5, M a d i s o n , W I . S A S Institute Inc. 2003. S A S / S T A T user 's guide. V e r s i o n 6, 4th ed., V o l . 2 . S A S Inst. Inc., C a r y , N . C . Schniirer , J . , and T . R o s s w a l l . 1982. F luoresce in diacetate hydro lys i s as a measure o f total m i c r o b i a l ac t iv i ty i n so i l and litter. A p p l i e d Env i ronmenta l M i c r o b i o l o g y 43 :1256 -1261 . Swischer , R . and C . C a r r o l l . 1980. F luoresce in diacetate hydro lys i s as an estimator o f m i c r o b i a l b iomass o n coniferous needle surfaces. M i c r o b i a l E c o l o g y 6 :217-226 . S u l l i v a n , T . S . , M . E . Stromberger, and M . W . Paschke. 2006. Para l l e l shifts i n plant and so i l m i c r o b i a l communi t ies i n response to b ioso l ids i n a s e m i - a r i d grassland. S o i l B i o l o g y and B i o c h e m i s t r y 38:449^159. Tsadi las , C D . , I . K . M i t s i o s , and E . G o l i a . 2005. Influence o f b ioso l ids appl ica t ion o n some so i l phys i ca l properties. Communica t ions i n so i l science and plant analysis 36 :709-716 . Whi t e , C , S. L o f t i n , and R . A g u i l a r . 1997. A p p l i c a t i o n o f b ioso l ids to degraded semiar id rangeland: Nine -yea r responses. Journal o f Env i ronmenta l Quality 26 :1663-1671 . . Y o u n g , G . , M . A . Fenger, and H . A . Lut tmerd ing . 1992. So i l s o f the Ashcrof t M a p A r e a . M O E Techn ica l Repor t 23 / B C S o i l Survey Report N o . 26, Integrated Management B r a n c h , V i c t o r i a B C . 61 Chapter 4: Effects of biosolids on soil physical properties in a stand of irrigated alfalfa in the southern interior of British Columbia3 4.1 Introduction B i o s o l i d s are the residual solids from m u n i c i p a l wastewater treatment faci l i t ies that meet regulatory requirements for land appl icat ion. The sol ids are s tabi l ized b y h i g h temperature digest ion to reduce vector attraction and pathogens, degrade organic matter, and dewatered to facilitate hand l ing and transport. B i o s o l i d s are c lass i f ied as class A or B depending on the leve l o f pathogen and bacteria reduction. The Greater V a n c o u v e r R e g i o n a l Dis t r i c t ( G V R D ) treats over 1.2 m i l l i o n litres o f wastewater every day to produce over 15,000 d ry tonnes o f b ioso l ids every year that c o u l d be a valuable s o i l nutrient and organic matter amendment to forage product ion systems. The effect o f so l id wastes, i nc lud ing b ioso l ids , on s o i l phys i ca l properties w i l l u l t imate ly depend o n the rate o f decomposi t ion , quantity appl ied, and method o f so i l incorporat ion (Kha lee l , 1981). B i o s o l i d s have been shown to alter the so i l m i c r o b i a l c o m m u n i t y due to the h igh ava i lab i l i ty o f nutrients and metals that effect so i l processes (Cogger et a l . , 2006; S u l l i v a n et a l . , 2006). S i m i l a r effects o f b iosol ids appl icat ion o n b i o l o g i c a l properties i n numerous studies have been attributed to chronic tox ic i ty f rom avai lable metals such as Z n and C u (Cogger et a l . , 2006). B i o s o l i d s load ing rates should be based on loca l s o i l condi t ions because the extent to w h i c h metals are available i n a g iven ecosystem is determined b y so i l p H , water content, and m i c r o b i a l act ivi ty . No te : a vers ion o f this chapter w i l l be submitted for publ ica t ion . B M W a l l a c e , M K r z i c , T A Forge , K Broersma , and R F N e w m a n . Effects o f b ioso l ids on s o i l phys ica l properties i n a stand o f irr igated alfalfa i n the southern interior o f B r i t i s h C o l u m b i a . 62 In B C , class A b ioso l ids are c o m m o n l y appl ied i n the southern interior o f B C at rates less than 20 M g ha" 1 once every f ive years. T h i s o n l y represents less than a 2 % increase i n s o i l C when a moderate minera l iza t ion rate o f 3 0 % and a so i l depth o f 30 c m are considered (Cogger et a l , 2006). M u c h more s o i l organic matter m a y be needed i n the so i l system before improvements i n so i l qual i ty are seen. C a r b o n minera l iza t ion f rom bioso l ids i n a laboratory incubat ion experiment ranged f rom 14 to 3 7 % o f total b io so l i d s -C i n the first year ( G i l m o u r et a l . , 2003). Greater contact w i t h s o i l part icles due to the incorporat ion o f b ioso l ids into the top 10 - 15 c m along w i t h adequate s o i l water content f rom i r r igat ion practices should induce m u c h more organic matter minera l iza t ion as compared to surface appl ied b ioso l ids ( K h a l e e l et a l . , 1981). K l a d i v k o and N e l s o n (1979) reported greater aggregate size and stabili ty, aeration porosi ty (macropores), and a decrease i n b u l k densi ty one year after the appl ica t ion o f b ioso l ids at 56 and 90 M g ha" 1 and subsequent incorporat ion into a silt l oam so i l i n Indiana. Improved access o f b ioso l ids der ived C to the so i l m i c r o b i a l commun i ty m a y have a pos i t ive effect on so i l phys i ca l properties from increased C minera l iza t ion . The m a i n objective o f this study was to determine the effects o f b ioso l ids o n so i l phys ica l properties (stabil i ty o f so i l aggregates, bu lk density, and aeration porosi ty) i n an irrigated alfalfa stand i n the southern interior o f B C . The hypotheses were that b ioso l ids appl ica t ion improves the stabil i ty o f s o i l aggregates, increases aeration porosi ty, and reduces s o i l b u l k density relative to untreated and fer t i l ized plots. The addi t ional objectives were to (i) determine the dis t r ibut ion o f s o i l total C and N among aggregate size fractions and (ii) determine the hydro lys i s o f f luorescein diacetate ( F D A ) , an indicator o f m i c r o b i a l ac t iv i ty i n aggregates larger than 2 m m from b ioso l ids -amended, fer t i l ized, and non-amended so i l . The hypotheses associated w i t h these objectives were that b ioso l ids appl icat ion w o u l d increase F D A hydro lys i s ac t iv i ty and s o i l total C and N i n stable aggregates relative to untreated and fer t i l ized treatments. 63 4.2 M a t e r i a l and Me thods 4.2.1. Site Description The study was conducted on the exis t ing long-term experiment (established i n 2001) mainta ined b y Agr i cu l tu re and A g r i - F o o d Canada. The study site is located at the Ashcrof t R a n c h , B C ( 5 0 ° 4 0 ' N , 1 2 1 ° 2 1 ' W ; elevat ion 258 m) , 10 k m south o f Cache Creek, B C . The so i l is a silt l oam Orth ic B r o w n C h e r n o z e m developed f rom surf ic ia l deposits i n c o l l u v i a l fans and f luv ia l gravels covered w i t h a th in veneer o f aeolian material ( Y o u n g et a l . , 1992). The so i l on the study site has a p H o f 8.4, 3 9 % sand, 4 7 % silt, and 14% clay, v a r y i n g amounts o f coarse fragments (1 - 4 4 % b y vo l . ) , and a saturated electr ical conduc t iv i ty o f 1.04 dS m" 1 . The reg ion is characterized b y a semi- to sub-arid c l imate regime w i t h hot, d ry summers and moderately c o o l winters, often w i t h litt le snowfa l l (Lavender et a l . , 1990). Ave rage annual air temperature i n this r eg ion i s 8 . 9 °C , w h i l e average J u l y temperature is 2 2 ° C . T h e number o f frost-free days averages 143 i n the va l l ey bot tom w i t h an average number o f 2539 g r o w i n g degree-days. A n n u a l precipi ta t ion is 243 m m ; majori ty o f ra infa l l is rece ived dur ing M a y to September (89 m m ) ; and the average snowfa l l is 142 c m ( Y o u n g et a l . , 1992). S ince the f ie ld was irr igated regular ly dur ing the g r o w i n g season weather condi t ions are not presented i n this chapter, but can be found i n chapters 2.2 and 3.2. In June 2005, mon th ly precipi ta t ion was nearly 30 m m above the 1971 - 2000 June average for this region, w h i c h delayed the first harvest o f alfalfa past the point o f p r ime matur i ty as indicated b y the heavy f lower set. In fal l o f 2001 , the experiment was l a id out i n a r andomized complete b l o c k design w i t h four treatments i n each o f four b locks . Treatments used i n the study were: (1) no b ioso l ids and no fert i l izer appl ica t ion (Contro l ) , (2) N + P fert i l izer (300 k g N + 400 k g P ha" 1 as a mixture o f 64 a m m o n i u m phosphate and urea) appl icat ion (Fert i l izer) , (3) b ioso l ids appl ica t ion at 20 dry M g ha" 1 (B io -20) , and (4) b ioso l ids appl icat ion at 60 dry M g ha" 1 (B io -60) . The fert i l izer appl ica t ion rate was determined to prov ide s imi la r first-year potent ia l ly avai lable N (300 k g N ha" 1) and total P (400 k g P. ha"1) as i n the B i o - 2 0 treatment. Plots were 16 m w i d e and 200 m i n length and exc luded from any cattle grazing. S o i l was d isked (15 c m depth) immedia te ly after a l l treatments were appl ied i n the spr ing 2002 and planted to oats (Avena sativa L . ) i n June 2002. F o l l o w i n g the harvest o f the oat crop i n Augus t 2002, alfalfa was seeded and was regular ly irrigated w i t h "whee l l i n e " lateral m o v e sprinklers. A l f a l f a was cut for hay three to f ive t imes dur ing the g r o w i n g season. H a y yie lds per cut were between 2 to 4 M g dry matter ha" 1 (Forge et a l . unpubl ished data). Prev ious research at this site (Forge et a l . , prog, rep.) measured the organic C and to ta l .N concentrat ion i n s o i l f o l l o w i n g b iosol ids appl icat ion. S o i l was sampled i n the fa l l over three years starting i n 2002 and once i n spring 2003 at this site b y taking 20 2.5 cm-diameter cores to a depth o f 15 c m i n each plot . In 2003, samples at two addi t ional depths (15-30 and 15-45 cm) were also taken i n the spring. S o i l C and N both increased l inear ly w i t h increasing b ioso l ids appl icat ion ( A p p e n d i x 3). Signif icant increases (P < 0.05) were found i n so i l organic C and total N sampled at the 0-15 c m depth w h e n b iosol ids were appl ied at 60 M g ha" 1 i n the spring o f 2004. 4.2.2 Soil Properties Aeration Porosity and Bulk Density S o i l aeration poros i ty and bu lk density were determined o n undisturbed so i l core samples. S o i l cores were taken f rom 0-7.5 c m depth on M a y 12, 2005 and o n M a y 31 , 2006 w i t h a double-cyl inder , drop-hammer sampler and a 7.5-cm-diameter b y 7.5-cm-deep core. Three samples were taken per transect running through the midd le o f each plot. Samples were wrapped i n plastic and 65 stored i n the refrigerator a t 4 ° C unt i l analysis (i.e., June 2006). S o i l cores were weighed , and then progress ively saturated i n a container w i t h tap water for an average o f 20 hours. Af te r saturation, the cores were we ighed and p laced o n a tension table (Danie l son and Sutherland, 1986), w h i c h contained a tension m e d i u m o f s i l i con carbide sand (grit 400). A e r a t i o n porosi ty, i.e. so i l pores hav ing a diameter >50 u,m was determined o n a water tension table adjusted to -6 k P a o f matr ic potential for a per iod o f 20 hours. Water - f i l l ed pore-space was calculated f rom the mass /volume o f water that was retained i n the so i l at -6 k P a , relative to the s o i l vo lume. The cores were then dr ied for 24 hours at 1 0 5 ° C . S o i l bu lk density was determined as the mass o f dry so i l per unit v o l u m e o f f ie ld-moist so i l (B lake and Hartge, 1986). Coarse fragments (diameter >2 m m ) w i t h i n the sample were screened out and weighed. V o l u m e o f minera l coarse fragments was determined from dry mass, assuming a particle density o f 2.65 M g m" 3 . B u l k densities o f minera l s o i l samples were calculated as the mass o f dry, coarse fragment-free s o i l per v o l u m e o f f ie ld-moist so i l , where vo lume was also calculated on a coarse fragment-free basis. Aggregate Stability Samples for aggregate stabil i ty determination were col lec ted o n M a y 12 (Spring) , June 28 (Summer) , and October 10 (Fal l ) o f 2005 and on M a y 31 (Spring) , J u l y 10 (Summer) , and October 6 (Fa l l ) o f 2006. T w o composi te s o i l samples were taken per plot. E a c h composi te sample consisted o f five i nd iv idua l samples taken every 5 m a long a transect running through the midd le o f each plot . Samples were col lected w i t h a hand t rowel at 0-5 c m depth. Samples were transported to the laboratory i n c losed, plastic containers, and stored i n the refrigerator at 4 ° C . Aggregate stabil i ty was assessed us ing a var ia t ion o f the wet s i ev ing method ( N i m m o and Perk ins , 2002). F i e l d mois t samples were first passed through a 6 - m m sieve and col lected o n a 2-m m sieve. The pre-sieved 2-6 m m mois t sample (o f about 10 g) was p laced on top o f a nest o f 66 sieves w i t h openings o f 2, 1, and 0.25 m m , and wetted i n a humid i f ie r for 1 hour to m i n i m i z e disrupt ion caused b y air trapping. T h i s was performed immedia te ly before wet s iev ing . W e t s iev ing was performed for 10 minutes i n a motor-dr iven mechanica l device w i t h a ver t ical stroke o f 2.5 c m at a rate o f 30 strokes per minute. The m o t i o n o f the system had both a ver t ical stroke and an osc i l la t ing act ion through an angle o f 3 0 ° . Af te r the sieves were r emoved from the water, the mater ial retained on each sieve was oven dr ied at 6 0 ° C for 24 hours, we ighed , and the mass f rom each size fraction was expressed as a percentage o f the total s o i l mass. The results for aggregate stabil i ty were expressed as the mean weight diameter ( M W D ) , w h i c h represents the summat ion across size fractions o f the product o f the mean diameter o f each size fraction (Z),) and the propor t ion o f the sample weight occur r ing i n that size fraction (W,) (MWD = £ WgD,). Correct ions were made for minera l particles retained on each sieve to a v o i d biased interpretations o f water stable aggregates. Total C and N of SoU Aggregates Tota l so i l C and N were determined on aggregates col lected dur ing June 16, 2005 sampl ing . Aggregates i n the 2-6, 1-2, and 0.25-1 m m size fractions f o l l o w i n g wet - s iev ing were saved, oven dr ied at 6 0 ° C for 24 hours, and analyzed for total C and N b y dry combus t ion (Ne l son and Sommers , 1982) us ing the L E C O C N S - 2 0 0 0 automated analyzer (Leco Corp . , St. Joseph, M I ) . Hydrolysis of Fluorescein Diacetate The compound f luorescein diacetate (3', 6 ' -d iacetyl f luorescein [ F D A ] ) is h y d ro l yzed b y esterases, proteases, and lipases i n plant, fungal, and bacterial cel ls and is indica t ive o f s o i l m i c r o b i a l ac t iv i ty (Schnurer and R o s s w a l l , 1982). The fluorescent product o f this reaction 67 (fluorescein) f o l l o w i n g an incubat ion per iod is e l iminated f rom the c e l l and can be quantif ied b y V i s i b l e Spectrophotometer (Pye U n i c a m , SP6-350) b y measur ing fluorescence at 490 n m . H y d r o l y s i s analysis f o l l o w e d the procedure as proposed b y Green et a l . (2006) where 0.75 g o f f ie ld mois t s o i l was p laced i n a flask, 50 m L o f 60 m M sod ium phosphate buffer ( p H 7.6), and 0.50 m L o f 4.9 m M F D A substrate solut ion were added. The flask was c losed w i t h a stopper, swi r l ed for a few seconds, and p laced i n a water bath incubator for 3 h at 3 7 ° C . Quant i f ica t ion o f m g f luorescein k g _ 1 so i l 3 h r w a s done b y compar ing the absorbance to a standard curve made w i t h a stock solut ion o f f luorescein. Sample co l l ec t ion for this analysis was done on M a y 31 , 2006. T w o composi te samples consisted o f f ive i nd iv idua l samples taken every 5 m along a transect running through the midd le o f each plot. F i e l d mois t samples were first s ieved through a 6 - m m sieve and then through a 2-m m sieve. A sub-sample o f 10-15 g o f 2 to 6 m m aggregates from each composi te sample was stored and kept refrigerated at 4 ° C un t i l analysis. 4.2.3 Statistical Analysis S o i l b u l k density and aeration porosi ty data were analyzed as a randomized , complete b l o c k design w i t h four repl icat ions and three subsamples per plot . Aggregate stabil i ty and F D A hydro lys i s data were analyzed as a randomized, complete b l o c k design w i t h four replicat ions and two subsamples per plot. Ca rbon and N concentration w i t h i n stable aggregates was analyzed as a randomized , complete b l o c k design w i t h four replications. The S A S general l inear mode l procedure was used ( S A S Institute Inc., 2003). Probabi l i t ies and l v a l u e s obtained b y the A N O V A are tabulated i n A p p e n d i x 3. F o l l o w i n g a significant F-test, differences between treatment means were evaluated us ing F i sher ' s protected least s ignificant difference ( L S D ) and considered significant at P < 0.1. 68 4.3 Resul ts and D i s c u s s i o n 4.3.1 Bulk Density and Aeration Porosity S o i l bu lk density was s ignif icant ly (P < 0.1) lower i n the B i o - 6 0 treatment relat ive to the control i n 2005 and 2006 (Table 4.1). In 2005, bu lk density was reduced f rom 1.41 M g m" 3 i n the control to 1.18 M g m" 3 i n the B i o - 6 0 treatment. S i m i l a r l y , i n 2006 s o i l b u l k density i n the control was 1.25 M g m" J and 1.12 M g m" i n the B i o - 6 0 treatment. Genera l ly , s o i l bu lk density decreases w i t h increasing rates o f b ioso l ids appl icat ion (Clapp et a l , 1986). One year f o l l o w i n g the incorporat ion o f b ioso l ids appl ied at 56 M g ha" 1 K l a d i v k o and N e l s o n (1979) reported significant reductions i n bu lk density o f about 10% as compared to non-amended treatments o n a s i l ty l oam so i l i n Indiana. Ae ra t i on poros i ty was s ignif icant ly increased (P < 0.1) f rom the B i o - 6 0 treatment relative to the fert i l izer treatment b y 0.04 m 3 m" 3 . S ince b ioso l ids were incorporated into the top 10-15 c m o f the so i l , there was greater b ioso l ids to so i l contact, as compared to the adjacent crested wheatgrass and native grassland sites. A larger exposed surface area w o u l d lead to greater organic matter minera l iza t ion b y so i l microbes that c o u l d stimulate greater macroar thropod act iv i ty leading to greater pore space, and the reduct ion i n b u l k density. A d d i t i o n a l l y , an increase i n root growth c o u l d also lead to the observed change i n phys i ca l properties. K l a d i v k o and N e l s o n (1979) d i d not report any change i n aeration poros i ty f o l l o w i n g a single appl ica t ion o f b ioso l ids . 69 Table 4.1 - S o i l bu lk density and aeration poros i ty o n four treatments i n M a y 2005 and M a y 2006 at the irr igated alfalfa study site. B u l k density ( M g m" 3) Ae ra t i on porosi ty (m 3 m~ 3 ) Treatments 2005 2006 2006 C o n t r o l 1.41a 1.25a 0.19ba Fer t i l i zer 1.32ba 1.25a 0.17b B i o - 2 0 1.29ba 1.22a 0.19ba B i o - 6 0 1.18b 1.12b 0.21a P 0.030 0.070 0.030 Z L S D 0.114 0.085 0.03 ZLSD= Least significant difference (« =12) P< 0.1 4.3.2 Aggregate stability There were no differences i n the M W D dur ing any sample pe r iod (F ig . 4.1). The o n l y except ion was fa l l sampl ing 2005 w h e n b ioso l ids appl ied at 60 M g ha" 1 s ignif icant ly (P < 0.1) increased the M W D b y nearly 0.4 m m as compared to the B i o - 2 0 treatment. There were no differences i n so i l water content dur ing any sample per iod due to regular i r r igat ion throughout the g r o w i n g season. B i o s o l i d s were incorporated into the so i l b y d i sk ing at this site, w h i l e o n the adjacent crested wheatgrass and native range sites b ioso l ids were appl ied to the so i l surface wi thout further incorporat ion. Surface appl icat ion o f b ioso l ids o n those two dry land sites led to a more pronounced increase o f M W D and aggregates > 1 m m , relative to the irr igated alfalfa site. Because the site is irr igated regularly, b i o l o g i c a l ac t iv i ty is not l imi t ed and m a y induce greater aggregate turnover. S o i l water content was measured to be just b e l o w f ie ld capaci ty dur ing most o f the g r o w i n g season, and M W D has been shown to decrease w i t h the increase o f s o i l water content (Angers , 1992; Haynes and Swif t , 1990; H e r m a w a n and B o m k e , 1996; K r z i c et a l . , 2000) . 70 Figure 4.1 - The mean weight diameter ( M W D ) (a, b) and water content (c, d) o f s o i l aggregates dur ing 2005 and 2006 g rowing seasons at the irr igated alfalfa site. E r ro r bars represent the standard error o f the mean ( « = 8 ) . Bars w i t h the same letter w i t h i n sampl ing times are not s ignif icant ly different (P > 0.1). The proport ions o f 2 - 6 m m aggregates (F ig . 4.2a) were s igni f icant ly (P < 0.1) increased b y the B i o - 6 0 treatment dur ing spring and fal l sampl ing i n 2005. There were no clear differences i n the propor t ion o f aggregates > 1 m m dur ing any other sampl ing per iod . Surface appl icat ion o f b ioso l ids o n crested wheatgrass and native grassland sites had significant effects o n the propor t ion o f s o i l aggregates, especia l ly aggregates > 1 m m . There were also a greater proport ion o f aggregates > 1 m m as compared to smaller aggregates. There were no fluctuations i n so i l water content, as seen i n p rev ious ly i n the dry land trials, w h i c h c o u l d exp la in the lack o f temporal changes i n the size and propor t ion o f aggregates i n 2005. 71 Spring Summer Spring Summer Figure 4.2 - F rac t ion o f total so i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2005 g r o w i n g season at the irr igated alfalfa site. E r ro r bars represent standard error o f the mean (n=8). Bars w i t h the same letter w i t h i n sampl ing t imes are not different (P> 0.1). The o n l y significant (P < 0.1) difference i n the propor t ion o f aggregates i n any size fraction was observed i n spr ing 2006 i n the 0.25 - 1 m m size fraction ( F i g . 4.3c). The largest propor t ion o f aggregates was i n the fert i l izer treatment w h i l e the control had the lowest propor t ion o f aggregates i n this size category. N o difference was observed between the two b ioso l ids treatments. 72 Figure 4.3 - F rac t ion o f total so i l sample present i n four aggregate size classes (2-6, 1-2, 0.25-1, and < 0.25 m m ) dur ing the 2006 g r o w i n g season at the irr igated alfalfa site. E r ro r bars represent standard error o f the mean ( « = 8 ) . Bars w i t h the same letter w i t h i n sampl ing t imes are not different (P> 0.1). 4.3.3 Total Carbon and Nitrogen of Soil Aggregates The greatest concentration o f C was found i n 2 - 6 m m and 1 - 2 m m aggregate size classes from the B i o - 6 0 treatment ( F i g . 4.4). Fer t i l i ze r treatment had the smallest concentration o f C i n the largest aggregates ( 2 - 6 m m ) , relative to a l l other treatments. N o differences i n C concentration were found i n the smallest (0.25 - 1 m m ) aggregates. A s seen i n the aggregate stabil i ty data, there were no differences i n C concentrat ion among the control , fertil izer, and B i o -20 treatments i n any size fraction. A n increase i n so i l organic C i n aggregates > 1 m m cou ld also lead to a reduct ion i n bu lk density, as seen from the B i o - 6 0 treatment (Table 4.1). Converse ly , the fert i l izer treatment had the smallest C concentration i n large aggregates ( 2 - 6 m m ) and the lowest aeration porosi ty (Table. 4.1). 73 Aggregate Size Classes (mm) Figure 4.4 - Carbon concentration of stable aggregates in three size classes (2-6, 1-2, and 0.25-1 mm) from soil sampled on June 16, 2005 from the irrigated alfalfa site. Error bars represent standard error of the mean («=4). Bars with the same letter within size classes are not different (P >0.1). Biosolids generally increased the concentration of N in stable aggregates from all size fractions relative to control and fertilizer treatments (Fig. 4.5). The Bio-60 treatment significantly (P < 0.1) increased the N concentration relative to the control in both aggregate size fractions > 1 mm by almost 0.1 g kg" 1 . The N concentration in 0.25-1 mm aggregates was significantly increased in the Bio-20 (0.21 g kg-1) treatment relative to the control (0.16 g kg"1) treatment. 74 0.5 Aggregate Size Classes (mm) Figure 4.5 - Nitrogen concentration of stable aggregates in three size classes (2-6, 1-2, and 0.25-1 mm) from soil sampled on June 16, 2005 at the irrigated alfalfa site. Error bars represent standard error of the mean («=4). Bars with the same letter within size classes are not different (P > 0.1). The C:N ratio of aggregates from the Bio-60 treatment was significantly lower (P < 0.1) relative to other study treatments (Fig. 4.6). This was true for all aggregate size fractions The greatest difference in C:N ratio was observed from the 2-6 mm size fraction where the ratio was 12.4 in the control and 11.4 in the Bio-60 treatment. 75 o 20 1 5 A 1 0 5 A i ^ H Control i i Fertilizer i ^ H Bio-20 I7771 Bio-60 <L a a a a a a ba ba ^ 2-6 1-2 0.25-1 Aggregate Size Classes (mm) Figure 4.6 - The C : N ratio o f stable aggregates i n three size classes from so i l sampled on June 16 2005 at the irrigated alfalfa site. E r ro r bars represent standard error o f the mean ( « = 4 ) . Bars w i t h the same letter w i t h i n size classes are not different (P > 0.1). 4.3.4 Hydrolysis of Fluorescein Diacetate Fluoresce in diacetate ( F D A ) is hyd ro lyzed b y a number o f different m i c r o b i a l endocel lular enzymes (e.g., proteases, lipases, and esterases) (Green et a l . , 2006). The hydro lys i s o f F D A is an indicator o f overa l l m i c r o b i a l act ivi ty and has been correlated w i t h direct measurements o f m i c r o b i a l biomass (Swischer and C a r r o l l , 1980). N o differences i n the concentration o f f luorescein produced f rom the hydro lys i s o f F D A were found among the study treatments (F ig . 4.7). Treatments had a range o f 13.74 m g fluorescein kg" 1 so i l 3 hr" 1. Cons ide r ing that a l imi t ed number o f differences were observed i n chemica l and phys i ca l properties at this study site it is not surprising to find no change i n F D A hydrolys is . 76 200 H Control Fertilizer Bio-20 Bio-60 Figure 4.7 - T h e hydro lys i s o f f luorescein diacetate ( F D A ) i n the 2-6 m m aggregate size class i n June 2006 from the irrigated alfalfa site. Er ro r bars represent standard error o f the mean (n=S). 4.4 Conc lus ions B i o s o l i d s appl ied at 60 M g ha" 1 increased aggregate stabil i ty and decreased so i l bu lk densi ty as compared to other treatments. F i v e years f o l l o w i n g a s ingle appl ica t ion o f fertil izer, noticeable decreases i n aeration poros i ty and the C concentration i n 2 to 6 m m aggregates were s t i l l noticeable. 4.5 References Anger s , D . A . 1992. Changes i n so i l aggregation and organic carbon under corn and alfalfa. S o i l Science Soc ie ty o f A m e r i c a Journal 56 :1244-1249 . B l a k e , G . R . , and K . H . Hartge. 1986. B u l k density. Pages 363-375 i n A . K l u t e (ed.) Me thods o f s o i l analysis. Part 1. 2nd ed. A g r o n o m y M o n o g r a p h 9. A S A - S S S A , M a d i s o n , W I . Cogger , C . G . , T . A . Forge , and G . H . N e i l s e n . 2006. B i o s o l i d s r ecyc l ing : ni t rogen management and so i l ecology. Canad ian Journal o f S o i l Science 86 :613-620 . 77 Danielson, R.E. and P.L. Sutherland. 1986. Porosity. Pages 4 4 3 - 462 in A . Klute, ed. Methods of soil analysis. Part 1. 2nd ed. Agronomy Monograph 9. A S A - S S S A , Madison, W L Gilmour, J.T., C.G.Cogger , L.W. Jacobs, G .K . Evanylo, and D . M . Sull ivan. 2003. Decomposition and plant available N in biosolids: laboratory studies, field studies, and computer simulation. Journal of Environmental Quality 32:1498-1507. Green, V . S . , D.E. Stott, and M . Diack. 2006. Assay for fluorescein diacetate hydrolytic activity: optimization for soil samples. Soi l Biology and Biochemistry 38:693-701. Haynes, R.J . , and R.S. Swift. 1990. Stability of soil aggregates in relation to organic constituents and soil water content. Journal of Soi l Science 41:73-83. Hermawan, B. and A . A . Bomke. 1996. Aggregation of degraded lowland soil during restoration with different cropping and drainage regimes. Soi l Technology 9:239-250. Khaleel, R., K .R. Reddy, and M.R. Overcash. 1981. Changes in soil physical properties due to organic waste applications: A review. Journal of Environmental Quality 10:133—141. Kladivko, E.J. , and D.W. Nelson. 1979. Changes in soil properties from application of anaerobic sludge. Journal of the water pollution control federation 51:325-332. Krz ic , M . , K. Broersma, D.J. Thompson, and A . A . Bomke. 2000. Soi l properties and species diversity of grazed crested wheatgrass and native rangelands. Journal of Range Management 53:353-358. Lavender, D.P., R. Parish, C M . Johnson, G. Montgomery, A . Vyso, R A . Wi l l is , and D. Winston. 1990. Regenerating Brit ish Columbia's forests. University of Brit ish Columbia Press, Vancouver, B C . Nelson, D.S. and L. E. Sommers. 1982. Total carbon, organic carbon, and organic matter. Pages 539-579 in A . L; Page, R. H. Mi l ler , and D. R. Keeney, ed. Methods of soil analysis. Part 2. 2nd ed. Agronomy Monograph 9. A S A - S S S A , Madison, WI. N immo, J.R. and K .S . Perkins. 2002. Aggregate stability and size distribution. Pages 317- 328 In J .H. Dane and G . C Topp (eds.) Methods of Soi l Analysis. Part 4: Physical Methods. S S S A Book Series 5, Madison, WI. S A S Institute Inc. 2003. S A S / S T A T user's guide. Version 6, 4th ed., Vol .2 . S A S Inst. Inc., Cary, N C . Schntirer, J . , and T. Rosswall . 1982. Fluorescein diacetate hydrolysis as a measure of total microbial activity in soil and litter. Appl ied Environmental Microbiology 43:1256-1261. Sull ivan, T.S., M . E . Stromberger, and M.W. Paschke. 2006. Parallel shifts in plant and soil microbial communities in response to biosolids in a semi-arid grassland. Soi l Biology and Biochemistry 38:449^159. 78 Y o u n g , G . , M . A . Fenger, and H A . Lut tmerding . 1992. So i l s o f the Ashcrof t M a p A r e a . M O E Techn ica l Repor t 23 / B C S o i l Survey Report N o . 26, Integrated Management B r a n c h , V i c t o r i a B C , 79 Chapter 5: General Summary N a t i v e grasslands, crested wheatgrass pastures, and irr igated alfalfa are three c o m m o n forage product ion systems o f the southern interior o f B C . S o i l qual i ty parameters o n these three adjacent sites under those three forage product ion systems were improved five years f o l l o w i n g a single appl ica t ion o f G V R D class A biosol ids . A t the crested wheatgrass ( C W ) site, f ive years after a s ingle surface appl ica t ion o f b ioso l ids at 60 M g ha" 1 significant (P < 0.05) increases o f M W D and the propor t ion o f aggregates > 1 m m , the concentration o f C and N w i t h i n aggregates, and the hydro lys i s o f F D A were observed. F i v e years after a s ingle surface appl icat ion o f b ioso l ids at 20 M g ha" 1 at the native range ( N R ) site, greater (P < 0.1) aggregate stabil i ty ( M W D and the propor t ion o f aggregates > 1 m m ) , C and N concentrations o f stable aggregates, and so i l bu lk density were observed relative to the untreated control and chemica l fert i l izer treatments. The increase i n so i l C f rom the B i o - 2 0 treatment cou ld also expla in the decrease i n so i l bu lk density f rom this treatment at the N R site. A d d i t i o n a l l y , the fert i l izer treatment had near ly 5 0 % more s o i l aggregates <0.25 m m as compared to a l l other treatments dur ing summer and fal l s ampl ing i n 2006. A t the irrigated alfalfa ( IA) site, b ioso l ids appl ied at 60 M g ha" 1 increased the M W D and the propor t ion o f 2 - 6 m m aggregates relative to a l l other treatments dur ing fa l l sampl ing i n 2005 only . B i o s o l i d s appl ied at 60 M g ha" 1 decreased the bu lk density i n 2005 and 2006. Converse ly , f ive years f o l l o w i n g a single appl icat ion o f fertil izer, noticeable decreases were s t i l l detected i n aeration poros i ty and the concentration o f C i n 2 - 6 m m aggregates. 80 Aggregate stabil i ty, C and N concentrations o f aggregates, and b u l k density were achieved f rom b ioso l ids appl icat ion at 20 M g ha" 1 at the N R site, yet s ignificant increases were o n l y seen f rom the B i o - 6 0 treatment at the C W site. B i o s o l i d s appl ica t ion had no effect on aggregate stabil i ty at the I A site, but d i d decrease bu lk density w h e n appl ied at 60 M g ha" 1. S ince N and heavy metal contents restrict appl ica t ion l imi t s , b ioso l ids w i t h a greater C content w o u l d be more suited to rangeland fer t i l izat ion programs at this site. S o i l phys ica l properties were improved f rom b ioso l ids appl ied at 20 M g ha" 1 at the N R site, and had greater concentrations o f total C and N i n stable aggregates. N o clear changes i n aggregate s tabi l i ty were seen from b ioso l ids appl ica t ion at the I A site, yet a reduct ion i n b u l k density occurred i n 2005 and 2006 from the B i o - 6 0 treatment. F i n a l l y , a reduct ion i n aeration poros i ty was measured i n fert i l izer plots at this site. 81 APPENDICES A p p e n d i x 1 - B r i t i s h C o l u m b i a ' s trace element concentrations for Class A and B b ioso l ids guidelines set out i n the Organic Mat te r R e c y c l i n g Regu la t ion ( O M R R ) and reported i n Nu t r i fo r A n n u a l reports 2002-05. OMRR Class A Biosolids OMRR Class B Biosolids Parameter Unit Regulatory Annacis Island Regulatory Lions Gate Lulu Island Limits 2003 2004 Limits 2003 2004 2003 2004 Solids % N / A 3 1 . 3 3 0 . 7 N / A 3 4 . 1 3 3 . 4 2 3 . 4 2 3 . 5 TKN mg/kg N / A 4 4 , 0 0 0 4 4 , 3 0 0 N / A 3 2 , 3 0 0 3 4 , 3 0 0 6 3 , 5 0 0 6 4 , 1 0 0 NH4 mg/kg N / A 9 , 2 0 0 9 , 0 0 0 N / A 5 , 5 8 0 5 , 7 2 0 1 0 , 5 0 0 9 , 8 1 0 Fecal Coliform MPN/g < 1 0 0 0 2 6 4 7 < 2 , 0 0 0 , 0 0 0 2 3 , 1 6 9 2 7 , 8 0 0 2 9 7 , 4 0 8 2 8 0 , 0 0 0 Arsenic mg/kg 7 5 6 6 . 3 7 5 2 . 7 2 . 5 5 . 1 4 . 6 Cadmium mg/kg 2 0 3 3 . 5 2 0 1 . 9 1 . 8 5 . 9 4 Chromium mg/kg 1 0 6 0 6 9 1 0 7 1 0 6 0 4 9 4 6 8 1 6 1 Cobalt mg/kg 1 5 0 7 . 1 8 . 1 1 5 0 3 2 . 8 4 . 1 5 . 3 Copper mg/kg 2 2 0 0 1 2 8 0 1 2 3 0 2 2 0 0 1 3 2 0 1 2 0 0 1 7 2 0 1 3 8 0 Lead mg/kg 5 0 0 9 5 1 8 3 5 0 0 7 1 7 1 6 1 6 1 Mercury mg/kg 5 3 . 3 3 . 4 1 5 6 6 . 2 3 . 7 3 . 9 Molybdenum mg/kg 2 0 1 3 1 4 2 0 8 . 4 9 . 6 1 2 1 2 Nickel mg/kg 1 8 0 2 1 2 3 1 8 0 3 6 3 2 5 2 5 5 Selenium „mg/kg 1 4 5 . 7 5 . 8 1 4 4 . 3 4 . 3 5 . 4 4 . 9 Zinc mg/kg 1 8 5 0 8 5 8 1 0 1 0 1 8 5 0 5 5 4 5 9 8 8 2 7 8 4 9 82 Appendix 2 - Particle size analysis by block from the crested wheatgrass (a), native range (b), and irrigated alfalfa sites (c). Two runs were averaged from one sample in each block. a) Crested wheatgrass % Sand Silt Clay Blocks 1 54 40 7 2 51 37 12 3 46 41 14 4 55 34 11 b) Irrigated alfalfa % Sand Silt Clay Blocks 1 22 62 15 2 45 38 16 3 61 27 12 4 59 28 13 c) Native range 0, Vo Blocks Sand Silt Clay 1 51 35 13 2 , 54 35 • 10 3 57 32 10 4 48 40 12 83 Appendix 3a - ANOVA tables for the aggregate stability data. Significance is based on a = 0.05 at the Crested wheatgrass (a), and a = 0.1 at the native range (b) and irrigated alfalfa (c) sites. a) CW Spring Water Content MWD 2 - 6 mm 1 - 2 mm 0.25 -1 mm < 0.25 mm 2005 Source d f F P F P F P F P F P F P Block 3 0.43 0.73 2.73 0.11 2.91 0.09 0.45 0.72 3.2 0.08 2.22 0.16 Treatment 3 10.65 0.003 4.57 0.03 3.92 0.06 6.99 0.01 0.98. 6.44 3.46 0.06 Experimental error 9 Total 15 Summer Block 3 6.66 0.01 1.33 0.32 1.36 0.32 1.29 0.34 1.38 0.31 1.22 0.36 2005 Treatment 3 59.67 <.0001 10.46 0.003 7.71 0.007 9.78 0.003 4.38 0.04 11.58 0.002 Experimental error 9 Total 15 Fall Block 3 4.82 0.03 1.1 0.4 1.08 0.41 1.49 0.28 1.33 0.32 1.79 0.22 2005 Treatment 3 3.79 0.05 9.83 0.003 7.96 0.01 12.64 0.001 0.08 0.97 12.19 0.002 Experimental error 9 Total 15 Spring Block 3 1.53 0.27 1.62 0.25 1.41 0.3 0.4 0.76 0.61 0.63 1.83 0.21 2006 Treatment 3 5.55 0.02 3.52 0.06 3.1 0.08 5.03 0.03 0.56 0.65 2.06 0.18 Experimental error 9 Total 15 Summer Block 3 1.06 0.41 1.13 0.39 1.11 0.39 0.95 0.45 1.76 0.22 0.73 0.56 2006 Treatment 3 6.02 0.02 12.94 0.001 10.85 0.002 5.48 0.02 4.13 0.04 20.73 0.0002 Experimental error 9 Total 15 Fall Block 3 4.73 0.03 0.24 .0.87 0.19 0.9 1.5 0.28 5.54 0.02 6.65 0.01 2006 Treatment 3 1.99 0.19 2.97 0.09 1.85 0.21 5.45 0.02 1.7' 0.24 8.89 0.005 Experimental error 9 Total 15 84 b) NR Spring Water Content MWD 2 - 6 mm 1-2 mm -0.25 - 1 m m < 0.25 mm 2005 Source d f F P F P F P F P F P F P Block Treatment 0.73 3.07 0.56 0.08 3.22 125 0.08 0.35 4.34 1.2 0.04 . 0.36 3.2 1.69 0.08 0.24 7.68 1.75 0.01 0.23 3.21 0.79 0.08 0.53 Block X Treatment 2.07 0.1 1.03 0.46 0.93 0.53 0.76 0.65 0.61 0.77 0.87 0.61 Sampling error Total 16 31 Summer Block 2005 Treatment 0.68 1.66 0.58 0.24 1.46 2.5 0.29 0.13 1.56 2.05 0.27 0.18 1.51 3.34 0.28 0.07 2.78 0.38 0.1 0.77 0.44 3.24 0.73 0.07 Block X Treatment 2.39 0.06 0.78 0.64 0.84 0.6 0.47 0.87 0.85 0.58 0.99 0.48 Sampling error Total 16 31 Fall 2005 Block Treatment 5.88 1.01 0.02 0.43 0.46 0.72 0.77 0.54 0.28 0.91 0.84 0.47 0.4 1.13 0.76 0.39 7.12. 2.07 0.01 0.17 3.07 0.19 0.08 0.9 Block X Treatment 0.34 0.95 0.68 0.72 0.68 0.72 0.54 0.83 0.44 0.89 0.96 0.51 ..Sampling error Total 16 31 Spring Block 2006 Treatment 11.88 0.002 5.32 0.02 2.49 6.39 0.13 0.01 3.45 0.06 7.47 0.008 3.89 1.03 0.05 0.42 1.74 3.61 0.23 0.06 0.79 3.0 0.53 0.09 Block X Treatment 0.25 0.98 0.87 0.57 0.81 0.62 1.32 0.3 1.0 0.48 0.9 0.55 Sampling error Total 16 31 Summer Block 2006 Treatment 3.79 0.05 0.77 0.92 0.47 4.28 0.54 0.04 0.73 4.38 0.56 0.04 8.75 0.005 2.85 0.1 1.02 6.09 0.43 0.02 0.81 3.21 0.52 0.08 Block X Treatment 2.97 0.08 0.78 0.64 0.75 0.66 1.66 0.18 0.52 0.84 1.01 0.47 Sampling error Total 16 31 Fall 2006 Block Treatment 5.1 2.03 0.02 0.18 2.07 3.21 0.17 0.08 1.98 2.61 0.19 0.12 5.87 4.2 0.02 0.04 2.84 2.31 0.1 0.15 3.68 7.4 0.06 0.01 Block X Treatment 1.26 0.33 0.63 0.75 0.57 0.8 0.36 0.94 0.3 0.97 0.64 0.75 Sampling error Total 16 31 85 c)IA Spring Water Content MWD 2 - 6 mm 1 - 2 m m 0.25 -1 mm < 0.25 mm 2005 Source d f F P F P F P F P F P F P Block 3 43.37 <.0001 7.21 0.01 5.25 0.02 14.67 0.001 7.2 0.01 7.02 0.01 Treatment 3 0.97 0.45 2.76 0.1 3.29 0.07 0.95 0.46 1.84 0.21 0.79 0.53 Experimental error 9 Total 15 *No subsamples taken Summer Block 3 35.57 <0001 4.04 0.04 2.78 0.1 5.35 0.02 1.64 0.25 4.92 0.03 2005 Treatment 3 0.77 0.54 1.13 0.39 1.1 0.4 1.63 0.25 1.56 0.26 1.33 0.32 Block X 9 2.25 0.08 2.21 0.08 1.8 0.13 1.53 0.22 0.66 0.73 , 3.44 0.015 Treatment . Sampling error 16 Total 31 Fall Block 3 16.57 0.0005 11.32 0.0021 17.5 0.004 13.22 0.0012 17.12 0.0005 6.34 0.01 2005 Treatment 3 0.69 0.58 3.14 0.08 2.95 0.09 0.87 0.51 0.93 0.47 2.26 0.15 BlockX 9 2.01 0.11 1.72 0.16 1.36 0.28 1.73 0.16 1.84 0.14 2.47 0.05 Treatment Sampling error 16 Total 31 Spring Block 3 24.12 0.0001 5.35 0.02 4.36 0.04 9.35 0.004 2.35 0.14 6.83 0.01 2006 Treatment 3 1.25 0.35 0.85 0.5 1.67 0.24 0.27 0.84 6.89 0.01 0.26 0.85 BlockX 9 7.65 0.0002 2.49 0.05 1.92 0.121 1.23 0.35 1.62 0.19 2.9 0.03 Treatment Sampling error 16 Total 31 Summer Block 3 12.31 0.0015 2.24 0.15 3.46 0.06 8.76 0.005 6.69 0.01 0.72 0.56 2006 Treatment 3 1.56 0.27 0.82 0.52 0.7 0.57 0.25 0.86 1.59 0.29 1.17 0.37 BlockX 9 8.78 0.0001 2.1 0.09 2.14 0.09 2.3 0.07 0.95 0.51 ' 2.6 0.05 Treatment Sampling error 16 Total 31 Fall Block 3 22.7 0.0002 2.43 0.13 1.66 0.24 1.663 0.25 4.2 0.04 4.87 0.03 2006 Treatment 3 2.06 0.18 1.09 0.4 1.23 0.35 1.58 0.26 .1.7 0.24 2.23 0.15 BlockX 9 2.02 0.11 1.18 0.37 1.78 0.15 4.44 0.005 0.99 0.48 0.52 0.84 Treatment Sampling error 16 • Total 31 86 Appendix 3b - ANOVA tables for the bulk density and aeration porosity data. Significance is based on a = 0.05 at the Crested wheatgrass, and a = 0.1 at the native range and irrigated alfalfa. Crested wheatgrass Source Block Treatment Block X Treatment Sampling error Total df 3 F P F P F P Aeration Bulk density porosity 2005 2006 2006 3.3 0.07 2.25 0.15 1.39 0.23 2.86 0.1 1.19 0.37 2.5 0.03 3.48 0.06 0.99 0.44 2.68 0.02 32 47 Native range Source Block Treatment Block X Treatment Sampling error Total df 3 F P F P F P Bulk density 2005 0.22 0.88 3.77 0.053 1.15 0.36 32 47 Irrigated alfalfa Source Block df 3 F P Bulk density 2005 28.16 <.0001 2006 12.26 0.002 Aeration porosity 2006 120.48 <.0001 Treatment Block X Treatment F P 9 F P Sampling error 32 Total 47 4.68 0.03 1.22 0.32 3.4 0.07 0.86 0.57 4.55 0.03 0.24 0.99 87 A p p e n d i x 3c - A N O V A tables for the aggregate associated C , N and C : N data. S igni f icance is based on a = 0.05 at the Crested wheatgrass, and a = 0.1 at the native range and irrigated alfalfa. Crested Wheatgrass Water-stable aggregates (mm) 1-2 0.25-1 Water-stable aggregates (mm) 2-6 1-2 0.25-1 Irrigated a!falia C Water-stable aggregates (mm) 26.03 5.15 1.79 <.0O01 0.02 0.22 ' 375 6.39 0.35 0.05 0.01 0.79 42.98 10.54 8.2 <.0001 0.003 0.009 26.03 51.32 10.27 <.0001 <.0001 0.0O3 treatment 3 2.25 4.02 3.70 0.15- 0.05 0.09 3.35 0.07 1.01 0.43 experimental 9 error Total 15 experimental 9 error Total 15 experimental 9 error Total 15 Water-stable aggregates (mm) 1-2 0.25-1 Water-stable aggregates (mm) 2-6 1-2 0.25-1 Water-stable aggregates (mm) 1.29 0.34 2.02 2.65 " 0.31 0.18 0.11 0.82 45.22 8.11 7.89 <.0001 0.006 0.007 treatment F experimental 9 error Total 15 24.08 45.98 15.33 <.0001 <.0001 <.0001 experimental 9 error Total 15 2.99 3,42 4.69 0.09 0.07 0.03 experimental 9 error Total 15 4.61 0.03 3.65 0.06 1.28 0.33 Water-stable aggregates (mm) 1-2 0.25-1 Water-stable aggregates (mm) 1-2 0.25-1 Water-stable aggregates (mm) 1.26 0.35 2.79 0.1 7.44 0.008 6.91 0.01 experimental error Total 5.13 0.02 0.77 0.54 4.05 0.O4 experimental error Total 2.82 0.10 0.81 0.52 0.93 0.74 experimental error Total 4.42 0.04 3.12 0.08 1.27 0.34 88 Appendix 3d - ANOVA tables for the FDA data. Significance is based on a = 0.05 at the Crested wheatgrass, and a = 0.1 at the native range and irrigated alfalfa. Crested Wheatgrass Native Range Irrigated alfalfa F D A F D A F D A 2006 2006 2006 Source df Source df Source df Block 3 Block 3 Block 3 F 0.58 F 6.55 F 19.27 P 0.64 P 0.01 P 0.0005 Treatment 3 Treatment 3 Treatment 3 F 3.92 F 1.69 F 0.61 P 0.04 P 0.24 P 0.63 Block X 9 Block X 9 Block X 9 Treatment F 1.4 Treatment F. 1.65 Treatment F 0.57 P 0.27 P 0.18 P . 0.8 Sampling error 16 Sampling t. 16 Sampling € 16 Total 31 Total 31 Total 31 89 A p p e n d i x 4 - To ta l so i l C and N from 2002 to 2004 i n bu lk so i l . Differences are significant at P < 0.05 as determined b y Fisher ' s protected L S D . 6 treatments (control ; fert i l izer; B i o - 1 0 to B i o -60). a) Crested wheatgrass b) Native Range a ) C a r b o n ( g k g ' 1 ) 2 0 0 2 - f a l l 2 0 0 3 - s p r i n g 2 0 0 3 - f a l l 2 0 0 4 - f a l l d e p t h ( c m ) 0 - 1 5 0 - 1 5 1 5 - 3 0 3 0 - 4 5 0 - 1 5 0 - 1 5 T r e a t m e n t c o n t r o l 1 7 . 5 9 b 1 6 . 9 4 1 8 . 3 9 14.11 1 3 . 0 0 b 2 0 . 2 7 b f e r t i l i z e r 2 0 . 7 7 b 1 8 . 2 3 2 0 . 0 0 1 5 . 2 8 1 5 . 0 5 b 2 0 . 3 2 b B i o - 1 0 2 0 . 5 4 b 1 7 . 9 6 18.01 1 9 . 3 3 1 4 . 1 7 b 2 3 . 8 1 b a B i o - 2 0 2 3 . 0 5 b a 1 8 . 0 2 1 6 . 9 5 1 4 . 1 4 1 6 . 6 8 b 2 9 . 2 7 b a B i o - 4 0 2 5 . 3 9 b a 2 0 . 9 7 1 7 . 2 6 1 6 . 5 7 2 2 . 3 4 b a 3 0 . 3 5 b a B i o - 6 0 3 0 . 9 1 a 2 3 . 8 8 1 6 . 8 8 1 4 . 8 9 3 4 . 2 7 a 4 6 . 5 1 a L S D 8 . 3 2 . 4 . 9 5 5 . 4 1 3 . 9 9 1 2 . 0 5 1 3 . 1 9 b ) N i t r o g e n ( g k g ' ' ) 2 0 0 2 - f a l l 2 0 0 3 - s p r i n g 2 0 0 3 - f a l l 2 0 0 4 - f a l l d e p t h ( c m ) 0 - 1 5 0 - 1 5 1 5 - 3 0 3 0 - 4 5 0 - 1 5 0 - 1 5 T r e a t m e n t c o n t r o l 1 . 3 8 b 1 . 3 4 b 0 . 8 4 0 . 3 4 1 . 2 5 b 1 . 4 1 b f e r t i l i z e r 1 . 8 2 b a 1 . 3 4 b 0 . 9 6 0 . 3 4 1 . 2 8 b 1 . 4 8 b B i o - 1 0 1 . 5 5 b 1 . 3 8 b 1.01 0 . 4 3 1 . 3 7 b a 1 . 8 1 b B i o - 2 0 l . 8 6 b a 1.4b 0 . 9 7 0 . 3 5 1 . 5 6 b a 2 . 0 8 b B i o - 4 0 2 . 2 b a 1 . 8 b a 0 . 9 3 0 . 5 0 1 . 9 8 b a 2 . 4 1 b a B i o - 6 0 2 . 9 6 a 2 . 2 a 0 . 9 9 0 . 3 4 2 . 8 9 a 4 . 3 6 a L S D 0 . 6 9 0 . 3 6 0 . 2 7 0 . 2 4 0 . 8 5 1 .10 a ) depth (cm) Treatment control fertilizer Bio-10 Bio-20 Bio-40 Bio-60 2002-fall 0-15 21.82 22.43 28.21 36.64 42.96 42.2 C a r b o n ( g k g ' 1 ) 2003 -spring 2003-fall 2004-fall 0-15 15-30 0-15 0-15 27.56 20.90 21.60 23.67 24.02 26.72 10.73 15.83 11.35 12.75 15.71 16.23 20.32 23.15 30.21 41.04 38.61 40.40 35.97 37.29 57.20 50.43 53.07 32.58 LSD 26.21 23.13 8.66 38.45 3 7 . 2 2 b ) depth (cm) Treatment control fertilizer Bio-10 Bio-20 Bio-40 Bio-60 2 0 0 2 - f a l l 0 - 1 5 . . 1.91 1.79 2 . 4 4 3.31 3.81 3 . 9 4 Ni t rogen (g kg" ) 2003 -spring 2003-fall 2004-fall 0-15 15-30 0-15 0-15 2 . 1 9 1.56 1.72 1.96 2 . 0 6 2 . 2 8 0 . 6 9 0 . 9 4 0 . 7 4 0 . 8 4 2 . 1 7 2 . 7 6 3 . 5 5 3 . 8 0 3 . 9 0 2 . 2 2 3 . 2 2 5 . 0 1 4 . 0 6 4 . 4 2 2 . 8 9 LSD c) Irrigated alfalfa a ) C a r b o n ( g k g " ' ) 2 0 0 2 - f a l l 2 0 0 3 - s p r i n g 2 0 0 3 - f a l l 2 0 0 4 - f a l l d e p t h ( c m ) 0 - 1 5 0 - 3 0 3 0 - 6 0 0 - 1 5 0 - 1 5 T r e a t m e n t c o n t r o l 2 2 . 7 8 2 4 . 0 8 1 5 . 1 0 2 4 . 0 8 2 4 . 6 6 b f e r t i l i z e r 2 3 . 5 7 2 4 . 5 0 1 5 . 2 0 . 2 4 . 5 0 2 4 . 8 3 b B i o - 1 0 2 2 . 8 4 2 1 . 6 9 1 5 . 4 4 2 1 . 6 9 2 5 . 0 1 b B i o - 2 0 2 5 . 0 8 2 6 . 1 4 1 7 . 3 8 2 6 . 1 4 2 6 . 9 3 b B i o - 4 0 2 4 . 2 3 2 4 . 7 8 1 4 . 7 9 2 4 . 7 9 2 6 . 4 3 b B i o - 6 0 2 5 . 8 8 2 9 . 2 5 1 5 . 3 8 2 9 . 2 5 3 4 . 6 7 a L S D 5 . 3 9 . 7 . 4 4 3 . 0 1 7 . 4 4 7 . 6 5 b ) N i t r o g e n ( g k g " ' ) 2 0 0 2 - f a l l 2 0 0 3 - s p r i n g 2 0 0 3 - f a l l 2 0 0 4 - f a l l d e p t h ( c m ) 0 - 1 5 0 - 3 0 3 0 - 6 0 0 - 1 5 0 - 1 5 T r e a t m e n t c o n t r o l 2 . 1 7 2 . 1 5 0 . 9 6 2 . 1 5 2 . 3 1 b f e r t i l i z e r 2 . 2 3 2 . 1 6 0 . 9 8 2 . 1 8 2 . 2 6 b B i o - 1 0 2 . 2 0 1 . 9 7 1 . 0 5 1 . 9 7 2 . 3 4 b B i o - 2 0 2 . 3 8 2 . 3 5 1 .27 2 . 3 5 2 . 5 2 b B i o - 4 0 2 . 3 7 2 . 2 1 1 .04 2 . 2 0 2 . 4 5 b B i o - 6 0 2 . 5 4 2 . 6 9 1 .03 2 . 6 9 3 , 0 6 a L S D 0 . 4 9 0 . 7 8 0 . 2 6 0 . 7 8 0 . 7 4 90 Appendix 5 - Experimental layouts at the Ashcroft ranch, a) Crested wheatgrass; b) Native range; c) Irrigate alfalfa. a) b) Ashcroft Ranch/Biosolids - Crested Wheatgrass A=controI; B=fertilizer, O10; D=20; E=40; F=60 Mg/harates Block 4 f—140 m plots! Block 2 ( ~ U 0 ro plott) B l o c k J (-110 mplo t i j f Block 1 (-90 m plots) "Tii Ashcroft Ranch/Biosolids - Native range A-conlrol; B=fcrtilizer, O10; D-20; E-40; F=60 Mg/ha (dry) rates Block 4 Fence . ' i - . - L . Entrarice to field' C) Ashcroft Ranch/Biosolids - Irrigated Alfalfa A=control; B=fertilizer, O10; D=20; E=40; F^60 Mg/ha rales Block 1 D| A | B | F | E IC 1 2 3 4 5 6 17 Block 2 F | C | B | D | E | A S-Hcff.?.".1.'! J.V.™. Block 3 D|C|EIFI A l B 9 10 11 12113 14 15 16 17 18119 20 21 22 23 24 Block 4 Cl D] F | A | E I B 91 

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