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Hydroseeding of forest road slopes for erosion control and resource protection 1977

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HYDROSEEDING OF FOREST ROAD SLOPES FOR EROSION CONTROL AND RESOURCE PROTECTION . . WILLIAM'WADE CARR B.Sc, Oregon State U n i v e r s i t y , 1975 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF RASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Faculty of Forestry, University of B r i t i s h Columbia) We accept t h i s thesis as conforming to the required standard . THE UNIVERSITY. OF BRITISH COLUMBIA September 1977 © W i l l i a m Wade Carr, 1977 In present ing th is thes is in p a r t i a l fu l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f ree ly ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th is thes is for s c h o l a r l y purposes may be granted by the Head of my Department or by h is representa t ives . It is understood that copying or pub l i ca t ion of th is thes is for f inanc ia l gain sha l l not be allowed without my wr i t ten permission. Department of Fores t ry The Univers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date October 3, 1977 ABSTRACT S o i l erosion r e s u l t i n g from logging road construction i s a serious problem a f f e c t i n g p h y s i c a l stream water q u a l i t y and road s t a b i l i t y i n B r i t i s h Columbia. This study investigates slope r e - vegetation by hydroseeding to a l l e v i a t e t h i s problem. Laboratory tests on the e f f e c t of f e r t i l i z e r s l u r r y contact on seed germination show a 30% loss i n T r i f o l i u m repens germination a f t e r 3 a 60-minute exposure to a so l u t i o n of 90 kg 10-30-10 f e r t i l i z e r per m of water (750 lbs f e r t i l i z e r per 1000 gallons water). Although there was no s i g n i f i c a n t e f f e c t of such exposure on Rhizobium inoculum, care must be taken to l i m i t seed soaking time i n the hydroseeder and to keep s l u r r y f e r t i l i z e r concentration as low as possible. F i e l d hydroseeding tests show no s i g n i f i c a n t advantage from separate applications of seed then f e r t i l i z e r , nor from the use of a mulch i n connection with s l u r r y a p p l i c a t i o n . The e f f e c t of seed- f e r t i l i z e r contact i n the s l u r r y did not appear to be operationally s i g n i f i c a n t . Mulching did not have a s i g n i f i c a n t e f f e c t on the com- p o s i t i o n of the vegetative cover established nor on the effectiveness of the plant cover i n erosion c o n t r o l . A l l hydroseeding treatments yielded s a t i s f a c t o r y vegetative cover (averaging 65%) and s i m i l a r vegetative composition. S o i l on untreated control p l o t s eroded an average depth of 2.3 cm (0.9 in) from September 1976 to A p r i l 1977. 3 This t r a n s l a t e s to 256 m of eroded s o i l material per km of logging road (540 cu yd per mile), assuming 1.5 ha of exposed side slope per km (6 acres per mile). The vegetation not only was successful i n h a l t i n g erosion from the vegetated areas, but i t also acted as a i i i catchment f o r s o i l p a r t i c l e s brought into these areas from upslope by gravity and water erosion. The one-step s l u r r y a p p l i c a t i o n of s e e d - f e r t i l i z e r - s o i l binder and water was as e f f e c t i v e i n vegetation establishment and erosion control as the other hydroseeding treatments and much cheaper. Based on 1976 costs, i t would take approximately $2000 to hydroseed a k i l o - meter of logging road ($3000 per mile) by t h i s method. This i s a small investment f o r road-side revegetation that can protect the i n t e g r i t y of a forest road (which may i n i t i a l l y cost upwards of $60,000/km), reduce road maintenance costs, and greatly benefit the adjacent aquatic environments. i v TABLE OF CONTENTS INTRODUCTION 1 BACKGROUND 8 S o i l binders 8 F e r t i l i z e r 8 Mulch 12 Seed Mix 14 S o i l Erosion 15 SCOPE OF THE STUDY 17 METHODS AND MATERIALS 22 Laboratory Experiments 22 Experiment 1: Rhizobium test 22 Experiment 2a: Seed germination tests 23 2b: Seed germination tests 24 F i e l d Experiments 25 Experiment 3: Species composition 26 Experiment 4: Percent plant cover 26 Experiment 5: Measurement of erosion 28 RESULTS AND DISCUSSION 31 Experiment 1 . . . 31 Experiment 2a and 2b 32 Experiment 3 35 Experiment 4 . . . . 40 Experiment 5 41 SUMMARY 48 LITERATURE CITED 53 APPENDIX I Percent plant cover a n a l y s i s of variance . . 56 APPENDIX II Measure of s o i l erosion analysis of variance. 57 V LIST OF TABLES 1. Cost components based on actual f i e l d operation with 1200 gallon hydroseeder 13 2. T o t a l cost per hectare 13 3. S i t e comparison 20 4. Species used i n f i e l d t r i a l s and germination test . . . . . 24 5. Treatments . . . . . . . . 25 6. Rhizobium v i a b i l i t y per gram of legume inoculum 31 7. Seed germination: seeds washed 33 8. Seed germination: seeds unwashed 34 9. Species frequency by block 36 10. Species frequency by treatment 36 11. Percent plant cover 40 12. Measured erosion 45 v i LIST OF FIGURES 1. Stream sedimentation and t u r b i d i t y from forest road construction at Koksilah, 1976, before hydroseeding . . . . 2 2. Culvert blockage from cut-bank erosion 2 3. Erosion undercutting forest road bank 3 4. Gully formation c u t t i n g into road surface 3 5. Small ( 9 5 0 - l i t e r capacity) hydroseeder used i n experiments 6 6. Hydro-slurry containing seed, f e r t i l i z e r , binder, and mulch 6 7. Graph of Osmotic P o t e n t i a l as a function of F e r t i l i z e r concentration and type 10 8. Location of study areas on southern Vancouver Island . . . . 18 9. Koksilah sidecast slope before treatment, Sept. 1976 . . . . 19 10. Koksilah cut-slope during treatment, Sept. 1976 19 11. Caycuse cut-slope before treatment, Sept. 1976 21 12. Plot photographed with normal color f i l m , A p r i l 1977 . . . . 27 13. Plot photographed with c o l o r - i n f r a r e d f i l m , A p r i l 1977 . . . 27 14. Rill-meter i n use at Koksilah, September 1976 29 15. Rill-meter i n use at Koksilah, A p r i l 1977 29 16. Frost a c t i o n on Koksilah cut-slope, Jan. 1977 38 17. Koksilah cut-slope i n September, 1976 42 18. Same cut-slope i n A p r i l 1977 42 19. Koksilah sidecast that caused the stream sedimentation seen i n Figure 1 (Sept., 1976) 43 20. Same sidecast slope i n A p r i l 1977. Note untreated c o n t r o l area between hydroseeded plots 43 21. Caycuse cut-slope, treatment and co n t r o l , A p r i l 1977 . . . . 44 v i i ACKNOWLEDGEMENTS I am indebted to Dr. R. P. Will i n g t o n , Dr. T. M. B a l l a r d , and Dr. A. A. Bomke f o r t h e i r advice, assistance, and constructive comments during t h i s project and during the preparation of t h i s t h e s i s . I am also indebted to Mr. Paul Ziemkiewicz for h i s advice and help during the experimental phases of t h i s project. I thank Mr. W. G. Burch and Mr. J . V. Toovey, of B r i t i s h Columbia Forest. Products Ltd., and the Resource Planning Group of B.C.F.P. for f i n a n c i a l support to undertake t h i s project. INTRODUCTION S o i l erosion from forest road construction i s a major management- related cause of forest stream t u r b i d i t y and sedimentation (Figure 1). A newly constructed forest road can have from 0.5 to 3.0 ha of exposed s o i l and s u r f i c i a l material per km (2 to 12 acres per mile) that are extremely vulnerable to the erosive forces of f r o s t and water (Personal communication, R. P. Wi l l i n g t o n 1976). Fredricksen (1965) found a 250- f o l d increase i n stream t u r b i d i t y and sedimentation during the f i r s t r a i n storms following construction of forest road on a small Oregon watershed. Not only does road bank erosion cause degradation of the phys i c a l q u a l i t y of stream waters, but i t also plays a s i g n i f i c a n t r o l e i n road s t a b i l i t y problems. Reduced d i t c h drainage capacity and culvert block- age (Figure 2), undercutting of road banks (Figure 3), and undermining of the road surface (Figure 4) are a l l causes of road i n s t a b i l i t y prob- lems that can be traced to s o i l erosion. The use of a vegetative cover on forest road banks not only decreases stream sedimentation, but can also a i d i n prolonging road l i f e and reducing maintenance costs. The recent studies of Dyrness (1975) and Megahan (1975) have quantified s i g n i f i c a n t reductions i n s o i l erosion achieved by revegetation of bare slopes beside forest roads. A plant and l i t t e r cover of 70 to 80% can e f f e c t i v e l y reduce s o i l erosion from both dry r a v e l and water erosion (Berglund 1976). The important functions of a vegetative cover are as follows (Berglund 1976): 1  Figure 4. Gully formation cutt i n g into road surface. 1) Vegetation protects the s o i l p a r t i c l e s from d i r e c t impact of raindrops. Raindrop energy w i l l be diss i p a t e d on vegetation instead of on the s o i l p a r t i c l e s . 2) Grasses and legumes can reduce the v e l o c i t y of surface runoff, which also d i s s i p a t e s the erosive energy and allows more time for i n f i l t r a t i o n . 3) Grass can r a p i d l y develop a f i n e , extensive root system that s t a b i l i z e s s o i l p a r t i c l e s by increasing resistance to erosive forces. 4) Established vegetation w i l l trap eroding s o i l p a r t i c l e s and prevent them from moving down the e n t i r e slope length. 5) The addition of organic matter to the s o i l not only makes s o i l more r e s i s t a n t to erosion but also i s important i n s o i l development. The following are a d d i t i o n a l functions of a vegetative cover: 1) A w e l l established grass cover can e f f e c t i v e l y slow ( i f not prevent) the invasion of red alder (Alnus rubra) on road edges, which would otherwise be held i n check with herbicides or c o s t l y pruning (Becker 1971). 2) Revegetation of slopes with grasses and legumes can aid i n the recovery of at le a s t part of the roadside area removed from f o r e s t production, by improving s o i l properties ( f e r t i l i t y and moisture holding capacity) and protecting the seedling from erosive damage. The a r t of roadside revegetation has been developed and refined by various highway departments throughout the United States and Canada. Their work provides an excellent basis for forest revegetation and 5 should be used i n development of f o r e s t r y methods. The most widely used revegetation p r a c t i c e i s the d i r e c t seeding of road slopes with grasses or grass-legume mixtures. Direct seeding has been proven e f f e c t i v e i n cover establishment and lends i t s e l f to mechanization. Hydroseeding or hydrograssing i s the a p p l i c a t i o n to s o i l of a seed and water s l u r r y that may contain f e r t i l i z e r , a chemical s o i l binder, and/or a mulch (Figure 5). Materials can be combined i n one s l u r r y f o r a si n g l e a p p l i c a t i o n or some components can be applied separately f or a multiple-step a p p l i c a t i o n (Figure 6). Either method provides e f f e c t i v e spreading on slopes. Hydroseeding i s not labor- intensive and therefore i s one of the more c o s t - e f f i c i e n t ' methods of roadside revegetation. The objectives of t h i s study were to answer the following ques- tions concerning hydroseeding as re l a t e d to i t s cost-effectiveness and use i n the f o r e s t environment. A. Since Rhizobium inoculum i s needed i f legumes are to f i x nitrogen, what i s the e f f e c t of f e r t i l i z e r concentration on Rhizobium v i a b i l i t y ? B. What i s the e f f e c t of f e r t i l i z e r s a l t s on seed germination i n the one-step s l u r r y a p p l i c a t i o n , where seed i s exposed to a concen- trated f e r t i l i z e r s o l u t i o n i n the hydroseeder tank? C. What species of grasses and legumes are most s u i t a b l e f or hydro- seeding on forest lands at two southern Vancouver Island l o c a - tions? D. Is a one-step s l u r r y a p p l i c a t i o n , including both seed and f e r t i l - i z e r , better than a two-step (or separate) a p p l i c a t i o n of seed then f e r t i l i z e r ? The trade-off may be reduced seed germination Figure 6. Hydro-slurry containing seed, f e r t i l i z e r , binder, and mulch. versus higher cost. Are the benefits of mulching j u s t i f i e d by i t s added cost? How much s o i l erodes from f o r e s t road slopes and what reduction i s possible as a r e s u l t of hydroseeding? How do the costs of d i f f e r e n t hydroseeding treatments compare? BACKGROUND Hydroseeding as a method of grass-legume establishment has only been practiced about 15 years. The development of new equipment and s l u r r y amendments i s proceeding r a p i d l y . These advances contribute greatly to the economic and operational advantages of hydroseeding over dry seed a p p l i c a t i o n on steep slopes. S o i l binders One of the more recent and most s i g n i f i c a n t advances i n hydroseed- ing has been the development of chemical s o i l binders. The s o i l binder i s an organic or inorganic substance added to a s l u r r y to give temporary s o i l cohesion, holding the seed and surface s o i l p a r t i c l e s i n place on steep slopes. Where wind and water would normally remove seed and other s o i l amendments from the slope i n a dry seed a p p l i c a t i o n before germination i s secured, the binders, which can l a s t up to 3 months (Armbrustand Dickerson 1971, Kay 1976) hold the seed i n place to help ensure even cover establishment. F e r t i l i z e r The a d d i t i o n of f e r t i l i z e r to a s l u r r y i s an excellent method of s i t e f e r t i l i z a t i o n that i s inexpensive, r e q u i r i n g l i t t l e a d d i t i o n a l time and no extra equipment. This l i q u i d a p p l i c a t i o n of soluble f e r t i l i z e r s provides an even d i s t r i b u t i o n of f e r t i l i z e r on i n f e r t i l e road cut and f i l l slopes that are not accessible to conventional non-aerial spreading 8 9 methods. Also, once dissolved, the nutrients may be r e a d i l y a v a i l a b l e to the f a s t germinating species, e.g., Lolium spp. and T r i f o l i u m spp. These advantages however, may be p a r t i a l l y o f f s e t by l o s s of seed germ- in a t i o n and plant v i t a l i t y , induced by immersion of seeds i n high con- centrations of f e r t i l i z e r s l u r r i e s . In s o i l , soluble f e r t i l i z e r s a l t s are dissolved i n the s o i l s o l u - t i o n surrounding the zone of a p p l i c a t i o n , which becomes quite concen- trated. Excessive concentration of soluble s a l t s i n contact with roots or germinating seed causes i n j u r i o u s e f f e c t s , e.g., plasmolysis, r e s t r i c - t i o n of a v a i l a b l e moisture, or actual s a l t t o x i c i t y (Tisdale and Nelson 1966). The increase i n s a l t concentration and r e s u l t i n g depression of osmotic p o t e n t i a l of the s o i l s o l u t i o n w i l l vary depending upon f e r t i l - i z e r grade and mix. Radar et a l . (1943) found, for a 448 kg/ha (400 l b / acre) a p p l i c a t i o n of f e r t i l i z e r , decreases i n osmotic p o t e n t i a l i n the s o i l ranging from .019 to 3.966 bars. In hydroseeding, however, there i s no s o i l to buffer the s a l t s o l u t i o n concentration and osmotic poten- t i a l s incurred are much lower. Osmotic p o t e n t i a l as a function of f e r t i l i z e r type and concentration i s shown i n Figure 7. At the highest concentration of 90 kg of f e r t i l i z e r per m of water (750 l b s . per 1000 gallons) or the equivalent of a 420 kg/ha a p p l i c a t i o n of f e r t i l i z e r , p o t e n t i a l s incurred range from -2.48 to -5.10 MPa. The f e r t i l i z e r s 0-0-61 and 34-0-0 are high i n potassium and nitrogen s a l t s r e s p e c t i v e l y , which are major contributors to the decrease i n osmotic p o t e n t i a l . Fortunately, i f the s o i l i s moist, the exposure of seed to such high concentrations i s l i m i t e d to the time between mixing and a p p l i c a t i o n . Even t h i s l i m i t e d exposure may be the cause for loss of legume v i t a l i t y and seed germination. 10 Figure 7. Graph of Osmotic P o t e n t i a l as a function of F e r t i l i z e r concentration and type. 0 30 660 90 F e r t i l i z e r Concentration (kg/m H20) 11 Brooks and Blazer (1963) showed that a f t e r a 30 minute exposure 3 to a s o l u t i o n of 108 kg of 10-20-10 f e r t i l i z e r per m water (900 l b s . per 1000 gallons water), germination of Kentucky 31 fescue (Festuca e l a t i o r ) was reduced from 98% to 61%. Personal communication with landscape contractors (L. Barberry of Barberry Bros. Sod Inc. 1975 and P. Sahlstrom of T e r r i s o l Hydrograss Ltd. 1976) appears to substantiate t h i s with observations that some species i n a seed mix never appear, although they had previously been used su c c e s s f u l l y . Part of t h i s problem may be a t t r i b u t e d to mechanical damage from the hydroseeder pumping system (Kay 1976), but i t appears that f e r t i l i z e r s a l t contact may also be a s i g n i f i c a n t contributor. F e r t i l i z e r s a l t contact may also account for a lack of legume v i t a l i t y observed by Kay (1976) a f t e r prolonged soaking i n a hydro- seeder. The problem i s a lack of legume nodulation by Rhizobium bacteria that are included with the seed i n the hydroseeder. The b a c t e r i a , i n a humus base, are coated on the seed with a s t i c k i n g agent to help ensure s u f f i c i e n t organisms i n the s o i l f o r i n f e c t i o n and nodu- l a t i o n . Without the n i t r o g e n - f i x i n g b a c t e r i a , legume establishment and v i t a l i t y are d e f i n i t e l y retarded (Lother and McDonald 1973), unless nitrogen d e f i c i e n c i e s are absent. The cause f o r t h i s lack of nodulation i n the hydroseeding may be i n i t i a l low v i a b i l i t y of Rhizobium, separation of the seed and bac t e r i a , Rhizobium mortality from soaking i n the f e r t i l i z e r s a l t s o l u t i o n , or repression (by a v a i l a b l e nitrogen) of i n f e c t i o n . New seed coating procedures ensure better and longer seed-inoculum contact, thus removing t h i s problem. However, the presence of excessive nitrogen i n the s o i l has been shown to repress legume nodulation (Dart and 12 Wildon 1970; Richardson, Jordon, and Gerrard 1957; Tanner and Anderson 1963). The temporary exposure to a nitrogen f e r t i l i z e r may be enough to repress nodulation. There i s also the p o s s i b i l i t y of Rhizobium mortality from plasmolysis caused by exposure to low osmotic p o t e n t i a l s i n a f e r t i l i z e r s o l u t i o n . Mulch The use of mulch i s often recommended with d i r e c t roadside seed- ing. Mulch i s no n - l i v i n g material o f f e r i n g instantaneous protection to the s o i l surface (Berglund 1976). Mulch may also improve the micro- environment of the seed by moderating evaporation and s o i l moisture content, and modifying s o i l and a i r temperatures (Brink and Maxwell 1965). Dyrness (1967) found mulches to be important i n h i s f o r e s t road- side revegetation study. There are a number of mulching materials a v a i l a b l e , such as e x c e l s i o r matting, jute netting, straw, and paper or p l a s t i c coverings (Dueck 1967; Kay 1976). These mulches, however, can be expensive,or labor intensive, and/or require s p e c i a l a p p l i c a t i o n equipment. The cost of these materials i s generally p r o h i b i t i v e i n the forest environ- ment. There has been recent development of hydro-mulches which are applied i n s l u r r y form with seed or separately. The most common hydro- mulch i s a c e l l u l o s e f i b e r by-product from the pulping industry (e.g., S i l v a f i b e r , Conwed, Spra^mulch). More recently, p e l l e t i z e d grass seed wastes ( J a c k l i n Organic Mulch) has been added to the l i s t of mulches that are applied i n s l u r r y form. A l l are adequate mulching agents that pro- vide the ease of s l u r r y a p p l i c a t i o n , which makes them r e l a t i v e l y inex- pensive compared to other types of mulches. The addition of a hydro-mulch to a single-step s l u r r y a p p l i c a t i o n does, unfortunately, at le a s t double the cost of basic hydroseeding by increasing both material costs (Table 1) and time of a p p l i c a t i o n (Table 2). Kay (1977) believes that proper time of seed a p p l i c a t i o n and good TABLE 1 COST COMPONENTS BASED ON ACTUAL FIELD OPERATION WITH 1200 GALLON HYDROSEEDER (1976) Material Seed F e r t i l i z e r Mulch Binder Equipment Operation Rate per Hectare Cost per Hectare 94 kg 440 kg 1100 kg 22 kg (with mulch) or 11 kg (without mulch) Variable with treatment $125 100 250 150 75 Variable (based on $150/ hour) TABLE 2 TOTAL COST PER HECTARE Treatment Steps Hours Unmulched Mulched 1 2 1 2 step step step step 3 6. 6 9 750 1200 1550 2000 (Based on 50 hectare operation) (1976) 14 agronomic practices w i l l give better r e s u l t s than r e l y i n g on mulching to o f f s e t any problems that may a r i s e . Also the p o s s i b i l i t y of inducing early seed germination i n an unfavorable macro-environment i s eliminated. Personal communication with people that are involved with hydroseeding (J. Morrow of N.W. S t a b i l i z a t i o n Chemicals 1977 and L. Barberry 1975) indicates that i n the long run, there appears i n many cases to be no s i g n i f i c a n t cover diffe r e n c e where mulched and unmulched areas are com- pared. The instantaneous s o i l protection of mulches may be somewhat superfluous with the use of a chemical s o i l binder. Seed Mix The method and timing of seed a p p l i c a t i o n are important consider- ations i n roadside revegetation, but most important i s the s e l e c t i o n of a proper seed mix for the area i n question. Without proper species s e l e c t i o n and combination, no amount of precaution or s o p h i s t i c a t i o n of a p p l i c a t i o n techniques w i l l a id i n cover establishment. A proper seed mix should contain species that are s u i t a b l e to the s o i l and s u r f i c i a l materials, topography, and climate of the treatment area. Species chosen should be compatible (aggressive species avoided), with at l e a s t one r a p i d l y e s t a b l i s h i n g , s h o r t - l i v e d species to provide quick cover while the slower developing but long-lived perennials develop (Brink 1964). As to actual species s e l e c t i o n f or revegetation i n western Canada and northwestern U.S., papers by Brink (1964), Hafenrichten (1963), MacLaughlan (1966), U.S. Environmental Protection Agency (1975), and Berglund (1976) a l l give excellent e c o l o g i c a l descriptions of species adapted to t h i s area. The paper by Berglund (1976) i s recommended, for 15 It deals s p e c i f i c a l l y with hydroseeding i n the forest environment. With some judiciou s consideration, h i s seeding recommendations for Oregon can be modified for use i n B r i t i s h Columbia. Also, the B.C. Department of Highways can be h e l p f u l i n more l o c a l i z e d grass-legume s e l e c t i o n . S o i l Erosion Surface s o i l erosion i s not as spectacular or obvious as mass wasting. However, over the l i f e of a road system and e s p e c i a l l y during the f i r s t few years a f t e r construction, i t can be a very serious problem a f f e c t i n g p h y s i c a l stream q u a l i t y and road s t a b i l i t y . Unfortunately, t h i s problem i s seldom given proper consideration by the B.C. f o r e s t r y community. The Federal F i s h e r i e s Act, section 33.1, provides regula- tions and f i n e s f or excessive stream sedimentation. The B.C.F.S. sup- plemental road design standards, SS-648, also provide regulation f o r erosion c o n t r o l . Both of these are seldom enforced ( p a r t i a l l y due to low work fo r c e s ) , and the erosion damage continues. Fredricksen (1965) found a 250-fold increase i n stream sedimenta- t i o n during the f i r s t r a i n f a l l s following construction of 2.5 km (1.65 miles) of logging road on a 100-hectare (250-acre) watershed i n the Willamette National Forest i n Oregon. Sediment l e v e l s continued to be higher than a companion undisturbed watershed for the next two years. Dyrness (1970), by measuring the p r o f i l e of a 7.6-m-high, 1:1 backslope, found a 1.14-cm (0.45-inch) s o i l l o s s over the f i r s t winter a f t e r road construction from water erosion. This i s roughly equivalent to 102 t/ha (45 tons/acre) of s o i l l o s t . S o i l l o s s by dry r a v e l l i n g over the summer was almost as great as the rain-caused l o s s , amounting to 1.2 cm (0.4 inches) of s o i l l o s s . These two losses t o t a l a 2.16-cm (0.85-in.) 16 s o i l l o s s over the f i r s t year, or approximately 193 t. of s o i l l o s t per hectare (85 tons per acre). A f t e r f i v e years, the annual los s was 0.51 cm (0.2 i n . ) , s t i l l accounting for a s o i l loss of 45 t/ha (20 tons/acre). Although a large portion of t h i s eroded s o i l temporarily comes to rest i n the road drainage system, e.g., ditches and c u l v e r t s , road drainage water and continual grader a c t i v i t y (sidecasting) eventually transports most of t h i s s o i l to neighboring streams. While i n the road drainage system, t h i s s o i l reduces e f f e c t i v e water-carrying c a p a c i t i e s of the drainage structures, jeopardizing road s t a b i l i t y . SCOPE OF THE STUDY The purpose of t h i s study, as stated i n the objectives, was to answer some questions and problems pertaining to the use of hydroseeding i n the forest environment. Five experiments, two i n the laboratory and three i n the f i e l d , were undertaken to f u l f i l l these objectives. The laboratory experiments deal with the problems associated with f e r t i l i z e r s a l t s . The f i e l d experiments pursue the effectiveness of operational hydroseeding. The project was funded by B r i t i s h Columbia Forest Products Ltd. B.C.F.P. has large timber holdings on southern Vancouver Island, which includes some watersheds with high f i s h e r y value. Due to the increase i n sedimentation r e s u l t i n g from road construction and possible damage to t h i s f i s h e r y resource, f i e l d hydroseeding t r i a l s were concentrated i n t h i s area. Two tes t locations were chosen on southern Vancouver Island, representing two of the three major p r e c i p i t a t i o n zones of the is l a n d (Figure 8). The Koksilah s i t e i s located near Shawnigan Lake i n an area of 180 cm (70 inch) of r a i n f a l l . The chosen road cut-slopes are on a very erodible fine-textured t i l l m aterial, with a t h i n clay layer 1.5 to 1.8 m (5 to 6 feet) from the surface. Recent heavy s i l t a t i o n of the Koksilah River has been traced to the cut and sidecast slopes of t h i s 3-year-old road (Figures 9 and 10). The Caycuse s i t e , near the west end of Cowichan Lake, receives i n 17 18 Figure 8. Location of study areas on southern Vancouver Island. 19 Figure 10. Koksilah cut-slope during treatment, Sept. 1976. 20 excess of 250 cm (100 inches) of p r e c i p i t a t i o n annually. The predomin- ant s o i l material i n t h i s area i s a very clayey g l a c i a l t i l l which, through heavy surface erosion from cut-slopes (Figure 11), i s r e s u l t i n g i n road s t a b i l i t y problems and high road maintenance costs. A compar- ison of the two s i t e s i s presented i n Table 3. TABLE 3 SITE COMPARISON Location: Elevation: R a i n f a l l : S o i l M a t e r i a l Aspect: Slope: Av. Slope Length: Treatment Blocks: Koksilah 305 m 180 cm ^Fine textured t i l l (with clay blanket) S to SE 70 - 90% 15 - 20 m 2 cut-slopes 2 f i l l / s i d e c a s t slopes Caycuse 305 m 250+ cm Clayey g l a c i a l t i l l (40-50% clay) SE 80 - 90% 12 m 3 cut-slopes 21 METHODS AND MATERIALS Laboratory Experiments The two laboratory experiments deal with the problem of high concentrations of f e r t i l i z e r s a l t s i n the hydroseeder and t h e i r e f f e c t on seed germination (Brooks and Blazer 1965) and legume v i t a l i t y (Kay 1976). The t e s t i n g c r i t e r i a f o r each experiment are based on opera- t i o n a l hydroseeding maxima. A contact time of 60 minutes and f e r t i l - 3 i z e r concentration of 90 kg of 10-30-10 f e r t i l i z e r per m (750 lbs/1000 gallons) of water were deemed as a maximum seed contact time and s l u r r y concentration that should occur i n the f i e l d operation of hydroseeding. This time and concentration were used i n i t i a l l y f o r both experiments. Experiment 1: The e f f e c t of f e r t i l i z e r s a l t s on Rhizobium inoculum v i a b i l i t y . The objective of t h i s experiment was to evaluate the e f f e c t of temporary exposure to a s a l t s o l u t i o n on Rhizobium v i a b i l - i t y and subsequent legume nodulation. The test was run using commerc- i a l l y a v a i l a b l e R. t r i f o l i i , white clover inoculum. Two s a l t solutions were used, each equivalent to an osmotic p o t e n t i a l of -2.5 MPa. * The f i r s t s a l t s o l u t i o n was prepared with KC1 according to Wiebe et a l 3 (1975). The other was prepared with 10-30-10 f e r t i l i z e r : 90 kg/m of solvent. In t h i s manner, both the Rhizobium mortality from s a l t t o x i c i t y or plasmolysis, and the influence of nitrogen on nodulation (Dart and Wildon 1970) were tested. A s t e r i l e buffer was the t h i r d s o l u t i o n used, serving as a c o n t r o l . 22 23 The method used for determining the number of v i a b l e Rhizobium c e l l s per gram of inoculum was the p l a n t - i n f e c t i o n technique prepared by Dr. Lucien M. Bordeleau, of the Ag r i c u l t u r e Canada Research Station at Sainte Foy, Quebec, for the Production and Marketing Branch of Canada Agr i c u l t u r e , Plant Products D i v i s i o n . The procedure i s based on J . Brockwell's 1963 work with the p l a n t - i n f e c t i o n method f o r determining Rhizobium numbers. B a s i c a l l y , t h i s method i s a most-probable-number (MPN) technique, with a series of f i v e - f o l d d i l u t i o n s of inoculum. Samples of each d i l u t i o n are then placed i n test tubes containing a growth medium and s t e r i l e legume seeds. Any observed nodulation i s a p o s i t i v e test at that d i l u t i o n l e v e l . By counting the number of p o s i t f ive tests at each d i l u t i o n l e v e l and r e f e r r i n g to a MPN table, as i n Brockwell (1963), the number of v i a b l e Rhizobium c e l l s per gram of tested inoculum i s obtained. In my study, the only deviation from the Bordeleau (1976) pro- cedure was with the i n i t i a l inoculum d i l u t i o n . The i n i t i a l inoculum d i l u t i o n , f o r both of the s a l t treatments, was agitated for 60 minutes i n the respective s a l t s o l u t i o n before subsequent d i l u t i o n s with a s t e r i l e buffer. The control treatment was agitated f o r 10 minutes i n i t i a l l y i n a s t e r i l e buffer. A l l subsequent d i l u t i o n s were with the s t e r i l e buffer and 10 minutes of a g i t a t i o n . Experiment 2a: The e f f e c t of f e r t i l i z e r - s l u r r y contact on seed germination. Although Brooks and Blazer (1965) showed that f e r t i l i z e r - seed contact could reduce seed germination, the objective of t h i s study was to t r y to e s t a b l i s h a r a t i n g system of species' s u s c e p t i b i l i t y to such f e r t i l i z e r contact. After a 60 minute exposure to a f e r t i l i z e r - 3 s l u r r y concentration of 90 kg 10-30-10 f e r t i l i z e r per m water, each of 24 the grass and legume species tested (Table 4) was washed and germinated according to the 1966 International Seed Testing Association guidelines. Each germination test consisted of three 100-seed samples. Species e x h i b i t i n g a negative germination response to the i n i t i a l f e r t i l i z e r 3 concentration would be tested at lower l e v e l s of f e r t i l i z e r , 60 kg/m 3 then 30 kg/m , (500 l b s . per 1000 gallons, then 250 l b s . ) . TABLE 4 SPECIES USED IN FIELD TRIALS AND GERMINATION TEST Grasses Phleum pratense - timothy Agrostis alba - redtop Lolium perenne - perennial ryegrass Lolium multiflorum - annual ryegrass D a c t y l i s glomerata - orchardgrass Festuca rubra - chewings fescue (var. commutata) Festuca arundinacea - t a l l fescue Festuca rubra - creeping red fescue Legumes T r i f o l i u m repens - white clover T r i f o l i u m pratense - red clover T r i f o l i u m hybridum - a l s i k e clover Experiment 2b: The e f f e c t of a r e s i d u a l f e r t i l i z e r coating (from s l u r r y soaking on seed germination. In the f i r s t part of experiment 2, f e r t i l i z e r - s e e d contact was ended a f t e r the 60 minute exposure to the s l u r r y by washing the seed. This v a r i a t i o n was designed to see i f continued f e r t i l i z e r - s e e d contact from a r e s i d u a l f e r t i l i z e r coating produced any a d d i t i o n a l negative e f f e c t s on seed germination. Due to li m i t e d space, only four species would be tested, two that would show an ef f e c t i n the f i r s t part and two that would not. The only change i n procedure was that seeds were not washed between the s l u r r y exposure and germination t e s t s . 25 F i e l d Experiments The three f i e l d experiments were performed on hydroseeding t e s t plots at the two chosen Vancouver Island l o c a t i o n s , Koksilah and Caycuse. The o v e r a l l design of the f i e l d plots was a randomized complete block, with four blocks (slopes) treated at Koksilah and three blocks treated at Caycuse. Each block consisted of four hydroseeding treatments and a c o n t r o l . The pl o t s were 15.24 m (50 feet) i n width. The hydroseeding s p e c i f i c a t i o n s and treatment descriptions are presented i n Table 5. The treatments are a combination of one and two-step applications (seed and f e r t i l i z e r together or applied separately) and the use of non-use of a mulch. The s p e c i a l seed mix was made up of the eight grasses and three TABLE 5 TREATMENTS No Mulch Mulch 1-Step Seed + F e r t i l i z e r + Binder Seed + F e r t i l i z e r + Binder + Mulch 2-Step Seed + Binder, followed by F e r t i l i z e r + Binder Seed + Binder, followed by F e r t i l i z e r + Binder + Mulch Sp e c i f i c a t i o n s Seed Rate: Mulch: F e r t i l i z e r : Binder: 100 kg/ha 670 kg/ha 450 kg/ha Special Mix J a c k l i n Organic Mulch 10-30-10 11 kg/ha (without mulch) Terra Tack I or 33 kg/ha (with mulch) Applicator: 950 l i t e r hydroseeder ( r e c y c l i n g a g itation) T e r r i s o l Hydrograssing Ltd., Vancouver 26 legumes i n Table 2, plus Festuca ovina (hard fescue) and Lotus c o f n i c - ulatus (birdsfoot t r e f o i l ) . The f i e l d experiments deal with species composition of established vegetative cover, per cent plant cover established, and the amount of erosion from the p l o t s . Experiment 3: Species composition of established vegetation. The species composition of the established vegetative cover was e s t i - mated by a frequency t e s t . This method i s b a s i c a l l y a l i s t i n g of a l l vegetation present within a small c i r c u l a r sample frame. In t h i s study, a 0.035 m c i r c u l a r hoop was used and f i v e random samples were taken i n each p l o t . A species was assigned a frequency of 20% for each of the f i v e samples i n which i t occurred. For example, i f T r i f o l i u m pratense was present i n three out of f i v e random samples, i t would be assigned a 60% frequency. The higher the frequency of a p a r t i c u l a r species, the more widespread the species i s , and the more l i k e l y i t i s to contribute s i g n i f i c a n t l y to t o t a l plant cover. Experiment 4: Estimate of percent plant cover. Each treated pl o t was photographed using 35-mm c o l o r - i n f r a r e d p o s i t i v e s l i d e f i l m and a Wratten 12 f i l t e r . ( Color-infrared f i l m was used to accentuate the s o i l - v e g e t a t i o n contrast as i l l u s t r a t e d by Figures 12 and 13). Once developed, s l i d e s were projected onto a 200-dot g r i d , and percent plant cover was determined. Care was taken to assure, approximately, the same sampling i n t e n s i t y per unit area for each s l i d e . The i d e a l photograph of each pl o t would have been v e r t i c a l (to avoid "shadow" e f f e c t s by t a l l e r vegetation). However, t h i s was not possible due to slope length and steepness. Therefore, each treatment block was photographed from the same angle (as s i m i l a r between blocks as possible) i n order to maintain uniform overestimation within each set Figure 12. Plot photographed with normal color f i l m , A p r i l 1977. 28 of p l o t s . By using the block design, the o v e r a l l comparison between treatments within the blocks was expected to be v a l i d . Experiment 5: Measure of s o i l erosion. The basic methodology for the erosion measurement i s the same used by Dyrness (1967), a measure of slope p r o f i l e change over a period of time being a measure of erosion. Mr. Don McCool ( a g r i c u l t u r a l engineer with the U.S. S o i l Conservation Service at Pullman, Washington) has developed a r i l l - m e t e r f or measuring surface r i l l erosion. The r i l l - m e t e r consists of a set of pins lowered from a portable apparatus to define a ground contour. The pins are photographed, and by d i g i t a l analysis and reconstruction of the o r i g i n a l ground contour, an estimate of r i l l erosion can be made. For t h i s study, an estimate of both r i l l and sheet erosion was needed since both contribute to road cut and f i l l slope degradation. Upon recommenda- tions by Mr. McCool, a modification of the o r i g i n a l r i l l - m e t e r was made. By e s t a b l i s h i n g two permanent pipes i n the slope, v e r t i c a l measurements from a standard bar could be made, thus de f i n i n g the ground contour. A comparison of ground contours measured before (Figure 14) and a f t e r treatment (Figure 15) would give a measure of net s o i l erosion. The modified r i l l - m e t e r was constructed from a 5.08 cm x 7.62 cm x 0.64 cm (2" x 3" x y ) channel aluminum bar. The bar was 1.25 meters (50") i n length with 25 permanent s l o t s established to allow v e r t i c a l measurement to the ground surface with a hand micrometer. The bar had adjustment b o l t s and c r o s s - l e v e l s on each end to insure a true v e r t i c a l measurement to the ground surface. Between the c r o s s - l e v e l s and the s l o t s constructed for the r i l l - m e t e r to f i t onto the pipes, any pipe movement (e.g., from f r o s t heaving, grader interference, f a l l i n g rocks) would be discovered. There were three sets of randomly located Figure 14. Rill-meter i n use at Koksilah, September 1976. Figure 15. Rill-meter i n use at Koksilah, A p r i l 1977. 30 pipes per p l o t . Any contour pipe suspect of movement was cause for that contour to be eliminated from the sample. The sum of the d i f f e r - ences between the September 1976 and A p r i l 1977 measurements for the 25 points would represent the contour i n the s t a t i s t i c a l a n a l y sis. RESULTS AND DISCUSSION Experiment 1: The e f f e c t of f e r t i l i z e r s a l t s on Rhizobium inoculum v i a b i l i t y . The minimum acceptable number of v i a b l e Rhizobium c e l l s per gram of commercial legume inoculum, according to Bordeleau 6 (1976), i s 1.0 x 10 c e l l s . For both s a l t treatments and the c o n t r o l , the f i n a l counts yielded at l e a s t 1.0 x 10 v i a b l e c e l l s per gram of inoculum tested (Table 6). This suggests that neither the temporary TABLE 6 RHIZOBIUM VIABILITY PER GRAM OF LEGUME INOCULUM Treatment Thousands of Viable C e l l s per Gram 21 days 31 days S t e r i l e Buffer: A 540 1090 B 540 1090 KC1: A 1410 4100 B 820 2690 10-30-10 F e r t i l i z e r : A 218 1410 B 380 1090 subjection of the inoculum to high s a l t concentration nor the exposure to the nitrogen of the f e r t i l i z e r had any e f f e c t of p r a c t i c a l s i g n i f - icance on Rhizobium v i a b i l i t y and subsequent nodulation. Thus, i t would appear that poor legume v i t a l i t y , caused by hydroseeding e f f e c t s on nodulation (Kay 1976), i s not a function of Rhizobium mortality M induced by s a l t s , i f the i n i t i a l inoculum v i a b i l i t y i s adequate. Instead, i t may r e f l e c t other f a c t o r s , e.g., separation of inoculum from the seed. Although the f i n a l Rhizobium counts were a l l s a t i s f a c t o r y , the differe n c e between the f i r s t and second counts does prove i n t e r e s t i n g . The control treatment showed a 2-fold increase, the s a l t treatment a 3-fold increase, and the f e r t i l i z e r treatment a 4-fold increase i n apparent Rhizobium numbers derived from r e s u l t i n g nodulation. This may suggest a "shock" e f f e c t on the ba c t e r i a from being subject to such a low osmotic p o t e n t i a l , causing delay i n the nodulation process. There may also be a further delay i n legume nodulation from the temporary nitrogen exposure. This i s consistent with the observation of Dart and Wildon (1970), that nitrogen presence delays nodulation of the legume Vigna sinensis within the f i r s t three weeks but has no e f f e c t on subsequent nodulation. Experiment 2a and 2b: The e f f e c t of f e r t i l i z e r - s l u r r y contact and r e s i d u a l f e r t i l i z e r coating on seed germination. In part one of the germination experiment, three species show a s t a t i s t i c a l l y s i g n i f - icant reduction i n germination as a r e s u l t of 1 hour contact with the 3 sol u t i o n containing 90 kg of 10-30-10 f e r t i l i z e r per m of water (Table 7). Festuca rubra var. commutata, Festuca aruridiriacea, and T r i f o l i u m repens exhibited decreases i n germination, with T. repens decreasing most (14%). Further t e s t i n g with a s o l u t i o n containing 60 kg f e r t i l - 3 i z e r per m of water showed no further reduction i n germination of these three species. Therefore, F. rubra var. commutata, F. arundinacea, and T. repens should be considered s l i g h t l y s e n s i t i v e to f e r t i l i z e r contact. 33: TABLE 7 SEED GERMINATION: SEEDS WASHED Percent Germination Species Control Level 1"*" Level 2^ Phleum pratense 82±5 82±6 Agrostis alba 72±8 72±7 - Lolium perenne 93±5 88±7 - Lolium multiflorum 99±1 96±3 - D a c t y l i s glometata 90±4 96±3 - Festuca rubra var. commutata 46±4 * 37±2 42±2 Festuca arundinacea 88±2 * 77±2 85±4 Festuca rubra 93±3 89±5 - T r i f o l i u m pratense 75±6 71±10 - T r i f o l i u m repens 78±3 64±5 79±5 T r i f o l i u m hybridum 78±3 73±11 — Level 1 = 90 kg 10-30-10 f e r t i l i z e r / m of water. 2 3 Level 2 = 60 kg 10-30-10 f e r t i l i z e r / m of water. ^denotes a s i g n i f i c a n t reduction i n germination at alpha = 0.05. In the v a r i a t i o n of t h i s experiment, r e s i d u a l f e r t i l i z e r was not rinsed from the seed a f t e r the 1-hour soaking period. The seeds were germinated with the r e s i d u a l f e r t i l i z e r coating i n order to duplicate f i e l d conditions. This time, two out of the four species tested showed a s i g n i f i c a n t negative germination response (Table 8). Festuca rubra was added to the l i s t of s e n s i t i v e species, and T. repens exhibited an ad d i t i o n a l negative response over the same f e r t i l i z e r l e v e l i n the f i r s t part. The combined e f f e c t of these germination tests i s an approxim- ately 30% reduction i n T. repens germination, i n d i c a t i n g the high s e n s i t i v i t y of t h i s species to f e r t i l i z e r s l u r r y contact. It i s noteworthy that a l l three fescues tested were s e n s i t i v e to f e r t i l i z e r contact. This agrees with Brooks and Blazer (1963), who 3'4> TABLE 8 SEED GERMINATION: SEEDS UNWASHED Percent Germination Species Control Level 1"*" Lolium multiflorum 99±1 97±2 Festuca arundinacea 88±2 73±7 Festuca rubra 93±3 * 81±1 T r i f o l i u m repens 78±3 ** 48±8 1 3 Level 1 = 90 kg f e r t i l i z e r / m of water. ^denotes a s i g n i f i c a n t reduction i n germination from the control at alpha = 0.05. **denotes an a d d i t i o n a l negative res- ponse over the seeds washed test (Table 7). also found a fescue (Festuca e l a t i o r ) s e n s i t i v e to f e r t i l i z e r s l u r r y contact. In t h e i r study, a 40% loss of germination was observed, whereas my experiment revealed only a 10% l o s s . The differ e n c e i s probably due to the d i f f e r e n t species used, type of f e r t i l i z e r , and f e r t i l i z e r concentration. In my experiments with operational test c r i t e r i a , although the 10% loss i n fescue germination from f e r t i l i z e r s l u r r y contact i s s t a t - i s t i c a l l y s i g n i f i c a n t , i t should not be considered o p e r a t i o n a l l y s i g - n i f i c a n t . Such a small los s would not j u s t i f y s p e c i a l treatment (e.g., separate and more expensive application) of fescues or exclusion of these species from future seed mixes. The Festuca genus includes some of the most important and widely used grasses f o r erosion c o n t r o l . Simply by allowing f o r such a loss i n germination when making up the seeding s p e c i f i c a t i o n s should compensate f or t h i s problem with 35- i n s i g n i f i c a n t extra cost. The negative e f f e c t on the legume germination i s not so r e a d i l y dealt with. The 30% l o s s of white clover (T. repens) poses a more serious problem, e s p e c i a l l y since t h i s widely used legume i s important to the nitrogen budget of developing vegetative cover. This and the other T r i f o l i u m spp. seeds are not afforded the protection of the palea or lemma as are most grasses. Their seed coat i s completely exposed, probably the cause for the greater negative e f f e c t of f e r t i l i z e r on T. repens germination. Separate a p p l i c a t i o n of leguminous species i s a p o s s i b i l i t y . A separate broadcast a p p l i c a t i o n of legume seeds, i n connection with_the regular hydroseeding, would rather inexpensively solve t h i s problem and aid i n assuring good legume establishment. Another p o s s i b i l i t y i s the use of seed p e l l e t i z i n g . Some promising new seed coating agents have been developed that increase seed germination (Vartha and C l i f f o r d 1969). These coatings also increase legume nodulation and v i t a l i t y by prolonging seed and inoculum contact, which would be of benefit as indicated by experiment 1. Experiment 3: Species composition of established vegetation. Only r a p i d - e s t a b l i s h i n g , f a l l - w i n t e r species were present i n early A p r i l 1977 when the frequency test was done. These are very important species i n the seed mix since they provide i n i t i a l erosion control and slope s t a b i l i z a t i o n over the f i r s t winter. With the slope i n t a c t , the cover can continue to develop toward a more permanent and stable plant community over the following spring. The r e s u l t s from the cover composition frequency sampling are summarized i n Tables 9 and 10. Table 9 represents the cover composition TABLE 9 SPECIES FREQUENCY BY BLOCK (Av. % frequency of a l l treatments) Blocks Koksilah Cay cuse Sidecast Cut-slop e Cut- slope Species Culvert Bridge Culvert C -5000 II III Grasses Lolium multiflorum 100 100 100 100 100 100 Lolium perenne 100 100 100 100 100 100 Festuca ovina 100 100 100 100 100 100 Festuca rubra 100 100 100 100 100 100 Dac t y l i s glomerata 100 65 60 85 95 65 Legumes T r i f o l i u m repens 60 60 20 30 30 30 Lotus corniculatus 35 25 0 5 5 15 T r i f o l i u m pratense 15 5 5 5 0 20 -Trifolium hybridum 0 0 0 0 55 30 TABLE 10 SPECIES FREQUENCY BY TREATMENT (Av. % frequency of a l l blocks) Treatment No Mulch Mulch Species ' one-step two-step one-step two-step Grasses Lolium multiflorum 100 Lolium perenne 100 Festuca ovina 100 Festuca rubra 100 Dac t y l i s glomerata 90 Legumes T r i f o l i u m repens 45 T r i f o l i u m pratense 15 Lotus corniculatus 25 T r i f o l i u m hybridum 5 100 100 100 100 100 100 100 100 100 100 100 100 70 70 80 45 20 45 10 5 10 10 5 10 10 10 20 3? of each block (slope), the average of the four seeding treatments per block. The cover frequency according to hydroseeding treatment i s sum- marized i n Table 10, which i s the average species frequency over a l l blocks. Only s i x of the o r i g i n a l seven treatment slopes are accounted f o r . Caycuse cut-eslope I was l o s t when the overhanging roots collapsed, destroying the vegetative cover present. As can be seen i n Tables 9 and 10, the grass component of the vegetative cover was very consistent between both blocks (slope type and location) and hydroseeding treatment. Lolium perenne and multiflorum, and Festuca rubra and ovina were the dominant grasses on a l l p l o t s . D a c t y l i s glomerata was present on a l l pl o t s but comprised a l e s s e r portion of the grass-legume stand. These grasses, t y p i c a l l y , are rap i d - e s t a b l i s h i n g and adaptable to a wide range of climates. On the cut-slopes at Koksilah, the importance of these early e s t a b l i s h i n g species was p a r t i c u l a r l y evident. These slopes were sub- j e c t to severe f r o s t heaving which increased t h e i r e r o d i b i l i t y (Figure 16). Although the upper portion of the vegetative mat was disrupted, the lower slope remained f u l l y vegetated. This i n t a c t vegetation acted as a catchment f o r slough material from the upper portion of the slopes, which prevented t h i s material from reaching the road drainage d i t c h . These grasses are now providing a source f o r r e - e s t a b l i s h i n g f u l l vegetative cover to the slope. It must be remembered that these grasses ( e s p e c i a l l y Lolium spp.) are f a i r l y s h o r t - l i v e d . A proper seed mix must contain slower-develop- ing, l o n g e r - l i v e d species, i n addition to the ra p i d - e s t a b l i s h i n g species. Continual monitoring of species succession i s important f o r a complete evaluation of the experimental seed mix. 38 Figure 16. Frost action on Koksilah cut-slope, Jan. 1977. Legume establishment was generally spotty and o v e r a l l , low f r e - quencies were incurred when measurements were taken i n early A p r i l 1977. This i s to be expected since the legume species used are t y p i c a l l y spring e s t a b l i s h e r s . On recent v i s i t s to the research p l o t s , legumes appear to be contributing much more to the vegetative cover and seem very healthy. There are, however, several trends developing i n the early obser- vations. T r i f o l i u m repens appeared to be the most dominant legume at a l l areas and treatment p l o t s . Lotus corniculatus had a s t a r t on most p l o t s , and should improve, for i t i s a slow but strong e s t a b l i s h e r . T. pratense had a c o n s i s t e n t l y low frequency value of establishment on a l l p l o t s . It would appear that t h i s legume should be removed from future seed mixes and i t s percentage of the seed given to one of the better e s t a b l i s h i n g legumes. T. hybridum was conspicuously absent at Koksilah and a co-dominant with T. repens -at Caycuse. A possible explanation of t h i s i s that the Koksilah area was subject to long periods of repeated freeze-thaw. T. hybridum, being very subject to w i n t e r - k i l l , may have been t o t a l l y destroyed i n t h i s area. More te s t i n g with t h i s species i s necessary, for i t appears that T. hybridum may be an erosion control legume of l i m i t e d c l i m a t i c a d a p t a b i l i t y . In comparing the d i f f e r e n t slopes treated, the cut-slopes at Koksilah had r e l a t i v e l y poorer legume establishment than the other slopes. These slopes, as previously stated, were subject to heavy f r o s t damage and the legumes used i n t h i s seed mix are subject to w i n t e r - k i l l (Hafenrichter 1964). With f a l l seed a p p l i c a t i o n s , a supplemental spring sowing of leguminous species may be necessary i f the following winter was harsh. A small cyclone seeder could inexpen- 40 s i v e l y achieve t h i s . One treatment, the one-step mulch a p p l i c a t i o n (1-M), d e f i n i t e l y had lower legume frequencies than the other treatments. In the labor- atory germination experiments, white clover (T. repens). was shown to be very susceptible to continued f e r t i l i z e r contact. The 1-M treatment could r e s u l t i n the longest s e e d - f e r t i l i z e r contact, f o r the mulch might slow the leaching of f e r t i l i z e r from the micro-environment of the seed, thus extending the contact time. Once again, a separate legume a p p l i c a - t i o n may be advisable i f a single-step mulching a p p l i c a t i o n i s the chosen method of hydroseeding. The prolonged exposure to f e r t i l i z e r could also have a deleterious e f f e c t on the accompanying legume inoculum (Rhizobium spp) . Experiment 4: Estimate of percent plant cover. The estimates of percent plant cover are summarized.in Table 11. From the Duncan's TABLE 11 PERCENT PLANT COVER Treatment No Mulch Mulch Block one-step two-step one-step two-step Ave. Koksilah 44 a* Cut-slope: culvert 50 40 40 45 C-5000 35 50 45 60 48 a Sidecast: culvert 75 80 75 75 76 b bridge 65 85 65 90 68 b Caycuse 68 b Cut-slope: II 70 70 65 65 III 85 40 90 60 69 b Average 63 c 61 c 63 c 66 c ^Averages followed by the same l e t t e r are not s i g n i f i c a n t l y d i f - ferent according to Duncan's M u l t i p l e Range Test at the 0.05 l e v e l of p r o b a b i l i t y . .41 Multiple Range test (alpha = 0.05), there were no s i g n i f i c a n t d i f f e r - ences i n cover establishment associated with differences i n a p p l i c a t i o n method (treatment). A l l hydroseeding treatments averaged 61-66% plant cover. The two cut-slopes at Koksilah (blocks 1 and 2) had reduced cover establishment (averaging 44% and 48%, respectively) from the f r o s t damage, and t h i s i s borne out by the Duncan's test f or blocks. Fortu- nately, the bottom portion of these two slopes remained f u l l y revegetated and the vegetation i s s t a r t i n g to spread over the e n t i r e slope. The remaining four slopes (blocks) averaged 68-76% plant cover, t h i s being within the Berglund (1976) c r i t e r i a f o r vegetative cover for successful erosion c o n t r o l . Figures 17 and 18, 19 and 20, and 21 i l l u s t r a t e the amount of plant cover obtained by hydroseeding. Although there was no s i g n i f i c a n t e f f e c t on plant cover e s t a b l i s h - ment from the use of mulch, early observations of seed germination and seedling establishment tend to substantiate the fears of Kay (1977) that mulch can adversely a f f e c t plant establishment. On the c o o l , shaded cut-slopes at Koksilah, the modification of surface s o i l temperatures by the mulch appears to have kept the surface temperatures of these p l o t s lower than unmulched p l o t s . This lower surface temperature caused a delay i n seed germination on these p l o t s , which may have been a serious problem i f cold weather had begun e a r l i e r and the seedings were not yet • hardy enough to survive. Experiment 5: Measurement of s o i l erosion. A summary of the amount of erosion per treatment i s given i n Table 12. Only three out of the four blocks at Koksilah were measured due to breakage of the two adjustment bolt s on the r i g h t side of the r i l l - m e t e r preventing accurate bar::placement on the permanent pipes. Also, only two contours per p l o t Figure 18. Same cut-slope i n A p r i l 1977. 43 Figure 19. Koksilah sidecast that caused the stream sedimentation seen i n Figure 1 (Sept., 1976). 44 45 TABLE 12 MEASURED EROSION (cm) Blocks Treatment No Mulch Mulch one-step two-step one-step two-step control Koksilah Sidecast: culvert bridge -1.2 1 0.4 -0.1 0.3 0.0 -0.4 -2.3 -1.8 1.8 3.1 Cut-slope: culvert -2.4 -1.9 -2.0 -3.1 2.0 Average -1.1 a* -0.8 a -1.3 a -1.6 a 2.3 b "'"Negative erosion means a net accumulation of s o i l material. ^Averages followed by the same l e t t e r are not s i g n i f i c a n t l y d i f - ferent according to Duncan's M u l t i p l e Range Test at the 0.05 l e v e l of p r o b a b i l i t y . were used i n the analysis of variance. Most of the p l o t s only had two sets of pipes l e f t undisturbed from f a l l i n g rocks, f r o s t heave, animal interference, or grader a c t i v i t y . On pl o t s where three contours were i n t a c t , a l l were measured and one randomly removed from the sample before a n a l y s i s . The reduced data produced meaningful r e s u l t s i n the s t a t i s t i c a l t e s t i n g at alpha equal to 0.05. The amount of s o i l erosion from these slopes averaged 2.3 cm (0.9 inches) of slope p r o f i l e l o s s , which i s s i g n i f i c a n t l y greater than the 0.5 cm (0.2 inch) los s observed by Dyrness (1975). Assuming the following: a. 1 cm/ha s o i l depth amounts to 89 t/ha (1 in/acre = 100 tons) b. 1.5 ha of bare side slope per km of logging road (6 acres per mile) c. 1 m3 of s o i l material has a mass of 1.2 t (1 cu yd = 1 ton), 3 th i s 2.3-cm (0.9-inch) slope los s i s equivalent to 256 m per km (540 cu yd per mile) of s o i l erosion on the Koksilah road system from A p r i l 4$ to September. Since erosion i s usually greater i n the f i r s t years a f t e r road construction (Dyrness 1970; Fredricksen 1965), the t o t a l erosion to 3 date for t h i s 3 year-old road system would be at l e a s t 768 m /km (1620 cu yd/mile). This measure does not include dry r a v e l over the summer, which i n the Dyrness (1970) study matched water erosion. This amount of s o i l movement, much of which may eventually enter the Koksilah River, can have a deleterious e f f e c t on the water q u a l i t y , f i s h e r i e s p o t e n t i a l , and aquatic environment of t h i s watershed. In combination with the e f f e c t on road slope s t a b i l i t y , drainage d i t c h capacity, and road surface i n t e g r i t y , there i s no doubt that surface s o i l erosion i s a serious although not highly v i s i b l e problem. Fortunately, the slopes treated by hydroseeding of a grass-legume seed mixture showed a d e f i n i t e h a l t of t h i s problem. The establishment of a vegetative cover not only c o n t r o l l e d surface erosion, but i n most cases (9 out of 12) acted as a f i l t e r or catchment for s o i l p a r t i c l e s c a r r i e d into the vegetation from outside of the established cover. This was most obvious on the cut-slopes which had only a p a r t i a l vegetative cover on the lower ha l f of the slope. From the data, the 2.0 cm (0.78 inches) of erosion (from the cut-slope control) was halted on the lower part and apparently most of the eroded material from the top part was accounted for by s o i l accumulation i n the vegetated area. The estab- lishment of a vegetative cover seems to be a very e f f e c t i v e and f a s t way of a l l e v i a t i n g the problems associated with surface s o i l erosion. Once again, there was no s i g n i f i c a n t d i f f e r e n c e between the v a r i - ous hydroseeding treatments i n t h e i r effectiveness for c o n t r o l l i n g erosion. The addition of mulch, and the extra s o i l binder of t h i s treatment, to the seeding operation did n o t . s i g n i f i c a n t l y reduce erosion. This i s contrary to the Dyrness work (1967, 1970, 1975), where mulch was important i n vegetation establishment and erosion c o n t r o l . From my study, mulching would be important i n erosion c o n t r o l only where cl i m a t i c and s o i l conditions suggest moisture or temperature problems that would i n t e r f e r e with successful vegetation establishment, and not as a general s p e c i f i c a t i o n with hydroseeding. The vegetative cover i s the key to e f f e c t i v e erosion c o n t r o l , not a temporary s o i l covering. This i s borne out by experiments 3, 4, and 5. A l l treatments resulted i n the same plant cover composition, percent plant cover, and as would follow, a l l treatments were equally e f f e c t i v e i n c o n t r o l l i n g erosion. SUMMARY A. The e f f e c t of f e r t i l i z e r s a l t s on legume inoculum, Rhizobium spp. Temporarily subjecting R. t r i f o l i i to high f e r t i l i z e r s a l t s o l u - tions did not a f f e c t c e l l v i a b i l i t y or subsequent successful plant i n f e c t i o n and nodulation. The presence of nitrogen i n the f e r t i l i z e r s o l u t i o n , at concentrations used i n operational hydroseeding, did not a f f e c t f i n a l nodulation but may have caused a delay i n early nodulation, which would agree with Dart and Wildon (1970). B. The e f f e c t of f e r t i l i z e r s a l t s on seed germination The temporary exposure to a -2.5 MPa f e r t i l i z e r s o l u t i o n f or 60 minutes did cause a los s of seed germinance for the three fescues tested and white clover ( T r i f o l i u m repens). Although the fescues l o s t approximately 10% germination, t h i s i s not o p e r a t i o n a l l y s i g n i f i c a n t and can be compensated for by applying extra seed (over-seeding). The 30% loss of white clover germination i s very serious and appropriate precautions should be taken. By l i m i t i n g seed soaking time i n the s l u r r y , using a seed coating agent, using high analysis f e r t i l i z e r s to reduce f e r t i l i z e r s a l t concentrations i n the s l u r r y , and applying extra seed, a separate seed a p p l i c a t i o n may be avoided ( r e s u l t i n g i n considerable savings). C. Early establishment of grass and legume species Five grasses dominated the vegetative cover a f t e r seven months 4,8 49 and provided important erosion control over the f i r s t winter after seed application. Lolium multiflorum, Lolium perenne, Festuca rubra, Festuca ovina, and Dactylis glomerata were the major components of this early plant cover. Legume establishment was f a i r l y low but has been improving since the spring. Trifolium repens and Lotus corniculatus appeared to be the most important leguminous species of this seed mix. T. hybridum was an excellent species at Caycuse and absent at Koksilah, suggesting that this legume may be limited in i t s climatic adaptability. T. pratense does not appear to be an effective erosion control legume where seed application i s by hydroseeding. Legume establishment was very poor on cut-slopes that were subject to severe frost damage. These species of legumes, not being cold-tolerant and being subject to winter-kill, may require a supplemental spring application after a severe winter. Follow-up of the plant succession on these plots is necessary to evaluate the whole seed mix for the slower-developing species have yet to appear. The grasses and legumes mentioned above should be given serious consideration for erosion control seed mixes to provide a quick plant cover and protect the site while longer-lived species develop. D. One-step slurry application versus multiple-step application There was no significant difference in vegetation establishment, composition, or effective erosion control due to separate seed applica- tion, (multiple-step slurry application). Although experiment 2 (seed germination) would suggest a difference, a shorter f e r t i l i z e r contact time, lower f e r t i l i z e r concentration, and over-seeding seem to have compensated for any negative effects that may have affected cover establishment. The single-step s l u r r y a p p l i c a t i o n i s safe as long as contact time, f e r t i l i z e r concentration and grade, and seed mix s e l e c t i o n are given proper consideration. When leguminous species are proposed to be a su b s t a n t i a l part of the eventual cover, seeds could be coated to help overcome any possible r e s i d u a l f e r t i l i z e r coating e f f e c t on germination. E. The e f f e c t of mulching The use of mulch did not r e s u l t i n more successful plant cover establishment or erosion c o n t r o l . Since mulching can more than double the cost of hydroseeding, care should be taken i n choosing areas to be mulched. Mulch should be used where c l i m a t i c or s o i l conditions sug- gest moisture or temperature problems for e s t a b l i s h i n g vegetation. The use of a chemical s o i l binder can i n many places provide temporary erosion resistance and aid i n uniform cover establishment at less cost. Also, any possible negative e f f e c t s on plant cover establishment from the use of a mulch may be avoided. F. The amount of s o i l erosion from forest roads and possible reductions The use of a vegetative cover s u c c e s s f u l l y halted erosion from forest road cut and sidecast slopes that have eroded 2.3 cm i n seven months. The grass-legume cover not only prevented erosion but also acted as a f i l t e r and catchment for s o i l p a r t i c l e s brought into the vegetated area from upslope by gravity, wind, and water. Erosion at 3 the Koksilah test area was equivalent to 256 m of sediment and s o i l material per kilometer (540 cu yd per mile) of logging road from Sep- tember 1976 to A p r i l 1977, most of which could be eliminated by slope revegetation. This erosion has been taking place for 3 years, at 51 probably higher rates, and the costs to the aquatic environment and road s t a b i l i t y , although not tangible, must be extremely great. G. The cost of hydroseeding The basic cost for hydroseeding a large area, i n excess of 50 acres, i s approximately $720/ha ($300/acre), based on 1976 p r i c e s (Table 2), f o r a one-step s l u r r y a p p l i c a t i o n without mulch. This type of a p p l i c a t i o n proved to be j u s t as e f f e c t i v e i n erosion co n t r o l and plant cover establishment as the more expensive treatments. Mulching can at l e a s t double the basic cost of hydroseeding and should only be used where vegetation establishment i s expected to be d i f f i c u l t . The cost f or hydroseeding a kilometer of logging road can range between $1100 and $2000 ($2000-$3000/mile) depending on the s i z e of the operation and acreage per kilometer. This can greatly reduce the high amount of eroded s o i l being deposited i n adjacent stream systems. This i s an external diseconomy that has tremendous impact on phy s i c a l water q u a l i t y and f i s h e r y p o t e n t i a l s . The e f f e c t on road s t a b i l i t y and road maintenance costs i s more tangible and d i r e c t l y a f f e c t s the licensee responsible f o r the road. Two thousand d o l l a r s i s a small investment when compared to road b u i l d i n g costs upwards of $62,000 per kilometer ($100,000 per mile) and road maintenance costs of $1200-3000 per kilometer ($2500-5000 per mile) annually. This investment can save a large portion of the road maintenance costs, help maintain the road surface and slope s t a b i l i t y thus protecting the i n i t i a l invest- ment of road construction, and greatly benefit the environment. More- over, hydroseeding can often be confined to l i m i t e d areas of high erosion r i s k , reducing the cost per kilometer of hydroseeding. The 52 chance to put back into production part of the acreage l o s t during road construction by enhancing s o i l development should also be considered. Roadside revegetation by hydroseeding can be very e f f e c t i v e i n c o n t r o l l i n g s o i l erosion from cut and sidecast slopes beside forest roads. With proper planning of the seed mix and other s p e c i f i c a t i o n s , an e f f e c t i v e vegetation cover should r e s u l t . The cost of hydroseeding i s small when compared to the tangible and int a n g i b l e costs involved i n forest road construction, road maintenance, and stream degradation. 53 LITERATURE CITED Armbrust, D. V., and J . D. Dickerson. 1971. Temporary wind and erosion c o n t r o l : cost and effectiveness of 34 commercial materials. Journal of S o i l and Water Conservation 26(4): 154-157. Becker, R. E. 1971. Beyond the road. Eighth Canadian Roadside Devel- opment Conference, June 1971. Center f o r Continuing Education, U.B.C. 4 pp. Berglund, E. R. 1976. Seeding to control erosion along f o r e s t roads. O.S.U. Extension Service, C o r v a l l i s , Oregon. 19 pp. Bordeleau, L. M. 1976. Method of t e s t i n g legume inoculants. Production and Marketing Branch of Canada A g r i c u l t u r e , Plant Products D i v i s i o n , Ottawa, Ontario. 16 pp. Brink, V. C. 1964. The s e l e c t i o n of plants f o r roadsides and highways i n the P a c i f i c Northwest. F i r s t Canadian Roadside Development Conference, U.B.C. Extension Department, pp. 57-62. Brink, V. C , and J . W. Maxwell. 1965. S o i l mulching f o r tu r f estab- lishment. Second Western Canadian Roadside Development Confer- ence, U.B.C. Extension Department, pp. 39-41. B.C.F.S. 1977. Minimum road standards: supplement SS-648. B r i t i s h Columbia Forest Service, V i c t o r i a , B.C. Brockwell, J . 1963. Accuracy of a p l a n t - i n f e c t i o n technique for count- ing populations of Rhizobium t r i f o l i i . Appl. M i c r o b i o l . 11: 377-383. Brooks, C. R., and R. E. Blazer. 1963. E f f e c t of f e r t i l i z e r s l u r r i e s used i n hydro-seeding on seed v i a b i l i t y . NAS-NRC Highway Research Record No. 53, Washington, D.C. pp. 30-34. Dart, P. J . , and D. C. Wildon. 1970. Nodulation and nitrogen f i x a t i o n i n Vigna sinensis and V i c i a atropurpurea: the influence of concentration, form, and s i t e of a p p l i c a t i o n of combined n i t r o - gen. Aust. J . Agric. Res. 21: 45-56. Dueck, A. E., N. P. Swanson, and A. R. Dedrick. 1967. Mulches for grass establishment on steep construction slopes. NAS-NRC Highway Research Record No. 206. pp. 53-59. Dyrness, C. T. 1967. Grass-legume mixtures f o r road s t a b i l i z a t i o n . USDA Forest Service Research Note PNW-71. Pac. Northwest For. and Range Exp. Sta., Portland, Oregon. 19 pp. . 1970. S t a b i l i z a t i o n of newly constructed road backslopes by mulch and grass-legume treatments. USDA Forest Service Research Note PNW-123. Pac. Northwest For. and Range Exp. Sta., Portland, Oregon. 5 pp. 54 Dyrness, C. T. 1975. Grass-legume mixtures for erosion control along forest roads i n western Oregon. Journal of S o i l and Water Con- servation 30(4): 169-173. Federal F i s h e r i e s Act. 1970. Canada Law and Statutes, R.S., c. 119, S. 1. Queen's P r i n t e r , Ottawa, pp. 3135-1364. Fredricksen, R. L. 1965. Sediment a f t e r logging road, construction i n a small western Oregon watershed. Federal Interagency Sediment Conference, 1963. USDA Miscellaneous P u b l i c a t i o n 970, paper #8. Washington, D.C. 4 pp. Hafenrichter, A. L., et a l . 1966. Grasses and legumes for s o i l con- servation i n the P a c i f i c Northwest and Great Basin States. USDA A g r i c u l t u r a l Handbook #339. Washington, D.C. 69 pp. International Seed Testing Assoc. 1966. International rules for seed t e s t i n g . Proceedings of the International Seed Testing Assoc. 31(1): 1-152. Wageningen, Netherlands. Kay, B. L. 1976. Hydroseeding, straw, and chemicals for erosion con-. t r o l . Agronomy Progress Report #77. Univ. of Cal., Davis. 14 pp. . 1977. Mulches f o r erosion control and plant establishment. Proceedings of Eighth International Erosion Control Assoc. Conf. Seattle, Washington, pp. 56-66. Lowther, W. L., and I. R. McDonald. 1973. Inoculation and p e l l e t i n g of clover f o r oversowing. New Zealand J . of Exp. Agric. 1: 175-179. MacLauchlan, R. S. 1966. Grasses and legumes for s t a b i l i z i n g s i l t producing areas i n the northwest (USA). Symposium on p r a c t i c a l aspects of Forest Watershed Management. OSU, C o r v a l l i s , Oregon, pp. 75-84. Radar, L. F., L. M. White, and C. W. Whittaker. 1943. The s a l t i n d e x — a.measure of the e f f e c t s of f e r t i l i z e r s on the concentration of the s o i l s o l u t i o n . S o i l Science 55: 201-218. Richardson, D. A., D. J . Jordan, and E. H. Garrard. 1957. The influence of combined nitrogen on nodulation and nitrogen f i x a - t i o n by Rhizobium m e l e l o t i . Canadian Journal of Plant Science 37: 205-214. Tanner, T. W., and I. C. Anderson. 1963. An external e f f e c t of i n o r - ganic nitrogen i n root nodulation. Nature, London 198: 303-304. Tisda l e , S. L., and W. L. Nelson. 1966. S o i l f e r t i l i t y and f e r t i l - i z e r s . The Macmillan Co., New York. 694 pp. 55 U.S. Environmental Protection Agency. 1975. Methods of quickly vegetating s o i l s of low p r o d u c t i v i t y , construction a c t i v i t i e s . E.P.A. P u b l i c a t i o n No. EPA-440/9-75-006. Washington, D. C. 467 pp. Vartha, E. W., and P. T. P. C l i f f o r d . 1969. Surface sowing of coated grass seed i n Tussock grassland. Tussock Grassland and Mountain Lands I n s t i t u t e Review, No. 16 (March): 45-47. Wiebe, H. H., et a l . 1971. Measurement of plant and s o i l water status. Utah A g r i c u l t u r a l Sta. B u l l e t i n 484. 71 pp. APPENDIX I Percent Plant Cover Analysis of Variance Treatment Blocks 1. Koksilah : cut-slope @ culvert 2. " @ C-5000 3. Koksilah : sidecast @ culvert 4. " @ bridge 5. Caycuse : cut-slope II 6. " " I I I Treatments 1. one-step 2. two-step 3. one-step with mulch 4. two-step with mulch Analysis of Variance Table at alpha = 0.05 term d.f. sum sq. mean sq. prob. block treat error t o t a l 5 3 15 23 4.06E-01 7.50E-03 2.50E-01 6.63E-01 8.12E-02 2.50E-03 1.67E-02 4.87 0.15 .0077 * .93 ns *denotes s i g n i f i c a n t test at 5 percent l e v e l . 14.06E-01 i s equivalent to 4.06 x 1 0 _ 1 . Duncan's Mult i p l e Range Test at 5 percent l e v e l Treatment Blocks : (1,2) (5,6,3,4) Treatments : (4,3,1,2) (Subsets of elements, no p a i r of which d i f f e r by more than the shortest s i g n i f i c a n t range f or a subset of that size.) 57 APPENDIX II Measure of S o i l Erosion Analysis of Variance Each of the contours measured i s represented by the sum of the d i f f e r - ences between the Sept. and A p r i l measurements for the 25 points. Treatment Blocks 1. Koksilah : cut-slope @ culvert 3. " : sidecast @ culvert 4. " : @ bridge Treatments 1. one-step 2. two-step 3. one-step with mulch 4. two-step with mulch 5. co n t r o l (no treatment) Analysis of Variance Table at alpha = 0.05 term d.f. sum sq. mean sq. F prob. block 2 9352.9 4676.4 2.15 .15 ns treat 4 38807. 9701.7 4.48 .014 * b x t 8 9583.4 1197.9 0.55 .80 ns error 15 32501 2166.7 t o t a l 29 90244 *denotes s i g n i f i c a n t test at 5% l e v e l Duncan's M u l t i p l e Range Test at 5 percent l e v e l Treatment Blocks : (3,4,1) Treatments : (4,3,1,2) (5) (Subsets of elements, no pair of which d i f f e r by more than the shortest s i g n i f i c a n t range for a subset of that size.)

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