Evaluation of Native Grass Sod for Stabilization of Steep Slopes Presented by:
Evaluation of Native Grass Sod for Stabilization of Steep Slopes Presented by: Kenley Stone M.S. Thesis Defense Overview Factors and concerns of erosion Common methods used to control erosion Literature Review Native Sod Hypotheses & Objectives Methods Data Collection Data Analysis Results Factors that Accelerate Erosion in Landscapes Removal of vegetation Disturbed riparian ecosystems Steep slopes Arid conditions Phyto-toxic soil Problems Associated with Erosion Landslides/Mudslides Sedimentation of rivers and streams Degraded water quality Common Methods Used to Control Erosion on Steep Slopes Broadcast seeding Drill seeding Hydroseeding/Hydromulch Straw-coconut fiber blanket Rip-rap Broadcast Seeding and Drill-Seeding Hydroseeding & Rip-Rap Rip-rap Straw-Coconut Fiber Blanket Literature Review Sodding is one of the most effective means of controlling erosion and preventing sedimentation damage (NCDWQ 1997). It has been shown that sod can remove up to 99% of the total suspended solids in runoff (USEPA 2002). Using simulated rainfall, sod reduced runoff rates 54-59% more compared to the other treatments that included wood excelsior, jute fabric, coconut fiber blanket, coconut strand mat, and straw (Krenitsky et. al. 1998). In Montana, Jensen and Sindelar (1979) concluded that if a large scale sodding machine could be developed, dryland sodding will become a highly desirable soil stabilization treatment. Native Sod Western wheatgrass (Agropyron smithii) Idaho fescue (Festuca idahoensis) Thickspike wheatgrass (Agropyron dasystachym) Canada bluegrass (Poa compressa) Potential Merits of Native Sod Immediately enhances aesthetic values of an area Provides immediate stabilization of steep slopes Can reduce runoff and sediment loss Can reduce noxious weed invasion Hypothesis & Objectives H1: Native sod will produce significantly greater production and cover compared to other treatments. Objective1: Measure plant growth characteristics on slopes treated with native sod compared to other plant establishment methods. Hypotheses and Objectives-Cont’d H2: Native sod will be more effective at controlling erosion than the other treatments Objective2: Determine runoff, sediment yield, and infiltration of slopes treated with native sod compared to other plant establishment methods Hypotheses and Objectives-Cont’d H3: RUSLE2 will predict sediment loss to be less on slopes treated with native sod compared to the other treatments Objective3: Model sediment yield on slopes treated with native sod compared to other plant establishment methods using RUSLE version 2.0. Hypotheses and Objectives-Cont’d H4: Costs of native sod will initially exceed those of the other treatments, but will not need maintenance in the future Objective4: Evaluate the cost of using native sod for steep slope reclamation compared to other plant establishment methods Methods Study Sites Highway Fill Mine Waste Ski Slope Highway Fill Site Description Located 20 km west of Bozeman South facing road fill 40% slope, loam Plant establishment and erosion control on similar sites has been difficult Treatments on the Highway Fill Broadcast Seed/Hydromulch Native Sod 3 replications Plot dimensions: 3.2 x 9.1 meters Broadcast Seed/ Straw Blanket Native Sod Mix (All three sites) Western wheatgrass (Agropyron smithii) Idaho fescue (Festuca idahoensis) Thickspike wheatgrass (Agropyron dasystachyum) Canada bluegrass (Poa compressa) Broadcast Seed Mix (Highway Fill & Mine Waste) Variety & Species Slender-Pryor (Agropyron tracycaulum) Thickspike-Critana (Agropyron dasystachyum) Western-C) Rosana (Agropyron smithii) Bluebunch-C) Secar (Agropyron spicatum) Green Needlegrass-Lodorm (Stipa viridula) Bluegrass, Big-C) Sherman (Poa ampla) Fescue, Sheep-Covar (Festuca Ovina) Coneflower, Yellow Prairie-V.N.S. (Rudbeckia fulgida) Bee Plant, Rocky Mountain-V.N.S (Cleome serrulata) Highway Fill 2003 2004 Ski Slope Site Description Located at the Yellowstone Club, Big Sky, MT A north facing skislope with a 35% gradient Clay loam Previous attempts at grass establishment and erosion control failed Treatments on the Ski Slope Native Sod Broadcast Seed with straw-coconut fiber blanket Broadcast Seed Three replications Plot dimensions: 3.2 x 9.1 meters Broadcast Seed Mix (Ski Slope) Pryor-Slender wheatgrass (Agropyron trachycaulum) Mountain brome (Bromus carinatus) White yarrow (Achillea millefolium) Orchard grass (Dactylis glomerata) Hard fescue (Festuca trachyphylla) Canada bluegrass (Poa compressa) Ski Slope 2003 2004 Mine Waste Site Description Located approximately 30 km west of Helena Abandoned mine spoil on a 70% slope pH 3.4, sandy loam Prior attempts at grass establishment and erosion control failed miserably Treatments on Mine Waste Site Broadcast seed with straw-coconut fiber blanket implemented by the USFS 3 years ago Broadcast seed with straw-coconut fiber blanket installed in 2003 Native sod Redtop sod (Agrostis stolonifera) Three replications Plot dimensions: 3.2 x 10 meters Mine Waste Site 2003 2004 Data Collection Plant Growth Characteristics Rainfall Simulation/Sediment and Runoff Measurements Model Sediment Loss Using RUSLE Cost Analysis Plant Growth Characteristics Above Ground Biomass Production Percent Basal Cover Percent Canopy Cover Percent Ground Cover Runoff & Sediment Yield at the Highway Fill Site A Meeuwig rainfall simulator was used to create a peak 10 year, 24 hour storm event on each plot Runoff and sediment were channeled to a collection trough and measured Key Inputs of RUSLE Rainfall/Runoff Erosivity Index Soil Erodibility Slope Length and Gradient Cover Management Eroded Hillslope Data Analysis Two way Analysis of Variance using Sigma Stat – Determined whether there is a significant difference between means of treatments and replications at a p-value of 0.05 – Student-Newman-Keuls Method Parameters: Basal, Canopy & Ground Cover, Production, Sediment Yield, Runoff, Infiltration Highway Fill Results 2004 (Perennial Grass) Treatment Native Sod Broadcast Seed/ Straw Blanket Broadcast Seed/ Hydromulch Mean Production (kg/ha) 748 a 286 b 102 b Mean Canopy Cover (%) 31.4 a 5.8 b 2.5 b Ski Slope Results 2004 (Perennial Grass) Treatments Native Sod Broadcast Seed/ Straw Blanket Broadcast Seed Mean Production (kg/ha) 1488 a 509 a 662 a Mean Canopy Cover (%) 68.2 a 21.8 b 19.8 b Mine Waste Results 2004 (Perennial Grass) Treatments Native Sod Redtop Sod Straw Blanket Installed 2003 2001 Mean Production (kg/ha) 631 a 417 ab 0b 138 ab Mean Canopy Cover (%) 28.8 a 18.8 a 0b 2.4 b Sediment & Runoff Results on the Highway Fill b 400 300 Sedim ent Loss 200 (kg/ha) a 100 a 0 Native Sod Broadcast Seed/Straw Blanket Broadcast Seed/Hydromulch b 16 14 % Runoff (runoff/precipitation applied) * 100 12 10 8 6 a 4 a 2 0 Native Sod Broadcast Seed/Straw Blanket Broadcast Seed/Hydromulch RUSLE2 Results Native Sod RUSLE2 Results-Cont’d Broadcast Seed/Straw Blanket RUSLE2 Results-Cont’d Broadcast Seed/Hydromulch Cost Analysis Results Treatment Native Sod Total Costs $34,216 Broadcast Seed/Straw Blanket Broadcast Seed/ Hydromulch $17,178 $4,051 *Estimated over a 1 hectare sloped area with a 100 km mobilization distance Potential Applications of Native Sod Sensitive Areas – Steep slopes – Riparian areas – Channels and drainage ditches – Ski slopes – Highway cuts Acknowledgements I thank Bitterroot Turf Farms, Corvallis, MT. for funding a notable portion of this research, propagating the native grass, and providing installation support during test plot development. Special thanks is due to the Montana Department of Transportation, Helena, MT. , most notably Mr. Phil Johnson, for providing funds for this research and technical support during test plot implementation and report preparation. I thank the U. S. Forest Service, Helena, MT. , specifically Duane Harp and Lois Olsen, for providing support during test plot development. I also thank Mr. Bill Hartsog who facilitated access to the Yellowstone Club, Big Sky, MT. and provided support during test plot implementation. I gratefully acknowledge the efforts of Melissa Mitchem, MSU graduate student, for the support provided during field data collection.
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