Evaluation of Erosion and Sediment Control Cover Types for Long-term Vegetation Establishment on Disturbed Slopes

Abstract

Study of erosion control techniques is necessary for the reduction of sediment loss from construction sites and other disturbed slopes. One of the most effective methods of reducing erosion is to establish a vegetative cover as soon as possible. This study evaluates six cover treatments and one bare soil treatment. The effectiveness of each cover type to reduce runoff and sediment yield was evaluated over an eight-month period on 10x25 outdoor plots in Auburn, Alabama. Plots were constructed at 4:1 slope and instrumented with fabricated samplers capturing 1/20th of plot runoff volume and sediment yield during rain events. Along with standard covers such as wheat straw and erosion control blankets, four hydromulch treatments were tested, two of which had lime, fertilizer, and seed applied as a pre-mixed slurry. All other treatments had agronomic rates of lime and fertilizer incorporated into the soil before handseeding and cover placement. The establishment of a 75% bermudagrass cover took approximately 90 days from planting. Visual and photographic observation indicated three general stages of cover establishment, including: 1) 0% to 50% of vegetation cover, which occurred between May 24 and July 9, having the highest sediment yields; 2) 50% to 75% of vegetation cover from approximately July 16 to July 30, with decreasing sediment yields; and 3) 75% to 100% cover from approximately August 20 to December 26, with significantly decreased sediment yields. Preliminary results from the first year indicate that agronomic incorporation of fertilizer and lime before hydroseeding or other mechanical cover is an effective means of establishing vegetation on steep slopes, with over a 30-fold reduction in sediment yield over bare soil control plots. Preliminary results provide information for replicated follow-up treatments on 21 new plots, to include polyacrylamide addition with selected mechanical and biological covers.