About the research

The rainfall simulator at the Auburn University Erosion and Sediment Control Test Facility (AU-ESCTF) was used to produce 2, 4, and 6 in. per hr rainfall intensities and has test plot dimensions of 8 ft. wide by 40 ft. long on a 3H:1V slope. Each rainfall experiment was an hour long with three sequential 20-minute rainfall intervals of increasing rainfall intensities of 2, 4, and 6 in. per hr, following ASTM D6459-19. Calibration testing was performed on each rainfall intensity to verify the rainfall drop size distribution, intensity, and uniformity. The test plots of bare soil (control test), loose, tacked, and crimped straw along with four hydraulically applied mulches and one dry applied hydraulic mulch, four erosion control blankets, two soil conditioners, and bare soil control tests were evaluated. Following the completion of testing, the Revised Universal Soil Loss Equation (RUSLE) was used to calculate the product C-factor from the incremental rainfall depth and soil loss results. The rainfall simulation tests performed on the sandy loam soil resulted in an average soil loss of 738 lb for bare soil, 143 lb for loose straw, 97 lb for loose straw with Tacking Agent 3, and 169 lb for crimped straw. Longevity testing was performed on the straw applications following the initial product test resulting in a total soil loss 611 lb for bare soil, 287 lb for loose straw, 131 lb for loose straw with Tacking Agent 3, and 82 lb for crimped straw. The initial and longevity test results were combined to determine which practice reduced the overall soil loss. The loose straw with Tacking Agent 3 resulted in the highest reduction in soil loss of 83% (i.e., 17% soil loss of the control test–bare soil), which was closely followed by the crimped straw with a reduction in soil loss of 81%. Hydraulic mulches, erosion control blankets, and soil conditioners (i.e., polyacrylamide and agricultural gypsum) were evaluated on a loam soil. The three of the hydraulic mulches resulted in similar C-factors of 0.55 for Eco-Fiber, 0.46 for Soil Cover, and 0.53 for Terra-Wood. The premium product, ProMatrix was able to control erosion better, resulting in a C-factor of 0.33. The Edge Pellets dry applied hydraulic mulch also resulted in a C-factor of 0.33. Erosion control blankets tests resulted in C-factors of 0.05 for Curlex I, 0.14 for S150, and 0.12 for ECX-2. The jute blanket tested as part of the soil conditioner study resulted in a C-factor of 0.41. The combination of PAM and jute as well as the combination of gypsum and jute resulted in C-factors of 0.56 and 0.1 respectively.