Research has shown that hydromulch containing specific blends of cotton mixed with other agricultural byproducts is effective in providing protection from rainfall-induced erosion of soil surfaces prior to establishment of vegetation and in stimulating seed germination. To evaluate the effect of ingredient proportions on hydromulch blends incorporating low-value biomass byproducts, a cooperative research program was conducted between the U.S. Department of Agriculture and Colorado State University. Following construction of a rainfall test facility, 16 hydromulch blends (recipes) containing various quantities of identical components were tested under controlled rainfall intensities. Variations in biomass particle size, percent primary ingredient, percent polyacrylamide and percentage of other identical ingredients were systematically varied and tested as a hydromulch. Test plots consisted of sandy-loam and clay-loam soils. The soil and organic content of runoff was collected and recipes evaluated for their effectiveness in providing protection against rainfall-induced soil erosion. Standard errors and mean comparisons of total loss (soil and organic matter) and proportional soil loss were used to determine the best hydromulch recipe across both soil types. Two hydromulch recipes displayed promising results with lower total loss and more consistent results than the other recipes evaluated.