Impact of polyacrylamide delivery method with lime or gypsum for soil and nutrient stabilization

Abstract

Applying lime or gypsum as soil conditioners in concert with polyacrylamide (PAM) can reduce soil erosion more than applying the conditioner or the PAM alone, but little is known about the relative impact of different combined application methods. Laboratory rainfall simulations were conducted for 1 hour with runoff collected in 20-minute intervals to compare runoff sediment, sediment-bound P and NH4-N, and dissolved Ca and S loads. Treatments were bare soil, lime, gypsum, PAM-coated lime or gypsum prills, and lime or gypsum prills applied with separate PAM-coated paper mulch granules. All treatments, except gypsum, reduced sediment and sediment-bound P loads compared to bare soil (p 0.05). Runoff dissolved Ca loads (for lime and gypsum) and S loads (for gypsum) were significantly reduced by the PAM-coated conditioner treatments compared to the conditioner applied with separate PAM granules. Dissolution tests indicated that the PAM coating reduces the dissolution rate of the lime and gypsum, suggesting a possible mechanism accounting for differences between the two PAM treatments. This work suggests that the use of PAM in conjunction with lime or gypsum can be an effective erosion control tool, reducing sediment and nutrient losses and that coating lime or gypsum with PAM may have added benefit.