Gypsum's Influence on Corn Yield and P Loss from an Eroded Southern Piedmont Soil.

Gypsum (CaSO₄) has been shown to reduce dissolved P in surface water runoff from pastures fertilized with poultry litter (PL). However, limited research has evaluated gypsum’s influence on P loss under row crops. Moreover, can gypsum effectively reduce P loss when applied only to grass buffer strips at the edge of an agricultural field? Thus, a study was conducted to evaluate the influence of using FGD gypsum as a soil amendment for reducing P loss from corn plots fertilized with PL with and without buffer strips. Phosphorus loss was evaluated from plots where gypsum was applied to corn plots (no buffer) vs. grass buffer strips only. Rainfall simulations were used to create runoff immediately and 6 wk after PL applications.  The greatest P loss occurred in rainfall simulations occurring immediately after PL application. Dissolved P loss was drastically reduced following FGD gypsum applications in runoff events occurring immediately and 6 wk after PL application regardless of whether FGD gypsum was applied to the soil surface under corn or the grass buffer strip. Results from this study show that gypsum may be used as a management practice to reduce P loss from row crop systems following PL application.