Sediment and Nutrient Losses from Field-scale Cropland Plots Treated with Animal Manure and Inorganic Fertilizer

A field-scale plot study was conducted at Virginia Tech’s Prices Fork Research Farm, to evaluate the transport of nutrients in runoff from manure and fertilizer applied at P-based agronomic rates to cropland planted to corn. Simulated rainfall events representing 2to 10-year storms in southwest Virginia, occurring 1 and 2 days following manure and fertilizer application were used to generate runoff. Plots were treated with surface applied poultry litter, surface applied and incorporated dairy manure, incorporated inorganic fertilizer, and no fertilizer (control). Application rates were based upon agronomic phosphorus (P) requirements of corn. The concentration of total suspended solids and nutrients decreased from the first to the second simulated rainfall event; however, the edgeof-field mass loss or yield increased due to increased runoff volume. Surface application of dairy manure resulted in 25–50% lower runoff volumes and 35–60% lower total suspended solid yields when compared to surface applied poultry litter. Surface applied poultry litter produced the greatest total P and dissolved reactive P losses. Results of this study suggest that manure applied based on crop P requirements can still yield significant edge-of-field nutrient losses, if rainfall occurs soon after application.