EFFECTS OF POULTRY LITTER APPLICATION RATE AND RAINFALL INTENSITY ON QUALITY OF RUNOFF FROM FESCUEGRASS PLOTS

A 4 x 2 factorial experiment with three replications was conducted to determine how quality of runoff from grassed areas treated with poultr y (Gallus gallus domesticus) litter is impacted by litter application rate and rainfall intensity for storms occurring 1 d after application . Poultry litter was applied at 0, 218, 435, and 870 kg N ha-1 to plot s established with fescuegrass (Festuca arundinacea Schreb.) on a Capt ina silt loam soil (fine-silty, mixed, mesic Typic Fragiudult). Simula ted rainfall was applied 24 h after litter application at 5 and 10 cm h-1 until runoff had occurred for a duration of 0.5 h. Flow-weighed co mposite samples were collected and analyzed for total Kjeldahl nitroge n (TKN), ammonia nitrogen (NH3-N), nitrate nitrogen (NO3-N), total pho sphorus (TP), dissolved reactive phosphorus (DP), chemical oxygen dema nd (COD), total suspended solids, and electrical conductivity. Increas ing the litter application rate significantly increased runoff concent rations of all litter constituents investigated. Concentrations of TKN , TP, DP, and COD significantly decreased with increasing rainfall int ensity because of more runoff and the associated dilution. Masses of l itter constituents transported off the plots via runoff significantly increased with both litter application rate and rainfall intensity. Fo r a given rainfall intensity, the proportions of applied litter consti tuents lost in runoff were generally indendent of application rate wit h the exception of total N at the high rainfall intensity.