ABSTRACTIONS AND RUNOFF FROM FESCUE PLOTS RECEIVING POULTRY LITTER AND SWINE MANURE

This study was conducted to assess the effects of animal manure type ( poultry litter vs. swine manure), application rate (218 vs. 435 kg nit rogen/ha), rainfall intensity (50 vs. 100 mm/h), and interactions on i nitial abstraction, runoff, total abstraction, and curve number for a simulated storm occurring one day after application to plots covered w ith ''tall'' fescue. Manure application rate had no significant effect s on the hydrologic parameters. The data were then averaged across man ure application rates and incorporated with control plot data to deter mine the effects of manure treatment (control, poultry litter, and swi ne manure), rainfall intensity, and interaction on the four hydrologic parameters. No differences in mean hydrologic parameter values betwee n the control and litter-treated plots were detected. Initial and tota l abstractions for the swine manure-treated plots were only approximat ely 50% of those observed from the control and poultry litter-treated plots. Runoff from the swine manure-treated plots was three times that observed for the control and poultry litter-treated plots at the 50 m m/h rainfall intensity. Curve number for the plots receiving swine man ure was 15% greater than that for the control and poultry litter-treat ed plots. The short-term differences in hydrologic characteristics of the swine manure-treated plots may be attributed to the addition of wa ter via the liquid manure and to soil surface sealing by fine manure p articles. Additional work was performed to determine whether the appli cation of the manures affected the hydrologic parameters for longer (4 to 14 days) drying intervals between application and first simulated storm. The results indicated that when the manures were applied at 218 kg nitrogen/ha, hydrologic parameters for the manure-treated plots we re no different from those for untreated plots for drying intervals of four days or greater.