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 nitrogen/ha), rainfall intensity (50 vs. 100 mm/h), and interactions on initial abstraction, runoff, total abstraction, and curve number for a simulated storm occurring one day after application to plots covered with “tall” fescue. Manure application rate had no significant effects on the hydrologic parameters. The data were then averaged across manure application rates and incorporated with control plot data to determine the effects of manure treatment (control, poultry litter, and swine manure), rainfall intensity, and interaction on the four hydrologic parameters. No differences in mean hydrologic parameter values between the control and litter-treated plots were detected. Initial and total abstractions for the swine manure-treated plots were only approximately 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 mm/h rainfall intensity. Curve number for the plots receiving swine manure was 15% greater than that for the control and poultry litter-treated plots. The short-term differences in hydrologic characteristics of the swine manure-treated plots may be attributed to the addition of water via the liquid manure and to soil surface sealing by fine manure particles. Additional work was performed to determine whether the application 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 were no different from those for untreated plots for drying intervals of four days or greater.