Effect of pasture renovation on nutrient runoff from pastures fertilized with manure
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Pasture renovators, which are also known as aerators, are used by growers to increase pasture productivity. The increased productivity is believed to be due to increased infiltration of rainwater, since yield increases are normally only observed during drier years when water is limiting growth. If infiltration is significantly increased by renovating, then runoff should be decreased. Reductions in the amount of water running off pastures should result in reductions in phosphorus (P) and nitrogen (N) runoff. The objectives of this study were to determine the effects of pasture renovation on pasture hydrology (infiltration and surface runoff), nutrient (P and N) runoff, and forage production. Two sites located within the Piney Creek Basin in Arkansas, USA, were selected for this study. There were 3 fertilizer treatments for each soil; unfertilized, 8.97 Mg/ha of poultry litter (4 tons/acre), and 46,728 L/ha swine manure (5,000 gal/acre). Rainfall simulations were conducted after 1 day, 3 mo and 13 mo. after renovation in 2001 and 2002. The time to runoff was significantly longer on renovated land, the amount of infiltration was greater and the volume of runoff was less than that on unrenovated land. On average the amount of runoff was reduced by 45% with renovation, which translated into reductions in nutrient runoff of roughly the same magnitude. Total P loads in runoff were reduced by 43% with renovation; total N loads were reduced by 55%. Forage yields were not different on this first study, probably because the plots received simulated rainfall during dry periods of the year. Hence, forage yields were measured on a second study the following year. Pasture renovation significantly increased yields (27% higher on renovated plots). These data indicate that pasture renovation is a best management practice that can be used to reduce nutrient runoff from pastures, while improving productivity.
