Reduction of nitrate leaching with haying or grazing and omission of nitrogen fertilizer.
In some high-fertility, high-stocking-density grazing systems, nitrate (NO(3)) leaching can be great, and ground water NO(3)-N concentrations can exceed maximum contaminant levels. To reduce high N leaching losses and concentrations, alternative management practices need to be used. At the North Appalachian Experimental Watershed near Coshocton, OH, two management practices were studied with regard to reducing NO(3)-N concentrations in ground water. This was following a fertilized, rotational grazing management practice from which ground water NO(3)-N concentrations exceeded maximum contaminant levels. Using four small watersheds (each approximately 1 ha), rotational grazing of a grass forage without N fertilizer being applied and unfertilized grass forage removed as hay were used as alternative management practices to the previous fertilized pastures. Ground water was sampled at spring developments, which drained the watershed areas, over a 7-yr period. Peak ground water NO(3)-N concentrations before the 7-yr study period ranged from 13 to 25.5 mg L(-1). Ground water NO(3)-N concentrations progressively decreased under each watershed and both management practices. Following five years of the alternative management practices, ground water NO(3)-N concentrations ranged from 2.1 to 3.9 mg L(-1). Both grazing and haying, without N fertilizer being applied to the forage, were similarly effective in reducing the NO(3)-N levels in ground water. This research shows two management practices that can be effective in reducing high NO(3)-N concentrations resulting from high-fertility, high-stocking-density grazing systems, including an option to continue grazing.
Owens
L B
LB
USDA-ARS, P.O. Box 488, Coshocton, OH 43812, USA. owens@coshocton.ars.usda.gov
Bonta
J V
JV
D000818:Animals; D000829:Animals, Domestic; D001673:Biodegradation, Environmental; D004787:Environmental Pollution / Q000517:prevention & control*; D005308:Fertilizers; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen; D010945:Plants, Edible; D006109:Poaceae; D012995:Solubility; D014873:Water Pollutants / Q000032:analysis
D005308:Fertilizers; D009566:Nitrates; D014873:Water Pollutants; D009584:Nitrogen