Nitrogen leaching from grassland ecosystems managed with organic fertilizers at different stocking rates

Abstract

ABSTRACTThis study shows the effect of organic fertilizers at different stocking rates, on nitrogen (N) leaching, measured using zero-tension lysimeters under undisturbed grassland soil. The experiment included two organic fertilizer types – cow dung with dung water (D) and slurry (S), both at a range of stocking rates: 0.9 LU (livestock unit) ha−1, 1.4 LU ha−1, 2.0 LU ha−1 (corresponding to 54, 84 and 120 kg N ha−1, respectively) and a control (C) treatment. In percolated water, the contents of ammonia nitrogen (NH4+–N) and nitrate nitrogen (NO3−–N) were studied. The average concentration of NH4+–N ranged from 0.91 to 1.44 mg l−1 on fertilized plots compared to 0.55 mg l−1 on the control plot. The average concentration of NO3−–N ranged from 5.2 to 9.5 mg l−1 on fertilized plots compared to 3.2 mg l−1 on the control plot. The results of this study showed that the use of organic fertilizers at chosen stocking rates influenced N leaching, but the concentration of N did not exceed the limits for drinking water permitted by Czech legislation. Stocking rates at 2.0 LU ha−1 and below do not result in elevated N concentrations in percolated water that pose environmental threat.