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Chemistry and Ecology

Year: 2009  |  Volume: 25  |  Issue: 5  |  Page No.: 359 - 369

Effects of anaerobically digested pig slurry application on runoff and leachate

K. Zhu, H. L. Choi, H. Q. Yao, A. Suresh and D. I. Oh

Abstract

Land application of the effluent of anaerobically digested pig slurry is becoming common practice in integrated crop and livestock farming. However, the loss of nutrients, in particular nitrogen and phosphorus, within the water bodies is still a main concern of this practice. The objective of this study was to evaluate nitrogen and phosphorus losses in runoff and leachate for four application rates of anaerobically digested pig slurry (25.0, 70.1, 140.2, and 210.3 kg N ha-1) for Chinese cabbage grown in lysimeters. Simulated rainfall events, occurring one week after slurry application, were used to generate runoff. The yields of nutrients, biochemical oxygen demand and chemical oxygen demand in runoff and leachate increased linearly or logarithmically with slurry application rates. A combination of long rainfall duration (90 minutes) and lower rainfall intensity (33.3 mm hr-1) induced higher nutrient concentrations in the runoff, but lowered the nitrogen concentration in the leachate. The application doses of anaerobically digested pig slurry before sowing, nutrient supplementation and fertilisation time management are the key factors in reducing nutrient contamination of water courses.

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