Journal of Food, Agriculture and Environment

Comparative study on dissolved N and P loss and eutrophication risk in runoff water in contour and down-slope

Author(s):

Qian Ma ^{1, 2}, Xingxiu Yu ^2*, Guoan Lü ¹, Qianjin Liu ²

Recieved Date: 2010-06-28, Accepted Date: 2010-10-24

Abstract:

In contour tillage system, the direction of the plant lines was against the slope, resulting in a decrease of runoff and sediment loss with respect to traditional down-slope tillage. The objective of this work was to analyze the differences of NO₃^-–N, NH₄⁺-N and P loss in runoff water with the intention of observing possible eutrophication risks in this water, in contour and down-slope. The work was carried out on brown soil with conventional cultivation of peanut. Simulating rainfall of two different intensities (40 mm·h^-1 and 70 mm·h^-1) was used in the study at the begining of September, 2008. The results showed, under the same rainfall intensity, the concentration of P in runoff water was higher in contour than in down-slope tillage, while the concentrations difference of NO3^-–N, NH4⁺-N between the two tillage methods were not consistent. Contour can effectively reduce the runoff and the losses of dissolved inorganic nitrogen (NO3^-–N + NH4⁺-N) and P in runoff water compared to down-slope tillage, which will be more obvious under the conditions of high rainfall intensity. The losses of dissolved inorganic nitrogen and P in runoff water were 43% and 5% less, respectively, in contour than in down-slopes tillage at the 40 mm·h^-1 rainfall intensity, and were 68% and 55%, respectively, at 70 mm·h^-1. The N/P ratios in runoff water produced by contour and down-slope tillage suggest a certain eutrophication risk in water, which shows an increasing trend within the rainfall process. Compared with down-slope tillage, contour can not only hinder the increasing trend of eutrophication risk, but also can significantly lower the risk level, and thus effectively reduce the effect of agricultural runoff on eutrophication.

Keywords:

Contour tillage, down-slope tillage, runoff water, loss of nitrogen and phosphorus, eutrophication risk

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Journal: Journal of Food, Agriculture and Environment
Year: 2010
Volume: 8
Issue: 3&4
Category: Environment
Pages: 1042-1048

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