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环境科学学报 2010
N losses from different cropping modes in the purple hilly region of the Sichuan Basin
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Abstract:
N loss in agriculture is an important source of non-point pollution. To characterize N losses from different cropping modes in the purple hilly region of the Sichuan Basin, N loss in runoff and infiltration of 8 available rainfall events from December 2008 to August 2009 were studied in 4 representative cropping modes: M1 (Chinese milk vetch-rice), M2 (fallow land-Soybean-fallow land), M3 (fallow land-Ginger) and M4 (Corn-Sweet potato). N losses increased with the increase of rainfall events. The ranked order of N loss was: M3 ((30.388±2.86)kg·hm-2) > M4 ((17.118±1.677)kg·hm-2) > M2 ((10.987±1.108)kg·hm-2) > M1 ((6.090±1.051)kg·hm-2) during the studied period. M4 had the highest amount of runoff and infiltration, while M3 showed the highest N losses from both runoff and infiltration. In addition, N losses were relatively lower in the non-cropping period, and only a few variations were observed among cropping modes. However, the losses of dissolved N and total N from both runoff and infiltration showed the same order as: M3 > M4 > M2 > M1. Nitrate N was the main N form in N losses from both runoff and infiltration regardless of the cropping modes. The proportion of ammonium N and dissolved N to total N loss from infiltration was higher than that in runoff. The results provide data for selection of cropping mode, optimization of cropping habitat, and regional control of non-point pollution from agriculture.
