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Nitrogen balance and groundwater论文简介： The annual nitrogen budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systemsin Shandong province, north China. The N surplus values were 349, 3327 and 746 kg N ha-1, with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha-1 in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha-1 at 90-180 cm depth in wheatemaize, greenhouse vegetable and orchard systems, respectively.Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs.
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zhangjinglun1987
沙发
2012-03-20 17:20:20
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jackyhailin1
板凳
谢谢！学习中！
2012-01-31 14:32:31
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