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农田土壤净氮矿化对土壤氮素流失和农业非点源污染有重要影响.以丹江口库区五龙池小流域夏玉米黄棕壤为例,进行原位矿化试验,通过与无覆膜耕作土壤相比较,研究覆膜耕作条件下土壤净氮矿化在夏玉米生长期内的变化.结果表明:夏玉米整个生长期内,覆膜耕作土壤净氨化量、净硝化量和净氮矿化量均明显高于无覆膜土壤,分别高6.63、12.96和19.59mg·kg~(-1);覆膜耕作土壤净氨化速率表现为在苗期较高、抽穗期最低、成熟期增至最高的变化特征,而土壤净硝化和净氮矿化速率均呈现苗期较高、拔节期最低、成熟期升至最高的变化过程;覆膜耕作土壤净氮矿化速率均与土壤全氮和NO_3~--N含量、土壤含水量之间呈显著线性关系.覆膜可有效调节土壤水热条件,促进土壤净氮矿化.
The net nitrogen mineralization of farmland soil has an important effect on soil nitrogen loss and agricultural non-point source pollution.Taking Huang Xia brown soil of summer corn in Wulongchi catchment of Danjiangkou reservoir as an example, The results showed that during the whole growth period of summer maize, net net ammonification, net nitrification and net nitrogen removal of mulched tillage were significantly higher than those under net tillage The mineralized amount of soil was significantly higher than that of uncoated soil, which was 6.63, 12.96 and 19.59 mg · kg -1, respectively. The net ammonification rate of mulched soil was higher at seedling stage, lowest at heading stage and mature stage To the highest, and the rates of net nitrification and net nitrogen mineralization showed the process of higher seedling stage, lowest jointing stage and highest maturity stage. The net nitrogen mineralization rate of mulched tillage soil was similar to that of soil Nitrogen and NO_3 ~ - N content and soil water content showed a significant linear relationship.Cover film can effectively regulate soil water and heat conditions, and promote soil nitrogen and mineralization.