不同施氮水平下旱作水稻土壤无机氮的动态变化及其吸氮特征

田间条件下用半腐解稻草覆盖后对旱作水稻进行了氮肥不同用量 0 (N0 ) ,90 (N90 ) ,15 0 (N150 ) ,2 10 (N2 10 )和2 70 (N2 70 )kg·hm-2 试验 ,研究了施氮后土壤中无机氮 (NH4 -N、NO3 -N)的动态变化及水稻吸氮特征。结果表明 ,不同施氮水平下旱作水稻土壤速效氮以硝态氮为主 ,水稻的产量以N2 10 处理最高 ,水稻的植株含氮量及氮素的累积主要发生在生长发育的中期 ,氮肥的表观利用率也以N2 10 处理最高 ,随着氮肥用量的增加水稻对土壤氮的依存率逐渐降低

Dynamics of soil inorganic N in rice crop cultivated on upland condition and N absorption by rice supplied with different N fertilizer rate

Different rates of nitrogen fertilizer i.e.0 (N0),90 kg*hm－2(N90)，150 kg*hm－2(N150)，210 kg*hm－2(N210)，270 kg*hm－2(N270) were applied to the soil mulched with half-decomposed rice straw in which rice crops were grown on upland condition to study the dynamics of NH+4-N and NO-3-N of the soil,nitrogen absorption and its content in different organs at various growth stages.Rssults indicated that the main form of soil available nitrogen was NO－3-N no matter how much nittogen was applied to soil.The highest rice yield and nitrogen fertilizer use efficiency were found in the treatment of N210.The largest amount of nitrogen absorption and accumulation occurred at the middle rice growth stage.The dependence of rice on soil N was decreased with increasing of nitrogen fertilizer application rate.