冬小麦／夏玉米轮作体系中土壤氮素矿化及预测

应用田间试验结果研究了冬小麦和夏玉米生长期的土壤氮素矿化量，并用间隙淋洗好气培养试验结合一级动力学模型对田间氮素矿化量进行了预测。结果表明，土壤氮素矿化量在年际间和作物间的变异很大，夏玉米季一般高于冬小麦季，从而导致夏玉米季施用氮肥的增产作用不明显，冬小麦季矿化量占当季作物最高吸氮量的31％～60％，夏玉米季占62％～108％，加上起始Nmin的供氮，造成了作物产量尤其是夏玉米产量对施入氮肥反应不明显，土壤氮素净矿化量均随土壤供氮量的增加而显著减少，在一般供氮量范围内(0～300kgN·hm^-2)均表现为净矿化,一级动力学模型只能预测作物整个生育期土壤氮素矿化总的趋势，并不能反映某一阶段矿化量的变化，但模型能在种植作物以前估计出土壤氮素净矿化量，从这个意义上说，模型的预测作用仍是不可低估的。

Soil nitrogen mineralization and its prediction in winter wheat-summer maize rotation system

The mineralization of soil nitrogen in winter wheat-summer maize growth season was studied with field experiment, and its prediction was made by interval leached aerial incubation combined with first-order dynamic model. The results showed that the amount of soil mineralized nitrogen had a large variation among years and crops. The soil nitrogen mineralization was lower in winter wheat growth season than in summer maize growth season, resulted in the yield increment of summer maize being not significant with increasing nitrogen fertilization rate. The amount of soil mineralized nitrogen occupied 31%-60% of the total nitrogen uptake by winter wheat and 62%-108% by summer maize. It was understandable why crop yield (especially summer maize) was not significantly response to applied nitrogen fertilizer. The amount of soil mineralized nitrogen decreased with increasing soil nitrogen supply. The mineralization was positive in normal nitrogen supply range(0-300 kg N.hm-2). The first order dynamic model could only predict the whole trend of mineralization in growth season, but could not reflect its variation in some growth stages. The role of the model was still important in view of the prediction of nitrogen mineralization before sowing.