定位施肥对潮土剖面无机氮动态的影响

Effect of Different Fertilizer Management on Mineral Nitrogen in Fluvo-aquic Soil

研究了长期定位试验条件下连续施肥对土壤剖面无机氮分布与累积状况的影响。结果表明:①过量及偏施氮肥使冬小麦各生育期0～100cm 土壤剖面中 NO_3^-N 总量明显增加,施氮270kg·hm^(-2)比施用常量氮肥(135kg·hm^(-2))残留于土壤剖面内的 NO_3^--N 高出3倍;②270kg·hm^(-2)氮肥配施7500kg·hm^(-2)鸡粪,使0～100cm 土壤剖面内的 NO_3^--N 总量平均降低1倍,可有效减轻过量 NO_3^--N 对地下水的污染;③单施氮肥的处理,在适当配施磷肥后,土壤中残留的 NO_3^--N 也降低了1～4倍;④单施氮肥条件下,NO_3^--N在0～100cm 土壤剖面内呈均匀分布;氮肥与磷肥及有机肥配施,NO_3^--N 主要分布在0～60cm 土层内,防止了 NO_3^--N 向深层土壤中淋失;⑤在合理的施氮水平下,作物的产量较高,肥料利用率也较高,对环境选成的威胁也减小,是持续农业的优化施肥方案。

The accumulation and distribution of mineral N in soil profile and the evaluation of nitrogen recovery were studied under the condition of long term fertilizer experiment.The ex- periment adopted split plot design with 2 main treatments including an annual application of 7 500kg·hm^(-2)of poulty manure(M) and no application of poultry manure(F),nine sub- treatments designed as 3×3 including three nitrogen levels of 0,135,270 kg·hm^(-2)and three phosphorus levels 0,67.5,135 kg·hm^(-2).The results showed:①The content of NO_3^--N in 100 cm soil profile increased significantly when N fertilizer was applied,the residual NO_3^--N was four times higher of N 270 kg·hm^(-2)than that of N 135 kg·hm^(-2)at harvesting stage of winter wheat.②The content of NO_3^--N was decreased by 50% when equal N fertilizer was applied with poultry manure 7 500 kg·hm^(-2)together,which may decrease the risk of contami- nation of excessive NO_3^--N on ground water.③Soil NO_3^--N content decreased by 50% when P fertilizer was applied with N fertilizer together.④NO_3^--N was distributed in 0～100 cm soil profile uniformly when N fertilizer was applied alone,while NO_3^--N was mainly distributed in 0～60 cm soil profile when N fertilizer was applied in combination with P fertilizer and poultry manure;⑤In the reasonable range of N fertilizer,the yield of crops was higher;and N fertil- izer recovery was also higher;and the risk of contamination of NO_3^--N on ground water decreased consequently.