小麦/玉米轮作模式下氮肥运筹对土壤氮素残留及下茬作物的影响

为明确不同类型土壤小麦/玉米轮作模式下土壤氮素残留对后茬作物的影响,本研究在砂壤土和砂姜黑土2种土壤条件下,分别对小麦/玉米季氮肥运筹对土壤氮素残留及其对下茬作物的影响展开研究。研究结果表明：施用氮肥提高产量的同时,提高了小麦、玉米收获后土壤氮素残留量。随着追氮后移,土壤氮素残留量提高,特别是提高了残留氮素在上层土壤中的分配比例。在后季作物不施用氮肥的情况,前茬作物残留氮素对后季小麦、玉米的产量及其构成因素有一定的促进作用;但是在后季作物正常施用氮肥的情况下,前季作物残留氮素的影响不显著。不同类型土壤间比较发现,砂姜黑土试验地的氮素残留量大于砂壤土,且上层土壤残留比例较高。在后茬作物不追氮素的情况下,砂姜黑土种植作物产量下降幅度较小,高于砂壤土;在后茬作物追氮的情况下,砂壤土产量提高幅度显著高于砂姜黑土。可见,在本试验条件下小麦/玉米季土壤残留氮素对下茬作物有一定促进作用,但随着下茬作物氮肥用量的增加这种增产效应不再明显。黏性土壤的保肥能力更强,但是对施入氮肥的敏感性较低。

Effect of Nitrogen Fertilizer Management on Soil Nitrogen Residue and the Following Crops Under Wheat-maize Rotation System

To determine the effect of nitrogen fertilizer management on soil nitrogen residue and the following crops under wheat-maize rotation system, in the present study, different nitrogen fertilizer levels and application stages were set in both mortar black and sandy loam soils. The results showed that the application of nitrogen fertilizer could increase the yield and the accumulation of nitrogen in soil at the ripe stage. Backward nitrogen application could increase soil nitrogen residue, especially the proportion in upper soil. Residual soil nitrogen could increase the yield of the following crops without the application of nitrogen fertilizer, however there was no effect under normal nitrogen application. There was significant difference between mortar black soil and sandy loam soil. At the ripe stage, the accumulation of nitrogen in mortar black soil was more than that in sandy loam soil, especially the distribution in upper layer of soil. The following crops had higher yield in mortar black soil under no nitrogen fertilizer application, but the yield increase in sandy loam soil is significantly higher with nitrogen fertilizer application on the following crops. The results indicate that residual soil nitrogen could increase the yield of the following crops, but that could be eliminated by nitrogen application.