灌溉方式和施氮量对棉田氮肥利用率及损失的影响

Effects of irrigation mode and N application rate on cotton field fertilizer N use efficiency and N losses

在田间条件下,研究不同灌溉方式(滴灌和漫灌)和不同施氮水平(0、240、360、480kgN·hm-2)对棉田氮肥利用率及损失的影响,并定量分析了氮肥被植株吸收、土壤硝态氮残留,以及氨挥发、硝态氮淋溶损失、硝化反硝化损失等氮素循环转化途径.结果表明:滴灌棉花籽棉产量、植株吸氮量和氮肥利用率均显著大于漫灌.漫灌土壤硝态氮残留量显著高于滴灌;在不同施氮量处理中滴灌土壤氨挥发损失量占肥料氮施用量的比例为0.06%～0.14%,且显著高于漫灌;滴灌和漫灌硝态氮淋溶损失量占肥料氮施用量的比例分别为4.4%和8.8%,与漫灌相比,滴灌能显著降低淋溶水中硝态氮淋失量;滴灌和漫灌肥料氮的硝化-反硝化损失量分别占肥料氮施用量的17.9%和16.8%.硝态氮淋溶和硝化-反硝化损失是新疆棉田氮素损失的主要途径.

A field experiment was conducted to study the effects of different irrigation modes （drip irrigation and furrow irrigation） and different N application rates （0,240,360 and 480 kg N·hm-2） on the fertilizer N use efficiency and N losses in a cotton field in Xinjiang,Northwest China.The main N cycling pathways,such as the N uptake by cotton plant,NO3--N residual in soil,NH3 volatilization,NO3--N leaching,and nitrification-denitrification,were quantitatively monitored.Compared with furrow irrigation,drip irrigation increased the seed cotton yield,plant N uptake,and fertilizer N use efficiency significantly.The NO3--N residual in soil was significantly greater under furrow irrigation than under drip irrigation.With the application of fertilizer N,the N loss from NH3 volatilization under drip irrigation occupied 0.06%-0.14% of applied N,and was significantly greater than that under furrow irrigation.The N loss from NO3--N leaching under drip irrigation and furrow irrigation was 4.4% and 8.8% of the applied N,respectively.Compared with furrow irrigation,drip irrigation could significantly decrease the NO3--N leakage rate in leakage water.The nitrification-dinetrification loss under drip irrigation and furrow irrigation was 17.9% and 16.8% of the applied N,respectively.It was suggested that NO3--N leaching and nitrification-denitrification were the main N losses in the cotton fields of Xinjiang.