Abstract

Attention is growing on the use of excessive nitrogen (N) and water in agricultural systems in Northwestern China because of lower water and N use efficiency. The soil NO₃ ⁻ dynamics and yield for cotton (Gossypium hirsutum L.) under the combined effects of drought and N additions, however, remain unclear. We investigated the effects of drought stress (367, 618, and 917 mm yr⁻¹) and N application levels (0, 150, 225, and 300 kg N ha⁻¹) on soil nitrate nitrogen (NO₃ ⁻) and yield in two years. Compared with optimum irrigation (917 mm), drought stress (618 and 367 mm yr⁻¹) significantly increased residual NO₃ ⁻ and decreased N loss. The 300 and 225 kg N ha⁻¹ treatment significantly increased NO₃ ⁻ content in most soil layers up to 200 cm depth, but N loss was also at a maximum with 300 kg N ha⁻¹. Applying 225 kg N ha⁻¹ with moderate drought stress (618 mm yr⁻¹) resulted in the highest cotton yields (2952 kg ha⁻¹⁾ and plant N uptake (148.7 kg ha⁻¹). Compared with the treatment of 150 kg N ha⁻¹ application with moderate drought stress (618 mm yr⁻¹), N agronomic use efficiency under the combination treatment of 225 kg N ha⁻¹ with moderate drought stress (618 mm yr⁻¹) had some decrease, but the difference was not significant. These results showed that reducing the N application rate to 225 kg N ha⁻¹ with moderate drought stress could be an optimum management practice for achieving high-yield, high-N use efficiency and could reduce soil N losses.

摘要

由于水和氮的利用效率较低，在西北地区的农业系统中越来越多地使用过量的氮和水。土壤NO ₃ ^-棉花动力学和产率（陆地棉下干旱和N加法的组合效果L.），但是，目前仍不清楚。我们研究了干旱胁迫（367，618，和917毫米年的效果^-1）和N应用级别（0，150，225，和300公斤氮公顷^-1对土壤硝态氮）（NO ₃ ^- ）的产量和两年 具有最佳灌溉（917 mm）时，在干旱胁迫进行比较（618和367毫米年^-1）显著增加的残余NO ₃ ^-减少了氮的损失 在300和225公斤氮公顷^-1治疗NO显著增加₃ ^-在大多数土层含量高达200厘米深，但氮损失也是在用300公斤氮公顷的最大^-1。在中等干旱胁迫下（618 mm yr ^-1）施用225 kg N ha ^-1可获得最高的棉花产量（2952 kg ha ^-1）和植物氮素吸收（148.7 kg ha ^-1）。与处理工艺150千克氮公顷相比^-1应用中度干旱胁迫（618毫米年^-1），N农艺利用效率的组合治疗225千克氮公顷下^-1中度干旱胁迫（618毫米年^-1）有所降低，但差异不明显。这些结果表明，在中等干旱胁迫下将氮肥施用量降低至225 kg N ha ^-1可能是实现高产，高氮利用效率并减少土壤氮素流失的最佳管理方法。