调亏灌溉与氮营养对玉米根区土壤水氮有效性的影响

为探索调亏灌溉与氮营养对玉米根区土壤水氮有效性的影响，采用盆栽玉米试验，研究了水分调亏时期和不同施氮量对玉米根区土壤硝态氮迁移动态和水氮利用的影响。结果表明：施氮量决定根区土壤硝态氮含量，各生育阶段的灌水量和养分吸收影响硝态氮的变化动态。调亏灌溉的玉米根区中、下层土壤硝态氮含量介于常规灌溉的高水和低水处理之间。抽穗期结束时根区中、下层土壤硝态氮含量与施氮量呈正相关关系。施氮量、调亏时期对干物质和全氮累积量影响显著。拔节期水分亏缺对干物质累积量影响最大，苗期水分亏缺影响次之，抽穗期水分亏缺影响最小。苗期亏水、高氮处理的水分利用效率最高。高氮处理的植株全氮累积量最大，是无氮处理的2.54～3.23倍。低氮调亏灌溉的氮肥表观利用效率都大于30%，比高氮调亏灌溉的高约6.6%。最佳的水氮组合为抽穗期亏水低氮处理。

Effects of regulated deficit irrigation and nitrogen nutrition on validity of water and nitrogen in maize rootzone soil

The objective of this study was to explore the effects of regulated deficit irrigation and nitrogen nutrition on validity of water and nitrogen in maize rootzone soil with pot experiment. The influence of regulated deficit irrigation and nitrogen nutrition on dynamics of NO3--N in rootzone soil and validity of water and nitrogen were studied. Results showed that soil NO3--N content was determined by N rate, and the dynamics of NO3--N in rootzone soil was affected by irrigation amount and nutrient uptake in each growing stage. Soil NO3--N contents in middle and lower soil layer of regulated deficit irrigation were at between that of low and high irrigation amount of normal irrigation, and there was a positive correlation between the content of NO3--N in middle and lower soil layer and N rate at the end of heading stage. N rate and water deficit period had a notably significant effect on accumulative dry matter and total nitrogen. Water deficit at jointing stage affected accumulative dry matter mostly, followed by that at seedling stage, and the least at heading stage. The treatment with high nitrogen rate and water deficit at seedling stage had the maximum water use efficiency; the treatment with high nitrogen rate had the maximum total nitrogen accumulation, which was 2.54-3.23 times of that in the treatment of zero nitrogen. The nitrogen apparent using efficiency under regulated deficit irrigation and low nitrogen was greater than 30%, which was 6.6% more than that under regulated deficit irrigation and high nitrogen. The best coupling treatment was water deficit at heading stage and low nitrogen.