控制灌溉氮肥减施对土壤氮素分布及氮素利用率的影响

Effects of reducing nitrogen fertilizer application on soil nitrogen distribution and nitrogen use efficiency under water-saving irrigation

为明确黑土稻田控制灌溉条件下氮肥减施对土壤氮素分布及氮肥利用率的影响,研究控制灌溉与常规淹灌下氮肥减施对土壤0~60 cm土层矿质氮、可溶性有机氮(SON)和微生物量氮(MBN)、产量及氮肥利用率的影响。结果表明,在常规淹灌与控制灌溉模式下,NH_(4)^(+)-N累积量均与土层厚度呈负相关关系,NO_(3)^(-)-N累积量均随土层深度增加呈先升后降趋势,且在控制灌溉模式下氮素施入量与矿质氮累积量呈正相关。控制灌溉模式下SON累积量与土层深度呈负相关。MBN在两种灌溉模式下均主要累积在0~20 cm土层,且与土层深度呈负相关,N1、N2处理表层MBN累积量较CK处理分别升高8.14%、6.02%。更有利于保持黑土供氮能力,维持土壤氮库稳定。与CK处理相比,控制灌溉的氮肥偏生产力分别升高5.74%~29.79%,氮肥农学效率分别升高17.10%~3.96%,氮肥表观利用率分别升高19.16%~3.28%。综合考虑土壤氮素转化及氮肥利用率控制灌溉减施10%水平氮肥为最优处理。

In order to clarify the effect of reduced nitrogen fertilizer application on soil nitrogen distribution and nitrogen use efficiency under water-saving irrigation in black soil rice fields. The effects of reduced nitrogen application under controlled irrigation on the mineral nitrogen, soluble organic nitrogen(SON) and microbial biomass nitrogen(MBN), yield and nitrogen utilization efficiency of the soil layer of 0-60 cm soil were studied. The results showed that under the two irrigation modes, the accumulation of NH_(4)^(+)-N was negatively correlated with the thickness of the soil layer, while the accumulation of NO_(3)^(-)-N first increased and then decreased with the increase of soil depth, and was under control. There was a positive correlation between the amount of nitrogen applied and the accumulation of mineral nitrogen under the irrigation mode. There was a negative correlation between the SON accumulation and soil depth under controlled irrigation mode. The MBN was mainly accumulated in the 0-20 cm soil layer under the two irrigation modes, and it was negatively correlated with the soil depth. The cumulative amount of the MBN in the surface layer of N1 and N2 treatments increased by 8.14% and 6.02%, respectively compared with CK treatment. It was more conducive to maintaining the nitrogen supply capacity of the black soil and maintaining the stability of the soil nitrogen pool. Compared with CK treatment, the partial productivity of nitrogen fertilizer under controlled irrigation increased by 5.74%-29.79%, the agronomic efficiency of nitrogen fertilizer increased by17.10%-3.96%, and the apparent utilization rate of nitrogen fertilizer increased by 19.16%-3.28%.Comprehensive consideration of soil nitrogen conversion and nitrogen use efficiency to control irrigation and reduce the application of 10% nitrogen fertilizer was the optimal treatment.