长期施用不同剂量氮肥对高粱产量、氮素利用特性和土壤硝态氮含量的影响

本研究于2015—2019年以晋杂34、辽杂27、晋饲2号、晋糯3号和汾酒粱1号为研究对象,设0(N0)、75(N75)、150(N150)、225(N225)、300(N300)、450 kg hm^-2(N450)6个氮素水平,调查其对产量性状、淀粉含量和土壤硝态氮以及氮素利用特性指标的影响,以探讨高粱合理的氮素施用方案。结果表明,高粱的产量、穗粒数及植株地上部氮素累积量,随施氮水平的增加呈先增加后趋于稳定的趋势,其中以N75处理增幅最大,较N0处理最大增幅分别可达23.68%、48.05%和51.86%;籽粒淀粉含量、5年叠加氮肥利用率、5年叠加氮肥农学效率和氮素5年叠加表观回收率随施氮水平的增加都存在不同程度的降低,其中N75处理下5年叠加氮肥利用率为63.01%,较N150处理提高了76.91%;籽粒淀粉产量则随施氮水平的增加呈先增加后降低的趋势。连续施氮4~5年后,施氮量≥225 kg hm^-2,残留的硝态氮在60~200 cm土层逐年累积,且在0~200 cm土层存在明显的累积峰,硝态氮淋失风险加剧。施氮量75~150 kg hm^-2之间,在满足高粱植株基本生长需求的同时,可以弥补了土壤氮库的消耗,有效降低了土壤硝态氮的淋失,亦有利于高粱产量和籽粒淀粉产量的形成。

Effects of long-term nitrogen fertilization with different levels on sorghum grain yield,nitrogen use characteristics and soil nitrate distribution

To determine a suitable nitrogen fertilizer application rate,an experiment was conducted using Jinza 34,Liaoza 27,Jinsi 2,Jinnuo 3,and Fenjiuliang 1 with six nitrogen(N)fertilization levels,including 0(N0),75(N75),150(N150),225(N225),300(N300),and 450 kg hm^-2(N450).The effects of long-term nitrogen fertilization with different levels on sorghum grain yield,nitrogen use characteristics and soil nitrate nitrogen distribution were investigated.The grain yield,grain number and N accumulation of sorghum increased initially and then tended to be stabile with the increase of nitrogen fertilizer application.Among them,the maximum increase of sorghum under N75 treatment compared with that under N0 treatment was 23.68%,48.05%,and 51.86%,respectively.With the increase of nitrogen fertilizer application,the grain starch content decreased,while the grain starch yield increased firstly and then decreased.Nitrogen apparent recovery rate,nitrogen fertilizer agronomic efficiency and nitrogen use efficiency which were accumulated for five years were reduced significantly with the increase of nitrogen fertilizer application.Compared with the N150 treatment,nitrogen use efficiency accumulated for five years under N75 treatment,which was 63.01%,was increased by 76.91%.When nitrogen fertilizer application was beyond 225 kg hm^-2,after four to five years later,nitrate nitrogen residue was increased rapidly in the 60–200 cm soil layer year by year,NO3^?-N accumulation peaks distributed in the 0–200 cm soil layer and the risk of nitrate nitrogen leaching was increased.In view of the yield,starch yield,nitrogen utilization and environmental benefit,the reasonable nitrogen fertilizer application for sorghum was between 75 kg hm^-2 and 150 kg hm^-2.