秸秆全量还田与氮肥用量对水稻产量、 氮肥利用率及氮素损失的影响

【目的】在我国水稻生产中探讨秸秆全量还田与氮肥配施的理论与技术,阐明秸秆还田对水稻产量、 氮素利用率及氮素损失的影响,对于提高水稻产量和氮素利用效率、 减少氮污染具有重要意义。【方法】2009~2011年,以水稻南粳46为材料,在江苏常熟农业生态实验站进行原状土柱模拟试验。试验采用裂区设计,主区为秸秆全量还田(S)和无秸秆还田(S0); 副区为氮肥用量(N),设置N 120、 180、 240和300 kg/hm2 4个氮水平,以不施氮肥(N0)为对照。分析了水稻基肥期、 分蘖期、 穗肥期的氨挥发量和土壤80 cm处渗漏水全氮含量,土壤0—15 cm全氮含量,水稻产量,以及水稻籽粒和秸秆氮含量,计算水稻生育期氮肥的氨挥发损失率、 淋溶损失率、 土壤残留率以及水稻的氮肥利用效率。【结果】水稻产量随氮肥适宜用量增加而增加,与单施氮肥相比,秸秆还田下水稻平均增产6.3%,其中N 240 kg/hm2 处理产量最高; 水稻的氮肥利用率随施氮量的增加呈下降趋势,秸秆还田能够提高水稻的氮肥利用率,氮肥农学效率和氮肥表观利用率较单施氮肥分别提高1.4~3.4 kg/kg和1.8%~4.2%; 水稻田氨挥发损失量、 氮肥淋溶损失量和土壤残留氮量均随施氮量的增加而增加,在N 240 kg/hm2水平下,秸秆还田氨挥发损失量增加18.2%、 土壤残留氮量增加10.1 kg/hm2,减少氮素淋溶损失量30.9%,氮肥总损失率降低6.0%。【结论】在秸秆全量还田下,配施适量的氮肥,可以提高水稻对氮肥的利用率,增加产量,同时减少氮肥损失。本试验中,以麦秸全量还田配施N 240 kg/hm2为最优组合。

Effects of straw incorporation plus nitrogen fertilizer on rice yield,nitrogen use efficiency and nitrogen loss

【Objectives】 Exploration of the theory and technology of N application along with total straw incorporation has great significance for raising rice yield and N use efficiency, alleviating nitrogen pollution in rice production in China.【Methods】 A split plot field experiment was conducted using monolith lysimeter with a local rice Nanjing 46 as material in Changshu Agro-ecological Experimental Station, Jiangsu Province, China from 2009 to 2011. The main plot was total wheat straw incorporation (S) and no straw incorporation (S0); the sub-plots were four N rates: 120 kg/hm2 (N1), 180 kg/hm2 (N2), 240 kg/hm2 (N3) and 300 kg/hm2 (N4), with no N application as control (CK). The amount of ammonia volatilization, total N contents in leachate and soil, the N contents in straw in different growth periods and grains were determined, the rice yields were investigated.【Results】 The rice yield was increased with the increasing of N application rate. Compared with no straw incorporation treatments, the average rice yields of S+N treatments were increased by 6.3%, and the highest yield was obtained in SN3 treatment. N use efficiencies were declined with the increasing of N rates in rice reason, which could be enhanced by straw incorporation. Agronomic N efficiency and N apparent recovery in S+N treatments were all higher than those of N treatments by 1.4-3.4 kg/kg and 1.8%-4.2% respectively. With the increasing of N application rate, the amount of N residual, ammonia volatilization and N leaching in paddy field increased. Compared with no straw incorporation, the amount of ammonia volatilization and N residual in paddy field with straw incorporation was increased by 18.2% and 10.1 kg/hm2 respectively at N application rate of 240 kg/hm2, and the N leaching and total N loss were reduced by 30.9% and 6.0% respectively.【Conclusions】 Under the straw completely incorporation, optimum N application rate could increase the N efficiency and rice yield, reduce the total N loss. In this research, the wheat straw incorporation with N application of 240 kg/hm2 is the optimal mode.