密植减氮对三熟区不同肥力红壤稻田作物产量和耕层氮素的影响

2017-2018年在长江中游三熟制区(江西进贤)开展油菜—早稻—晚稻3季作物田间试验,初步探究了油稻稻秸秆还田下密植减氮对不同肥力红壤稻田作物产量和耕层氮素的影响,为三熟制区资源节约型与环境友好型生产技术发展提供参考。结果表明:在油稻稻三熟秸秆还田条件下,提高土壤肥力和增加种植密度能够促进油菜及双季水稻群体生长,显著提高作物产量。增密30%、减氮20%的密植减氮处理,可以满足油稻稻3季作物生育期内的氮素需求,保证作物正常生长,并明显提高氮肥利用率。总体而言,密植减氮栽培能够达到甚至略高于常规栽培的产量水平,尤其是在高肥力条件下。短期内的密植减氮栽培并不会造成耕层土壤全氮含量及库容量显著降低,但在低肥力条件下显著降低了耕层的碱解氮含量及库容量。

Effects of High-density and Low-nitrogen on Crop Yield and Soil Nitrogen Storage in Plough Layer of Red Paddy Field with Different Soil Fertility in Triple-cropping Area

In 2017-2018, a field experiment of rape-early rice-late rice in red paddy field was conducted in triple-cropping areas (Jinxian of Jiangxi) in the middle reaches of the Yangtze River, to study the effects of higher planting density and lower nitrogen rate with straw returning on crop yield and soil nitrogen storage of red soil with different fertility, providing a reference for the development of resource conservation and environment-friendly production technology in the triple cropping system area. The results showed that under the condition of returning three crop straws to the field, increasing of soil fertility and planting density could significantly promote the increasing of growth and yield of both rice and rapeseed. The treatment of 30% higher planting density with 20% lower nitrogen application rate could meet the nitrogen demand of the three crops growth, ensure the normal growth of the crops, and significantly improve the nitrogen utilization rate. In general, the crops yield of the treatment of high planting density combined with low nitrogen rate could reach or even slightly higher than that of the conventional cultivation, especially under the condition of high fertility. In the short-term, high planting density combined with low nitrogen rate cultivation did not significantly reduce the total content and storage capacity of both total nitrogen and alkali nitrogen in plough layer soil, but significantly reduced the alkali nitrogen content and the storage capacity of the plough layer soil under the condition of low fertility.