太湖地区稻田不同轮作制度下的氮肥减量研究

通过设置不同轮作制度及施氮量, 研究其对稻季的田面水氮素含量、氮素径流损失、产量及土壤养分的影响, 结果表明: 在江苏宜兴地区, 冬季种植紫云英或黑麦草替代小麦种植, 从而减少稻季化学氮肥的施用是可行的。紫云英或黑麦草参与轮作还田, 提高了土壤的供氮水平, 促进了水稻对氮素的吸收利用, 产量显著提高, 且冬季种植无需施用氮肥, 减少了冬季旱地土壤的氮素损失, 降低了环境负荷; 在总施氮量相等的情况下, 提高肥料中有机肥比例可以降低稻田田面水中的总氮含量, 降低了因田面水外排导致的氮素径流损失,且绿肥种植成本低, 尤其是紫云英对无机氮肥的替代性强, 可以有效降低稻季的施肥成本。在江苏宜兴地区,如适当地将传统的小麦?水稻轮作制度改为紫云英?水稻轮作制度, 并在稻季减少120 kg·hm?2 的纯氮投入, 则可兼顾经济效益、产量效益和环境效益。

Reduction of nitrogen fertilizer application under different crop rotation systems in paddy fields of Taihu Area

In a paddy rice field experiment with different crop rotation systems and nitrogen application rates, surface water nitrogen content, nitrogen lose via runoff, soil fertility and rice yield were determined. Based on the experiment, chemical nitrogen fertilizer application during rice season in alfalfa-rice or rye-rice rotation systems can be reduced, and not in wheat-rice rotation system in Yixing, Jiangsu Province. Alfalfa-rice and rye-rice rotation systems enhanced soil nitrogen content, promoted rice nitrogen absorption and significantly improved rice yield. Because there was no nitrogen fertilization in winter, nitrogen loss via field water runoff into natural water bodies dropped during this period. The increase of organic fertilizer ratio under the same nitrogen application did also dropped total nitrogen in surface water. The green manure, especially alfalfa, was not only low cost but also effectively replaced chemical nitrogen fertilizers, which resulted in lowered cost of rice production. Replacing traditional wheat-rice with alfalfa-rice rotation system and reducing 120 kg·hm?2 of nitrogen application during rice season resulted in economic benefits and yield increase and environmental sustainability in Yixing, Jiangsu Province.