秸秆还田对土壤有机质和氮素有效性影响及机制研究进展
Review of research progress on the influence and mechanism of field straw residue incorporation on soil organic matter and nitrogen availability
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摘要: 秸秆还田作为全球有机农业的重要环节, 对维持农田肥力, 减少化肥使用, 提高陆地土壤碳汇能力具有积极作用。秸秆还田主要通过增加土壤有机质和提高氮肥利用率来改善农田生产环境, 获得高农业生产能力。有效的秸秆还田能为土壤中的微生物提供丰富的碳源, 刺激微生物活性, 提高土壤肥力; 同时矿化的秸秆组分能促进土壤氮循环和矿化, 提高氮素有效性。秸秆还田能够促使集约化高氮输入的农田生态系统维持正常的碳氮比例, 减少氮素淋洗损失, 改善土壤结构板结和连作障碍等现象。目前我国农田秸秆还田率不足50%, 与欧美国家高达90%多的秸秆还田率相比, 还具有很大的发展潜力。因此加强我国秸秆还田率能够逐渐改变我国耕地土壤存在的有机质含量和品质下降、氮素损失严重等现象。目前应进一步深入研究秸秆还田对有机质及氮素有效性的影响机制, 并结合长期监测试验, 以及多种秸秆还田技术进行比较研究, 发展适合当地秸秆还田模式, 促进我国农业生态系统的可持续性。Abstract: Straw residue incorporation, as a key practice of global organic agriculture, was critical for maintaining soil fertility, reducing fertilizer use and improving soil carbon sequestration in farmlands. Straw residue incorporation has improved farmland environments for safe and high production capacity by increasing soil organic matter and reducing nitrogen fertilizer application. Effective straw residue incorporation improved soil microbial conditions by supplying abundant carbon, stimulating microbial activity and enhancing soil fertility. Also mineralization of straw residue promoted normal soil nitrogen cycle and mineralization and improved nitrogen efficiency. Straw residue incorporation maintained normal carbon-nitrogen ratio with intensive high nitrogen input in farmland ecosystems, reduced nitrogen loss via leaching, loosened up hardened soil structures and mitigated obstacles related with continuous cropping. Recent straw residue incorporation rate in China was under 50% while it was over 90% in European and American countries. This implied that there was still plenty of room for China to make a full use of straw residue incorporation potential. Thus it was possible to improve straw residue incorporation rate in China which will gradually enhance soil organic matter content and prevent nitrogen loss and soil quality decline in farmlands. It was beneficial to refocus intensive research on the mechanisms of soil organic matter and nitrogen availability. It was also beneficial to compare long-term monitoring experiments with various technological methods of straw residue incorporation in order to develop suitable local straw residue incorporation techniques. Such efforts had the potential to promote sustainable agricultural ecosystem and agricultural production in China.