不同培肥方式下干湿交替影响稻田养分供需机制的研究

Reducing the excessive input of water and fertilizer in agricultural production, and improving and enhancing the soil fertility have become an imperative demand of realizing high yield of crop and efficiency of resource. The fertilizer cultivation measures like the combined application of organic fertilizer and returning crops straw to the field can improve the function of soil nutrient supply and so on. Meanwhile, alternate wetting and drying has become the most common water-saving irrigation technology in rice production at present. However, there is still lack of systematical research on rice yield, soil fertility, water and fertilizer use efficiency under the condition of the combination of alternate wetting and drying with different fertilizer cultivation measures. Consequently, in this project, alternate wetting and drying paddy fields under different fertilizer cultivation measures were taken as the research object: (1) analyse the change regulation of microbial community structure, function, and physicochemical property of the topsoil during the drying-wetting-drying cycle in the key growth periods of rice; (2) investigation the effect of soil microecology and soil nutrients on root characteristics of rice; (3) reveal the coupling relationship between different combinations of alternate wetting and drying with different fertilizer cultivation measures and rice yield. Finally, clear the impact mechanism of alterate wetting and drying with different fertilizer cultivation measures on the nutrient supply and demand of rice field. Expect to provide theoretical basis for the water-fertilizer coupling optimization management in the actual production.

减少农业生产中水、肥的过量投入，改善和提升土壤地力，是兼顾作物高产和资源高效的迫切需求。有机肥配施、秸秆还田等培肥措施均有利于土壤养分供应等功能的改善。同时，干湿交替已成为当前水稻生产中最普遍的节水灌溉技术。然而，干湿交替与不同培肥方式相组合，对水稻产量、土壤肥力以及水、肥利用效率等的影响仍缺乏系统的研究。因此，本项目以不同培肥方式下干湿交替稻田为研究对象：（1）分析水稻关键生育期土壤旱-水-旱循环周期内，耕层土壤微生物群落结构、功能及土壤理化性质的变化规律；（2）探讨土壤微生态和土壤养分对水稻根系特性的影响；（3）揭示干湿交替与培肥方式不同组合与水稻产量的偶联关系，最终明确不同培肥方式下干湿交替影响稻田养分供需的机制。以期为实际生产中水-肥耦合优化管理提供理论依据。

本项目以不同培肥方式下干湿交替稻田为研究对象，以节水、减肥、减排、提质的农田可持续发展为目标。揭示了干湿交替节水灌溉技术与有机培肥相结合的管理模式，对水稻产量，灌水量节约程度，化肥生产效率的提升潜力；探索表层和亚表层土壤理化指标、土体土与根际土细菌群落构建过程对干湿交替灌溉与有机培肥措施的响应规律；从稻季干湿交替与有机培肥的适宜组合对麦季产量，土壤理化指标及生物学特性影响方面，阐明其对后茬小麦生产的遗留效应。主要结论如下：.（1）不同培肥方式的适宜干湿交替灌溉，主要从整个水稻生长季的灌溉频率和单次灌水量两者相互协调的基础上，减少田间土壤水分蒸发，进而减少灌溉水用量，其节水潜力约15%。相同干湿交替灌溉模式下，有机配施有增加节水效率的潜力，此潜力与有机肥替代比例密切相关。此外，土壤有机质含量、可溶性碳、氮、速效钾、全氮等均呈增加趋势，说明有机配施及适度干湿交替灌溉有利于土壤肥力的持续或提升。.（2）将土体土和根际土统一分析，发现土体土细菌群落之间的距离显著高于根际土，说明根际土的细菌群落更加保守，可能发挥着更为核心的生态功能。确定性过程和随机性过程对两者细菌群落组合过程的贡献不同，确定性过程更有助于土体土细菌群落的组装，而根际土细菌群落的组装更多受随机性过程的控制，且随速效钾浓度的增加，随机性过程对根际细菌群落组装的相对贡献增加，说明速效钾浓度是平衡细菌群落确定性和随机性塑造过程的关键因子。.（3）稻季灌溉方式对后茬麦季土壤理化性质的影响大于培肥方式；灌溉和培肥方式对一些较低丰度细菌影响显著；共生网络分析表明，细菌模块化聚类模式与土壤速效磷含量及部分土壤胞外酶活性显著相关；纯化肥条件下，适度干湿交替灌溉显著提高了麦季土壤细菌的反硝化、亚硝酸盐呼吸及硫代谢能力。一定程度上反应了有机配施的土壤具有更强的恢复性，即干湿交替灌溉与有机配施能改善土壤对外界环境变化的缓冲性能，提高其抗逆性。