秸秆生物炭与硝化抑制剂配施对南方典型水稻土氮素转化过程的影响

Rice is the main crop in Taihu area. And farmers often apply excessive fertilizer for high yield. For this, a series of environmental problems were caused by a large amount of nitrogen into the atmosphere and environment through runoff, ammonia volatilization, N2O emission and so on. How to reduce the nitrogen emissions from paddy field under the premise of high-yield is the current research focus. And application of nitrification inhibitor or straw charcoal is two methods used in the present. The incorporation of nitrification inhibitor is an effective way to reduce nitrate leaching losses, N2O emissions and increase the nitrogen use efficiency. However, the ammonium nitrogen loss from ammonia volatilization and leaching increases with the incorporation of nitrification inhibitor increased. Straw charcoal has a larger specific surface area and certain adsorption characteristics on ammonium nitrogen. And it could regulate the soil nitrogen pool. Is there a positive effect on the soil nitrogen pollutant emission and nitrogen use efficiency in paddy field after the coupling of straw charcoal? For these, pot experiment with three major types of paddy soil in south China (huangnitu (clay soil), magantu (loam soil), rangxingaoshatu (sand soil)) will be applied in this study. The effect of interaction of straw charcoal and nitrification inhibitor on nitrification and denitrification process and microbial response, N utilization and loss (ammonia volatilization, leaching, and N2O discharge) will be studied. According to these, the process of soil nitrogen transformation and the response of soil ammonia oxidizing and denitrification microorganisms will be assessed. The results will clarify the interaction of straw charcoal and nitrification inhibitor and its microbial response mechanisms. The results will provide technical support and scientific basis for agricultural non-point source pollution reduction in paddy field in south China.

水稻是太湖流域主要种植作物，为追求高产，农户常过量施入化肥，使大量氮素通过径流、氨挥发、N2O排放等途径进入环境，引发系列问题。如何在保证产量的同时有效削减农田的氮环境排放，是当前研究热点。施用硝化抑制剂和添加生物炭是目前增产减排中广泛采用的两个手段。施用硝化抑制剂能够减少稻田硝态氮淋洗和N2O排放，提高氮素利用率，但增加了氨挥发排放和径流铵态氮损失。秸秆生物炭有较大的比表面积，对铵氮有较好的吸附作用，能够调节土壤氮库。但两者配施能否发挥正向交互作用，减少硝化抑制剂施用后稻田土壤铵氮损失，不得而知。本研究拟通过土柱试验，选用3种典型水稻土（黄泥土（黏土）、马肝土（壤土）、壤心高砂土（砂土）），分析生物炭和硝化抑制剂配施对土壤氮素转化过程的影响，以及土壤氨氧化和反硝化微生物的响应，明确生物炭和硝化抑制剂配施在不同土壤类型下的增产减排效应。研究结果为南方稻田面源污染减排提供技术支撑和科学依据。

氨挥发损失是稻田氮素损失的主要途径。施用硝化抑制剂和生物炭是目前稻田增产减排中广泛采用的两个手段。其中，硝化抑制剂能够增加水稻产量，提高氮素利用率，但增加了稻田氨挥发排放和径流铵态氮损失。生物炭有较大的比表面积，对铵氮有较好的吸附作用，能够调节土壤氮库。但两者配施能否发挥正向交互作用，减少硝化抑制剂施用后稻田土壤铵氮损失，不得而知。为此，本研究通过土柱试验，选择4种典型南方水稻土，分析了生物炭和硝化抑制剂单施及配施对水稻产量、氮素吸收利用、氮素环境排放和微生物区系结构等的影响，并对其可能的机制进行了探讨。研究发现1）硝化抑制剂能够增加水稻产量和氮素吸收利用，提高了氮素转运能力，且增加效应不受土壤类型影响。生物炭处理的水稻产量和氮素吸收利用整体与常规施肥一致，但在不同类型土壤表现不尽一致。二者交互效应显著降低了氮素利用率。基于15N示踪结果，研究创新性的发现硝化抑制剂添加增加的水稻氮素吸收量主要来自土壤。2）由于硝化抑制剂对土壤硝化过程的阻控和生物炭的物理碱性影响，硝化抑制剂、生物炭单施和二者配施均增加了马肝土稻田季节氨挥发损失量，二者配施处理的氨挥发损失量显著高于常规施肥处理。硝化抑制剂和生物炭添加对红壤水稻土稻田氨挥发损失量无显著影响。生物炭添加不能解决硝化抑制剂添加后的氨挥发损失增加风险。3）稻田系统的N2O排放量较低，硝化抑制剂和生物炭单施及配施对不同类型土壤的N2O季节的影响均不显著。4）短期内硝化抑制剂和生物炭添加对稻田土壤的微生物种群丰度无显著影响。