基于氮肥增效剂的堆肥及其农田利用的NH3和N2O控制研究

Large amounts of NH3 and N2O emissions during the processes of composting and its land application seriously affect the fertilizer efficiency of product and air quality. Nitrification inhibitor (NI) and urease inhibitor (UI), as common nitrogen fertilizer synergist (NFS), could effectively control NH3 and N2O emissions from farmland. However, the mechanism of NFS controls NH3 and N2O emissions during the processes of composting and its land application composting is not yet clear, and the research of the joint control of NI and UI on NH3 and N2O is lack. In this proposal, using the experience from farmland conduct the emissions of NH3 and N2O from the full process of composting and land application of compost. The characteristic of NH3 and N2O during the composting when added one or two NFS will be confirmed firstly, and found the optimized scheme of the addition of NI and UI. Then, the influence of land application of compost on the emissions of NH3 and N2O will be study using the pot experiment. Finally, the relationships between nitrogen compounds, functional bacteria (such as ammonifying bacteria, denitrifying bacteria and denitrifying bacteria), functional genes (amoA, nirK, nirS and nosZ) and key enzyme activity (urease, protease and nitrate reductase) and the emissions of NH3 and N2O will be analyze, and revealed the mechanism of the effects NFS on NH3 and N2O emissions during the processes of composting and its land application and propose the optimizing control of NFS during the whole process. This study is aiming to supply theoretical basis and technical support for the control of the emissions of NH3 and N2O during the processes of composting and its land application.

堆肥及其农田利用过程中NH3和N2O排放严重影响产品肥效及大气环境质量。硝化抑制剂（NI）和脲酶抑制剂（UI）作为常用的氮肥增效剂（NFS）可有效控制农田中NH3和N2O排放。然而关于NI和UI联合调控堆肥及其堆肥品在农用全过程中NH3和N2O排放及其减排机制尚不明确。因此，本项目借鉴农田中减排措施，首先明确NI和UI单独及联合添加对堆肥各温度阶段NH3和N2O排放的影响，确定优化组合方案；然后探讨添加NFS的堆肥品在农用过程中NH3和N2O的排放特征；最后综合分析全过程中氮素、功能菌群（氨化菌、硝化菌和反硝化菌）、功能基因（amoA, nirK, nirS和nosZ）和关键酶（脲酶、蛋白酶和硝酸还原酶）活性与NH3和N2O排放的耦合关系，揭示NH3和N2O的减排机制，并提出基于NFS调控的优化控制工艺。本项目有望为堆肥及其农田利用全过程中NH3和N2O的排放控制提供理论依据和技术支撑。

堆肥过程中NH3和N2O排放严重影响产品肥效及大气环境质量。脲酶抑制剂（UI）和硝化抑制剂（NI）作为常用的氮肥增效剂可有效控制农田中NH3和N2O排放。然而关于NI和UI单独或是联合调控堆肥中NH3和N2O排放及其减排机制尚不明确。因此，本项目选择NI和UI为添加剂，研究不同添加量和添加方式对猪粪堆肥中NH3和N2O排放、氮素形态、微生物群落、氮转化功能基因和酶活性的影响。同时研究过程中发现UI和NI会对微生物产生抑制作用，从而延缓堆肥进程，因此也对矿物联合抑制剂对堆肥过程的影响开展研究。主要结果如下：添加0.5%和1% UI分别降低了堆肥中22.2%和21.5%NH3排放量，提高了9.7%和14.3%总氮含量。同时UI可抑制高温期脲酶、纤维素酶和蛋白酶活性，而增加了降温期和腐熟期酶活性，而且添加UI（1%）使得amoA、nirS、nirK和nosZ基因丰度在腐熟期分别提高了26.1%，163.4%、30.2%和136.5%，并增加了高温期细菌群落丰度和多样性，而降低了厚壁菌门和变形菌门的丰度。NI添加显著降低了高温期NH4-N的含量和整个时期NO3-N的含量。堆肥结束时，总氮含量提高了14.8%，此外NI的添加抑制了高温期纤维素酶和蛋白酶活性。添加方式中，NI覆盖在物料表面对NH3和N2O的排放无显著影响，NI与物料混合使NH3排放增加了32.5%，NI混合处理和混合与覆盖相结合处理显著降低了35.1%和51.8%的N2O排放量。此外，P（火山石）和P+NI处理降低了41%和22%的NH3排放量，21%和34%的N2O排放量。P和P+NI在属水平上显著增加了真菌群落丰富度。UI和UI+NI处理使堆肥中NH3排放量分别降低了26.3%和24.3%，UI+NI处理中N2O排放量降低了63.9%，但UI处理并没有降低N2O排放。UI和NI联合添加显著增加了高温期nirS基因丰度，而降低了腐熟期amoA基因丰度。综上得出，UI和NI主要通过降低高温期微生物丰度和相关酶活性，减缓了高温期的氨化作用和后期的硝化作用，减少了氮素损失；同时通过二者联用或是与矿物联用更能有效的减少NH3和N2O的排放，并减少对微生物的抑制作用。本项目的实施为堆肥过程中NH3和N2O的排放控制提供理论依据和技术支撑。