沼液还田土壤氮素损失通量及其微生物学机理研究

Nitrogen in soils is quit important for the growth of crops, control of nitrogen loss in agricultural soils is critical for agricultural industry. Now, biogas slurry returning to agricultural soils is widely recognized and used as it is an effective means for the resource utilization of biogas slurry, however, the effect of biogas slurry on the nitrogen loss of agricultural soils is still unknown. To our knowledge, there are mainly three pathways for the nitrogen loss of soils, including denitrification, ANAMMOX and N-DAMO. This project is designed to study the long term/short term effect of biogas slurry on the nitrogen loss of agricultural soils using field and simulation experiments. In order to find the key environmental factors in biogas slurry that influences the nitrogen loss and its relative microbial mechanism, the abundance, diversities, communities and activities of denitrifiiers, ANAMMOX bacteria and N-DAMO bacteria will be studied in soils with or without biogas slurry. The results of the project will help us to evaluate the advantages and disadvantages of biogas slurry returning to agricultural soils from the point of nitrogen loss of soils. The project also will help us to make better use of biogas slurry in the future.

土壤氮素对作物生长的重要性不言而喻，控制土壤氮素损失是农业生产的关键问题。沼液还田作为废物资源化利用的有效手段，已被广泛认可和普遍使用。迄今，有关沼液还田对土壤氮素损失通量影响的研究几乎是空白。已知的微生物主导的氮素损失路径主要有三条：反硝化、厌氧氨氧化和亚硝酸盐型甲烷厌氧氧化。本项目拟以沼液还田和施肥土壤作为研究对象，采用大田实验和模拟实验两种研究尺度，对两类土壤中反硝化、ANAMMOX和N-DAMO微生物的数量、多样性、群落结构、活性及其主要影响因子进行研究，评价沼液还田对土壤氮素损失通量的长期和短期影响，阐明沼液中影响土壤氮素损失通量的关键环境因子，揭示沼液还田影响土壤氮素损失通量的微生物学机理。本项目的结果可为从氮素损失/保持角度评价沼液还田的利弊提供数据支撑；可为更好地进行沼液资源化利用提供科学依据；可为沼肥农业生态系统中氮素循环通量的研究奠定理论基础。

沼液还田是废物资源化利用的一种有效手段。沼液还田后土壤氮素损失通量如何变化尚未可知，该问题的研究对于土壤氮素保持和作物生长具有重要意义。本研究利用荧光定量PCR、高通量测序和稳定同位素标记等手段，在大田实验和实验室模拟土柱反应器两种尺度上，探索了沼液还田后反硝化、厌氧氨氧化（Anammox）、亚硝酸盐型甲烷厌氧氧化（N-DAMO）三类主导土壤氮素损失过程微生物的数量、多样性和反应活性的变化，计算了沼液还田后土壤氮素损失通量的变化趋势（与传统施肥土壤相比较），揭示沼液还田影响土壤氮素损失通量的微生物学机理。本项目的结果可以为更好地进行沼液资源化利用提供科学依据。结果发现：1）与传统施肥土壤相比较，沼液还田土壤中反硝化菌的数量更少、N-DAMO菌的数量更多，两类土壤中Anammox菌数量无显著差异。2）与传统施肥土壤相比较，沼液还田土壤中反硝化和Anammox的活性更低，两类土壤中N-DAMO活性无显著差异。3）与传统施肥土壤相比较，沼液还田土壤的氮素损失通量更低。4）硝态氮是沼液中影响土壤氮素损失通量的关键环境因子。