添加蚯蚓堆肥对稻田气态氮损失的影响规律及机制研究

Serious resource-wasting and environmental problems due to the low utilization rate and high continuous accumulation of agricultural waste have gradually brought more attention to the society. Vermicomposting is a low-cost technique to transform organic waste into biodegraded and stabilized by-products (vermicompost) through earthworms, numerous studies have reported that vermicompost would benefit on soil quality and plant production; however, their overall effects on environment have only drawn little attention. Meanwhile, gaseous nitrogen emission from the rice fields is one of the major reasons that leads to farmland nitrogen loss, such as eutrophication of surface water and atmosphere environment. Therefore, it is scientifically significant and practically important to explore effect on addition of vermicompost for gaseous nitrogen loss from rice field. Previous studies found that addition of vermicompost significantly decreased the flux of ammonia volatilization at the stage of panicle fertilizer. In this study, both indoor culture and pot experiments aim to investigate the patterns of addition of vermicompost for gaseous nitrogen loss from rice field. Also, this study attempts to explore the mechanisms through the adsorption characteristics of vermicompost, soil physicochemical and biological properties and soil-water interfacial biofilm, combined with 15N isotopic tracing and microbiological analyses technology. In conclusion, our research will help to understand the ecological environment effects of vermicompost, improve the theory of vermicompost ecosystem service function, and serve as theory to guide productive practice.

农业废弃物的积累和不当利用造成的资源浪费和环境问题正逐步被社会所关注。循环利用可更新资源，利用蚯蚓处理农业废弃物而得到的蚯蚓堆肥已表现出对土壤质量和作物生产的促进作用，但在环境效应的方面研究甚少，同时稻田气态氮素排放是农田氮素损失的重要途径，对水体富营养化和大气环境皆有严重影响，因此研究蚯蚓堆肥对稻田气态氮损失具有现实和科学的意义。前期试验研究发现，添加蚯蚓堆肥降低了水稻穗肥期氨挥发排放量。本研究拟通过室内培养和盆栽试验相结合，研究添加蚯蚓堆肥对稻田气态氮排放的影响规律，并从蚯蚓堆肥本身吸附特性、土壤理化及生物学性质以及稻田土壤界面生物膜等角度，结合15N同位素示踪和微生物分析技术，阐释添加蚯蚓堆肥对稻田气态氮损失影响的内在机制。研究结果有助于阐明添加蚯蚓堆肥对稻田产生的生态环境效应，完善蚯蚓堆肥在土壤生态系统中服务功能的理论，为指导生产实践提供理论依据。

农业废弃物的积累和不当利用造成的资源浪费和环境问题正逐步被社会所关注。循环利用可更新资源，利用蚯蚓处理农业废弃物而得到的蚯蚓堆肥已表现出对土壤质量和作物生产的促进作用，但在环境效应的方面研究甚少，本研究试图在添加蚯蚓堆肥来促进提升土壤肥力和作物产量。然而，同时添加蚯蚓堆肥和生物质炭是否具有协同作用，是否会增加气态氮损失等方面仍存在疑问。本研究在三种蚯蚓堆肥施加量(0, 1 wt%, 3 wt%)的基础上结合是否添加生物质炭两种处理来探讨对整个水稻生长期气态氮损失和水稻生长的影响，同时观测蚯蚓堆肥生物膜的基本特征，结合15N同位素示踪和微生物分析技术研究其还田对水稻生长的影响，以及其后效对小麦的发芽及幼苗生长的影响研究。研究发现：（1）在3wt% 蚯蚓堆肥施用条件下，累计氨挥发和氧化亚氮排放显著增加。在施用蚯蚓堆肥的基础上，添加生物质炭显著降低了累计氧化亚氮的排放14.1-18.6%。同时，混施蚯蚓堆肥和生物质炭能显著增加水稻产量，对单位产量上气体氮损失量无显著影响。（2）检测到蚯蚓堆肥生物膜含有IAA，含量是自然生物膜含量的两倍，稻田添加蚯蚓堆肥生物膜显著地提高了水稻根系生物量及其产量，并在水稻的根系里检测到较高的15N丰度。（3）添加自然生物膜或蚯蚓堆肥生物膜都显著地提高了小麦种子的发芽率，同时蚯蚓堆肥生物膜表施增加了小麦幼苗地上部生物量约26.7%，地下部生物量约36.0%。该研究结果有助于阐明添加蚯蚓堆肥对稻田农业生产的生态环境效应，完善蚯蚓堆肥在土壤生态系统中服务功能的理论，为指导生产实践提供理论依据。