生物炭与灌溉方式对盐渍化农田温室气体排放的影响规律与耦合响应机制

Greenhouse gas emissions has become the hot issues of international concern. The greenhouse gas emissions of farmland ecosystem is closely related to the global climate change. This project is mainly focus on studying corn in the salinization area based on character of holding water, fertilizer and straw biocharf carbon emission reduction, to research the response of salinity farmland greenhouse gases emission on different irrigation modes (border irrigation of Yellow River, groundwater drip irrigation) and bichar aoolication. Through indoor test and field plot experiment, to discuss on influences mechanism of biochar on greenhouse gas emission mechanism and carbon emission reduction effect under different irrigation mode. At the same time, to test and analysis of soil - root - water - carbon - nitrogen atmosphere interface exchange process of biology, chemistry, physics and crop root, soil structure, breathing, and the farmland ecosystem carbon - nitrogen coupling water cycle regulation mechanism; Reveal the different water carbon fertilizer coupling conditions under different irrigation methods on farmland soil microbial functional groups and their impact on greenhouse gas emissions laws and mechanism; Put forward under different irrigation farmland water the coordination regulation mechanism of carbon and nitrogen cycle, carbon and nitrogen cycle model to simulate water. Lastly, this research results will provide for theoretical and technical support of regulation of greenhouse gases and farmland ecosystems and farmland - carbon - nitrogen coupling water cycle research.

温室气体排放已经成为国内外共同关注的热点问题。农田生态系统温室气体排放与全球的气候变化密切相关。本课题以盐渍化灌区主要作物玉米为研究对象，利用秸秆生物炭吸水、保肥、改土和固碳减排等特性，研究不同灌溉模式下（引黄畦灌、地下水滴灌）盐碱化农田温室气体（CO2，CH4，N2O）对秸秆生物炭、灌溉方式的响应。通过室内试验与田间小区试验结合的方式，探求不同灌溉模式下施加生物炭和不同施肥水平对温室气体排放的影响机理及固碳减排效应；测试分析土壤-根系-大气界面水-碳-氮交换的生物、化学、物理过程和作物根系-土壤结构、呼吸、酶及其对农田生态系统温室气体排放的调控机制；揭示不同灌溉方式下生物炭和不同施肥条件对于农田土壤微生物功能群及其对温室气体排放的影响规律与机理；提出不同灌溉方式下农田温室气体协同调控机制。为盐渍化农田温室气体调控和农田生态系统水-碳-氮耦合循环研究提供理论和技术支撑。

河套灌区作为我国北方重要的商品粮生产基地，受气候条件、灌排不畅、地下水位高等影响，土壤盐渍化程度严重，导致土壤生产力较低，盐分胁迫严重制约了当地农业生产和生态的可持续发展。本课题以河套灌区盐渍化农田为主要研究对象，通过对比不同灌溉方式（引黄畦灌、地下水滴灌）下施加生物炭对农田温室气体排放规律的时空变化影响和耦合响应机制开展研究。研究发现，（1）不同改良措施条件下，滴灌条件下施用生物炭、秸秆深埋和石膏，盐分降低幅度更大，效果明显；黄河水灌溉较滴灌条件下积盐程度高，说明滴灌条件下结合改良剂对盐分淋洗、抑制表层盐分积聚效果更佳。（2）滴灌条件下秸秆深埋、石膏+有机肥、石膏均降低土壤pH值，黄河水灌溉对土壤pH影响较小；不同灌溉方式下生物炭、秸秆深埋处理明显提高耕层土壤温度，且黄灌处理高于滴灌处理；生物炭与石膏显著增加土壤养分含量。（3）生物炭和石膏显著降低温室气体排放通量、排放强度（GHGI），其中滴灌条件下排放强度降低16.77%~34.93%。土壤温度与CO2排放呈显著正相关。生物炭处理下土壤含水率与CO2排放强度呈显著负相关，生物炭、秸秆（深埋、覆盖）处理下各层土壤含水率与CH4排放呈显著正相关。（4）分析土壤碳通量的日变化可知，碳通量排放整体表现出白天排放量大于晚上。（5）综合分析土壤温室气体排放通量的季节动态变化及年际变化特征可知，改良措施可降低农田土壤CH4和N2O的综合增温潜势，最终降低温室气体排放强度，其中生物炭、脱硫石膏加有机肥和秸秆深埋的效果较好。（6）不同改良剂对葵花生长状况均有促进作用，且滴灌条件下各处理葵花生长较黄灌好，滴灌条件下添加改良剂对葵花产量有促进作用。.综上所述，不同改良措施可有效改善土壤理化性质，提高葵花各项生育指标、增加产量，减少农田温室气体的排放。因此，在河套灌区盐渍化土壤中施入多种改良措施对盐碱地治理、农业经济发展和生态环境保护具有重要意义。