绿洲灌区禾豆间作农田温室气体减排调控机制研究

Greenhouse gas emission from arable field is a hot topic recently，cereal-legume intercropping systems can improve nitrogen use efficiency and reduce greenhouse gas emission from farmland, and adopting appropriate agronomic regulations is an effective way to reduce greenhouse gas emissions, however, little information is available about the regulation mechanism on reducing greenhouse gas emission via the integration of cereal-legume intercropping system with agronomic regulations. Therefore, we carried out a research on maize-pea as a typical cereal-legume model intercropping system under three agronomic regulations: tillage practices, nitrogen fertilizer application managements and irrigation levels. The factors of greenhouse gas emission, soil ecologic indicator and crop growth characteristics are investigated as follow: emission rate of Nitrous Oxide (N2O), soil respiration rate, spatio-temporal dynamic of soil carbon and nitrogen, ratio of nitric and ammonium nitrogen, crop dry matter accumulation, plant nitrogen accumulation, as well as soil temperature, soil water content, and pH values. The purpose of this research aims to: look into the relationship between parameters and gas emission; reveal key factors which contribute to reduce greenhouse gas emission; discuss the relationship between soil C/N, interspecific relationships, environment factors with greenhouse gas emissions; provide academic and practical evidence for the synergy effects on reducing greenhouse gas emission via the integration of cereal-legume intercropping system with agronomic regulation. Overall, based on the results of all above mentioned experiments, we could conclude a regulation mechanism for reducing the greenhouse gas emissions. The results of this project will enrich carbon emission theory in farmland under cereal-legume intercropping, explore potential of greenhouse gas reduction, and promote the development of such a nitrogen-saved and environment-friendly intercropping system.

农田温室气体排放是近年来科学界的研究热点，禾豆间作能提高氮素利用效率，减少温室气体排放量，而合理的农艺措施亦可减少农田温室气体排放，但农艺措施嵌套于禾豆间作中的温室气体减排潜力和调控机制缺乏系统深入的研究。本研究将农艺调控措施与禾豆间作集成应用，在耕作方式、施氮制度和灌水水平三种不同农艺措施下，以绿洲灌区典型禾豆间作模式玉米间作豌豆为研究对象，通过检测N2O排放速率、土壤呼吸速率和土壤碳氮动态变化、硝态氮和铵态氮构成、温度、水分、pH 值、作物干物质累积、植株氮素累积等温室气体排放特征、土壤生态因子和作物生长指标，解析各因子与温室气体排放的相关关系，明确农艺措施和间作对温室气体减排的协同效应，揭示禾豆间作农田温室气体排放的关键驱动因子，阐明农艺措施对禾豆间作温室气体减排的调控机制。项目成果将对丰富农田温室气体减排理论，挖掘温室气体减排潜力，发展氮肥节约型、环境友好型间作生产积极推动作用。

农田温室气体排放是近年来科学界的研究热点，禾豆间作能提高氮素利用效率，减少温室气体排放量，而合理的农艺措施亦可降低农田温室气体排放，但农艺措施嵌套于禾豆间作中的温室气体减排潜力和调控机制有待进一步研究。本研究将农艺调控措施与禾豆间作集成应用，在不同耕作方式和灌水水平农艺措施下，以绿洲灌区典型禾豆间作模式玉米间作豌豆为研究对象，通过检测温室气体排放特征、土壤生态因子和作物生长特性指标，分析各因子和温室气体排放的相关关系，阐明农艺措施对禾豆间作温室气体减排的调控机制。.研究表明，在传统灌水与减量灌水两种灌水水平下，覆膜免耕农田土壤CO2排放速率较传统覆膜耕作分别低9.9%和9.7%，土壤N2O排放速率分别低13.8%和12.6%，且减量灌水可降低农田温室气体排放。在0~20 cm和20~40 cm土层，覆膜免耕间作处理较传统耕作单作玉米处理0.25~1 mm粒径大团聚体含量分别提高了32.19%、33.97%，MWD值提高了19.83%、23.58%，GMD值提高了29.23%、31.03%，0~20 cm土层的土壤有机碳提高了32.67%。相关性研究表明，农田温室气体排放与土壤无机氮、土壤脲酶活性、微生物量碳氮、0~10 cm平均土壤温度和0~120 cm平均土壤含水量呈显著正相关关系，且与作物群体干物质累积速率呈线性相关，土壤CO2排放速率与N2O排放速率随着作物干物质累积速率的增长而增加。通过宏基因组测序分析发现，不同处理土壤微生物基因数目无显著差异，但免耕间作土壤微生物门水平α-多样性显著高于其他处理；免耕条件下，间作显著降低了氮循环中norB基因丰度，降低反硝化能力，减少土壤氮损失，而提高了tktA/tktB、pyc、FBA/fbaA、porB等土壤固碳基因丰度，有利于土壤碳的固存。.因此，将覆膜免耕、减量灌水等农艺措施集成应用于禾豆间作农田，可调控与温室气体排放相关的土壤生态因子和微生物特性，减少农田温室气体排放，提升土壤碳固存。项目成果将对丰富农田温室气体减排理论，挖掘温室气体减排潜力，发展氮肥节约型、环境友好型间作生产产生积极推动作用。