基于沟垄集雨种植技术的旱作农田土壤氧化亚氮排放机制研究

Rainfed area of northern China is very important agricultural region for the nation. Some studies have shown the agricultural practices, such as tillage and fertilization had significantly effect on N2O emission. The ridge and furrow rainfall harvesting (RFRH) system is one of the most effective measures for increasing crop yield in the rainfed region. The RFRH system could change N2O fluxes due to the variation of soil moisture and soil temperature. However, the mechanism of N2O emission under RFRH system is rarely reported. Therefore, this study focuses on N2O emission under RFRH system and conventional flat in rainfed field, and take RFRH system as the water-heat factor to couple with fertilizer (fertilizer factor), to investigate the characteristic of N2O emission under RFRH system, and the temporal and spatial distribution of N2O emission in different soil layer of the furrow and ridge, clarify the effect mechanisms of RFRH system to N2O emission combined laboratory analysis. Calculated and investigated the adjustment measure of N2O emission under RFRH system. We anticipate this study will be useful for perfecting the RFRH system and improving the RFRH system application in rainfed region of China.

旱作农区是我国农业生产的重要区域，已有研究表明，施肥、耕作等农艺措施对这一区域农田土壤氧化亚氮（N2O）排放具有显著影响。沟垄集雨种植技术作为一种有效的集水农艺措施，对旱作农区粮食的增产起到了积极作用。沟垄集雨种植技术由于垄与沟微地形的改变以及地膜对土气界面水汽交换的阻隔，对土壤水热运动影响强烈，从而可能影响N2O的排放过程，但是目前关于沟垄集雨种植模式下土壤N2O排放机理方面的研究很少。本研究以土壤N2O排放为研究对象，以传统平作为对照，通过田间原位监测，将沟垄集雨种植模式作为水热调控因子，并与施肥量（肥因子）进行耦合，查明旱作农田沟垄集雨种植模式下土壤N2O排放特征以及该模式下土壤剖面不同土层N2O浓度的时空变异规律，同时结合土壤理化性质揭示水、热、肥耦合对土壤N2O排放的影响机制，明确沟垄集雨种植技术对土壤N2O排放的调控作用，为沟垄集雨种植技术的进一步优化及其在旱作农区推广应用提供

氧化亚氮（N2O）是大气中重要的温室气体之一，农田土壤对大气中 N2O 的贡献率高达60%。大量研究表明，施肥、耕作等农艺措施对农田土壤N2O排放具有显著影响。但是，关于旱作农田沟垄集雨种植模式对农田土壤N2O排放的影响及其机理，还缺乏相关研究。本项目以春玉米为研究对象，分别在沟垄集雨种植和平作下设置不施肥、尿素基施、尿素基施加追施（大喇叭口期）、缓释肥基施4个施肥处理，研究沟垄集雨种植和氮肥对春玉米田土壤 N2O排放的影响。研究结果表明，沟垄集雨种植和氮肥施用显著影响了春玉米整个生育季内土壤的N2O排放，施肥和降雨（或灌溉）均会增加各处理的N2O排放，而且年际之间各处理N2O排放水平存在差异。采用温室气体排放强度（GHGI）指标综合分析玉米产量与N2O全球增温潜势，2015和2016年结果表明，和平作相比，沟垄集雨种植模式下GHGI分别减少了4%和20%。相同种植方式下，缓释肥处理温室气体排放强度均显著低于其他施肥处理。两年间沟垄集雨种植下缓释肥处理温室气体排放强度最低，分别为16.8、23.5 kg CO2-eq kg-1 yield。说明在沟垄集雨种植模式下使用缓释肥能够从时间尺度上提高土壤氮素供应与作物需氮的吻合度，在降低了农田温室气体排放强度同时促进了玉米生长，提高了产量。相关性分析结果表明，春玉米田土壤N2O排放强度主要受土壤含水量和土壤铵态氮含量的影响。