玉米马铃薯间作对土壤N2O排放的影响及其微生物响应机制

Intercropping, as a planting model, have been widely spread and applied in agricultural production. Previous studies on intercropping concentrate primarily on the yield, resource utilization, interspecies relations; little information was available to show environmental impacts of intercropping, like soil N2O emissions. Based on the main planting pattern in Yunnan, intercropping of maize/potato, adopting closed static chamber, acetylene inhibition techniques and quantitative PCR of functional gene, high throughput sequencing and the followed multivariate methods, this research will focus mainly on: (1) revealing the effect of maize/potato intercropping on soil N2O emissions and its mechanism compared with sole cropping; (2) exploring the microbial response mechanism to varying soil N2O emissions in intercropping in comparison to sole cropping; and (3) the effect of nitrogen fertilizer application on soil N2O emissions in maize/potato intercropping and effective measures to reduce soil N2O emissions in intercropping. The studies in the project, thereafter, can enrich intellectual system of N2O emissions in farmland soil, and provide theoretical and decision-making basis for realizing sustainable development of high-yield, high-efficiency and environment-friendly agriculture utilizing rational intercropping.

间作种植模式在农业生产上得到大面积推广和应用。当前人们对间作的研究主要集中在间作条件下作物产量、资源利用、种间关系等，很少关注间作对土壤N2O排放的影响。本项目基于云南春季作物主要种植模式玉米马铃薯间作，应用田间原位密闭静态箱法，结合室内乙炔抑制培养试验，利用功能基因定量PCR、高通量测序手段以及微生物分子生态学分析方法，主要研究（1）相比于玉米、马铃薯单作，玉米马铃薯间作对土壤N2O的影响及其主要控制因素；（2）玉米马铃薯间作影响土壤N2O排放的微生物响应机制；和（3）氮肥施用量对间作土壤N2O排放的影响及其合理施用量范围。本研究可丰富不同种植模式农田土壤N2O排放的环境效应理论，为利用合理间作实现农业高产、高效、环境友好的可持续发展目标提供决策支持。

农作物相互搭配进行间作，种植历史悠久，应用广泛。当前，有关间作增产、控病、资源高效利用等作用已被大量研究和生产实践所证实，但尚缺乏对其环境效应，如温室气体N2O 排放的认识，使人们难以综合评价间作在协调作物高产、资源高效与环境友好的现代可持续农业发展中的作用。因此，本项目基于玉米马铃薯间作，以玉米和马铃薯的单作为对照，开展4个氮水平的4年田间小区试验，应用田间原位密闭静态箱法和功能基因定量PCR等方法，研究了间作对土壤N2O排放的影响及氮转化关键微生物响应。研究结果表明：.（1）玉米马铃薯间作具有显著土壤N2O减排效应。间作玉米和马铃薯平均减少N2O排放22.7%和29.0%，降低单产N2O排放量16.4%—28.7%，降低N2O排放系数30.6%—34.4%。.（2）土壤空隙含水量、土壤温度、NO3--N、溶解性全氮、溶解性有机氮与玉米和马铃薯种植土壤N2O排放均呈现显著正相关关系，NH4+-N与玉米和马铃薯种植土壤N2O排放呈显著负相关。溶解性全氮含量显著影响土壤N2O排放，且对土壤N2O排放呈献最大。.（3）间作对土壤硝化势有显著影响，影响关系及作用大小与施氮量密切相关。间作降低了土壤中AOA、AOB amoA丰度。单作玉米土壤中narG、nirS基因拷贝数显著高于间作玉米，而单间作玉米土壤的nosZ基因拷贝数均没有显著差异。NO3--N、DON、TDN与NH4+-N是影响土壤氮转化微生物数量的重要因子。.项目实施明确了玉米马铃薯间作对土壤N2O排放的影响及其关键控制因子和氮转化功能微生物响应效应，丰富不同种植模式农田土壤N2O排放的环境效应理论，为利用合理间作实现农业高产、高效、环境友好的可持续发展目标提供决策支持。