洱海流域农田面源污染控制的土壤碳氮共济机制

Agriculture non-point source pollution prevention and control research have regional characteristics in Erhai lake watershed because of its unique landscape, non-point source pollution laws and the way of agricultural production. Farmland non-point source pollution control is the key to improve the Erhai lake water quality, soil carbon and nitrogen management may be the important measures to contain nitrogen non-point source pollution. Firstly, this project will clear the quantity of carbon and nitrogen in soil, clearly define the mass fraction of carbon and nitrogen in the soil through dissection of soil carbon and nitrogen composition characteristics, chemical composition and component. Through field experiment study of soil carbon and nitrogen reciprocity mechanism and reverse factors, understanding the internal and external factors of the carbon and nitrogen fraternal relations form, clear different carbon and nitrogen management field to the effect of carbon and nitrogen in all aid, influencing soil carbon and nitrogen in all aid state key agronomic measures and environmental factors; In the field monitoring and simulation tests study the process and mechanism of the soil nitrogen loss under different soil carbon and nitrogen in all aid situation to clarify carbon and nitrogen regulation of nitrogen loss control. Erhai lake farmland soil carbon and nitrogen in all aid mechanism research will help us to provide theory support of the field carbon and nitrogen management and non-point source pollution prevention and control.

洱海流域由于独特的地貌、面源污染发生规律和农业生产方式，农田面源污染防控研究具区域特殊性。农田面源污染控制是改善洱海水质的关键，农田土壤的碳氮管理可能是遏制氮素面源污染的重要措施。本项目首先通过解剖土壤碳氮的组分学特征、化学组成及成分，明确洱海流域农田土壤中的碳氮数量、质量，明确碳氮在土壤不同库中的质量分数和数量；通过田间试验研究揭示土壤碳氮的互惠机制和逆转因素，摸清碳氮共济关系形成的内外因素，明确不同碳氮田间管理方式对碳氮共济效应的影响，探明影响土壤碳氮共济状态的关键农艺措施和环境因子；采用田间监测和模拟试验，研究在不同土壤碳氮共济情景下土壤氮素流失机制和过程，阐明碳氮调控对氮素流失的阻控机理。通过本项目研究揭示洱海农田土壤碳氮共济效应的形成机理，明确碳氮共济效应在控制氮素面源污染的过程中如何发挥作用。洱海农田土壤碳氮共济机制研究有助于为洱海流域面源污染的防治提供田间碳氮管理的理论支撑。

农业面源污染是湖泊流域氮、磷主要的污染源，如何解剖洱海流域农田土壤碳氮关系，了解土壤碳氮的存在特征、数量、质量以及转化过程，土壤碳氮自身“同舟共济”应对氮素面源污染问题的机制十分必要。本项目围绕洱海流域农田土壤碳氮关系研究，以期揭示揭示洱海流域农田土壤碳氮数量、质量和组分特征，剖析碳库和氮库组成及其相互关系，探明土壤碳氮共济效应的作用机理及其对控制氮素面源污染的机制和过程。项目通过田间试验、盆栽实验、定位监测、实验室检测等方式开展研究。明确了水稳性团聚体尤其是>2mm的大团聚体能保持土壤结构的稳定性，土壤有机质含量越高，土壤氮素越不容易流失；降低土壤的氮库，提高土壤碳氮比，能够减少土壤矿质氮素残留至24.40mg·kg-1；改变耕作制度可以显著增加土壤有机碳储量，提高氮素利用率，减少土壤氮素过剩，从而降低水稻土壤氮素流失的风险。改变耕作方式的土壤C/N比值比习惯处理提高了约11.40%。免耕覆盖和有机肥倍增的溶解性有机氮含量分别提高了28.20%和28.68%，微生物量氮增加了32.43%和20.94%，有机肥处理的氮流失系数明显下降。改变耕作制度全年氮利用率从21.6%上升到34.4%。本研究研究显示了可以通过显著增加土壤有机碳储量，提高氮素利用率，减少土壤氮素过剩，从而降低水稻土壤氮素流失的风险。平衡的的土壤碳氮共济状态有助于降低氮素面源污染的风险，土壤碳氮共济失调可能会带来严重的氮素流失。本项目发表核心期刊以上论文5篇；申请国家专利5项。4项获得授权，1项获得受理，培养硕士研究生1名。