地膜残留对土壤水氮运移和棉花根系影响研究

Recently, as agricultural film mulching technology is spreading rapidly,the agricultural plastic film residue pollution become more and more serious,due to the plastic film residue exist in the soil.The plastic film residue in the filed canbring a set of side effects, such as destructing soil structure of plow layer, influencing soil permeability and hindering the movement of moisture and nutrient, which affect crop growth and development and finally result in decreasing crop yield. Moreover, it has been a main barrier to agricultural sustainable development in some region. But, at present, very few researches involves this sturdy about movement of moisture and nutrient elements, but yet not examining the effect on root architecture, mechanism interaction between soil moisture, nitrogen and crop root system. Thus, this project has certain plans, with utilizaton of the methods of field test and the control experiment, the isotope technology, the moisture monitoring technology and the non-destructive micro root window root system monitoring technology, to carry the study on the movement characteristics of water and nitrogen in soil, the spatial and temperate pattern of water and nitrogen under different film residue pollution level,and to describe the cotton root asystem and its physiology characteristic which affect by plastic residue pollution. It studies the mechanism interaction between root system and water and nitrogeni the soil. The processing of water and nitrogen movement are clarified, and determing the key parameters of root system and movement of water and nitrogen affected by the plastic film residues pollutiong level, and to support new theory and techqiues for contorlling and fighting agricultural film residue pollution.

随着地膜覆盖技术广泛应用,地膜残留污染问题越来越严重，残膜破坏土壤耕层结构、影响土壤通透性、阻碍土壤中水分和养分运移，影响作物生长发育和导致作物减产等问题已成为农业可持续发展的一个重大障碍。但关于残留地膜污染影响土壤水分、养分运移和作物生长发育的研究甚少。本项目拟利用大田控制试验和土柱模拟控制试验，并采用稳定同位素技术、Trims水分定位监测技术和非破坏性微根窗根系监测技术，在轻度、中度和重度地膜残留污染条件下，农田土壤水氮运移特征和影响因素研究；研究不同残膜污染水平下棉花根系构型和根系生理特点，并研究探讨不同残膜污染水平下水氮运移与根系相互作用关系。探明残留地膜对土壤中水氮运移和棉花根系构型的影响，阐明不同残膜污染水平下土壤水氮的运移过程，水氮运移与棉花根系构型和生理特性的相互作用机理，确定影响水氮运移和棉花根系生长的关键参数，为地膜残留污染农田的治理提供技术支撑。

地膜的大量使用已经在我国引起了严重的残膜污染，尤其是在棉花种植农田，地膜残留现象更为显著。地膜残留可能通过改变土壤物理性质和作物根系发育，影响到土壤水分和氮素的运移过程和作物水氮利用。探索地膜残留对土壤水氮运移、根系发育及二者互反馈作用对于研发地膜残留污染治理措施及覆膜农田水氮管理措施具有重要理论意义。为此，本项目从不同残膜污染水平下土壤水氮运移特征，不同残膜污染水平下棉花根系构型和生理特性，不同残膜污染水平下水氮运移与根系的相互作用三个方面开展了相关研究。本项目通过土柱试验研究，基本摸清了点源供水条件下地膜残留对水氮运移的影响。相关研究结果表明土壤残膜会增加土壤水分的横向运移并抑制其垂向运移，并且在水氮共运移过程中，地膜残留量的增加会引起氮素分布不均匀性的增加，但氮素分布不均匀程度与残膜量具有非线性关系；通过大田条件下作物蒸散、蒸发、土壤含水量等方面的研究，发现地膜残留量越大，棵间蒸发以及蒸发占蒸散的比例越高，降低棉田地膜残留量可有效地减少无效耗水，提高水分利用率；通过定量观测地膜残留量与棉花单株总根长、根表面积及根粗之间的关系，发现在一定范围内的地膜残留（本研究中为90-180kg/ha）不会对棉花根系发育起抑制作用，而当残膜量超过一定范围（本研究中为180kg/ha），地膜残留对棉花根系发育会产生明显的抑制。这进一步解释了地膜残留下无效耗水比例较高的原因，即地膜残留可能通过抑制根系发育进一步抑制根系吸水从而降低了作物水分利用效率。综上，本项目从土体水氮运移、农田耗水结构、作物根系发育三方面阐明了地膜残留影响水氮运移和利用的机制，充分论证了在覆膜农田中减少地膜残留量的必要性，进一步完善了覆膜农田水氮管理理论体系。