不同灌溉量和残膜水平下绿洲棉田水氮均匀度及盐分运移研究

The soil physical structure would be changed by mulch residue, and the moisture and nutrient of soil transport were hampered, Especially in arid regions such as Xinjiang, plastic film led to infiltration of groundwater was difficult, It would be resulted in soil salinization. But, in currently the film pollution researches on water and nitrogen use and distribution contamination of salt movement were less.The project intends to test of field and soil column controlled trial, the stable isotope techniques would be used, Trims locate moisture monitoring technology would be used too. the uniformity distribution of water and nitrogen and using and salt migration would be studied under different levels of irrigation amount in plastic film mild and severe pollution cotton fields. the main factors of water and nitrogen uniformity would be seeked under different levels of plastic film cotton fields; The interaction mechanism of water and nitrogen movement and salt were elucidated under different amounts of plastic film and different irrigation levels on plastic film. The measures and mechanisms of water and nitrogen using were identified at different levels of contamination in cotton plastic film. It would provide technical support for the management of residual contamination of farmland mulch.

地膜残留导致土壤物理结构改变，使得土壤水分、养分运移受阻，特别在新疆等干旱地区，残膜导致地下水难以下渗，造成土壤次生盐碱化。但是目前有关地膜污染对水氮利用和分布均匀性以及对盐分运移影响的研究甚少。本项目拟利用大田控制试验和土柱模拟控制试验，采用稳定同位素技术、Trims水分定位监测技术，在轻度和重度残膜污染棉田，开展不同灌量对不同残膜水平棉田水氮利用和分布均匀性，以及盐分的运移的研究。旨在探明不同残膜水平下棉田水氮均匀性及其主要影响因素；揭示不同灌溉量和不同残膜水平对棉田土壤水氮均匀度影响；阐明灌溉量与残膜量对棉田土壤水、氮及盐分运移交互作用机理；确定不同残膜污染水平下棉田水分和氮素高效利用的机理。为防控地膜残留污染和促进地膜技术的合理应用提供理论依据。

地膜残留导致土壤物理结构改变，使得土壤水分、养分运移受阻，特别在新疆等干旱地区，残膜导致地下水难以下渗，造成土壤次生盐碱化。但是目前有关地膜污染对水氮利用和分布均匀性以及对盐分运移影响的研究甚少。本项目利用大田控制试验和土柱模拟控制试验，在轻度和重度残膜污染棉田，开展不同灌量对不同残膜水平棉田水氮利用和分布均匀性，以及盐分的运移的研究。结果表明：(1)南疆阿克苏地区连续多年植棉棉田的残膜含量大致在225kg/hm2，尚不至于减产。但随着残膜量增加和生育时期的推移水肥状况发生恶化，造成了蕾铃的凋落，导致单株棉铃重的显著降低最终造成棉花产量降低。(2)残膜的存在降低了土壤水利用率和WUE，增加灌溉显著增大了棉田蒸散量，WUE和E/ET逐渐降低，对棵间蒸发量的影响较小。(3) 残膜量越大，土壤水分在湿润体内分布不均匀程度越大。残膜造成的水分分布不均匀程度因灌溉而降低。 (4) 增加残膜量，无机氮沿水平和垂直方向上的阻碍作用明显增强，分布均匀性变差。增加灌溉可削弱残膜的阻碍作用。(5) 残膜抑制干物质的积累与分配，减少了养分输入量，致使产量降低；增加灌溉产量可增加10.1%～13.4%，但耗水量却增大6.8%～29.2%。 (6) 残膜对湿润锋的垂向运移有显著的阻碍作用，但残膜量的多少对湿润锋垂向距离变化没有显著影响。土壤中的残膜会提高土壤稳定入渗率，残膜区土壤湿润体变小。(7) 土壤盐分随残膜量的增加出现先减小后增大的趋势，随残膜量增加盐分的均匀分布变差，残膜阻碍土壤盐分向下运移，导致次生盐渍化。高灌量可减少残膜对盐分的阻碍。本研究结论为防控地膜残留污染、开展残膜阈值对作物水分生产潜力、农田水资源承载预警等工作提供理论依据。