膜下滴灌农田水盐迁移对土壤-残膜-根系多界面系统的响应机制及模拟研究

The drip irrigation under mulch played an important roles in saving water, controlling salinity and increasing crop production, and have developed radidly in recent years. however, plastic film mulch is hard to degrade by itself, and bring about large plastic pollution and seriously influence water and fertilization use efficiency and agriculture sustainable development.The project study the response.mechanism of soil water and salt migration on plastic residual film in drip irrigation under mulch, and the simulation of soil water and salt in multi-interfaces of soil-residual film-crop roots.The experiments will be carrid out including the effects of residual film on soil structure and soil hydrodynamic parameters by CT image techenology, the influence of residual film on soil water and salt non-uniform distribution using dye tracer and the mesurement of root distribuiton,crop growth and yield.Combing the theory of probability and random and intruducing blocking factor of residual film, the functional relationship of residual film and soil hydrodynamic parameters,and crop root distribution model will be studed, and the stochastic model of soil water and salt movement will be proposed based on Hydrus model. The soil water and salt would be simulated by the model under different situations, and the optimal irrigation program and application pattern of dirp irrigation field under residual film would be proposed for a successful spread of drip irritaon and agricultural sustainable development.

膜下滴灌技术由于具有明显的节水、控盐和增产效应，近年来得到跨越式发展，然而农用地膜为聚乙烯材料，难以自降解，农膜残留问题日益严峻，严重影响了水肥高效利用及农业可持续发展。本项目主要针对盐渍化地区膜下滴灌农田水盐迁移对农膜残留的响应机制，以及土壤-残膜-根系多界面系统中水盐迁移模拟开展研究。借助CT扫描技术和相关试验研究探索不同残膜量对土壤结构和水动力学参数的影响机制，利用染色示踪技术研究不同残膜量对土壤水盐非均匀分布的影响过程，并定位连续监测不同残膜量对土壤水盐、作物根系分布及作物生长指标和产量的影响。结合随机理论，引入残膜阻碍因子建立残膜与土壤动力学参数的函数关系，作物根系生长分布随机模型，并在Hydrus源码基础上构建农膜残留滴灌农田土壤水盐随机模型，并对不同情景进行模拟，以期建立残膜存在下滴灌农田最优灌水模式，为农业可持续发展奠定理论基础。

膜下滴灌技术能具有明显的节水、控盐和增产效果，所以发展推广非常快，但是农膜残留问题十分严重，多年连续应用会显著影响农田水肥高效利用及农业可持续发展。但农膜残留对土壤水盐迁移和作物生长的影响尚不明确，本项目通过4年的田间、室内试验和模拟研究，阐明了土壤物理、水力性质对残膜的响应机制，掌握了不同残膜量对玉米根层生长的影响，探明了不同残膜量和灌溉水平下膜下滴灌农田土壤水盐迁移过程，并提出农膜残留条件下节水高效型灌溉制度。主要成果如下：（1）土壤容重、饱和导水率和饱和含水率随残膜量的增加呈下降趋势，土壤总孔隙度则呈上升趋势，当土壤中残膜量达到450kg/hm2后继续增加，残膜对土壤物理和水力性质的影响逐渐减少。（2）CT图像显示土壤中片状黑斑面积随残膜量的增加明显增加，其中400 kg/hm2处理黑斑面积是无膜处理的19倍。（3）随着残膜量的增加，玉米根长密度和根重密度均呈下降趋势，比根长呈增加趋势。（4）土壤中残膜使得根量总体减少，但单位根量的吸水能力却增强。（5）在0-30cm土层，常量和减量灌溉下（15 m3/亩，10 m3/亩），随着残膜量增加平均土壤含水率和电导率越高，而增量灌溉下（20 m3/亩）则相反；在30-100cm土层与之相反。（6）基于染色示踪技术显示土壤中的残膜量越多，土壤优先流越明显，土壤水流动变异性越大；随着入渗量增加，残膜引起的优先流和变异性越明显。（7）农膜残留阻滞玉米冠层生长，特别在玉米生长前期，土壤中残膜量越多玉米冠层发育越差。（8）通过Logistic生长模型及水盐运移规律确定了危害作物生长的残膜量阈值(300kg/hm2)并提出适合盐渍化地区含残膜农田的灌溉水量。综上所述，本项目为膜下滴灌下农膜残留量标准的相关政策法规制定和膜下滴灌的可持续性发展提供理论依据和技术支持。