膜下滴灌农田暗管排水技术土壤水盐运动机理研究

Xinjiang, the province which is located in inland arid region, is in the condition of water scarcity, thus water saving irrigation techniques are developing rapidly here. Up to now, the drip irrigation area has covered over 30 million acres. However, with the development of water saving irrigation, the irrigation without drainage gradually causes the large area of abandoned farmland drainage systems, this in turn results in the accumulation of field soil salinity which leads to the growing threat of secondary salinization to farmland. In view of this current situation of water saving irrigation in Xinjiang, and using the closed drainage technology under mulched drip irrigation farmland, the project carries on the research of water and salt transport mechanism concerning the closed drainage technology under mulched drip irrigation farmland. Making use of 15N isotope tracer technique and the monitoring technology of soil water and salt, combining numerical simulation and software simulation, by the monitoring of drainage volume, drainage quality and 15N isotope of drainage, and by the continuous monitoring of the change in field soil salinity as well as by the combined monitoring and analyzing of field soil and 15N isotope in drainage flow, this project aims to research on the law of movement of water and salt under mulched drip irrigation with the closed drainage technology, to reveal the movement mechanism of soil water and salt under that condition. And through numerical simulation and model construction for water and salt movement under mulched drip irrigation, this project is designed to accurately describe the process of water and salt movement under drip irrigation farmland with closed drainage and to provide a theoretical basis and technical support for the development of mulched drip irrigation.

新疆处于内陆干旱区，水资源匮乏，因此节水灌溉技术发展迅速，滴灌面积已经超3000万亩。但是由于节水灌溉的发展，农田排水系统大面积废弃，形成了农田有灌无排现状，造成田间土壤的盐分累积，导致农田次生盐渍化的威胁日益严重。项目针对新疆节水灌溉的现状，在膜下滴灌农田使用暗管排水技术，进行膜下滴灌农田暗管排水技术的水盐运移机理研究。项目利用15N同位素示踪技术、原位土壤水盐监测技术、数值模拟与软件模拟相结合，通过对排水流量、排水水质、排水中的15N同位素监测；对田间土壤盐分变化的定点连续监测；以及对田间土壤和排水中的15N同位素的监测与分析，研究膜下滴灌农田暗管排水的水盐运移规律、揭示膜下滴灌农田暗管排水的土壤水盐运动机理、并对膜下滴灌农田暗管排水的水盐运动规律进行数值模拟，建立水盐运动规律模型，旨在准确描述滴灌农田暗管排水的水盐运动过程，为膜下滴灌技术发展提供理论依据与技术支持。

随着膜下滴灌的长期使用，农田土壤积盐问题日益受到关注。为了探究滴灌条件下暗管排水规律和土壤脱盐、洗盐效果和膜下滴灌暗管排水条件下棉田土壤盐分变化规律，本项目基于石河子大学现代节水灌溉兵团重点实验室和新疆122团盐碱地分别进行室内模型试验和大田试验，室内试验通过土柱试验研究分析了不同暗管埋深和灌水量对暗管排水排盐效果及土壤脱盐效果的影响，基于土槽试验探究了灌水过程对暗管排水排盐规律及土壤脱盐效果的影响，并利用HYDRUS软件模型模拟验证了灌溉排水过程中土壤水盐运移规律，大田试验基于连续八年（2012-2019）进行田间试验获得的数据，本研究旨在探讨比较在长期使用膜下滴灌的条件下，应用明沟和暗管两种排水技术对土壤盐分、地下水、水盐排放、土壤盐分均衡、作物产量以及经济效益影响，研究结果为旱区膜下滴灌条件下明沟和暗管排盐技术的推广和应用提供了理论支撑和科学依据。