非灌溉季节长期膜下滴灌棉田土壤盐分时空迁移机理研究

Soil salinization has always been one of the most important issues to be solved urgently in the world of land resources and ecological environment. The long-term drip irrigation of salt water is a new component of salinization in Xinjiang. With the application of drip irrigation technology in Xinjiang, emergence of water-saving soil salinization problems. Many studies focused on the drip irrigating season or the crop growth period, and the research on the evolution regularity or influencing factors of long-term drip irrigation under non-irrigation season was relatively weak. Therefore, this project aims at the mechanism of spatial and temporal migration of soil salinity in farmland under long-term film mulching drip irrigation in the non-irrigated season in the typical oasis area of northern Xinjiang. Explored the mechanism of drip irrigation duration, freezing and thawing, ice water infiltration, evaporation and groundwater dynamics on salt migration, clarify the spatial and temporal migration of salt in soil and the main influencing factors under film mulching drip irrigation, and reveal the key process of salt migration (freeze-thaw phase) and migration mechanism, construct the mathematical model of soil salt migration, put forward the control measures of soil salinity in non-irrigation season in arid area, For further studying the regulation and regulation of salt migration in irrigated or basin-scale ecosystems under the conditions of large-scale and water-saving in arid areas, and provide the basis for the basic data and research paradigms, and provide important theoretical basis for sustainable application of drip irrigation under arid area.

土壤盐渍化始终是世界性土地资源与生态环境领域内亟待解决的重要问题之一，长期膜下滴灌盐分问题是新疆盐渍化问题一个新的组成部分，随着新疆膜下滴灌技术应用年限增长，出现节水灌溉型土壤盐渍化问题。诸多研究时段集中在膜下滴灌的灌溉季节或作物生育期内，对于非灌溉季节长期膜下滴灌盐分的演变规律或影响因素研究相对比较薄弱。因此，本项目针对北疆典型绿洲区非灌溉季节长期膜下滴灌农田土壤盐分时空迁移机理进行研究，探究滴灌年限、冻融、冰水入渗、蒸发和地下水动态等对盐分迁移的作用机理，阐明滴灌土壤盐分时空迁移规律与主要影响因素，揭示盐分迁移关键过程（冻融阶段）与迁移机理，构建土壤盐分迁移数学模型，提出干旱区非灌溉季节农田土壤盐分调控对策，为进一步开展干旱区规模化节水条件下灌区或流域尺度生态系统盐分迁移规律与调控研究提供基本认识过程、模型系统、基础数据和研究范例，为干旱区膜下滴灌可持续应用提供重要理论依据。

土壤盐渍化始终是世界性土地资源与生态环境领域内亟待解决的重要问题之一，长期膜下滴灌盐分问题是新疆盐渍化问题一个新的组成部分，随着新疆膜下滴灌技术应用年限增长，出现节水灌溉型土壤盐渍化问题。本项目针对北疆典型绿洲区非灌溉季节长期膜下滴灌农田土壤盐分时空迁移机理进行研究，探究滴灌年限、冻融等对盐分迁移的作用机理，阐明滴灌土壤盐分时空迁移规律与主要影响因素，揭示盐分迁移关键过程（冻融阶段）与迁移机理，构建土壤盐分迁移数学模型，提出干旱区非灌溉季节农田土壤盐分调控对策。根据课题目标，项目组开展了连续4年的田间定位监测，明确了棉田总盐分布特征随长期膜下滴灌从表聚型向底聚型转变的时空变化规律，证实了长期膜下滴灌对棉田土壤盐分的淋洗作用和盐分逐年降低的趋势。揭示了非灌溉季节冻融过程中盐分迁移的三个特征阶段：冻结过程中表层土壤中的盐分积累、解冻过程中土壤盐分的减少和解冻过程后土壤盐分的重新增加。并确定了冻融过程中盐分累积的两个特征阶段中土壤盐分累积主要与初始土壤含盐量和土壤容重成正相关关系，而与土壤粘粒含量无明显相关关系。通过探地雷达250 MHz和1000 MHz频率天线的组合，结合修正的Dobson介电模型，较好的反演出膜下滴灌棉田的含盐量，并捕捉冻融作用下盐分的迁移过程，并通过SHAW模型成功模拟棉田土壤水温盐的分布特征。结合北疆棉秆还田措施调控棉田土壤水热条件，减轻膜下滴灌棉田土壤盐分的表聚，降低了融后土壤储盐量，从而营造良好的播前环境。研究为干旱区长期膜下滴灌节水，控盐及地力提升综合调控技术模式，为长期膜下滴灌可持续应用提供重要理论依据。依托本项目共培养硕士研究生4名，博士生2名；发表学术论文28篇，其中SCI检索11篇，EI检索2篇，中文核心17篇；申请国家发明专利1项；部分成果荣获全国农业节水科技奖二等奖和新疆水利科学技术奖一等奖各1项。