Assessment of water and solute transport characteristics during salt accumulation and leaching, and establishment of proper soil management for sustainable agricultural production in arid and semi-arid regions.

本研究的目的是弄清干旱地区盐分积累和淋溶后的溶质运移，并建立适当的土壤管理，以防止过度灌溉导致的土壤退化。本研究利用大型水柱对恒高地下水位条件下盐分积累过程中蒸发过程中的水流和溶质运移进行了测量。通过测定盐分含量、水分含量与土壤反照率之间的关系，发现土壤表面反照率随累积盐分质量的增加而增大。利用盐分积累形成的盐结皮数字分析方法，研究了结晶化土壤的水平分布。讨论了砾石覆盖对蒸发的影响，重点讨论了土壤表面上下水汽输送的阻力。讨论了淋洗水质对盐渍土水力性质的影响，并对碱化土的团聚体稳定性进行了评价。移动…讨论了土壤中更多的阳离子在积累和淋溶过程中的作用。开发了土壤水分流动、溶质和热量运动的一维数值模拟软件WASH-1D，以模拟降雨引起的盐分蒸发和淋溶过程中的积盐。提出了一种流量控制的稳态蒸发方法，用于测定低水头条件下的非饱和导水率。讨论了一种测定土壤导热系数的简单方法，以及水分、溶质浓度和温度对沙丘沙地导热系数的影响。在籽粒高粱栽培过程中，观察到连续灌溉和间歇灌溉土壤水分电导率的差异。对地下水咸化沙化旱地在海水入侵条件下的土壤水盐动态进行了测量和模拟。研究表明，沙地覆盖对防止土壤盐碱化是有效的。较少

Objective of this study was to clarify solute movement following salt accumulation and leaching in arid areas and to establish proper soil management to prevent soil degradation from over-irrigation. In this study, measurement of water flow and solute transport during evaporation was carried out during salt accumulation process under constant high ground water level using large column. After measuring the relationships among salt content, water content and soil albedo, it was found that the albedo of soil surface increased with increasing mass of accumulated salt. The horizontal distribution of rystallizied soils was investigated using digital analysis of salt crust caused by salt accumulation. Effects of gravel mulch on evaporation with emphasis on resistance to water vapor transfer above and below the soil surface were discussed. Effects of leaching water quality on hydraulic properties of saline soils were also discussed and the aggregate stability of sodic soils was evaluated. Move … More ment of cations under accumulation and leaching processes in soils was discussed. WASH-1D software for one-dimensional numerical simulation of water flow, solute and heat movement in soils was developed in order to simulate salt accumulation with evaporation and leaching due to rainfall. A flux-controlled steady-state evaporation method was proposed for determining unsaturated hydraulic conductivity at low matric pressure head values. A simple method of measuring soil thermal conductivity as well as the influences of water content, solute concentration, and temperature on thermal conductivity of dune sand were discussed. Differences in electrical conductivity of the soil water between continual and intermittent irrigation were observed during grain sorghum cultivation. Dynamics of soil water and salt in sand-dressed upland field with salinized ground water due to sea water intrusion was measured and simulated. It was established that sand dressing was useful to prevent soil salinization. Less