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.

本研究的目的是阐明干旱地区盐分累积和淋溶后的溶质运动，并建立适当的土壤管理，以防止过度灌溉造成的土壤退化。采用大柱法，在恒定高地下水位条件下，对盐积累过程中蒸发过程中的水流和溶质运移进行了测量。通过测定土壤含盐量、含水量与土壤蒸发量的关系，发现土壤表层蒸发量随积盐量的增加而增加。通过对盐结皮的数值分析，研究了盐渍土的水平分布。本文讨论了砾石覆盖对蒸发的影响，着重讨论了砾石覆盖对土壤表面上、下水汽输送的阻力。探讨了淋洗水质对盐渍土水力性质的影响，并对苏打土团聚体稳定性进行了评价。移动 ...更多信息 讨论了阳离子在土壤中积累和淋溶过程中的作用。为了模拟降雨引起的盐分累积、蒸发和淋溶过程，开发了一维土壤水分、溶质和热量运动数值模拟软件WASH-1D。提出了一种确定低基质水头下非饱和导水率的流量控制稳态蒸发法。讨论了土壤导热系数的简易测定方法以及水分、溶质浓度和温度对沙丘砂导热系数的影响。研究了高粱栽培过程中连续灌溉和间歇灌溉土壤水电导率的差异。对海水入侵引起地下水盐渍化的高地土壤水盐动态进行了观测和模拟。结果表明，沙培对防止土壤盐渍化是有效的。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