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Soil salinization under large-scale irrigation agriculture in Central Asia

中亚大规模灌溉农业下的土壤盐碱化

基本信息

批准号：
16405023
负责人：
FUNAKAWA Shinya
金额：
$ 5.7万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

To analyze the potential risk of secondary soil salinization, an extensive soil survey was conducted with special reference to salt concentration in deeper layers of soils in different regions of Kazakhstan and Uzbekistan. A clear regional trend was found in terms of contents of soluble salts in the 100-200 cm layers of soils. 1) In the Hi watershed, the contents of soluble cations tend to be low. 2) In the Fergana regions, the contents of soluble cations and SAR are relatively low, but are increased in the lower watershed of Syr-Darya River. 3) In northern Kazakhstan, soluble cations are usually high in subsoils with a high proportion of Na. Thus the salt contents in deep soil layers are primarily determined by geochemical factors. There is a higher fundamental risk for secondary salinization in the lower watershed of Syr-Darya River and northern Kazakhstan than in the alluvial fans such as the Hi and Fergana basins.Then process and risk of soil salinization in rice-based system was analyzed in respective farm scale, with special emphasis on the effect of topography and groundwater level. This study examined the relationships between soil salinity, crop yield and affecting factors including local terrain for two farms. Both farms are characterized by a gentle slope, flat area and localized depressions. Most of the paddy fields showed wash-out of salts during the irrigation period except in waterlogged fields situated in depressions. Rice yield was adversely affected by the remaining soil salinity, deep ponding water and insufficient drainage capacity in the lower part of the irrigation system. Salt accumulation in the upland fields appeared to increase with cropping years, and was associated with groundwater depth that became shallower at the lower parts of the irrigation systems, adversely affecting the crop growth in most fields.

为了分析土壤次生盐渍化的潜在风险，在哈萨克斯坦和乌兹别克斯坦不同地区进行了广泛的土壤调查，特别是土壤深层的盐分浓度。100-200 cm土层中可溶性盐含量有明显的区域变化趋势。1)在Hi流域，可溶性阳离子含量趋于较低。2)在费尔干纳地区，可溶性阳离子和SAR的含量相对较低，但在锡尔河下游流域增加。3)在北方哈萨克斯坦，可溶性阳离子通常是高钠比例的底土。因此，深层土壤含盐量主要由地球化学因素决定。锡尔河下游流域和哈萨克斯坦北方地区次生盐渍化的基本风险高于Hi和Fergana流域等冲积扇地区，在此基础上分析了不同农田尺度下水稻种植系统土壤次生盐渍化的过程和风险，重点分析了地形和地下水位对土壤次生盐渍化的影响。本研究探讨了两个农场土壤盐分与作物产量及地形等影响因素之间的关系。这两个农场的特点是缓坡，平坦地区和局部凹陷。除洼地涝渍田外，大部分稻田在灌溉期间都出现了盐分流失现象。水稻产量受到土壤残留盐分、积水较深和灌溉系统下部排水能力不足的不利影响。高地的盐分积累似乎随着种植年限的增加而增加，并与灌溉系统下部的地下水深度变浅有关，对大多数农田的作物生长产生不利影响。