Interrelationship between nutrient and water uptake of crops and salt accumulation in the soil under arid conditions

本研究旨在探讨干旱条件下地下水位高的土壤中盐分累积的机理。研究中引入的因素是土壤的理化特性、地下水位和土壤上生长的植物。所用土壤为沙丘土、湿润土、改良冲积土和红黄壤。使用的植物是大豆、卷心菜和玉米。在沙丘土中，地下水位对土壤水分剖面和蒸散量有显著影响。30厘米的水平使表层土壤层干燥。高地下水位增加了蒸散量，但没有造成盐分在表层的积累。植物生长所增加的耗水量也不会导致盐分的积累。由于沙丘土CEC较低，随水迁移的盐分并未被固定。在红黄壤中，地下水位和作物生长对土壤水分剖面的影响不大，但对土壤盐分的累积有较大影响，尤其是作物生长对土壤盐分的累积影响较大。Na^+在地下水中的迁移和分布也受土壤阳离子交换速率的影响，砂姜黑土和冲积土的盐分积累量介于沙丘土和红黄壤之间。

The purpose of the study was to investigate the mechanism of salt accumulation in the soils with high groundwater levels under arid conditions. The factors brought in the study were physico-chemical characteristics of the soil, groundwater level, and growing plants on the soil. The soils used were the Dune soil, Masa soil, improved Alluvial soil and Red and Yellow soil. The plants used were soybean, cabbage and corn. Several groundwater levels between 15cm and 35cm were kept using mariots.In the Dune soil, the groundwater level strongly influenced the soil water profile and evapotranspiration. The 30cm level made the surface soil layr dried. The high groundwater levels increased the evapotranspiration, but did not accumulated the salts in the surface soil layr. Neither an increased water consumption by growing plants brought about the salt accumulation. It seemed that the salts moved with water were not fixed due to the low CEC of the Dune soil. This might be supported by the fact that the salt accumulation in the surface soil layr increased with the increasing clay content and CEC of the soil.In the Red and Yellow soil, the groundwater levels and growing plants had a little effect on soil water profile, but had a large effect on the salt accumulation in the surface soil layr, especially under growing crops. Also the movement and distribution of Na^+ in the groundwater was influenced by the exchanging rate with cations in the soil.The salt accumulation in the Masa soil and the Alluvial soil was in the middle between the Dune soil and the Red and Yellow soil.