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高地下水位土壤的盐分积累机制。研究中引入的因素包括土壤的物理化学性质、地下水位和土壤上生长的植物。所用土壤为沙丘土、麻砂土、改良冲积土和红黄壤。使用的植物是大豆、卷心菜和玉米。在沙丘土壤中，地下水位对土壤水分剖面和蒸散量影响较大。30 cm土层使表层土壤变干。高地下水位增加了蒸散量，但不积累表层土壤盐分。生长植物耗水量的增加都不会导致盐分的积累。由于沙丘土壤的CEC较低，盐分随水运移似乎并不固定。这可能与土壤表层盐分积累量随土壤粘粒含量和阳离子交换量的增加而增加有关。在红壤和黄壤上，地下水位和生长植物对土壤水分剖面影响不大，但对表层盐分积累量有较大影响，尤其是在作物生长的情况下。Na+在地下水中的运移和分布也受土壤中阳离子交换率的影响，马萨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.