陕西省延川县孙家塬经济林土壤水分和水分平衡

对陕西省延川县孙家塬枣树林和苹果林4m深度土层水分的变化进行了研究,并对土壤水分有效性、土壤干层及其水循环等方面进行了分析。结果表明,枣树林地含水量平均为10.6%,还有4.5%的土壤水资源可以利用。苹果林地4m深度范围内平均含水量为7.4%,2.0—4.0m深度范围内土壤水资源基本耗尽。苹果林地土壤含水量自上向下呈现高—低—高分层变化特点,枣树林地土壤水分剖面垂向分层不明显。枣树林地和苹果林地土壤水分基本都呈难效水状态,但枣树林土壤水分接近中效水,土壤水分对苹果林生长具有严重的抑制作用,对枣树林的生长基本没有抑制作用。枣树林地2.0—4.0m深度范围仅有轻度干层发育,苹果林地土层2.0—4.0m深度范围有轻度干层、中度干层和重度干层发育。苹果林地和枣树林地土壤干层切断了深层水分与上层的联系。水循环主要表现为地表水循环,基本不存在地下水循环,形成了土壤—植物—大气的水分循环模式,属于异常水分循环类型。干层长期发展会导致该区地下水位的持续下降和地下水资源减少。该区土壤水分条件更适于发展枣树经济林。

Soil Water Content and Water Balance of Economic Trees at Sunjiayuan in Yanchuan County of Shaanxi Province

The variation characteristics of soil moisture of jujube and apple trees, soil water availability, dried soil layer and the influence of dried layer to the soil reservoir, and water cycle and balance in the depths of 0-4.0 m at Sunjiayuan in Yanchuan County, Shaanxi Province were analyzed. The results showed that the average soil moisture of jujube tree was 10.6% in the depths of 0-4.0 m and there is about 4.5% available water. The average soil moisture of apple land was 7.4% in the depths of 0-4.0 m which indicates available water was exhausted nearly. Soil moisture of apple tree land presented layered change of "high-low-high" from up to down, and jujube forest vertical change in soil moisture profile was not obvious. Soil water of the jujube and apple trees land was almost difficult available water, but soil water of the jujube trees land is near middle available water. Absorbing soil water was inhibited to some extent for apple trees, but almost no effect on jujube trees. Jujube tree land had only developed mild dried soil layer in the 2.0-4.0 m soil layer, and apple trees land had developed mild, moderate and severe dried soil layer. The bond between deep soil water and the surface of apple and jujube tree land was cut off by dried soil layer. Water cycle was mainly surface water cycle, and underground water circulation did not exist nearly. Soil-plant-atmosphere water cycle model was formed and it belonged to abnormal water cycle type. Dried soil layer developing toward the steady speed would lead to underground water level continuous depression and underground water resource decreased. Soil water in the region was more suitable for developing jujube trees.