Soil Moisture Study Yanchuan Economy

In order to the rational and effective utilization of soil water resources and the realization of the increases in grain production and the sustainable development of agriculture, the paper studied the variation characteristics of soil moisture of applejujube and pear tree land in the depths of0～4.0m at Yanchuan. A compartment model was used to study the vertical changes of soil moisture of apple trees.Besides, it studied the soil water availability, dried soil layer and the influence of dried layer to the soil reservoir, and water cycle and water balance of the three kinds of economic tree land.The main conclusions were described as follows:(1) The soil moisture of apple tree land reduced rapidly and fluctantly from up to down in the0～1.1m soil layer, and between near1.1m and4.0m declined, then increased and decreased at the subsequent, to be in relative steady state. The soil moisture of jujube tree land increased from up to down in the0-0.4m soil layer and was in relative steady state from near0.4m to4.0m. The soil moisture of pear tree land reduced first then increased from up to down in the0～1.5m soil layer and was in relative steady state in the1.5～3.0m soil layer and increased below3.0m. Average water content of each drilling profile of jujube tree land was the highest (10.6%), jujube tree land was second (10.0%), and apple tree land was lowest (7.1%).(2) The compartment model could objectively and well reflect the process of the vertical changes of soil moisture of apple tree land.The goodness of fit was0.936.(3) Except soil water of individual soil layer of pear tree land in semi-available water, soil water of the three kinds of economic tree land was difficult available water and absorbing soil water was inhibited. Soil water of apple tree land below0.9m soil layer was close to unavailable water, the whole profile of jujube tree land was close to semi-available water, and some soil layer of pear tree land was close to semi-available water. If in continuous drought, the normal growth and development of apple tree was most vulnerable to disadvantageous effect, pear tree was second and jujube tree was least.(4) Each profile of apple, jujube and pear tree land in the2.0～4.0m soil layer existed dried soil layer. Apple tree land had developed mild dried soil layer, moderate dried soil layer and severe dried soil layer.Jujube tree land had only developed mild dried soil layer. Pear tree land had developed mild dried soil layer and moderate dried soil layer.(5) The vertical migration of soil water and the bond between deep soil water and the surface of apple, jujube and pear tree land was respectively slowed and cut off by dried soil layer.Water cycle was mainly ground water cycle, and didn’t exist basically groundwater circulation. Soil-plant-atmosphere water cycle model was formed and belonged to abnormal water cycle type.Dried soil layer developing toward the steady speed would lead to underground water level continous depression and underground water resource decreased.(6) Effective regulation reservoir capacity of apple, jujube and pear tree land was large and accounted for91.8%、66.8%and71.3%respectively of effective reservoir capacity. Soil water content of the three kinds of economic tree land was low and the land possessed big water storage potentiality and limited regulating capacity. Dried soil layer made deep soil water compensation to economic forest land in drought season weakened, weakened regulating capacity of soil reservoir to drought to some extent and had influence on the normal growth and development of economic tree.