Water consumption of deep soil layers and eco-environmental effects of agricultural ecosystem in the Loess Plateau

Weibei upland in southern part of the Loess Plateau is a rainfed farming area where the soil water controls the water application of plants. Different plants cultivated successively for a long term may affect water contents of deep soil layers. But constant increase of agricultural productions and continual growth apple tree can lead to soil drought and form a desiccative layer below the soil surface layer, which could affect the water cycle of return into soil. This paper reported that effects of different cultived land use patterns on deep soil water contents in the upland of the Loess Plateau and compared to the results of a long-term experiment. The main results were as following: The soil water content of bare land was highest in soil profiles, and its mean water content was 21.98%. Then, the water contents of uncultivated land and tobacco land were smaller than that in the bare land. Young acacia and ten-year apple tree consumed as same water as that of high-yield field, furthermore, fifteen-year apple tree and artificial alfalfa used much more water than that of high-yield crops. The apple tree consumed a great quantity of water from the deeper soil layers, which could lead to the desiccation of soil. Because most fields are high-yield field and apple orchard on the Weibei upland, their average soil water content of deep layers were 12%～14%. That a large number of apple tree planted will result in the desiccation of field soils on the upland, which will affect the water cycle in this area.