Topsoil Physical Properties And Water Characteristics Of Apple Orchards In Weibei Region Shaanxi Province

Weibei region in Shaanxi Province is the world's best suitable area for apple, but the area is drought, water shortage and difficult to use, therefore, soil water become the first limiting factor in apple production. Soil water characteristics of orchards have great impact on the growth of apple tree, while the physical properties of topsoil directly affect the soil water characteristics in the range of root. For this reason, the soil physical and water properties of apple orchards in Weibei region were determined to analyze the distribution and different levels of relevance and variability, service for the study of ecological characteristics of apple orchard and soil water movement law on the Loess Plateau region, promote the development of apple industry and the scientific use of water resources.Through determine the basic physical properties and water characteristics of topsoil in 12 demonstration apple garden in Weibei region of Shaanxi Province to analyze the soil physical structure and water features in different apple orchards by combination of correlation analysis and equation fitting method. Obtained the following main conclusions:(1) Topsoil in apple orchards is higher silt content and low clay content in mechanical composition: The soil in Ansai is sandy loam, the sand content of up to 76.55%, most of the other samples more than 50% silt content for the silty loam, the clay content of soil in most less than 10%. Soil bulk density have little variation and increased with soil depth. Total porosity decreased gradually. Part of the total porosity of soil samples varied greatly, Show differences.(2) The soil structure of apple orchards in Weibei region is good, water stable aggregates are suitable for the growth of apple trees: Different distribution of soil aggregates varies considerably, the aggregate content of diameter between 0.5mm to 1mm in the middle is the highest, with the increase of soil depth, different aggregate sizes varying in content. The mean weight diameter of topsoil is range between 0.33mm to 1.58mm. Soil organic matter and clay content have important role in aggregate stability, which increased significantly with the organic matter content increase.(3) Soil water characteristic curves of topsoil in apple orchards show: Soil water decreased significantly within the soil water suction increased under low water suction. In the case of low water suction (<100kPa), measured water characteristic curve equation with the power function can be well fited and correlation is high. Soil water suction and water content can be translated as a reference, and for the analysis of different soil texture and water holding capacity. Further more, provide the conditions for the rational and efficient use of soil water and scientific guidance for irrigation.(4) Soil water retention and hydraulic conductivity characteristics of topsoil in apple orchards show: With soil depth increase, saturated water content lower; fluctuations in the distribution of soil field capacity, reflecting the characteristics of topsoil water spatial variability; soil saturated hydraulic conductivity have certain fluctuations, the overall slightly lower in the soil profile showed heterogeneity. Soil effective water content change along the soil profile in law is not strong; Ansai soil has slightly high soil water availability while Pucheng soil is low. Soil texture, bulk density, structure, organic matter content, temperature and other factors are all have impact on soil water movement. The more aggregate content and smaller bulk density, the more gentle water retention curve at low suctions. The accumulation of organic matter can improve soil structure, porosity condition and soil hydraulic conductivity, and also help to maintain soil moisture and increase soil water content.