Spatial Variability Of Soil Salinity Under Drip Irrigation Conditions In Orchard Of Southern Xinjiang

Soil salinization is one of the main barriers in agricultural production in arid and semi arid areas, especially in southern Xinjiang. Understanding the characteristics of spatial distribution of saline soil and salt ions is important in establishing strategies for soil salinity management. Geostatistics,based on the regional variable theory,has been proved to be one of the most effective methods to analyze the spatial distribution and its variation law of soil properties. It is the foundation to well manage the soil and prevent the soil salinization for fully understanding the spatial distribution of soil salinity.In the present study, the spatial variability of soil salinity in different soil layers were studied by means of GIS,semivariograms of geo-statistics and Kriging method in 2 department 2-6E of 224 regiment of 14 division to quantificationally analyze the spatial variation of soil Salt and salt ions in Study area . The main results are as follows:1.Statistical analysis showed that tota1 salts showed strong variability. According to the classified soil salinity of Xinjiang, the main salt types of the study area is chlorinate in 0～10 cm soil layers and 10～30 cm soil layers is chlorinate-sulfate, in remaining layers the main salt types is sulfate- chlorinate.Ions in the salt, all layers of K⁺ showed moderate variability. In addition to 0～10cm soil layers Na⁺ is high variability, the other layers showed moderate variability. Mg²⁺ showed moderate variability in 70～100,100～140cm soil layers, other layers show strong variability. In addition to 0～10cm soil layers Ca²⁺ is moderate variability, the other layers showed high variability. HCO₃^- showed strong variability in 100～140cm soil layers, other layers show moderate variability. Cl^- showed moderate variability in 50～70,70～100,100～140cm soil layers, other layers show strong variability. In addition to 30～50cm soil layers SO₄^2- is high variability, the other layers showed moderate variability. CO₃^2-was not detected in the experiment.2. Spatial structure analysis shows that ratio of C0/C0+C is between 49%～63.6% belongs to the spatial correlation of moderate intensity. From the range point of view, layers of soil salinity changes in the spatial autocorrelation in line.Ions in the salt, Mg²⁺(in 30～50,100～140cm soil layers),Cl^-1(in 140～180cm soil layers),SO₄^2-(in 0～10,70～100,100～140cm soil layers)have poor spatial correlation.Mg²⁺ (in 0～10cm soil layers),Ca²⁺ (in 0～10cm soil layers),Na⁺(in 0～10cm soil layers),Cl^-1(in 0～10cm soil layers),HCO₃^-(in 0～10,50～70cm soil layers) have a constant variation.The semivariogram of Mg²⁺was best described by the Exponential model, other layers was best fitted by the Spherical mode1. The semivariogram of Ca²⁺,K⁺,Na⁺,HCO₃^-,SO₄^2- was best fitted by the Spherical mode1. The semivariogram of Cl^-1 was best described by the Exponential model, other layers was best fitted by the Spherical mode1.3. The results obtained by the kriging interpolation:The spatial distribution maps of salt salinity interpolated by Kriging interpolation all show apparently strip and block.Ions in the salt, the spatial distribution of SO₄^2- is the most complex ,and spatial distribution of Ca²⁺and K⁺ is relatively simple.Overall , the entire plain has been basically free from soil salinization, the prevention and secondary salinization is essential in farming practice management.