Evaluation on Effect of Soil Improvement of Wind-Break and Snow-Prevent Zoology Project Constructed

This study sampled soils from different forest age wind break forest, the farmland and desert. And tested the soil organic matter, rapidly available N,P and K; total N, P and K; salt content, pH, soil porosity, soil unit weight and physical clay content. The results show: with the increase of forest age, the content of rapidly available P tends to descend, the content of total N increases distinctly, the content of total P keeps former level basically; soil organic matter, rapidly available N and K decrease firstly and then increase; the soil pH of forest belt has obvious decline tendency;the total salt and K + contents of upper soil layer(0~20cm) decrease distinctly; the content of Na + increases distinctly, the content of Ca 2+ ,Mg 2+ just have little change;SO 4 2- and Cl - descend first and then increase; HCO 3 2- increase slightly. The total content of soluble salt, K + and SO 4 2- of lower soil layer (20~40cm) descend distinctly, the change of the content of Ca 2+ ,Mg 2+ and Cl - is not distinct, Na + increases distinctly; soil unit weight descends, soil porosity increases, physical clay increases. The soil fertilitys comprehensive index value shows: with the increase of wind break forest age, soil fertility tends to increase distinctly.