Change Of The Soil Quality In Assart Oasis

In this paper, as a case of Karamay, we have studied on space-time changement of soil quality in oasis of arid area. We measured quality for different land use types and years in same type by combinativing field sampling for Karamay in Xinjiang and analysis in laboratory, which is directed by former theory of soil quality. Then we did integrated evaluation of soil quality for different land use types, and had drew some conclusions as followed:In four land use types, the soil bulk density of layers(0～15cm) for farmland and tree land is bigger than the other land use types.The organic matter of every layer in manpower Tamarix Bulrush land is bigger; organic matter of Tamarix Bulrush land release efficiency nitrogen which result ration of C/N is higher; total nitrogen of all layers in farmland variety great as being effected by mass use of nitrogen in agriculture; deadwood and defoliation of tree,shrub and bulrush pooled in 5cm layer to result that quick nitrogen is the biggest among all layers.The total salt of nature shrub tree land for every layer being bigger than farmland explain that nature shrub thee land strongly stand salt and farmland for basification in this area; that the nutrient of face layer is bigger than the ground layer may be explained by that vegetation gather nutrient to be stored in deadwood and defoliation.According to analyze soil quality of different year vegetation, we found that: the longer year the bigger bulk density , variety coefficient change little ,which show that soil quality trend for the same direction along with time of culture period; compared several times , soil C/N in 15-30cm layer of 5-year farmland is sharply different from 6-year, and in 30-50cm between 5-year,2-year and 6-year also great different from each other; the salt and ration of conductance for all layers is consistent.By analyzing soil quality of 4 kinds of land use types in Kalamay agriculture development area according to principal component analysis, we draw the conclusions: nature shrub tree land is affected little by mankind, a great deal of organic matter return to soil every year, and root system can improve soil physical quality, can absorb salt from soil, so the soil quality of nature shrub tree land is the best; the soil quality of farmland is better than the soil quality of manpower Tamarix Bulrush land, which may be reasoned that man make for soil quality by irrigation to exclude salt and fertilizing organic muck in the earlier oasis digging up period. Soil physical qualities of tree land get harden and worsen for flooding irrigation, furthermore climate in Kalamay is dry and rainless , the other irrigation is very long time after the former one, so soil get harden severity and result soil physical quality get worse and worse.