Study On Soil Fertility Comprehensively Evaluation Under The Different Land-using Ways In Karst Table Mountainous Land Cropped Location

Soil fertility is the supplying ability of the necessary nutrient elements which are needed by the crops in the soil. Soil elements content are the key indexes that are used to evaluate the soil fertility.lt could objectively reflect the true condion of soil to a certain degree to comprehensively evaluate soil fertility of the typical region. It could provide the scientific basis for optimizing the Land-use structure and improve the way of using chemical fertilizer and farming measures. The karst regions of one of the most special and important geomorphological types in south of China. It's landform and lithology are special and soil forming ability is low, losing of the nutients and soil and water is serious. And it has higher fifficulty to control. The karst low mountain and hill of southeast Chongqing has a broad distribution and High activity coefficient, chich would result in losing of soil nutrients and the eutrophication of the Yangtse river water bodies. Which could directly threaten the safety of the Changjiang Gorges. So comprehensive evaluation studying of soil fertility under the different land-using ways in the typical karst table mountainous land cropped area could provide the scientific basis for optimizing the Land-use structure and improve the way of using chemical fertilizer and farming measures. And it could provide the basic data to soil erosion comprehensive controling of karst cropped region in the three gorges reservoir area.The typical karst table mountainous cropped land as research object, the main content of this paper is the spatial distributing studying of soil fertility of Wawubao table mountainous cropped region in Siyuan village,Yuelai town, Shizhu county. We vastly measured the nutrient indexes including SOM,TN,AN,TP,AP,TK and AK, and comprehensively analysed the horizontal and vertical changing law under the 5 different land using ways in researching region. The result could provide the scientific foundation to optimize land using way and reform cropping system and soil management.The result shows that:1) The soil nutrients content has a low whole level and half the samples'are in the middle and low level.2) The soil samles SOM, TN, AN, TP, AP, TK, AK value declined and their fertilizer conditions were getting lower from surface to floor section. Their main difference happened in surface and middle section.3) The land using way has obvious effect to accumulation and distribution of the soil fertilizer, the A,B,C land using way are better than D and E.4) By optimizing the land using way, farming measures and fertilizing modes, we can effectively balance the nutrients supplying ability of soil and decrease the nutrients loss resulting from agricultural area pollution source pollution of project region.