Influence Different Land Utilization Types Of On Soil Property In Guizhou Province

In order to investigate the influence of different land utilization types on soil property in karst ecological fragile, four kinds of land utilization types(forest, grassland, shrub and farmland) under different altitude gradients were chosen as objects of study, we studied the influence of soil bulk density, porosity, fractal dimension of soil particle-size distribution, p H, organic matter, total nitrogen, available nitrogen, phosphorus, potassium, available microelements(Fe, Mn, Cu, Zn, Mo, B) under four kinds of land utilization types by combining the method of field sampling and laboratory analysis, meanwhile, we also assessed the different altitude gradients and soil fertility under different landutilizationtypes in Guizhou Province by soil Integrated Fertility Index(IFI), the results showed that:(1) Sum of the soil bulk density was 1.04-1.69 g·cm-3, which was gradually increased with the increasing of soil depth(0-10 cm,10-30 cm,30-50cm), and the increasing range was 7.81%-19.25%; the soil bulk density of same soil layer in low and middle altitude areas showed that farmland > shrub > grassland > forest. Soil porosity and fractal dimension of soil particle-size distribution were gradually decreased with the increasing of soil depth, and the decreasing range was 36.39%-60.59% and 0.62%-8.51%, the fractal dimension of soil particle-size distribution was the highest in different altitude gradients and different land utilization types.(2) p H in different altitude gradients in Guizhou Province was 4.26-7.34. The contents of soil organic matters in low, middle and high altitude areas was 65.92 g·kg-1, 43.54 g·kg-1 and 58.54 g·kg-1, the contents of the organic matters was gradually decreased with the increasing of soil depth, and the decreasing range was 4.58%-67.33%; And the contents of the soil organic of shrub was the highest in low and middle altitude areas.(3) The soil total nitrogen, available nitrogen, available phosphorus and available potassiumpresented the enrichment phenomenon in soil surface, and the average enrichment ratio was 47.62%. The soil total nitrogen, available nitrogen and available potassium of farmland areas was the lowest in low altitude, and the contents of the soil available phosphorus in shrub was higher than other 3 kinds of land utilization types; The total nitrogen and available potassium of forests in middle altitude areas was the highest, the contents of the available nitrogen and available phosphorus in shrub was the highest; The content of soil total nitrogen, available nitrogen, available phosphorus and available potassium in high altitude areas was shrub > grassland > forest > farmland.(4) The soil available microelements showed the enrichment phenomenon in soil surface, and the enrichment ratio was 46.89%. The contents of soil available Fe, Mn and Cu in low altitude areas was significantly higher than other three kinds of land utilization ways; The contents of available Fe in forest and available Mn, Cu, Zn and Mo in farmland and grassland in middle areas was higher; The contents of available Cu and Mo in forest in high areas was higher, and the contents of available Zn in shrub was highest. The content of available B and Mo was lower, and the available B was at the level of extremely low, which cannot meet the requirement of the plant growth.(5) The soil fertilitywas gradually decreased with the increasing of soil depth, and the decreasing range was 5.85%-31.82%; The soil fertility in low and high altitude areas was forest > grassland > shrub > farmland, which in middle altitude area was grassland > forest > shrub > farmland. And the soil fertility in different altitude gradients under the same way of land utilization type in forest and grassland was high > low > middle altitude, low > high > middle altitude in shrub and middle > low > high altitude in farmland.In conclusion, the land utilization type affected the soil characteristics in Guizhou Province deeply. Protecting and improving the farmland ecosystem has an essential significance on sustainable development of food security and ecological environment.