Effects Of Land Reclamation And Return Farmland For Grassland On Soil Quality In Minqin Oasis

Soil quality is fundamental to the sustainable development of agriculture. The impact factors of soil quality include climate, ecological systems,landform and other natural and man-made factors. Land use displayed the human's effect of management and decision-making. Different ways of the land uses affect the soil nutrient flow, detention and transform, and it's rules are also important. Reasonable land use can improve soil structure and the quality of air and water. To evaluate the effect of land uses on soil quality, soil samples after returning farmland to grassland for two, five and ten years, and after using as farmland for two, five and ten years were collected in 285 plots and with 5 depths(0-20cm,20-40cm,40-60cm,60-80cm,80-100cm)each, hoping to provide scientific basis for better land management measures. the preliminary results achieved are:1. Land reclamation and return farmland for grassland, the content of soil organic matter, total nitrogen, available N are reducing with the depth of soil level, the content of soil organic matter is significantly positively correlated with total nitrogen and available N (r=0.49, r=0.41, p=0.01) The content of available P in arable land that applied phosphorus fertilizer is higher than uncultivated land and abandoned farmland. The content of available K in arable land is highest, and is higher in uncultivated land than that abandoned farmland. Available potassium and available phosphorus keep the same trends with organic matter that with the increasing of soil depth the content are decreasing gradually.2. With the increasing of abandoned years, the content of soil organic matter is increasing. The content of soil organic matter that Abandoned cultivation for grass last for ten years is highest and then five years is higher than two years, while the trends of sandy arable is opposite with Abandoned cultivation for grass. The soil moisture content of abandoned farmland and barren is higher than that of reclamation land.3. Soil pH value is significant negative correlation with soil organic matter, total N, available K and available P. Soil pH value is positive correlation with soluble salt(r = 0.48, p = 0.01). Soil pH value that Abandoned cultivation for grass last for ten years is highest and then five years is higher than two years, while the trends of sandy arable is opposite with abandoned cultivation for grass. The soil moisture content of abandoned cultivation for grass and reclaimed wasteland is higher than sandy arable, The soil moisture content is positive correlation with soil organic matter(r=0.59,p=0.01), available P is positive correlation with soil organic matter, total N, available N and available K.4. With the years lasting for changing abandoned cultivation to grass, soil quality is improving, as the increasing of cultivation, soil quality is declining. MinQin oasis should actively implement the policy of returning farmland to forest and grassland, protect and improve the ecological environment and realize sustainable utilization of land resources...