Nutrient Spatial Distribution And Fertility Characters Of Farmland In Quangjiao County,Anhui Province

Farmland is the important material foundation to the survival and development of humans. Farmland fertility has a direct influence not only on the production but also on the quality of farm products. During past three decades since second national general soil survey, large changes have happened in soil nutrient contents and farmland quality.Nutrient imbalance, bad soil physicochemical property and basic soil fertility are now severe challenges for us. Consequently, it is essential to conduct a new investigation and evaluation on soil nutrients and farmland quality.In the present thesis, soil nutrient conditions were studied and spatial variations were analyzed in Quanjiao County, Anhui Province. At same time, farmland resource database was created, and soil fertility evaluation system was established using Delphi method and layer analytical method and farmland fertility was evaluated in Quanjiao city. The primary results and conclusions are as follows:1. Soil nutrient characteristics in Quanjiao county. The mean contents of soil organic matter, total nitrogen, available phosphorus, rapidly available potassium, available copper,available manganese, available zinc and available boron were 19.047g/kg, 1.26 g/kg,10.8mg/kg, 135 mg/kg, 1.44 mg/kg, 3.58 mg/kg ? 59.49 mg/kg and 0.54 mg/kg,respectively.2. Large spatial variations were observed for all the nutrients. Among of them,available phosphorus and boron showed the largest spatial variations, with variation coefficient of 1.26 and 1.00. Soil organic matter, total nitrogen, available zinc and available boron showed middle variation. The soil available copper and manganese contents were abundant, and soil organic matter contents were mainly in class four level and other nutrients were mainly in class three level according soil nutrient grading standards. The areas lack of soil organic matter, total nitrogen, available phosphorus, rapidly available potassium, available copper, available manganese, available zinc and available boron accounted for 64.31%?8.96%?48.25%?19.77%?16.32%?0.37%?0.04% and 46.59%of total farmland area, respectively.3. Farmland fertility evaluation in Quanjiao county. Based on farmland nutrient characteristics and fertility conditions in different regions, we evaluated farmland fertility.The land areas of first class, second class, third class, fourth class and fifth class were respectively 3906.27, 12072.43, 14199.69, 7591.36 and 4232.37 hectare, which accounted for 9.3%, 28.7%,33.8%,18.1% and 10.1% of total farmland area, respectively. The different class of land areas showed that third class > second class > fourth class > fifth class > first class. We finally analyzed the existing problems on land use and put forward directions for soil improvement and the ways to fertilize the soil according to local soil conditions.4. Spatial distributions of different classes of land were analyzed. The results showed that the first class of land mainly distributed in southern diked region. The primary soil type was loggogenic paddy soil and primary soil textures included loam and heavy loam.The second class of land mainly distributed in middle gentle region and plain region. The primary soil types were loggogenic paddy soil and percogenic paddy soil, and primary soil textures included loam and heavy loam. The third class of land mainly distributed in gentle hilly region. The primary soil types were percogenic paddy soil and bleached paddy soil,and primary soil textures included loam and heavy loam. The fourth class of land mainly distributed in gentle hilly region and river low-lying region.The primary soil types were submergic paddy soil and yellow-brown soil, and primary soil textures included heavy loam and loam. The fifth class of land mainly distributed in middle-lower region of hill.The primary soil types were brown limestone soil and submergic paddy soil, and primary soil texture was heavy loam.