Research on Trend of Main Soil Nutrients in Lixiahe Agricultural Zone——A Case Study of Baoying County of Jiangsu Province
里下河农区主要土壤养分变化趋势分析??以江苏省宝应县为例

Based on the data of soil testing and formulated fertilization in 2005 with the data of soil survey in 1984, 1989 and 2000, the changing trends of soil nutrients such as organic matter, available P and K was studied in Baoying City. The results indicated that there were similar changing trends for soil organic matter, available P and K. Soil organic matter and available K decreased but available P changed less from 1984 to 1994. Soil organic matter, available P and K increased from 1994 to 2005, which were significantly higher than the data of the second soil survey. Spatial distributions in these years were different for soil organic matter and available P but similar for available K. In different soil types, organic matter and available P increased while available K changed less. The increasing range of soil nutrients was in an order of available P > organic matter > available K.