Spatial-temporal evolution of soil fertility in Yellow River Delta——Case study in Kenli County

Through comparison of soil fertility quality between 1986 and 2003,we discussed the regularity of soil fertility evolution at Yellow River Delta.The soil fertility index weights were reckoned using correlation analysis method,and soil fertility quality was evaluated using ARCGIS adapting integrated Quality Index.Compared to 1986,54.22% soil fertility quality of Yellow River Delta in 2003 showed little or no change,but a drop in the forest land and dryland and an enhancement in irrigated field in the western were observed.Soil organic matter in 41.14% region dropped,while it showed little or no change or increase in arable land;46.96% region showed little or no change for hydrolysable N,while an enhancement in western arable land and southeast forest grass land,and a drop in the dryland along both the Yellow River banks were found.Soil available P increased in arable land,dropped in mud flat and showed little or no change in the salt wasteland;soil rapidly available K dropped in over half(50.74%) area except forest and meadow land,in which it increased.Soil salt decreased in about half(47.29%) area,but little or no change in arable land,didn't change on plough land and increased along the Yellow River were observed.