Investigation and analysis On soil fertility of cultivated farmland in Hai’粕County，Jjangsu Pl vinoe

Nearly 1000 fixed positions were investigated and analyzed in Hai’an County，Jiangsu Province．The results shoW that the cuhivated soil organic matter，total N，available P，available K increase by 9．8％ ，7．4％ ，190％ and 18．3％respectively，higher than those in 1991，and by 41．3％ ，31％ ，245．2％ and 18．6％ respectively，higher than those in 1982．The soil physical and chemical properties are improved grea tly．The evolution of soil fertility is related to the eoordi-nate development in planting，breed ing and processing，manuring of a grea t quantity of organic fertilizer，spreading of bal-anced fertilization technique，and optimizing of planting system and tillage mode in the county．