Abstract:
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.