The Tai Lake Region is traditionally an ecologically sustainable agricultural area due to the intensive application of traditional organic fertilizer, however in the past fifty years, agricultural management practices such as fertilizer usage and cropping systems changed in this situation. It was found that soil organic carbon (OC) content decreased significantly from 1959 to 1981 due to the application of mineral fertilizer, which nearly replaced completely the traditional organic fertilizer, and then soil OC increased slightly from 1981 to 2004 attributed to the changes of cropping systems and fertilizer application, particularly vegetable production, which resulted in the significant increase of organic fertilizer application.