Differences in Soil Fertility Parameters between 1981 and 2006 in Jingzhou County, China Associated with Changes of Agricultural Practices

Land managements and agricultural practices in China changed significantly during the past 25 years. Differences in soil fertility parameters between 1981 and 2006 in Jingzhou County, China were investigated, with the changes of land management and agricultural practices. The results showed that, from 1981 to 2006, soil pH and organic matter decreased by 3.35% and 32.2%, while total nitrogen (TN), available N (AN), available phosphorus (AP), and available potassium (AK) increased by 0.4 g kg⁻¹, 21 mg kg⁻¹, 8 mg kg⁻1, and 32 mg kg⁻¹, respectively. The above presumably resulted from more application of inorganic fertilizers (especially acid and/or physiologically-acid fertilizers), less application of organic fertilizers, little growing of green manure, and removal of crop residues and straws. Balanced application of organic and inorganic fertilizers is urgent to improve organic matter, soil pH, and soil fertility in this area