Evaluation on Soil Fertility in Sichuan Tobacco Planting Areas

In order to clarify the soil fertility status of tobacco-growing soil in Sichuan Province, Soil samples were tested and soil fertility limiting factors were analyzed by using principal component analysis combined with the cluster analysis. The results showed: (1) the soil fertility factors in the study area were from medium variability to strong variability, the variability of available sulfur and trace elements were intensive with variation coefficient more than 90%; (2) the influence on soil fertility by soil total nutrient contents and available nutrient contents was greater than that by the trace elements; that by nitrogen and phosphorus was greater than that by the potassium, and the organic matters and pH also had a greater influence; (3) the IFI values of soil samples were from 0.0928 to 0.5074. The IFI values were divided into the high, medium and low levels by the cluster analysis with their proportion 10.78%, 55.88% and 33.34% respectively; (4) the differences of organic matters, total nitrogen, total phosphorus, available nutrient, water-soluble boron, available zinc and available iron contents were significant in the three fertility degrees, which meant these were the main factors in limiting tobacco-growing soil fertility. These could provide a reference for rationally improving tobacco-growing soil fertility in Sichuan province.