Comprehensive Evaluation on Status of Soil Fertility in Qujing Tobacco-growing Area

[Objective] The study aimed to make clear the status of soil fertility in Qujing tobacco-growing area and provided the theoretical basis for the production of tobacco with good quality.[Method] 340 soil samples were selected from the tobacco-growing areas in 9 counties or cities of Qujing City in Yunnan Province and the methods of factor analysis and membership function of fuzzy mathematics were used to estimate the status of soil fertility in Qujing tobacco-growing areas.[Result] There was significant variation on the soil fertility in Qujing tobacco-growing areas.The soil fertility index(SFI)values of all soil samples ranged from 0.311 to 0.900,with an average of 0.671 and the variation coefficient of 14.57%.According to the size of SFI values,the soil fertility could be divided into 5 grades of high,higher,medium,lower and low.The soil with fertility at more than medium grade accounted for 99.12%,in which,the soil with fertility at high and higher grade accounted for 10% and 67.94%,resp.[Conclusion] The comprehensive fertility index in tobacco-growing areas of Qujing City was higher and the soil samples with high and higher comprehensive fertility index accounted for 77.94% of total soil samples.But the contents of organic matter and available N were higher in general,the contents of total P,total K and available Mg were lower and the B content was seriously deficient.It was suggested that controlling N fertilizer,supplying Mg fertilizer and increasing B fertilizer should be paid more attention in balanced fertilization in Qujing tobacco-growing areas.