The soil fertility quality is one of the most critical indicators of soil productivity. It directly affects the yield, quality and agricultural efficiency of Chinese medicinal materials. In order to establish the American ginseng planting soil fertility quality evaluation method based on the effective components of American ginseng, Wendeng district, Weihai city, Shandong province, the main producing area of American ginseng, was cited as a case for the study. Twenty-two 4-years American ginseng sampling sites are located at 7 towns. The samples of soil and plant root were collected in the autumn of 2017-2019. The saponin contents of American ginseng and 11 soil chemical properties were measured. The minimum data set(MDS) for assessment of the quality of soil fertility quality was established by correlation analysis and principal component analysis. The evaluation indexes were normalized by membership function. Soil quality index(SQI) that indicates soil comprehensive fertility quality level was calculated according to the critical value of membership function and weight value of each soil index in MDS. The results showed that the total saponin(Rg_1+Re+Rb_1) content of American ginseng in samples ranged from 1.76% to 7.94%. The yield of 8 plots in 2019 ranged from 3 818.7 kg·hm~(-2) to 8 996.4 kg·hm~(-2). MDS includes organic matter, alkaline nitrogen, exchangeable calcium, exchangeable magnesium, effective iron, effective copper, and effective zinc. Based on the mean of 4.825% of total saponin, threshold value of SQI for the region was determined to be 0.15, and 86.36% of soil samples in the county were above the threshold value. The methods and parameters are applicable to selection of high quality American ginseng planting sites and guiding rational fertilization. It also provides a reference for the evaluation of soil fertility quality of other medicinal plants.
Keywords: American ginseng; Wendeng district; membership function; minimum data set; saponin content; soil fertility quality.