The researchers evaluated soil fertility in Qujing to improve tobacco quality. They used fuzzy math and statistics to measure soil nutrients, finding moderate levels of pH, organic matter, nitrogen, potassium, sulfur, and chlorine. Nitrogen levels were high, while phosphorus and potassium were rich. Most soils were in good condition, with Luoping and Malong having the highest fertility. Fuyuan and Huize had the lowest fertility. Soil fertility decreased with higher altitude in Qujing.