Abstract: To investigate the effects of mineral conditioner on soil fertility in sloping pepper farmland, a field plot experiment was set up in Xiangtan, Hunan Province. There were five treatments, including conventional fertilization (CF), and CF combined with mineral conditioner at rates of 750 (T1), 1500 (T2), 2250 (T3), and 3000 kg·hm^-2 (T4). We examined the effects of different application rates of mineral conditioner on soil pH, cation exchange capacity (CEC), soil organic matter (SOM), nutrient content, and enzyme activities. Compared with CF, T2, T3, and T4 treatments significantly increased pepper yield and economic benefits by 39.3% to 51.7% and 60.0% to 77.6%, respectively. T4 treatment significantly increased soil pH by 15.2%. T3 treatment significantly increased soil available phosphorus content by 41.5% and available potassium content by 28.9%. T2 treatment significantly increased soil urease activity by 17.7%, while T3 treatment significantly increased soil acid phosphatase activity by 7.2%. Compared with CF, T4 treatment significantly increased soil integrated fertility index (IFI) by 16.4%. Pepper yield was significantly positively correlated with IFI, soil CEC and sucrose enzyme activity, soil pH, hydrolyzable nitrogen and available potassium contents. Principal component analysis (PCA) indicated that the contents of soil available nutrients, pH value, CEC, and sucrose enzyme activity were the main factors influencing soil quality and pepper yield. In conclusion, appropriate application of mineral conditioner could effectively alleviate soil acidification, increase CEC, enhance the contents of available phosphorus and available potassium, improve soil urease and acid phosphatase activities, and elevate overall soil fertility. In particular, the treatment with 2250 kg·hm^-2 mineral conditioner showed better improvement effect.

Key words: slope farmland, soil quality, cultivated land improvement, pepper, yield