Abstract: Using sweet potato (Ipomoea batatas L.) as the test materials, four treatments were set up: CK (conventional application of chemical fertilizer), T1 (conventional application of chemical fertilizer + microbial agent + humic acid water-soluble fertilizer + organic fertilizer), T2 (10% reduction of the conventional application of chemical fertilizer + microbial agent + humic acid water-soluble fertilizer + organic fertilizer), T3 (20% reduction of the conventional application of chemical fertilizer + microbial agent + humic acid water-soluble fertilizer + organic fertilizer). The effects of different fertilization treatments on the agronomic traits, economic output, partial productivity, and key quality indicators of sweet potatoes were investigated to identify the optimal fertilization strategy. The results showed that compared with CK, the yields and output values of sweet potatoes in T1, T2 and T3 increased, but only T3 showed an increase in net income, which was 12 875.4 yuan/hm² higher than CK. The partial productivity of inorganic chemical fertilizer in T1, T2, and T3 increased by 2.56%, 18.41%, and 52.26%, respectively, compared with CK, while the partial productivity of total fertilizer decreased, with the smallest difference observed between T3 and CK. The crude fiber content in tubers of T1, T2, and T3 was extremely significantly higher than that of CK（P<0.01）, increasing by 33.33%-36.67%. The starch content in T3 was extremely significantly higher than that in the other treatments（P<0.01）, increasing by 8.40%-12.66%, while the soluble protein and soluble sugar contents were lower than those in CK. Based on a comprehensive evaluation of all indicators, the optimal fertilization strategy was the 20% reduction in conventional chemical fertilizer combined with microbial inoculant, humic acid water-soluble fertilizer, and organic fertilizer.

Key words: sweet potato (Ipomoea batatas L.), optimized fertilization, economic output, partial productivity, quality