Effects of chemical and bio-organic fertilizers on tuber yield, nutrient accumulation, soil fertility of edible sweet potato

In order to provide basic support for fresh edible sweet potato production, the effects of different proportions of bio-organic fertilizer and chemical fertilizer on dry matter accumulation, yield, quality and soil nutrient content of fresh edible sweet potato were investigated. The fresh edible cultivar ‘XiGua Hong’ was chosen as the test variety, and field experiment was carried out. Six treatments were set up: no fertilization (CK), conventional single application of fertilizer (FP), optimized single application of fertilizer (OPT, recommended fertilizer rate), bio-organic fertilizer instead of 30% fertilizer (OF30, recommended fertilizer rate), bio-organic fertilizer replacing 50% fertilizer (OF50, recommended fertilizer rate), and single application of bio-organic fertilizer (OM). The OF50 treatment results in the highest potato weight per plant and root yield, which is 28.2% greater than that observed under FP. Under OF50 and OF30 treatments, the number of potatoes formed per plant and crown-root ratio are significantly higher than CK. The accumulation of nitrogen, phosphorus, and potassium in sweet potato plants under OF50 is notably higher respectively than OPT (by 23.4% - 28.9%). The soluble sugar content in root tubers treated with OF50 is significantly higher than other treatments, ranging by 22.6% - 46.2%. VC content in root tubers under OF50 is also the highest, significantly exceeding that of FP by 24.0%. Furthermore, crude protein in root tubers under OF50 significantly exceeds that of FP by 16.4%. There are no significant differences in soil organic matter, available potassium, total nitrogen, available phosphorus content among all fertilizer treatments. However, OF50 also exhibits the highest total nitrogen and available phosphorus content, which is significantly higher than CK by 34.9% and 1.77 times, respectively. Soil alkaline phosphatase content is highest under OM, significantly exceeding levels observed in other fertilizer treatments by 31.2% - 140%. Sucrase, dehydrogenase, urease activities in the soil do not show significant differences among different fertilization treatments. Soil total nitrogen content and soil dehydrogenase activity are positively correlated with soluble sugar content. Application of bio-organic fertilizer can significantly increase soil alkaline phosphatase, total nitrogen, and available phosphorus content. Replacing 50% of chemical fertilizer with bio-organic fertilizer can significantly enhance the number of potatoes produced per plant, plant weight, and root yield, resulting in higher soluble sugar, VC, and crude protein content, as well as an increased crown-root ratio and nutrient accumulation in plants. This approach is an effective practice to improve sweet potato yield and quality while maintaining soil fertility.