Effects of chemical and bio-organic fertilizers on tuber yield, quality, and soil fertility of edible sweetpotato

  Objectives  We compared the effects of chemical and bio-organic fertilizers on sweetpotato’s yield and quality to provide fertilization support for its efficient and high-quality production.

  Methods  Field experiments were conducted in the hilly area of Jinan, Shandong Province, in 2018 and 2019 using sweetpotato cultivar ‘Jishu 26’ as the test material. The four treatments included no fertilization (i.e., control), single chemical fertilizer (T1), bio-organic fertilizer (T2), and combined chemical and bio-organic fertilizer application (T3). The plant samples were collected at 50, 100, and 150 days after planting (DAP) to measure dry matter accumulation (DMA) and root yield. Tuber quality and soil fertility in 0–20 cm soil depth were analyzed at the harvest stage.

  Results  Compared with T1, T2 and T3 increased DMA in plants and roots at 150 DAP in both years (P < 0.05) . The highest and lowest root yield was recorded in T3 and T1, respectively. Compared with T1, T2 increased soil dehydrogenase and sucrase activities in both years and increased soil urease and alkaline phosphatase activities in 2019 (P < 0.05) . Similarly, soil available P, K, organic matter, reducing sugar content, soluble sugar, and vitamin C increased in the tubers in T2, promoting dry matter translocation to the tubers. Compared with T2, T3 (P < 0.05) increased DMA in plants and tubers at 100 and 150 DAP in both years and increased soil alkaline phosphatase and dehydrogenase activities in 2019. Soil alkaline phosphatase and dehydrogenase were beneficial to increasing soil alkali-hydrolyzable N and available P. For the root quality, T3 increased the contents of carotenoids and vitamin C in the tubers and showed no significant effect on reducing sugar and soluble sugar contents. The tuber quality indexes were (P < 0.05) positively correlated with soil organic matter, available P, readily available K, and soil enzyme activities.

  Conclusions  Continuous chemical and bio-organic fertilizers application increased soil alkaline phosphatase and dehydrogenase activities, benefiting high soil alkali-hydrolyzable N and available P contents. The mixed fertilizer application promoted higher dry matter accumulation, root yield, sugar and vitamin C contents in the tubers. Our results demonstrate that mixed fertilizer application is suitable for efficient and high-quality production of edible sweetpotato.