Fertilizer Management, Soil Chemical Properties, Leaf Mineral Contents, and Fruit Quality in Passion Fruit Orchards on Amami-Oshima Island

Excessive phosphorus and potassium fertilization in passion fruit orchards on Amami-Oshima Island, Japan, is linked to reduced fruit quality. The study found that eight out of 12 commercial orchards had excess available phosphorus (P₂O₅) and exchangeable potassium (K), with high P levels decreasing Brix—a measure of fruit sweetness. Cattle manure compost application was identified as a primary contributor to P accumulation, while nitrogen (N) deficiency was noted in leaves, suggesting that increasing N while reducing P and K could improve fruit quality. Soil pH was also found to be elevated in some orchards, potentially due to chemical fertilizers or shell-containing topsoil, which may have suppressed vegetative growth. Additionally, fruit yield and diameter declined with longer cultivation years.

Arisawa, Z., Kondo, T., & Yamamoto, S. (2024). 奄美大島の商業パッションフルーツ園における施肥管理，土壌化学性，葉内ミネラルおよび果実品質の調査. The Journal of Island Studies, 25(1), 1–17. https://doi.org/10.5995/jis.25.1.1