Efficacy of Water Hyacinth-Derived Humic Acid on Soybean (Glycine max (L.) Merrill) Growth in Coastal Sandy Soil

Universitas PGRI Yogyakarta, Indonesia

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Abstract

This study assessed the impact of water hyacinth-derived humic acid on the growth of two soybean varieties (Anjasmoro and Gepak Kuning) in sandy coastal soil. Conducted in Bantul, Yogyakarta, the experiment utilized a completely randomized design with three replicates. Two variables were examined: soybean variety and humic acid concentration (control, 1%, 1.5%, and 2%). Measured parameters included root nodule count, dry weight of nodules, growth rates of plant height and stem diameter, leaf greenness, and filled pods per plant. Data were analyzed using ANOVA at a 5% significance level. Results indicated that humic acid concentrations of 1%, 1.5%, and 2% significantly enhanced plant height growth, stem diameter, and leaf greenness. Humic acid also notably affected the number of filled pods per plant, with the 2% concentration yielding the highest count (158.40). Specifically, the Gepak Kuning variety treated with 2% humic acid achieved the highest number of root nodules (27.83) and dry nodule weight (0.43 g). The findings suggest that water hyacinth-derived humic acid is a viable soil amendment for improving soybean productivity in coastal sandy environments.