The Influence of Black Soldier Fly Residue on Watermelon Growth and the Properties of a Coarse-Textured Ultisol

Improving the fertility status of nutrient-depleted soils is critical to achieving food security. The negative effects of chemical fertilizers on soils necessitate the global quest for eco-friendly, effective, and sustainable alternatives. This work assessed the effect of black soldier fly (BSF) residue application on soil properties and watermelon growth. The study was set up in a completely randomized design with six replications. The treatments were BSF1 (BSF applied at 10 t ha&minus:1), BSF2 (20 t ha&minus:1), BSF3 (30 t ha&minus:1), and control. The plant data collected in this study were vine length, leaf width, number of leaves, and stem girth, and the soil&rsquo:s physicochemical properties were determined. The results show that BSF residue-treated soils had 20.4&ndash:49.5% higher aggregate stability and 50&ndash:160% higher hydraulic conductivity than the control treatment. BSF residue-treated soils had significantly (p &le: 0.05) higher pH, total N, available P, exchangeable K, and organic carbon than the control treatment. BSF3 treatment had the highest effect on available P and soil pH relative to other amended treatments. High rates of BSF residue application did not significantly increase the total available N and P contents, which could suggest that BSF application at 30 t ha&minus:1 may not pose a risk of N and P pollution to water systems. BSF residue-treated soils improved (p &lt: 0.05) watermelon growth parameters relative to the control. Watermelon leaf length was significantly (p &le: 0.05) longer for BSF residue-treated soils than the control treatment. A similar trend was observed for the number of leaves, leaf width, and stem girth. At 4, 6, and 10 weeks after sowing, BSF residue-treated plants had 38.2&ndash:104%, 22.7&ndash:118%, and 25.7&ndash:103% longer vine lengths than the control treatment, respectively. The study results suggest that BSF residue application can enhance the fertility status of a coarse-textured ultisol for watermelon production.