The Effect of Combining Different Biochar Types, Goat Manure, and Moringa Leaf Extract on the Growth of Chilli (Capsicum annuum L.)
Low soil fertility and soil acidity are major constraints limiting chilli production in tropical regions, necessitating sustainable soil amendment strategies that utilize locally available biomass resources. Unlike previous studies that primarily evaluated individual biochar feedstocks, this study investigated integrated formulations combining six locally available agricultural- and marine-derived biochars enriched with goat manure and moringa (Moringa oleifera Lam.) leaf extract to enhance soil fertility and early chilli growth under acidic tropical soil conditions. This study evaluated the effects of different combinations of agricultural and marine waste-derived biochars, goat manure, and moringa leaf extract on soil chemical properties and the early growth of chilli (Capsicum annuum L.) cultivated under field conditions using polybags. The experiment was conducted from July to September 2024 in Lalowiu Village, South Konawe Regency, Southeast Sulawesi, Indonesia, using a randomized complete block design with eight treatments and three replications. The treatments consisted of various combinations of rice husk, corn cob, empty oil palm bunch, sago pulp, durian shell, and seaweed biochars enriched with goat manure and moringa leaf extract. Soil chemical properties and plant growth variables were analyzed using analysis of variance, followed by Duncan's Multiple Range Test at the 5% probability level. The integrated amendments improved soil fertility by increasing soil pH from 4.60 to 5.06, soil organic carbon from 0.76% to 1.12%, total nitrogen from 0.08% to 0.17%, available phosphorus from 6.23 to 11.73 mg 100 g⁻¹, and exchangeable potassium from 9.42 to 11.23 mg 100 g⁻¹. Significant improvements (P < 0.05) were also observed in vegetative growth. The B1 treatment produced the greatest leaf area (5.92 cm²), plant height at 20 and 30 days after transplanting (22.61 and 30.09 cm, respectively), and shoot dry weight (3.71 g), whereas root dry weight was not significantly affected. These findings demonstrate that integrated biochar formulations enriched with goat manure and moringa leaf extract effectively improve soil fertility and promote early chilli growth, providing a sustainable approach for managing acidic tropical soils through the utilization of locally available biomass resources. Keywords: Cation exchange capacity, pyrolysis feedstock, rhizosphere processes, carbon stabilization, tropical agroecosystems.