Application of Goat Manure and Coconut Shell Biochar to Improve the Growth and Yield of Lettuce (Lactuca sativa L.) on Inland Peat Soil

Abstract

This study evaluated the effects of goat manure and coconut shell biochar on the growth and yield of lettuce (*Lactuca sativa* L.) cultivated in inland peat soil and identified the most effective combination of application rates. The experiment was conducted from March to July 2026 using a factorial completely randomized design with two factors and three replicates. Goat manure was applied at 0, 10, and 20 t/ha, equivalent to 0, 48, and 96 g/polybag, while coconut shell biochar was applied at 0, 5, and 10 t/ha, equivalent to 0, 24, and 48 g/polybag. The nine treatment combinations produced 27 experimental units. Data were analyzed using analysis of variance, followed by Tukey’s honestly significant difference test at the 5% significance level. The combined application of goat manure and coconut shell biochar significantly affected lettuce growth and yield. The A2B2 treatment, consisting of 96 g/polybag goat manure and 48 g/polybag coconut shell biochar, produced the best overall response, with a plant height of 26.20 cm, 13.67 leaves, a leaf area of 166.26 cm², a fresh biomass weight of 121.67 g, and a shoot fresh weight of 117.00 g. These findings indicate that combining goat manure with coconut shell biochar can improve lettuce productivity on inland peat soil and may serve as a practical and sustainable soil management strategy.