Effects of biochar and bagasse compost on N, P, and K availability in tropical Inceptisols under the third planting season

Climate change accelerates soil nutrient depletion, leading to reduced soil productivity in tropical regions, thus requiring efforts to enhance soil fertility. Bagasse compost and biochar amandments improve nutrient availability in tropical Inceptisols and plant nutrient uptake. This study aims to examine the impact of biochar, compost, and their combination on soil nutrient availability and the uptake of shallot (Allium cepa L.) in the third planting season. The design used was a completely randomized factorial design with two factors consisting of types of residual materials applied at the beginning of the planting season, namely SB 0: no fertilizer, SB 1: sugarcane bagasse compost, SB 2: sugarcane bagasse biochar, and SB 3: sugarcane bagasse bio-compost, each at 10 tons/ha, and NPK fertilizer with varying dose levels: CF 0: NPK 0%, CF 1: NPK 50%, CF 2: NPK 100% (525 kg/ha). The results showed that the combination of sugarcane bagasse biochar + compost (2:4) (bio-compost) + NPK 50% (SB3CF1) significantly increased soil N, P, and K availability and plant tissue in the third planting season. These findings support the use of bagasse as a potential organic amendment to improve nutrient availability in Inceptisol soils and play a role in reducing global warming.