Formulation Geometric Engineering of Biomass-Based Slow-Release Fertilizers for Nutrient Management in Sapric Peat Soils

Peat soils pose critical limitations in agricultural productivity due to nutrient leaching and suboptimal nutrient availability. This study investigates the effectiveness of engineered slow-release fertilizer (SRF) formulations and geometries tailored to tropical sapric and hydrophobic peat, aiming to enhance nutrient retention and plant productivity. Two greenhouse experiments at IPB University evaluated the effects of slow-release fertilizers (SRFs) formulated from biomass compost combined with inorganic components (NPK, sludge, fly ash, and ammonium sulfate) using tapioca flour (5%) as a binder. The SRFs were first prepared and then applied to corn and bock choy. The testing encompassed varied fertilizer compositions and geometrical forms in pellet, crumble, small cylinder, and large cylinder. Cylinder formulation contributed to leaching mitigation, in which the nitrate leaching was improved from 0.14 to only 0.05 mg/m2 in 2 days and from 1.62 to only 0.48 mg/m2 in 35 days after application. The biomass compost-inorganic matrix proved instrumental in promoting nutrient synchronization with crop uptake, which could improve the biomass index from 0.32 at standard fertilizer to 1.20 with cylinder formulation. These findings highlight that strategic formulation and geometric design of SRF, can effectively reduce nutrient losses and substantially improve biomass growth and crop performance in peat-based agriculture.