Malaysian Journal of Sustainable Agriculture (MJSA)

Brunei Darussalam has long faced challenges associated with low-pH soils, which contribute to low crop productivity. These highly weathered soils are characterized by low nutrient availability and high concentrations of aluminium (Al) and iron (Fe), which strongly bind phosphorus (P) through chelation thus rendering it unavailable to plants. Although the application of inorganic P fertilizers partially alleviates P deficiency, substantial losses occur through leaching, fixation, and immobilization. The use of an organic soil conditioner (OSC) derived from chicken manure represents a practical and sustainable approach for improving soil P availability. An incubation study was conducted to evaluate changes in soil available P and selected soil chemical properties. The experiment was arranged in a Completely Randomized Design (CRD) with five treatments: T1 (0% OSC), T2 (100% OSC), T3 (75% OSC), T4 (50% OSC), and T5 (25% OSC), each with three replicates over a 30-day incubation. The application of OSC increased soil pH and electrical conductivity (EC). Moreover, this approach significantly reduced the soil exchangeable acidity, Al, and Hthrough dissolution and neutralization reactions involving organic anions. Consequently there was an increment of 402.411154.85 ppm available P with the treated soil compared with the control (T1). In addition, the increase in soil organic carbon and organic matter enhanced P availability by promoting nutrient cycling and reducing P fixation. These findings demonstrate that OSC effectively ameliorates soil acidity and enhances P availability, indicating its potential to improve crop productivity on mineral acid soils.