Evaluating Nitrogen and Phosphorus Dynamics Influenced by Animal Manure Biochar in Eutric Cambisol

Abstract Most cultivated soils in smallholder management exhibit a restricted natural capacity to provide crops with nitrogen (N) and phosphorus (P), which are vital for growth and productivity. Manure-based biochars (MBCs) are strongly advocated because they contain considerable concentrations of N and P. Therefore, this study aimed to produce and evaluate four MBCs; cattle (CMB), goat (GMB), sheep (SMB), and poultry (PMB), pyrolyzed at 400 °C, with a focus on comparing their N and P release patterns when applied to soil at rates designed to achieve equivalent enhancement of soil organic carbon (SOC). A 46-day incubation experiment involving soil and biochar was conducted using sandy loam Eutric Cambisol to explore the changes in N and P when mixed with MBCs at a set biochar dosage equivalent to raising SOC from 0.7 to 2%. The application of SMB, PMB, GMB, and CMB resulted in a decrease in ammonium-N (NH 4 -N) concentration by 9.61, 12.5, 14.6, and 15.0% at day 25 compared to the initial concentrations, respectively. Nitrate N (NO 3 -N) content increased from day 11 in soils amended with MBC due to the nitrification of available nitrogen. Olsen-P was released at rates of 38.11(CMB), 37.14 (GMB), 34.53 (PMB), and 14.10% (SMB) after 18 days of incubation. The results reveal that MBCs can serve as valuable organic carbon-based amendments that supply essential plant nutrients by enhancing nitrification and increasing the bioavailability of P.