Nitrogen, phosphorus and sulphur mineralization kinetic as affected by biochar, manure and ash amendments—An incubation study

Studies on the effect of biochar, manure and manure ash on soil nutrient kinetics are rare. Therefore, an incubation study was conducted to investigate nitrogen (N), phosphorus (P), and sulphur (S) kinetics in soils amended with biochar (B), B + cattle manure (BCM), B + goat and sheep manure (BGSM), B + poultry manure (BPM), farm yard manure (FYM), CM ash (CMA), GSMA, PMA, and wood ash (WA). Manure and manure ash were applied at 120 kg N ha⁻¹; B was applied at 5 tha⁻¹.Total mineral nitrogen (TMN), available P and S were determined at 2 weeks interval. Results revealed that soils treated with WA and PMA had the highest liming (pH 9.88) and salinity (820 μS m⁻¹), respectively. The overall cumulative release of TMN, P and S in soil treated with PMA was 1, 7 and 16% higher than BPM amended soils, respectively. The least percentage of TMN, P and S mineralized was in soil treated with BCM (13.5%), BPM (12.3%) and WA (9.3%), respectively. The first order and power functions were able to capture the kinetic release of N, P and S in the soil and amendments. TMN had significant correlation with nitrate–N (r = 0.925, p ≤ 0.001) ammonium-N (r = 0.737, p ≤ 0.01), sulphate (r = 0.823, p ≤ 0.01) and phosphate (r = 0.702, p ≤ 0.01). The study concluded that the application of manure ash or manure with biochar encourages the timely release of TMN, P and S as well as improving the salinity and pH of the soil.