Effect of sterile rice spikelets derived biochar amendment on nutrient leaching and availability in paddy soil under continuous standing water

ABSTRACTUndisturbed soil columns were used to study the effect of sterile rice spikelets-derived biochar (SRSB) on NH4+-N, available P, and available K leaching and nutrients availability in a paddy soil under continuous standing water (CSW) condition. The experiment was conducted for two crop cycles and comprised of three treatments: recommended dose of sole chemical fertilizers (CF), CF+SRSB (2 t ha−1), and control. In both crop cycles, incorporation of SRSB reduced the leachate NH4+-N and available K concentrations, while increased the available P concentration compared to sole CF. The SRSB amendment reduced the cumulative losses of NH4+-N by 35–38% and available K by 23–25% than CF only. However, there was no significant variation in cumulative available P loss between SRSB and CF only. The reduced leaching loss of NH4+-N and available K could be attributed to the better nutrient adsorption capacity of SRSB. After completion of two crop cycles, the soil pH, soil organic carbon, soil total N, available P, and available K increased with SRSB amended soils than sole CF. This study showed positive effects of SRSB on retaining nutrients and increasing their availability in the soil which could benefit efficient fertilizer management in paddy soil under CSW