Enhancing Soil Nutrient Availability through Surface Application of Biochar and Organic Amendments with Different Liming Materials in Laterite Soils of Kerala, India

Aims: A 12-week column incubation study was conducted under laboratory conditions using the southern laterite soils (AEU-8) of Kerala, India, to evaluate the effect of co-application of biochar and other organic amendments with liming materials on soil nutrient availability. Place and Duration of Study: Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala Agricultural University, India between February 2023 and April 2023. Methodology: The 17 treatments studied included farmyard manure (FYM) at 20 t ha-1, humic acid (HA) at 10 kg ha-1, poultry manure (PM) at 1 t ha-1 and coconut frond biochar (CFB) at 10 t ha-1 each in combination with lime, dolomite, calcium silicate (CS) or phosphogypsum (PG) at lime requirement (LR) and a soil alone control. Results: Results indicated that co-application of organic amendments and liming materials significantly increased organic carbon (by 38.10 to 85.71%) and available nitrogen (30.43 to 95.65%), phosphorus (14.54 to 67.49%), potassium (4.77 to 109.87%) and sulphur (35.51 to 78.81%), compared to the control. CFB at 10 t ha-1 with dolomite as per LR, PM at 1 t ha-1 with lime as per LR, FYM at 20 t ha-1 with CS as per LR, CFB at 10 t ha-1 with lime as per LR and CFB at 10 t ha-1 with PG as LR, recorded significantly highest values for soil organic carbon and available nitrogen, phosphorous, potassium and sulphur, respectively, compared to other treatment combinations. Available Fe, Mn, Zn and Cu were recorded significantly highest for the control treatment, compared to other treatment combinations. Conclusion: In general, application of CFB at 10 t ha-1 with different liming materials (lime, dolomite, PG or CS as per LR) significantly improved soil nutrient availability while reducing excess micronutrient accumulation, thereby enhancing soil health and fertility. Therefore, co-application of biochar with different liming materials, integrated with the recommended dose of fertilizers, can be recommended to farmers as a sustainable practice to improve soil health and enhance crop yields.