Determination of optimal mixing ratio of organic fertilizer and biochar derived from agricultural waste to increase crop growth and soil carbon sequestration

Soil organic carbon (SOC) can be accumulated through various organic inputs such as organic fertilizers, compost, and biochar.While organic fertilizers are effective in supplying nutrients, they have limitations in stable carbon sequestration compared to biochar.Therefore, this study aimed to determine the optimal mixing ratio of organic fertilizer and biochar that can supply nutrients while ensuring sustained and stable carbon sequestration.The growth of lettuce, soil chemical properties, and soil carbon sequestration were evaluated through a pot experiment based on the mixing ratios of organic fertilizer and biochar derived from agricultural waste.The treatments in the pot experiment included no fertilizer (NF), inorganic fertilizer (IF), and biochar mixed organic fertilizer (BAOF), mixing ratios of organic fertilizer:biochar = 100:0, 90:10, 80:20, 70:30.The results showed that leaf length and width of lettuce increased by 1.70 -1.84 and 1.58 -1.78 times, respectively, in BAOF treatments compared to NF.The highest yield was observed in BAOF (100:0).The organic matter content increased with higher mixing ratio of biochar.SOC stock was observed in the following order: 11.93 (BAOF70:30) > 11.22 (BAOF80:20) > 10.35 (BAOF90:10) > 10.26 (BAOF100:0) t C ha -1 .In conclusion, mixing biochar with organic fertilizers promoted lettuce growth and led to increased soil carbon sequestration.These results indicated that the optimal mixing ratio was determined to be BAOF70:30.