Effect of biochar and organic amendments on improving soil quality and apple orchard productivity: a 2-year field study

Soil degradation poses a significant challenge to mature apple orchard productivity.This study aims to investigate the effects of organic amendments on soil properties, carbon management, greenhouse gas emissions, apple tree growth and fruit quality in South Korea.We supplied organic amendments, including livestock manure compost (LMC), pruned branch chip (PBC), and three concentrations of low temperature biochar (LTBC; 19.8, 99, 198 m 3 ha -1 ), as well as mid temperature biochar (MTBC) to the mature apple orchard field over two years.Upon various organic amendments, LTBC significantly improved soil physical and chemical properties, enhancing the capacity for cation exchange and water-holding, and reducing bulk density.Moreover, LTBC demonstrated lower CO 2 emissions compared to PBC, contributing to effective carbon sequestration and GHG mitigation.No significant differences were observed across treatments on nitrous oxide emissions.Interestingly, both LMC and LTBC boosted apple tree growth, development and fruit yield compared to other organic supplements, which may contribute to enhancing fruit nutrient contents.These findings highlight LTBC's ability to improve soil carbon storage and nutrient retention due to its high stability and resistance to decomposition.Identifying key organic amendments from this study will pave a way for reducing dependence on chemical fertilizers while enhancing orchard productivity.This study lays the groundwork for more research into how organic amendments work together and whether they are cost-effective for large-scale use, which will help apple production last and restore the soil.