Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

Volcanic grassland has a high soil organic carbon (SOC) stock, making it important for climate change mitigation. This study analyzed SOC stock in volcanic grassland soils and assessed the potential of volcanic grassland as a carbon sink by identifying the effect of management on SOC stock and stability. Soil samples in Jeju were collected from eight sites of generally well-managed grasslands (nominally-managed grassland, NG: applying fertilizer once annually and plant cover rate is 60 - 80%), which is considered as the representative SOC stock of volcanic grassland soil. To identify whether SOC stock increased by improved management (improved grassland, IG: applying fertilizer twice annually and plant cover rate is over 80%), soil samples were collected from two IG sites. Soil samples from NG and IG were analyzed for their SOC stock and stability using SOC fractionation. Our results revealed that the SOC stock of NG was 95 ton C ha^-1. It was 19% higher than the default value (80 ton C ha^-1) for grassland corresponding to a warm temperate climate suggested by IPCC 2006 Guidelines for National Greenhouse Gas Inventories. The SOC stock in the IG (150 ton C ha^-1) was significantly higher than NG (95 ton C ha^-1) by 58%. Especially, most of the increased SOC stock was stored in the stable fraction of Micro_POC (particulate organic carbon in microaggregate). Consequently, improved management of volcanic grassland in Jeju has the potential to offset 29% of carbon emissions from Jeju’s agricultural sector, underlining the importance of volcanic grasslands in climate change mitigation strategies.

Improved management in volcanic grasslands boosts SOC quantity and quality, aiding climate change mitigation.