Assessing Changes in Soil Organic Matter Accumulation of Agricultural Field from 2013 to 2020 in South Korea

Abstract

Soil organic matter (SOM) is an important indicator of soil fertility, health and quality. For proper managements of agricultural fields, a long-term monitoring of changes in SOM contents in field and estimation of national accumulation of SOM are required. In this study, SOM in agricultural fields of paddy and upland systems were investigated from 2013 to 2020 for all administrative provinces of South Korea. Total field area was decreased by 4.8% and 9.1% in 2016 and 2020, respectively, compared to 2013. In paddy field, SOM content was 27.9 g kg -1 in 2013, which was gradually increased by 1.1% in 2020. Despite that SOM content increased at a field scale, national SOM accumulation in paddy fields decreased due to reduced paddy area. In upland fields, SOM content was gradually increased by 6.5% from 2013 to 2020. Though SOM content increased, however, SOM accumulation in the total agricultural field at national scale was not affect due to less area than paddy field area. Therefore, total SOM accumulation was continuously decreased from 69.2 Tg in 2013 to 65.3 Tg in 2020 mainly due to decreasing paddy field area. This study showed that in spite of the SOM increase of both fields, national SOM accumulation is decreased with significantly decreasing total field area. Therefore, it is required to increase SOM accumulation at a field scale through proper management of SOM. In addition, it is also necessary to conserve paddy fields to enlarge agricultural SOM at national scale.