Variation Characteristics on Soil Physical Properties of Paddy Fields in Korea

다국어 초록 (Multilingual Abstract)

The monitoring of soil physical properties of paddy fields is to be conducted in accordance with the notification (No. 2017-12) of the Rural Development Administration of Korea. The monitoring began in 2007 and was also monitored in 2011, 2012, 2015, and 2019. This study was conducted to evaluate the trends of these monitoring results by year. The main soil series of the paddy soils monitored were centered on soils such as Jisan-series, which had a large area distribution, and the topography was mainly distributed in valley/alluvial fan and flat areas like as river alluvium. In addition, most of the soil texture consisted of sandy loam, loam, and silt loam. The bulk density of the paddy subsoil and plowing depth have been showing an increasing trend until 2019 from 2007. The plowing depth is less than 20 cm, which is the standard for determining appropriate soil depth, but in 2019, it was 19.3 cm, approaching the appropriate standard. The distribution ratio of bulk density of subsoil exceeding the standards notified by the Rural Development Administration had been exceeding 80% since 2012. Soil organic matter content in paddy fields tended to increase in both topsoil and subsoil.
The hardness of subsoil exceeded 20 mm which is the appropriate standard for paddy soil, except in 2019. As a result, it is believed that the plowing depth is increased by the introduction of large agricultural machinery, etc., making it possible to plow the soil deeper. However, the introduction of large agricultural machinery deteriorates the bulk density and hardness of the soil, so it is necessary to spread soil improvement methods such as subsoil crushing. It was also assessed that soil improvement, such as lowering the bulk density by increasing the organic matter content through continuous input of organic matter into the soil, was necessary.