Soil is an important natural medium for sup- porting plant growth and crop production. Recent changes in global climate and ecosystems are placing greater emphasis on the role of soil as a surface medium that connects water, atmosphere, and terrestrial ecosystems. In order to respond to increasing societal demands for detailed knowl- edge in this eld, it is necessary to gain a better understanding of the spatial distribution, temporal changes, and nutrient status of soils.

Previously, Korea’s soil classi cation methods emphasized the relationship between soil-form- ing factors and soil characteristics. Current clas- sifications are generally made by utilizing the Soil Taxonomy established by the United States Department of Agriculture (USDA). Forest soil is separately classi ed according to soil morpho- logical data such as soil color, moisture condition, and parent materials.

Korea has a fairly homogenous climate and vegetation pattern throughout its territory, but its soil distribution pattern is quite complex. This can be attributed to the country’s long history of intensive land use, diversi ed geological features, and rough terrain. According to Soil Taxonomy (which categorizes 12 orders of soil recognized on a global scale), Korea has 7 orders, 17 sub- orders, and 27 great groups of soils. In addition, approximately 400 soil series (the lowest level of soil classi cation) have been identi ed to date.

64.8% (6.13 million ha) of Korean territory is

covered with Inceptisols, which can be de ned as soils that do not have clear soil horizon develop- ment. The predominance of Inceptisols indicates that the land surface has undergone radical chang- es. For instance, rapid soil erosion constantly removes topsoil from slope surfaces, and active deposition in areas such as alluvial fans, valleys, and riverside ats hinders soil horizonation. The characteristics of Korean summers also serve as crucial factors of fast erosion; concentrated pre- cipitation, high temperatures, and high humidity interrupt the accumulation of organic matter and weaken soil formation processes. Additionally, freezing during the winter also prevents active differentiation of soil horizons.

Entisols, occupying 1.07 million ha (11.3%), have a weakly developed A horizon. Even in at areas, Entisols are commonly considered infertile as they have a low nutrient status and a decreased capacity for water storage. 58 soil series are currently classified as Entisols and 4 subgroups have been identi ed. Entisols are predominantly concentrated along major mountain areas – such as Taebaeksanmaek and Sobaeksanmaek – where active soil erosion occurs. Psamments (often found in sand deposits and shifting sand dunes) and Fluvents/Aquents/Orthents (mostly formed on riverbanks and tidal mud ats) are some identi- able suborders of Entisols.

Alfisols and Ultisols have a well-developed B horizon that characteristically appears in clay-en-

riched argillic horizons. These soils occupy 13.2% and 8.7% of the land, respectively. Al sols are located in riverside flatlands or on hillsides composed of neutral or basic rocks. Ultisols are acidic, and can usually be found along hillsides or foothills consisting of acidic rocks.

Andisols are formed in volcanic rocks and are mainly distributed on volcanic islands that were formed during the Quaternary eruption (such as Jejudo and Ulleungdo). They also appear in in- land regions, where they show local distribution in the Tertiary volcanic rock zones along Tae- baeksanmaek, Sobaeksanmaek, Gyeonggi-do, and the northern part of Gangwon-do. Andisols, how- ever, only occupy 1.4% of the total area of South Korea.

Histosols are developed in organic-rich envi- ronments. They can be observed throughout the coastal area of the South Sea and Jejudo. On the other hand, Mollisols – soils illuviated with or- ganic matter and nutrients – are common in the valleys of northern Sobaeksanmaek and southern Gangwon-do.

Korea is well-known for its success in combat- ing land degradation. By the end of the Joseon dynasty, many of its mountains were devastated due to long years of slash-and-burn farming and firewood logging. The Japanese Colonial Period and the Korean War that followed only further deteriorated the situation through severe forest degradation and consequent soil loss. Since the

1970s, however, many of the barren mountains have successfully been transformed into lush green forest areas and soil quality has steadily im- proved. Korea’s case of overcoming land degra- dation serves as a valuable example of sustainable development, particularly for developing coun- tries.