Korea is a mountainous peninsula in the Far East extending southeast from Manchuria. It is separated from Manchuria by the natural boundaries of the Yalu river, Mt. Baegdu and the Duman river. The Duman river separates Korea from Siberia at its mouth.
The Korea peninsula together with 3,579 islands mostly clustered off the southwestern coast, is flanked by two oceans, the East Sea on the east and the West Sea on the west.
The Korean peninsula lies longitudinally between 124°11'E - 131°52'E and latitudinally between 33°06'N - 43°N in the northern temperate zone of the Eastern Hemisphere. The overall area of the Korean peninsula is 221,392 square kilometers, or about 84,600 square miles. The communist-controlled zone, north of the truce line, comprises 122,370 square kilometers, while the Republic of Korea to the south is slightly smaller, with 99,022 square kilometers. The Korean peninsula is approximately 1,000 kilometers in north-south length, and 216 kilometers wide at its narrowest east-west point. Korea can be compared in size with the British isles or West Germany, and the southern part with Jordan or Holland.
Soil are formed from various parent materials under different environmental conditions. Their characteristic are very different, depending on the combination of soil forming factors. The influence of these factors is interdependent and, in fact, they exert a combined but by no means equal control on soil formation. They appear to be responsible for the 375 soil series recognizable in Korea as of 1984.
The soil forming factors pertinent to the formation of Korean soil are described in this chapter.
The climate of Korea belongs to the humid-temperate zone and is both continental and oceanic in character. The climate is relatively mild with a clear distinction between the four seasons.
July and August afford the hottest days, while the coldest winter days fall in December and January. All meterological stations report the mean summer temperature being about 20 to 25°C with a maximum in August, and mean winter temperature 5.0 to -5.0°C in south and -5.0°C to -20°C in north with a minimum in January.
The annual precipitation ranges from 1,000 to 1,380 mm except for most of northern Korea and a small area around Daegu. About 50 percent of the annual rainfall occurs in the months of July, August and September as a result of the influx of warm moist air from the Pacific Ocean where pressure conditions create the summer monsoon.
Because of a warm temperature climate with moderately high rain fall in summer, most of the Korean soils of the coastal plain, alluvium plain, terraces, hilly land and low mountains are relatively deep and well oxidized.
In Korea the principal native vegetation is forest. Very little of the original, virgin composition remains, mainly in the plateau of high mountain areas. The dominant vegetation consists of forest trees mains, mainly in the plateau of high mountain area. The dominant vegetation consists of forest trees with a varying undergrowth of shrubs and smaller plants but almost bare land occurs around the densely populated areas under non-cultivation. In recent year, there has been much reforestation, but many extensive areas are still barren and badly eroded.
The parent materials of Korean soils are varied. Most of the area are occupied by granites and granite gneisses of the late Archeozoic era. Some are occupied by Pre-cambrian metamorphic and Mesozoic sedimentary rocks. Several plutonic rock intrusions took place both in the late and earlier geological times. The general geology of Korea is shown Figure 2.
The mountain range of Taebaeg on the Gangweon-Do runs southward along the east coast with lateral branches and spurs extending in a southwesterly direction. The slope to the east is steep while those to the west are gentle. The mountain range slopes down toward the south, thus making the southern part of the country fairly level. In contrast, the northern part is mountainous and hilly land. Because of this, the southern region is the Korean granary and most of its population is concentrated in this area, except for Seoul.
The soils of Korea range from very young to old or mature. Soil that been in place for a long time and have approached equilibrium with their environment are considered mature of old.
In general, soils in the terraces, rolling peneplines, and hilly lands are the oldest, and soils of the tide-water region in the coastal plains and river wash of levee in the flood plains are the youngest on Korea. Most of the soils in the mountain region probably are no older than some soils in the continental inland plain.
Soils in Korea, south of the Demilitarized zone, have been classified into 13 Great Soil Groups, specifically Gley Soils, Alluvial Soils, Red-Yellow Soils, Regosols, Planosol-like Soils, Lithosols, Rankers, Brown Forest Soils, Acid-Brown Forest Soils, Organic Soils, Reddish-Brown Soils, Saline Soils and Volcanic Ash Soils in the old classification system(USDA 1938 plus 1949 Revision). 391 soil serieses were identified including Dogdo series in 2012, 486 soil types and 1,175 soil phases were established.
According to new soil classification system of the United States Department of Agriculture(Soil and 375 soil series. The dominant soils in Korea are Inceptiosols and Entisols. The Alfisols, Ultisols, Histosols and Mollisols are recognized, but are of small extent. The extents of the orders and suborders are shown in table 3.
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