If you are wondering what are the different types of soil on earth, then this article will prove to be more than helpful.
The surface of planet Earth is about 30 per cent land and the rest 70 per cent is covered by water -sea, rivers and lakes. The soil covers approximately one third of the land’s surface. Its thickness ranges from a few centimeters to tens of meters. It was originally formed by the slow erosion of the rocks into tiny pieces, which then mixed with organic matter and water to form soil. This thin skin plays a very vital role for the existence of many life forms, as well as for the productivity of the agricultural cords and animal farming that humans use as a source of nourishment. The factors that are responsible for soil formation (climate, topography, parent material, time and organisms) create many different types of soil on earth. In fact, there are several thousand different types of soil on earth. This might sound like an exaggeration to you, but each geographic area has its own soil with unique characteristics like color, texture, structure, density, porosity etc.
There are many methods to classify the different types of soil on earth according to determined criteria like depth, temperature, structure, salt content, organic matter content, moisture, texture, clay mineralogy, cation exchange capacity, and base saturation. The classification of soil into categories is very important. It enables us to determine the suitability of a soil for a particular plantation and ensures the productivity of the corps. Scientists have noticed that areas which share comparable soil-forming factors produce similar types of soil. There are many classification systems in use worldwide, but for the purposes of this article, we will only mention that of the American Agricultural Department classification (U.S.D.A.). The U.S.D.A. soil classification system recognizes 12 types of soil on earth: Alfisols, Aridisols, Entisols, Histosols, Inceptisols, Mollisols, Oxisols, Spodosols, Ultisols, Gelisols, Andisols, and Vertisols.
Alfisols form where there is moisture and warmth and constitute 10.1 per cent of soils worldwide. The most distinct characteristic of these soils are the horizons of clay accumulation, as well as their high aluminum and iron content.
Aridisols are soils that develop in very dry environments and include nearly 12 per cent of soils on Earth.
Entisols are immature soils that lack well-developed horizons. They are 18 per cent of soils worldwide.
Histosols are organic soils that develop in areas of poor drainage. They represent only 1.2 per cent of soils worldwide.
Inceptisols are young soils and constitute 15 per cent of soils in the world.
Mollisols are dark fertile soils formed in grasslands and are 7 per cent of soils worldwide.
Oxisols are soils rich in iron and aluminum oxides due to chemical weathering and heavy leaching. They are 7.5 per cent of soils worldwide.
Spondosols are acid soils. The basic characteristic of these soils is that they accumulate mixtures of organic matter and aluminum and represent 4 per cent of soils worldwide.
Ultisols are acid soils in humid climates and are very common to the southeastern United States. They are 8.1% of the soil worldwide.
Gelisols are soils of very cold climates and are found mainly in Alaska, Siberia and Canada. They constitute 9.1% of soils worldwide.
Andisols are volcanic ash soils and are very fertile. They constiture 1 per cent of soils worldwide.
Vertisols are heavy clay soils. They are found in Texas and they cover 2.4 % of the world’s surface.