The Soil Taxonomy of India is the primary soil classification system used in the country. It is based on the USDA Soil Taxonomy system, but with modifications to suit Indian conditions.

The basic unit of soil classification in the Soil Taxonomy of India is the soil series. A soil series is a group of soils that have similar characteristics in terms of texture, structure, mineralogy, and drainage.

There are 12 soil orders recognized in the Soil Taxonomy of India. These are: Entisols, Inceptisols, Vertisols, Aridisols, Mollisols, Spodosols, Alfisols, Ultisols, Oxisols, Histosols, Andisols, and Gelisols.

Mollisols are characterized by the presence of a thick, dark-colored surface horizon rich in organic matter. These soils are typically found in grasslands and prairies.

Aridisols are characterized by the presence of a hardpan layer that restricts root penetration. These soils are typically found in dry climates.

Spodosols are characterized by the presence of a spodic horizon, which is a layer of accumulation of organic matter and aluminum. These soils are typically found in forested areas.

Vertisols are characterized by the presence of a clay-rich subsoil that is sticky and plastic when wet and hard when dry. These soils are typically found in tropical and subtropical regions.

Oxisols are characterized by the presence of a lateritic horizon, which is a layer of accumulation of iron and aluminum oxides. These soils are typically found in tropical and subtropical regions.

Histosols are characterized by the presence of a histic horizon, which is a layer of accumulation of organic matter. These soils are typically found in wetlands.

Andisols are characterized by the presence of an andic horizon, which is a layer of accumulation of volcanic ash. These soils are typically found in areas with volcanic activity.

Gelisols are characterized by the presence of a gelisol horizon, which is a layer of perennially frozen soil. These soils are typically found in polar and subpolar regions.

Soil classification serves multiple purposes, including grouping soils with similar characteristics, understanding soil properties and behavior, and aiding in land use planning and management.

Soil classification helps in land use planning and management by identifying suitable areas for different land uses, providing information on soil fertility and productivity, and helping to identify areas at risk of erosion or degradation.

Soil classification faces challenges due to the complexity and variability of soils, the lack of standardized classification criteria, and the need for specialized knowledge and expertise.

Recent advancements in soil classification include the use of remote sensing and GIS technology, the development of new classification systems based on soil properties, and the integration of soil classification with other environmental data.