Alluvial soils, on the basis of their transporting agency, may be grouped under following two broad categories:
(A) By Agency of Water-(i) Riverine alluvium, (ii) Lacustrine alluvium, and (c) Coastal alluvium.
(B) By Agency of Winds-(iv) Loess soils, and (v) Sandy Soils.
(i) Riverine Alluvium-these soils occupy whole of the northern Great Plains except the arid tracts of Rajasthan. In southern Peninsula these are also noticed in the valleys and deltaic tracts of some large rivers. These are fertile soils utilised for the cultivation of wheat, rice, pulses, oil seeds, cotton, jute, sugarcane and vegetables. These are mainly divided into old riverine alluvium (Bhangar), and new riverine alluvium (Khadar).
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(ii) Lacustrine Alluvium-these are the result of the filling of the lakes occupying limited patches in West Bengal, Assam, Orissa and Tarai regions of Uttar Pradesh. Their middle strata contain fine particles and the abundance of humus makes the soil fertile.
(iii) Coastal Alluvium-these soils are found along the sea coast and contains recent deposits. Their colour ranges from bright red to red brown, light brown and deep brown. Soils are deep and saline wherever coming into contact with sea water. In Maharashtra the soils along the Konkan coast are called ‘Khar’. Coastal alluvium is well suited to the crops like rice, coconut etc.
(iv) Loess Soils-Loess is the finest particle of sand carried by winds from desert (Thar Desert) to the neighbouring areas of Haryana, Punjab, western Uttar Pradesh and western Madhya Pradesh. Here a thin layer of loess particles (sand) is spread over the surface soil in discontinuous patches. Such soils are not very important from agricultural point of view.
(e) Sandy Soils-these soils are found in the arid lands of Rajasthan (eastern Rajasthan). These are also carried by winds to the neighbouring areas of Uttar Pradesh, Madhya Pradesh and Delhi. Agra and Mathuradistricts are being invaded by such soils which are making agricultural areas infertile.
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Depending upon the texture, alluvial soils may be divided into two broad categories: (1) Dry alluvial soil (west of 85°E Long.), and (2) Wet alluvial soil (east of 85°E Long.).
1. Dry Alluvial Soils-these soils have been decomposed by the process of mechanical weathering. Here soil particles are comparatively bigger in size; soil-air is more and underground water table lower. Due to capillary action calcium and alkaline deposits appear on the surface, making the soil infertile. But by the use of manures and fertilisers these yield good results and are utilised in the cultivation of wheat, sugarcane, cotton, oil seeds etc.
2. Moist Alluvial Soils-their particles are finer with higher amount of soil-moisture and higher water table. Such soils are found in scattered patches in the delta, marshy lands (Sundarban), Tarai, and lacustrine areas.
Based on their mineral contents alluvial soils may be divided into following four sub-types: (a) calcareous alluvium, (b) coastal alluvium, (c) grey- brown alluvium, and (d) undifferentiated alluvium.
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Govind Ranjan and Dutta Biswas (1968) have identified four sub-types of alluvial soils, i.e. (a) coastal alluvium, (b) coastal sands, (c) deltaic alluvium, and (d) Gangetic alluvium.