This is the most crucial and pervasive kind. It covers forty per cent of land area. In fact the complete Northern Plains are made up of these soils. They have been brought down and deposited by three enormous Himalayan rivers- Satluj, Ganga and Brahmaputra-and their tributaries. Through a tapered outlet in Rajasthan, they continue into the plains of Gujarat. They are common in eastern coastal plains, in the deltas of Mahanadi, Godavari, Krishna and Kaveri.

The river deposits extremely refined particles of soil, called alluvium in their plains during the path of their long travail, spread over hundreds of kilometres and thousands of years. These soils consist of diverse ratios of sand, silt and clay. They are prevalent in the coastal plains and deltas. As one moves further inland in the river valleys, the soil particles appear pretty heavier in size. In the upper reaches of the river Valleys, i.e. near the place of their origin, the soils are coarser. Soil particles are larger and a long way from being smooth. Such soils are more familiar in piedmont plains, i.e. those that are near the foot of mountains.

Excluding the size of their grains or particles, soils are distinguished according to their age also. They are grouped in old alluvium and new alluvium types. The so called new alluvium may be even ten thousand years old. Locally the old alluvium is called `bangar`, and the new alluvium is called `khadar`. The old alluvium often contains kankar nodules, with calcium carbonates in sub-soil. The new alluvium is richer compared to the old.

Alluvial soils all together are exceptionally prolific. In general, they carry ample potash, phosphoric acid and lime. However, they are lacking in organic and nitrogenous substance. Soils in the drier areas are more alkaline. Alluvial soils sustain over half the Indian population.