Clay minerals are natural materials well known for their role in retention and persistence of organic and inorganic compounds in soil. Clay minerals are being modified through different processes to alter their charge and surface properties tailored for specific purposes. Modified clays in general include pillared layered clays, organoclays, nanocomposites, acid and salt-induced and thermally and mechanically induced modified clays. Pillared organoclays and nanocomposites constitute a novel class of materials, mainly one kind of modification of expanding 2 : 1 clay minerals.

Soil fertility status of hilly microwater watershed in Shivalik hills, was assessed in relation to three locality factors, viz. altitude, slope and aspect. It was found that at higher altitude (440-450 m) of watershed, the soil fertility parameters were less and more in lower altitude (420-430m).