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. Acid and salt treatments lead to modification of the catalytic properties of clays. Clay mineral–polymer
nanocomposites are the hybrids which exhibit a change in composition and structure on a scale of nanometres. Modified clay imparts slow-release property to fertilizers and enhances the water-holding capacity of soil. Therefore, understanding the methods of clay modification and properties of modified clays may facilitate development of agricultural management systems that ensure long-term sustainability of soil resources.