ABSTRACT
Sodic soils are generally associated with the presence of high concentrations of sodium salt and are considered as a subset of saline soils. They are generally considered as marginal and not suitable for cropping and left for grazing or under native ecosystems. As the human population increases, the need for increasing food production leads to increasing use of marginal land and increasing use of irrigation with poor quality water. These in turn lead to the development of secondary salinization and, associated with this, increasing soil sodicity in arable land. This entry describes the various observable field problems associated with the presence of high exchangeable sodium concentrations, all of which can be related to the fundamental processes of slaking and dispersion. The effective management of sodic soils is based on controlling one or both of these processes.
