Anomalies in classification of the salt-affected soils under USDA soil taxonomy

Out of 47 Mha of Indo-Gangetic semi-arid plain, an area of 2.37 Mha has turned into saltaffected soils. These are grouped into saline, saline-alkali and alkali soils. In Soil Taxonomy, the soils of recent alluvial plain are classified under Aquepts and Ustepts great groups of Inceptisols order. The salt-affected soils as well as normal productive soils of the region are also classified in the same great groups. Such placement of soils without referring its potential or limitation do not properly reflect their management needs and thus indicate anomalies in the Soil Taxonomy System. The Typic Haplustepts and Typic Calciustepts sub-groups of recent alluvial plain under the proposed revision qualify under Sodic Haplustepts and Sodic Calciustepts whereas the classification of normal soils will remain unchanged. In case of Petrocalcic Calciustepts and Fluventic Calciustepts where ESP is more than 15, an intergrade showing sodic properties needs to be introduced. The ESP >15 limit for clayey soils is too high and as such it may be narrowed down. Moreover ESP 15–98 kept in one class also needs modification. The salt-affected soils of active alluvial plain under the available provisions are classified in Typic Ustorthents and Typic Ustifluvents but since the soils depict ESP >15 there is a need to introduce salic and sodic classes at the sub-group levels for their meaningful interpretation considering their management.