Reclamation of sub-surface sodicity with Cut-soiler drainage for rice-wheat production in Indo-Gangetic Plains.

Arid and semi-arid regions experience less rainfall and high evaporation rates and are very sensitive to land use transitions. Salt-induced soil degradation is one of the major constraints in arid and semi-arid regions of India. In India about 6.73 Mha land is salt affected out of which around 3.78 M ha is under sodic soils. Around 2.5 M ha area is covered under salt affected soils in Indo Gangetic Plains (IGP), the most fertile landmass. Besides infelicitous crop management practices, injudicious use of sodic water possess grave risks to soil health. High Residual Sodium Carbonate (RSC) restricts the natural drainage, a rationale to surface and subsurface sodicity development. On farm residue burning is also a burgeoning problem in the semi-arid region of IGP where rice-wheat cropping system is predominantly followed. Fathoming the twin problem of sub-surface sodicity and residue burning the column study in semi-controlled condition is being conducted under ICAR-Central Soil Salinity Research Institute (Karnal) and the Japan International Research Center for Agricultural Sciences (JIRCAS) collaborative project. The treatments consisted surface application of gypsum (SA), surface and sub-surface placement (50 cm below the surface) of rice straw residue and gypsum that is an imitation of sub-surface Cut-soiler assisted drains in field condition. The columns were irrigated with water having RSC <2 meql^-1 and ~5 meql^-1. The results showed that comparatively the higher reduction in soil pH was recorded in the columns irrigated with RSC <2 meql water as compared to ~5 meql under surface application of gypsum along with sub-surface application of gypsum and residue both. Consequently, the rice yield increase about 31% and 23% in the foresaid treatment as compared to control. Therefore, surface application of gypsum along with cut-soiler assisted sub-surface placement of amendments found promising in reclamation of sub-surface sodicity and increase rice yields under sodic soils. [ABSTRACT FROM AUTHOR]