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Saline (chowdu) soil paddy management

Salt-affected paddy soils, known locally as chowdu in Telugu, occur along the coast and in inland tracts where high evapotranspiration concentrates soluble salts or sodium in the root zone. ICAR-Central Soil Salinity Research Institute (CSSRI) Karnal has developed a portfolio of salt-tolerant rice cultivars and a bio-reclamation package for these soils.

Principle

In saline soils, osmotic stress and specific-ion toxicity (chloride, sodium) reduce paddy germination, tillering and grain set. In sodic soils, high exchangeable sodium disperses clay, sealing the surface and reducing infiltration. Chemical reclamation displaces exchangeable sodium with calcium, often supplied by gypsum, while organic amendments improve structure and biological activity. Combining amendment with a salt-tolerant variety lowers the chemical dose needed to achieve acceptable yield.

Implementation

CSSRI's standard chemical reclamation prescribes either 50% of the soil's gypsum requirement applied to the surface 15 centimetres, or 25% gypsum combined with farmyard manure at 20 tonnes per hectare. Gypsum is incorporated into the surface layer before puddling so that calcium can displace adsorbed sodium during the wet phase. The CSR series of salt-tolerant rice cultivars is recommended in place of conventional varieties. Field experiments show that 25% gypsum plus a salt-tolerant variety gives grain yield comparable to 50% gypsum with a normal variety, halving amendment cost.

Adoption context

Salt-tolerant CSSRI varieties had been adopted across more than 7.5 million hectares between 2014 and 2019. In coastal tracts where vertical wells intersect brackish water, the practice is often combined with Horizontal Borewell systems that skim freshwater above the saline layer. Reclamation decisions follow Soil Testing for pH, EC and exchangeable sodium, and complement broader Soil Ph Management.

Limitations

Reclamation is multi-season and requires steady water supply for leaching. Gypsum quality and grinding fineness affect reaction rate. Continuous use of poor-quality irrigation water reverses reclamation gains. Field drainage is essential because amendments alone cannot remove salt from a profile that lacks an outlet.

See also: Soil Ph Management, Soil Testing, Horizontal Borewell, Paddy Water Management.

References

  1. Soil and Crop Management Division. ICAR-Central Soil Salinity Research Institute.
  2. Reclamation of Alkali Soils through Gypsum Technology. ICAR-CSSRI.
  3. Varieties Developed. ICAR-CSSRI.