La Union SWCD-Salinity Management Guide

When irrigating with water high in salinity, the excess salts introduced by irrigation must be routinely flushed out of the soil by providing adequate drainage and enough excess irrigation water to provide for both plant requirements and leaching.
The leaching requirement is related to the quality of drainage and irrigation water for an equilibrium condition.
Soil water salinity continually changes following an irrigation. This upper root zone is more thoroughly leached than the lower root zone, thus reducing the salinity effects where most of the water up-take occurs.
Saline soils do not respond to chemical amendments. Only leaching the salts through adequate drainage reclaims these soils.
Saline/Sodic and Sodic soils do respond to amendments and drainage. For saline-sodic soils, leaching is necessary and possible, but as salts are removed the sodium must be replaced to prevent dispersion of soil particles and reduction of permeability. Sodic soils have low permeability due to dispersion of soil by the sodium and requires replacing the sodium to improve the permeability so that leaching can proceed.
Maintaining good permeability is necessary since many crops are sensitive to oxygen stress caused by standing water.
For many crops the germinating and early seedling stage is the most sensitive period of being susceptible to salinity problems.