Management of Salt-Affected Soils - Practices of Irrigation and On-farm Water Management - page 310

Subsurface Irrigation

Subsurface drip irrigation pushes salts to the edge of the soil wetting front, reducing
harmful effects on seedlings and plant roots.

Mixing/Blending of Saline and Fresh Water

Highly saline water can be mixed with good quality or low salinity water to lower
the salinity to acceptable/tolerable limit. This approach is only possible where a
relatively better quality source is available, and that the better quality supply is not
enough to meet the demand. Mixing does not reduce the total solute content but
reduces the solute concentration due to dilution.
The salinity of the mixed water or the mixing ratio can be obtained by using the
following equation (Adapted from Ayers and Westcot, 1985 ) :

C m = ( C 1 × r 1 ) + ( C 2 × r 2 ) (8.16)

where

C m =

concentration of mixed water

C 1 = concentration of first category of water

r 1 = proportion of first category of water

C 1 = concentration of 2nd category of water

r 1 = proportion of 2nd category of water

and, r 1 + r 2 =1

The concentration can be expressed as mg/l, ppm, meq/l or, EC w (dS/m), but
must be consistent all throughout.

Alternate/Cyclic Irrigation with Saline and Fresh Water

Fresh and saline water can be applied at alternate sequence to minimize salinity
hazard. In such a practice, the nonsaline soil may turn to saline, and a saline soil to
more saline. Thus, any attempt to utilize saline water (even with conjunction with
fresh water) calls for the leaching of accumulated salts, which may be furnished by
natural rainfall, or applying additional irrigation water for leaching (i.e., LF).

Irrigation with Saline Water at Less Sensitive Growth Stages

All growth stages of crops are not equally sensitive to salinity stress. Irrigation
with fresh water at sensitive stage(s) and irrigation with saline water (or a mix)
at relatively insensitive stage(s) can facilitates optimum plant growth and yield.