Management of Salt-Affected Soils - Practices of Irrigation and On-farm Water Management - page 311

Irrigation at Alternate Furrows
Alternate furrow irrigation may be desired for single-row bed systems. This is
accomplished by irrigating every other furrow and leaving alternating furrows dry.
Salts are pushed across the bed from the irrigated side of the furrow to the dry side.
Care is needed to ensure enough water is applied to wet all the way across the bed
to prevent buildup in the planted area.
8.6.2.6 Biological Reduction of Salts
In areas with negligible irrigation water or rainfall available for leaching, biological
reduction of salts by harvest of high-salt accumulating aerial plant parts may be a
strategy to reduce the salt hazard. This can be done by plant uptake and removal. A
type of plant that is of particular interest for salinity affected areas is the saltbush,
which is able to tolerate saline conditions and draws salt up into its leaves.
8.6.2.7 Other Management Options
Salinity Avoidance
Salinity can be escaped through cultivating/adopting crop cultivars during the period
of low salinity potential of the soil, avoiding the high salinity period. Breeding
program can be launched to develop such variety.
Mulching/Crop Residue Management
Crop residue at the soil surface reduces evaporative water losses, thereby limiting
the upward movement of salt (from shallow, saline groundwater) into the root zone.
Evaporation and thus, salt accumulation, tends to be greater in bare soils. Fields
need to have 30-50% residue cover to significantly reduce evaporation. Under crop
residue, soils remain wetter, allowing fall or winter precipitation to be more effective
in leaching salts, particularly from the surface soil layers where damage to crop
seedlings is most likely to occur. Plastic mulches used with drip irrigation effectively
reduce salt concentration from evaporation.
In the soils showing poor water-transmission property, addition of amendments
like sand, rice-husk or rice-straw may be used to improve leaching under limited
water availability. The presence of subsurface drains may also help in increasing the
leaching of salts in silty clay-loam soil.
Physical Management
Several mechanical methods may be used to improve infiltration and permeability
in the surface layer and root zone and thus control saline conditions. These include
land leveling, deep plowing, and special planting technique.