Agriculture Reference
In-Depth Information
Knowing the source of salt problems can be helpful in diagnosing and managing
salt-affected fields.
8.2.2 Factors Affecting Salinity
The main factors affecting the intensity and extent of salinity are as follows:
•
soil moisture content
•
soil type
•
depth to saline water table
•
climate
•
irrigation method
•
irrigation frequency
8.2.2.1 Soil Moisture
Soil salinity can be difficult to notice from one season to the next because it is
influenced by moisture conditions. In wet years, there is sufficient leaching and
dissolving of salts so that they are not visible on the soil surface and some crop
growth may be possible. However, the excess water received in wet years contributes
to the overall salinity problem over time. In dry years, increased evaporation dries
out the soil and draws salts up to the soil surface, producing white crusts of salt. In
dry years, producers become more concerned with salinity because salts are highly
visible and little-to-no crop growth occurs in the affected areas.
Salt-affected soils can occur locally (only a few square meters in size, scat-
tered over a given landscape) or regionally (large areas several hectares in size).
Depending on moisture conditions, these areas can increase in size or intensify in
salt concentration.
8.2.2.2 Depth to Water Table
Overall outcomes are primarily dependent on the movement, salt content, and depth
of groundwater.
8.2.2.3 Method of Irrigation
Irrigation method and frequency have significant effects on growth and yield of crop
and also on salinity hazard. Drip irrigation gives the greatest advantages when saline
water is used. Sprinkler irrigation may cause leaf burn on sensitive crops with saline
water. Damage may be reduced by night irrigation and by irrigating continually
rather than intermittently.
8.2.2.4 Soil Factor
Soil properties such as fertility, texture and structure play a role in altering the
salinity response function. At high soil fertility levels, three will be a larger yield
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