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Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. [1] Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean.
The salt level is often taken as the soil salinity or the salinity of the irrigation water. Salt tolerance is of importance in irrigated lands in (semi)arid regions where the soil salinity problem can be extensive as a result of the salinization occurring here. It concerns hundreds of millions of hectares. [2]
The soil moisture regimes are defined based on the levels of the groundwater table and the amounts of soil water available to plants during a given year in a particular region. Several moisture regime classes are used to characterize soils. These categories are terminology modifiers at the soil suborder level of characterization.
Salinity (/ s ə ˈ l ɪ n ɪ t i /) is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal to ‰ ).
The soil salinity on the x-axis is represented by electric conductivity (ECe). In this example the crop has a salt tolerance (threshold) of ECe = Pb = 7 dS/m beyond which the yield diminishes. The Maas–Hoffman model is a mathematical tool to characterize the relation between crop production and soil salinity.
From figure 1 it is seen that 800 mm of water (or 8000 m 3 /ha) is required to bring the soil salinity down to 60% of its original value in the soil layer at 40 to 60 cm depth. When the salinity must be less than 60%, extrapolation of the leaching curve, the use of a leaching equation (see below) or a leaching model like SaltMod is necessary to ...
High levels of salt are often found in dry soils, more so than wet soils as it is diluted and washed through the soil profile. (Barry and Holwell et al., 2012). Secondary salinity is a direct result of human interaction with the land, during development, agriculture and irrigation.
SaltMod is computer program for the prediction of the salinity of soil moisture, groundwater and drainage water, the depth of the watertable, and the drain discharge (hydrology) in irrigated agricultural lands, using different (geo)hydrologic conditions, varying water management options, including the use of ground water for irrigation, and several cropping rotation schedules.