Soil Conservation - Salinity Management

Salinity Management

Salinity in soil is caused by irrigating the crops with salty water. During the evaporation process the water from the soil evaporates leaving the salt behind causing salinization. Salinization causes the soil structure to break down causing infertility and the plants cannot grow.

The ions responsible for salination are: Na+, K+, Ca2+, Mg2+ and Cl-. Salinity is estimated to affect about one third of all the earth’s arable land. Soil salinity adversely affects the metabolism of most crops, and erosion effects usually follow vegetation failure. Salinity occurs on drylands from overirrigation and in areas with shallow saline water tables. In the case of over-irrigation, salts are deposited in upper soil layers as a byproduct of most soil infiltration; excessive irrigation merely increases the rate of salt deposition. The best-known case of shallow saline water table capillary action occurred in Egypt after the 1970 construction of the Aswan Dam. The change in the groundwater level due to dam construction led to high concentration of salts in the water table. After the construction, the continuous high level of the water table led to soil salination of previously arable land.

Use of humic acids may prevent excess salination, especially in locales where excessive irrigation was practiced. The mechanism involved is that humic acids can fix both anions and cations and eliminate them from root zones. In some cases it may be valuable to find plants that can tolerate saline conditions to use as surface cover until salinity can be reduced; there are a number of such saline-tolerant plants, such as saltbush, a plant found in much of North America and in the Mediterranean regions of Europe.