Salinisation Soil salinisation is one of the major threats in irrigation agriculture. Soil salinity causes yield losses and can lead to structural instability of the soil if the sodium percentage is high. Salinization is reducing the world's irrigated area by 1-2 percent every year, hitting hardest in the arid and semi-arid regions. Primary salinisation occurs naturally where the soil parent material is rich in soluble salts, or in the presence of a shallow saline groundwater table. In arid and semi-arid regions, where rainfall is insufficient to leach soluble salts from the soil, or where drainage is restricted, soils with high concentrations of salts may be formed.

Secondary salinisation occurs when significant amounts of water are provided by irrigation, with no adequate provision of drainage for the leaching and removal of salts, resulting in the soils becoming salty and unproductive. Salt-affected soils reduce both the ability of crops to take up water and the availability of micronutrients. They also concentrate ions toxic to plants and may degrade the soil structure. The salt balance of soils can be significantly affected through improper soil and water management, for example through: improper irrigation schemes management, including: insufficient water application; insufficient drainage; irrigation at low efficiency (where most of the water leaks into the groundwater) and/or over-irrigation contribute to a high water table, increasing drainage requirements and causing waterlogging and salinity build-up; irrigation with saline or marginal quality water, which may be caused by intrusion of saline water into fresh water aquifers in coastal zones due to over-pumping.

Types of Irrigation FLOOD IRRIGATION SPRINKLER IRRIGATION DRIP IRRIGATION What are the positives and negatives of these techniques?

Suggested reading: and_science/blog/salinity_global_problem_es pecially_arid_and_semiarid_regions Salinisation and_science/blog/salinity_global_problem_es pecially_arid_and_semiarid_regions lwebsite/solution/agriculture.shtml Irrigation lwebsite/solution/agriculture.shtml