Soil Degradation Due to Irrigation

Irrigation

• Irrigation, which provides supplemental water for crops in areas where rainfall is insufficient or unpredictable, can degrade the soil. Proper timing of irrigation and calculation of the right amount of water to provide are vital to efficient irrigation practices, as farmers don't want to waste water, stress their crops or reduce their yields. Tools are available that can measure the water in soil to help guide irrigation practices.

Issues Related to Irrigation

• Irrigation can lead to the loss of soil. Soil degradation occurs when irrigated soils develop reduced fertility and experience erosion and surface runoff, leading to a reduced soil depth. According to the Infonet Biovision website, cultivation on sloped terrain, the use of shallow soils and lack of soil conservation efforts contribute to the problem. Irrigation can lead to soil degradation when certain farming methods are used, such as clear cutting or waterlogging the soil for paddy fields, which increases salinization and alkalinization in the topsoil, according to the UN Commission.

  Irrigation can cause water problems in addition to issues with soil. Plants grown on soils that drain freely or have a low capacity to hold water, such as sandy soils, require more fertilizer and pesticides, which can lead to leaching or runoff that can affect groundwater, according to the University of Minnesota Extension. Poor irrigation practices can lead to waste of water, materials, plant loss and economic loss.

Types of Degradation

• Degradation may occur when soil deteriorates or is displaced by wind or water erosion, loss of nutrients or the presence of pollution, salts or chemicals. Soil may lose its structure by becoming compacted, which hampers plant root development, or by forming a crust that does not allow water to penetrate readily. Types of degradation may go hand in hand, with one type leading to the other, according to the UN Commission. Several other factors influence degradation, including flooding, deforestation, high winds, heavy rains, drought, overgrazing and lack of soil conservation.

Before You Start

• Obtain a soil survey before you begin irrigating, recommends the North Dakota State University Extension. Fields may contain a mixture of irrigation categories from irrigable to nonirrigable, and a soil classified as nonirrigable should not be irrigated, as it provides no economic benefit and could compromise the soil's productivity. Conditional soils are those that can be irrigated but require maintenance and supervision.

  When evaluating your soil, consider the other factors affecting degradation. These include the slope of the site, the makeup of layers of the subsoil, the depth of each layer, and the soil structure, texture, color, amount of organic matter, and the carbonate and sodium content of each layer within the subsoil.