Saturation of soil with water, usually through irrigation, resulting in a condition under which most crop plants cannot grow. Although naturally wet soils are extremely common, human-caused waterlogging occurring on active croplands has created the most concern. Where fields are irrigated regularly, some means of drainage is usually necessary to let excess water escape, but if drainage is inadequate, water gradually accumulates, filling pore spaces in the soil. Once the oxygen in these pores is displaced by water, plant roots and soil microorganisms die. Waterlogging frequently occurs where flooding has been used. There are two main reasons for flooding: it is a simple, low-technology method of irrigation and in some cases it reduces harmful mineral concentrations in soils. Ideally, flood waters seep through the soil and into groundwater or stream channels, but in many agricultural regions, impermeable layers of clay block downward drainage so that irrigation water collects in the soil. Farmers who can afford it avoid this problem by installing some means of field drainage, such as perforated pipes below ground. However, the expense of this procedure is prohibitive in many regions.

See Also

Soil Conservation; Soil Eluviation