Flood Irrigation. Flood irrigation is the least expensive irrigation method where water is relatively cheap. It should only be used on very flat fields, where ponding is not a problem. Flooding is a good way to flush salts out of the soil. It is highly inefficient, however, when speaking of water loss through evaporation, and the anaerobic environment created by flooding can enhance microbial conversion of available soil nitrogen back to atmospheric nitrogen (denitrification).
Furrow Irrigation (with mulch). Furrow irrigation is relatively inexpensive where water costs are low. Furrows must be carefully dug to ensure an even distribution of water.
Sprinkler Irrigation: center-pivot (left), set line (center), wheel line (right). These methods are more expensive than flood or furrow irrigation, but are more efficient at using water. Still, much water is lost through evaporation, and problems due to foliar moisture-loving diseases can arise if overwatering occurs.
Drip or Trickle Irrigation. This is the most expensive, but most water-efficient, method. Low-quality water (high in salts) should not be used, unless filtered, due to potentially devastating effects of clogged emitters. Also, the use of water high in soluble salts will result in localized soil salinity buildup around plants, since drip irrigation is an ineffective leaching method.
