Many different types of crop irrigation are used in various parts of the world. The type of irrigation often depends on terrain and soil. The basic goal of irrigation is to make certain that the entire field receives the amount of water needed for maximum crop yield. Some of the most common forms of crop irrigation include surface flooding, furrow, rotation, and traveling guns. Other common forms of irrigation include the center pivot, drip, sprinkler, and sub-irrigation methods.
Surface flooding irrigation is usually performed by covering the entirety of the field with water and allowing it to soak into the soil. Furrow irrigation is typically carried out by partially flooding the field until the individual furrows fill with a sufficient amount of water. Both of these methods rely on a relatively flat field surface to work properly. The rotation method of crop irrigation utilizes portable sprinkler equipment that is moved from place to place within a field until the entire crop has been adequately watered. A traveling gun is basically a high-volume water hose on wheels that is moved to different areas of the field until the irrigation process is completed.
Center pivot crop irrigation makes used of a long, centrally located sprinkler boom that is rotated around the field during watering. A high-pressure water hose is connected to the fixed portion of the irrigator and the sprinkler boom is supported at various points by wheeled towers. The wheels of the tower supports are typically powered by hydraulic, pneumatic, or electrical means. A uniform rate of water is applied by increasing the size of the sprinkler nozzles in proportion to their distance from the center pivot. Crops are sometimes planted in a circular field to make better use of this method.
Drip irrigation is an efficient means of delivering water only to the root area of crops. This method typically utilizes a network of perforated piping to deliver a low-pressure stream of water to each plant in the field. This usually helps minimize the risk of water loss due to runoff and evaporation. In-line water pressure regulators are usually required when performing drip irrigation on steep slopes. This crop irrigation method is often computer controlled to prevent overwatering of the crop.
Sprinkler irrigation typically involves the use of multiple high-pressure sprinkler heads at various locations throughout the field. Sprinkler heads are typically arranged in some type of grid to ensure complete field irrigation. The water supply is piped to each individual sprinkler location, and the pressure of the water is used to drive the spring-loaded heads in a circular fashion. Sprinkler heads can be adjusted to rotate in either a partial or full circle. Sprinkler-type crop irrigation systems are sometimes computer programmed to operate during the evening hours and minimize water evaporation.
Sub-irrigation is a type of crop irrigation that makes use of perforated water supply lines buried just below the surface of the soil. This configuration is generally found in locations where the water table is higher than normal. Sub-irrigation temporarily raises the water table to allow crops to be watered at the root level. In wetland areas, it is sometimes utilized to lower the water table as well. A network of pumping stations, valves, piping, and ditches is often incorporated into sub-irrigation systems to either raise or lower the natural water table in these wetland fields.
