Furrow irrigation is a method of supplying water to crops through shallow, evenly spaced furrows. Furrows are made with a hipper that forms parallel beds, and are usually spaced 30 or 38 inches apart. Water flows from a pump to furrows in lay-flat plastic pipes. Holes are punched in the pipe to obtain the desired flow rate.
|2 to 3 acre-inches of irrigation water can be applied at once to recharge depleted moisture in the root zone||Land needs to be graded to assure uniform distribution of irrigation water|
|Initial capital investment, other than land grading, is relatively low||Furrow irrigation is not efficient on sandy soils; water soaks in before it reaches end of field|
|Water can be used even if it contains a moderate amount of colloidal material||Difficult to apply small amounts (< 1 acre-inch) of irrigation water|
|Water is not applied directly to plants, which reduces scalding of crop foliage||In some soils, lateral spread of water across beds is not adequate to provide full irrigation|
Sprinkler irrigation is the application of water under pressure to plants as a spray through nozzles. Pressure is usually obtained from a pump. Equipment can be fixed or continuously move. Center pivot systems are the most common type of sprinkler irrigation in Missouri.
|Efficient on medium- and coarse-textured soils||Deep ruts can form on clay soils from center pivot tires|
|Water can be applied at low rates (< 0.1 acre-inches)||Frequent applications may be needed to recharge soil depleted by crop|
|Fertigation and chemigation can be used for plant nutrition or pest control by injecting chemicals into the irrigation water||Sprinkler nozzles can clog with poor quality water|
|Center pivot systems can be programmed to start and stop at specified angles or time||Scalding can occur on crop foliage|
Flood irrigation supplies water to a field through pipes or ditches. Water flows over the ground and through the crop. Levees and gates are often used to control water depth. In Missouri, flood irrigation is commonly used in rice fields by cascade or side-let methods. In cascade flood irrigation, water enters the field at the highest elevation and cascades down through a series of levee gates. In side-inlet flood irrigation, layflat pipe is placed across levees and holes are punched to simultaneously deliver water to each zone of the field.
|Low initial investment for equipment is required||Least efficient form of irrigation. More water loss from evaporation, infiltration, and runoff|
|Runoff water can be recycled to improve efficiency||Building and taking down levees is labor intensive|
|Side-inlet flood saves 60% of water compared to cascade||Land usually needs grading to inable uniform water distribution|
Drip irrigation delivers water drop by drop to crop roots. Water is supplied under low pressure through plastic tubing manufactured with emitters to regulate flow rate. Tubing can be placed on the ground or buried beneath the soil surface.
|Saves water by minimizing evaporation||Method cannot be used with high iron content water because emitters become clogged|
|Nutrient losses from leaching is reduced||Maintenance is required to keep system going|
|No land grading required||Chewing on tubing from insects and rodents can cause water leaks|
|Can be used in irregular shaped fields||Mowers and trimmers can slice tubing|
Subirrigation delivers water to agricultural crops beneath the soil surface through a series of pipes and ditches. Used to raise and maintain a water table to a predetermined depth, subirrigation systems typically are permanently installed below the rootline.
|Less labor-intensive than other methods||Requires fairly uniform and permeable soils|
|Good for soils with low water retention capacity||Most effective with smooth, level topography|
|Can double as a drainage system||Water with high salt content can’t be used|
|Water loss through evaporation minimized||Requires adequate water supply throughout growing season|