Agricultural water users can optimize water use efficiency and protect the quality of water resources by applying basic information about irrigation systems, crop water use and management practices.
Nebraska relies primarily on groundwater to supply irrigation. According to a 2007 Census of Agriculture report, Nebraska ranks first nationally with about 8.5 million irrigated acres. Most of the irrigated acres receive groundwater, followed by acres receiving commingled ground and surface water.
- By August 2007 over 90,000 active irrigation wells were in operation. The highest density of wells are located in the Central Platte Valley where over 16 irrigation wells have been installed per square mile of land. The location of irrigation wells in 2007 reflects the availability of groundwater, the suitability of the land for irrigation and the need for irrigation to meet crop water requirements.
- The number of irrigation wells installed per decade peaked in the 1970s. Since the seventies about 10,000 wells were installed each decade.
- Irrigation development has caused declines of groundwater levels (depth to groundwater from the soil surface) in some areas of the state. The most severely affected areas are the Box Butte area, western end of the Republican River Basin and parts of the Blue River Basin.
- Natural Resources Districts (NRDs) have implemented management plans in these areas to regulate groundwater resources use.
Nebraska has a significant amount of land (over 565,000 acres) that is irrigated with surface water diverted from streams and rivers. The United States Bureau of Reclamation manages some surface irrigation districts (see map for Nebraska locations). Nebraska also has private irrigation districts such as the Central Nebraska Public Power and Irrigation District.
Research has shown that concentrations of nitrate - nitrogen have accumulated in the groundwater beneath areas where irrigation is intense and where the soils are permeable allowing for leaching of nitrogen fertilizer. Leaching is most severe for surface irrigation systems used to irrigate sandy soils. The Platte River Valley and Eastern Sandhills have been most severely affected.
Preventing further water quality degradation or improving water quality requires careful irrigation management along with proper fertilizer management.
Irrigation System Statistics
According to data from a 2003 USDA Survey, the proportion of system usage on irrigated land in Nebraska is similar to usage in most neighboring states.
- About 72% of the irrigated land in Nebraska is irrigated with sprinkler systems which are predominantly center pivots. Nebraska's Center Pivot Water Conservation Project is helping pivot irrigators become more efficient in their water management.
- Gravity irrigation is used on about 28% of the land in Nebraska with the majority of the gravity irrigated land using furrow systems. Advantages to furrow irrigation include lower initial investment of equipment and lower pumping costs per acre-inch of water pumped.
- Subsurface drip irrigation (SDI) systems are only used on a small portion of the land. SDI applies water directly to the crop root zone using buried polyethylene tubing. If designed, installed and managed correctly, SDI has the potential to be the most efficient irrigation method available.
- Corn is grown on 70% of the land irrigated for crops, followed by soybeans on 19% of irrigated land.
- Current challenges include the economics and cost of irrigation.
The University of Nebraska 's Bureau of Business Research conducted an Economic Impact Study in 2003, a drought year, to determine the impact of irrigated agriculture on Nebraska 's economy. The actual net total economic impact was computed as more than $4.5 billion; adjusted to $3.6 billion for normal precipitation conditions.