Irrigation is used to reduce the risk of crop failure where total precipitation is insufficient to meet crop water demands. Irrigation also allows crops to be grown in areas where precipitation is untimely, and can be used to protect plants and trees from frost damage. In the U.S. nearly 55 million acres of crop land were irrigated in 2008, according to the 2008 Census of Agriculture [1]. That is up nearly 2.5 million acres from the 2003 census. Nebraska, California, Texas, Arkansas, Idaho, Colorado, Kansas, Montana, Oregon, Washington, and Wyoming are the top ten states for the acres of irrigated crop land. Approximately 76% of the water originates from groundwater and the remainder from surface water sources. Nationwide, 54% of the irrigated acreage utilize sprinkler irrigation systems, 39% of acreage are gravity irrigated, 7 percent of acreage are irrigated by surface drip or micro irrigation systems, and 0.3 percent are irrigated using sub-irrigation systems.

In the North Central Region of the United States, approximately 15 million acres are irrigated. Nebraska leads the region in irrigated acres with over 8.5 million acres, followed by Kansas (2.6 million acres) and Missouri (1.2 million acres). These three states are on the western edge of the region where annual precipitation levels are insufficient during some portions of the growing season and where groundwater supplies are available for irrigation. The remaining states have irrigated acreages that range from 180,000 acres to 520,000 acres per state.

There has been a shift from gravity to sprinkler irrigation systems as well as increases in the amount of drip irrigation since 2003. Eighty three percent of the sprinkler systems are center pivots covering over 25 million acres nationwide. The other types of sprinkler systems include side rolls (6.1percent), solid sets (3.8%), hand move systems (3.5 percent), traveling guns (2.2 percent), and linear move systems (1.2 percent). Center pivot systems can be further categorized by the system water pressure. Only 6 percent of the center pivot systems were reported as operating at high pressure (60 psi or more), 42% were classified as operating at medium pressure (30 to 59 psi), and 51% were classified as operating at low pressure (under 30 psi) [1].


Table 1: Percent of the acres irrigated using electricity, natural gas, propane, and diesel-powered pumps in the 12-state region. (Data source: NASS 2008)


The cost to pump irrigation water depends on the type of energy used to power the pumping unit. Electricity and diesel fuel are used to power irrigation for about 79% of the land irrigated in the region (Table 1). Nebraska uses electricity or diesel fuel to power pumping plants used to irrigate approximately 7.58 million acres of cropland.  Natural gas and propane are used on about 16% and 5 percent of the irrigated acres in the 12-state region, respectively. Kansas leads the region in the use of natural gas for pumping plant power with approximately 1.4 million acres irrigated. Very few acres are irrigated with gasoline powered engines in any state in the region.

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