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Publication Type: Abstract Only Publication Acceptance Date: 10/22/2015 Publication Date: 10/22/2015 Citation: Evett, S.R. 2015. Recent trends/challenges in irrigated agriculture-Why is irrigation important in a discussion of agricultural migration? [abstract] October 21-23, 2015, Boulder, CO. Interpretive Summary: Technical Abstract: United States agriculture contributes 16% of the $9 trillion gross domestic product, 8% of U.S. exports, and 17% of employment while providing food to all citizens, despite the fact that only 2% of the U.S. workforces is on farms. Agricultural productivity has grown by 240% since 1948, while agricultural inputs have remained constant in 1948 equivalent dollars. This growth in productivity was largely fueled by increases in irrigated area and advances in irrigation efficiency, creating a blue revolution that preceded, but continued and augmented, the green revolution of the latter half of the 20th Century. A second blue revolution occurred with the conversion from gravity-flow surface irrigation to pressurized irrigation systems that apply water more uniformly and efficiently. In 1974 only 18.4% of irrigation was done using pressurized pipe systems, while by 2013 65.2% of irrigated lands were irrigated using either pressurized sprinkler or microirrigation systems. Since 1979, the more water efficient microirrigation systems have increased to occupy 9% of irrigated lands. Today, irrigation produces 40% of U.S. Crop market value on only 7.5% of cropped land. In the 17 western states, irrigation produces $117 billion in annual farm gate production value and $156 billion in annual economic impact. In the Plains states, irrigation produces >3 times the net revenue as does dryland farming by doubling water use efficiency (WUE) and stabilizing yields. Due to yield stabilization during frequent summertime droughts and the increase in WUE, irrigation has increased greatly in the eastern States (east of the approximately the 95th meridian). Since 1998, irrigation has increased 18% in the Midwest; >40% in Alabama, Georgia, Maryland, South Carolina and Tennessee; and 27% in Arkansas, which has become the third ranking irrigated state at 4.95 million acres irrigated. The U.S. Midsouth now has more irrigated land than California. Since 1979, the percent of total U.S. irrigated area has steadily decreased in the western states by 0.41% per year, while increasing at the same rate in the eastern states. Since U.S. irrigated area has remained steady at between 55 and 56 million acres since 1997, this amounts to a 0.23 million acre per year loss in the west and 0.23 million acre per year increase in the east during that 18-year period. Loss of irrigated land in the west is tied to increasing competition for water resources and declining resources due to drought. Multiple factors drive irrigation expansion in the east, including overall increased climate variability, which makes the yield stabilization afforded by irrigation key to maintaining profitability of production. The more rapidly increasing value of agricultural production since 2002 plays a role as lenders recognize that yield losses cause important economic losses. For example, the value of crops sold in 2012 was $212 billion compared with $100 billion in 2002. Despite steady population growth and increase in irrigated land, total freshwater withdrawals for irrigation peaked in 1980 and have trended downward since. This is largely due to the increase in pressurized systems and the concomitant decrease in annual depth of water applied from >25 inches in 1969 to <20 inches today. This efficiency comes, however, at a cost. Energy expenses for irrigation pumping rose to $2.7 billion in 2013, and producers spent $2.6 billion on expenses related to irrigation equipment, computer technology and other improvements. Approximately 75,000 farms changed irrigation equipment and management to save water and energy. As irrigation methods and management change and irrigation expands in the east, the nation is challenged to address uncertain applicability of management and technology advances made in the west to eastern conditions, including greater humidity, precipitation, and insect and disease pressur |
