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Center-pivot irrigation

March 04, 2023

Center-pivot irrigation (sometimes called central pivot irrigation), also called water-wheel and circle irrigation, is a method of crop irrigation in which equipment rotates around a pivot and crops are watered with sprinklers.[1][2] A circular area centered on the pivot is irrigated, often creating a circular pattern in crops when viewed from above (sometimes referred to as crop circles, not to be confused with those formed by circular flattening of a section of a crop in a field).[3] Most center pivots were initially water-powered, however today most are propelled by electric motors.

A satellite image of circular fields characteristic of center pivot irrigation, Kansas
Farmland with circular pivot irrigation

Center-pivot irrigation systems are beneficial due to their ability to efficiently use water and optimize a farm's yield. The systems are highly effective on large land fields.

History

Center-pivot irrigation was invented in 1940[4] by the farmer Frank Zybach,[5] who lived in Strasburg, Colorado.[4] It is recognized as an effective method to improve water distribution to fields.[3]

In 1952, Zybach went into business with A. E. Trowbridge, a friend from Columbus, Nebraska. Trowbridge put up $25,000 and got 49% of the patent rights. Zybach moved back from Colorado to Columbus, opened a shop, hired a few men, moved the height of the pipe up to 1.8 m (6 ft), and went into business. In the first two years of operation, they sold only 19 systems. The early designs were finicky and few farmers understood the systems. Zybach kept improving his designs and focused on making his machines better, rather than attempting to sell systems with problems.[6]

Zybach saw success with modified designs, which improved the systems operational efficiency. In 1954, he licensed his patent to Robert Daugherty and his company, Valley Manufacturing. Daugherty's engineers spent the next decade refining Zybach's innovation, making it sturdier, taller, and more reliable, and converting it from a hydraulic power system to electric drive. Daugherty's company went on to grow into Valmont Industries, with Valley Irrigation being its subsidiary.[7]

Overview

 
Pivot irrigation in progress on a cotton farm

Center pivot irrigation is a form of overhead sprinkler irrigation consisting of several segments of pipe (usually galvanized steel or aluminum) with sprinklers positioned along their length, joined together and supported by trusses, and mounted on wheeled towers.[1] The machine moves in a circular pattern and is fed with water from the pivot point at the center of the circle.[8]

For a center pivot to be used, the terrain needs to be reasonably flat; but one major advantage of center pivots over alternative systems that use gravity flow is the ability to function in undulating country. This advantage has resulted in increased irrigated acreage and water use in some areas. The system is used in parts of the United States, Australia, New Zealand, Brazil,[8] and in desert areas such as the Sahara and the Middle East.

Center pivots are typically less than 500 meters (1,600 ft) in length (circle radius) with the most common size being the standard 400-meter (1⁄4 mi) machine, which covers about 50 hectares (125 acres) of land.[8]

Center pivot irrigation nozzles
 
Rotator style pivot applicator sprinkler
 
End Gun style pivot applicator sprinkler

Originally, most center pivots were water-powered. These were replaced by hydraulic systems and electric motor-driven systems, usually driven by a motor mounted at each tower.

The outside set of wheels sets the pace for the rotation. The inner sets of wheels are mounted at hubs between two segments and use angle sensors to detect when the bend at the joint exceeds a certain threshold. When the angle is too large, the wheels rotate to keep the segments aligned. Typical periods for a full rotation include three days;[8] while other sources have the outer edge of the structure moving at 2 to 3 m (6.6 to 9.8 ft) per minute, which would equate to 14 to 21 hours for one full rotation of a 400-meter-radius (1⁄4 mi) system.[9]

To achieve uniform application, center pivots require an even emitter flow rate across the radius of the machine. Since the outer-most spans (or towers) travel farther in a given time period than the innermost spans, nozzle sizes are smallest at the inner spans and increase with distance from the pivot point. Aerial views show fields of circles created by tracings of quarter-mile or half-mile (400 or 800 m) radial irrigation pipes, which consume up to several thousands of gallons per minute."[10]

 
Center pivot irrigation at Irkhaya Farms in Al Rayyan, Qatar

Most center pivot systems now have drops hanging from a U-shaped pipe called a gooseneck attached at the top of the pipe[clarification needed] with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses and wind drift. There are many different nozzle configurations available including static plate, moving plate and part circle. Pressure regulators are typically installed upstream of each nozzle to ensure each is operating at the correct design pressure.

Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops. This type of system is known as LEPA (Low Energy Precision Application) and is often associated with the construction of small dams along the furrow length (termed furrow diking/dyking). Crops may be planted either in straight rows or in circles to conform to the travel of the irrigation system.

Linear or lateral move irrigation machines

 
A small center pivot system from beginning to end

Irrigation equipment can also be configured to move in a straight line, where it is termed a lateral move, linear move, wheel move or side-roll irrigation system.[11][12] In these systems the water is supplied by an irrigation channel running the length of the field. The channel is positioned either at one side or in a line through the center. The motor and pump equipment are mounted on a cart by the supply channel. The cart travels with the machine.

Farmers might choose lateral-move irrigation to keep existing rectangular fields. This can help them convert from furrow irrigation. Lateral-move irrigation is far less common, relies on more complex guidance systems, and requires additional management compared to center pivot irrigation. Lateral-move irrigation is common in Australia. There, systems are usually between 500 and 1,000 meters long.

Benefits

Center-pivot irrigation uses less labor than many other surface irrigation methods, such as furrow irrigation.[8] It also has lower labor costs than ground-irrigation techniques that require digging of channels. Also, center-pivot irrigation can reduce the amount of soil tillage. Therefore, it helps reduce water runoff and soil erosion that can occur with ground irrigation.[8] Less tillage also encourages more organic materials and crop residue to decompose back into the soil. It also reduces soil compaction.[8]

In the United States early settlers of the semiarid High Plains were plagued by crop failures due to cycles of drought, culminating in the disastrous Dust Bowl of the 1930s. Only after World War II when center pivot irrigation became available did the land mass of the High Plains aquifer system transform into one of the most agriculturally productive regions in the world.

 
The crops are planted in circles for efficient irrigation.

Negative effects

Fossil water is a non-renewable resource. Groundwater levels decrease when the rate of extraction by irrigation exceeds the rate of recharge. By 2013 it was shown that counterintuitively, as the water consumption efficiency of center-pivot irrigation improved over the years, farmers planted more intensively, irrigated more land, and grew thirstier crops.[10] This is an example of Jevons paradox.

In parts of the United States, sixty years of the profitable business of intensive farming using huge center-pivot irrigators has emptied parts of the Ogallala Aquifer (also known as the High Plains Aquifer).[10] One of the world's largest aquifers, it covers an area of approximately 450,000 km2 (170,000 sq mi) in portions of the eight states of South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico, and Texas, beneath the Great Plains in the United States.[13][14] The total water extraction from center-pivot irrigation in the area is estimated to be about 5.42 million acre-feet of water per year. [15]

In 1950, irrigated cropland covered 100,000 hectares (250,000 acres). With the use of center-pivot irrigation, nearly 1.2 million hectares (3 million acres) of land were irrigated in Kansas alone. At some places, during maximum extraction, the water table dropped more than 1.5 m (5 ft) per year. In extreme cases, wells had to be greatly deepened to reach the steadily falling water table.[10] In some places in the Texas Panhandle, the water table has been drained (dewatered). "Vast stretches of Texas farmland lying over the aquifer no longer support irrigation. In west-central Kansas, up to a fifth of the irrigated farmland along a 100-mile [160 km] swath of the aquifer has already gone dry." It would take hundreds to thousands of years of rainfall to replace the groundwater in the dried up aquifer.[10]

Role in culture

In the 21st century, recognition of the significance of the High Plains Aquifer has led to increased coverage from regional[16][17][18] and international journalists.[19] A May 2013 New York Times article "Wells dry, fertile plains turn to dust"[10] recounts the relentless decline of parts of the High Plains Aquifer System.

Writer Emily Woodson characterized the increased use of the center pivot irrigation system as part of a profound attitude shift towards modernism (expensive tractors, center-pivot irrigation, dangerous new pesticides) and away from traditional farming that took place in the mid-1970s and 1980s in the United States. A new generation chose high-risk, high-reward crops such as irrigated corn or peanuts, which require large quantities of groundwater, fertilizer and chemicals. The new family farm corporations turned many pastures into new cropland and were more interested in rising land prices than water conservation.[20][21]

See also

References

  1. ^ a b Mader, Shelli (May 25, 2010). . The Fence Post Magazine. Archived from the original on September 8, 2016. Retrieved June 6, 2012.
  2. ^ ddr.nal.usda.gov 2011-10-09 at the Wayback Machine Center pivot irrigation system modification to provide variable water application depths.
  3. ^ a b Gray, Ellen (May 3, 2012). "Texas crop circles from space". NASA. Retrieved June 6, 2012.
  4. ^ a b Morgan, Robert (1993). Water and the Land. Cathedral City, CA: Adams Publishing Corp. pp. 35–36. ISBN 0935030026.
  5. ^ Alfred, Randy (July 22, 2008). "July 22, 1952: Genuine Crop-Circle Maker Patented". Wired Magazine. Retrieved June 6, 2012.
  6. ^ "Center Pivot Irrigation Systems Take over During the 1950s".
  7. ^ "Valley Irrigation's History".
  8. ^ a b c d e f g . College of Agriculture, Food and Natural Resources, University of Missouri. July 3, 2008. Archived from the original on September 17, 2013. Retrieved June 6, 2012.
  9. ^ "Pressurized Irrigation Techniques: The center pivot irrigation systems" (PDF). UN Food and Agriculture Organization. 2007. Retrieved April 26, 2020.
  10. ^ a b c d e f Wines, Michael (May 19, 2013). "Wells Dry, Fertile Plains Turn to Dust". The New York Times.
  11. ^ Evans, R.O.; et al. (March 1997). (PDF). North Carolina Cooperative Extension Service, North Carolina State University. Archived from the original (PDF) on October 21, 2012. Retrieved June 6, 2012.
  12. ^ "Wheelmove Sprinkler Irrigation Operation and Management" (PDF).
  13. ^ Darton, N.H. 1898. Preliminary report on the geology and water resources of Nebraska west of the one hundred and third meridian. In: Walcott, C.D. (ed), Nineteenth Annual Report of the United States Geological Survey, 1897-1898, Part IV, pp. 719-785.
  14. ^ Dennehy, K.F. (2000). . USGS. Archived from the original on July 23, 2008. Retrieved May 7, 2008.
  15. ^ Cooley, D.J., Maxwell, R.M., Smith, S.M. (2021). "Center Pivot Irrigation Systems and Where to Find Them: A Deep Learning Approach to Provide Inputs to Hydrologic and Economic Models". Frontiers in Water. 3. doi:10.3389/frwa.2021.786016.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ^ "Shrinking aquifer looms as big problem for farms" 2009-02-04 at the Wayback Machine. Nancy Cole, Arkansas Democrat-Gazette. September 24, 2006. Last accessed October 24, 2006.
  17. ^ Column - Mansel Phillips: "Too many thirsty industries, not nearly enough water" 2013-06-15 at the Wayback Machine. Mansel Phillips, Amarillo Globe News. October 4, 2006. Last accessed October 24, 2006.
  18. ^ "Another sign of long-term water worries", Lincoln Star Journal, October 8, 2006. Last accessed November 20, 2012
  19. ^ Daily Telegraph (UK) Saturday Magazine Issue no 48,446 (dated 5 March 2011) pp 26-32 "High and Dry" Report by Charles Lawrence
  20. ^ Morris, John Miller (2003). Sherry L. Smith (ed.). The Future of the Southern Plains. Norman, Oklahoma: University of Oklahoma Press. p. 275. ISBN 0806137355.
  21. ^ Rainwater, Ken (January 1, 2004). "Book Review: The Future of the Southern Plains". Great Plains Quarterly Great Plains Studies. Lincoln, Nebraska: Center for Great Plains Quarterly Great Plains Studies, University of Nebraska.

Additional sources

  • Snyder, Cindy (January 18, 2011). "Center pivot irrigation systems cost big bucks". Times-News (Twin Falls, Idaho). Retrieved June 6, 2012.
  • Becker, Hank (October 2, 2000). "Can Crop Temperature Guide Center-Pivot Irrigation?". USDA Agriculture Research Service. Retrieved June 6, 2012.
  • Garner, Fay (February 2008). "Tuskegee Turf Farm Battles Drought With More Efficient Irrigation". USDA Natural Resources Conservation Service. Retrieved June 6, 2012.
  • Boyd, Vicky (February 16, 2012). . The Grower Magazine. Archived from the original on March 8, 2013. Retrieved June 6, 2012.

External links

 
Wikimedia Commons has media related to Center pivot irrigation.
  • Manjula V. Guru, Agricultural Policy Specialist and James E. Horne, President & CEO, The Kerr Center for Sustainable Agriculture, Poteau, Oklahoma
  • Kansas Geological Survey information on the High Plains / Ogallala Aquifer
  • Rapid Recharge of Parts of the High Plains Aquifer Indicated by a Reconnaissance Study in Oklahoma

March 04, 2023
center, pivot, irrigation, sometimes, called, central, pivot, irrigation, also, called, water, wheel, circle, irrigation, method, crop, irrigation, which, equipment, rotates, around, pivot, crops, watered, with, sprinklers, circular, area, centered, pivot, irr. Center pivot irrigation sometimes called central pivot irrigation also called water wheel and circle irrigation is a method of crop irrigation in which equipment rotates around a pivot and crops are watered with sprinklers 1 2 A circular area centered on the pivot is irrigated often creating a circular pattern in crops when viewed from above sometimes referred to as crop circles not to be confused with those formed by circular flattening of a section of a crop in a field 3 Most center pivots were initially water powered however today most are propelled by electric motors A satellite image of circular fields characteristic of center pivot irrigation Kansas Farmland with circular pivot irrigation Center pivot irrigation systems are beneficial due to their ability to efficiently use water and optimize a farm s yield The systems are highly effective on large land fields Contents 1 History 2 Overview 3 Linear or lateral move irrigation machines 4 Benefits 5 Negative effects 6 Role in culture 7 See also 8 References 9 Additional sources 10 External linksHistory EditCenter pivot irrigation was invented in 1940 4 by the farmer Frank Zybach 5 who lived in Strasburg Colorado 4 It is recognized as an effective method to improve water distribution to fields 3 In 1952 Zybach went into business with A E Trowbridge a friend from Columbus Nebraska Trowbridge put up 25 000 and got 49 of the patent rights Zybach moved back from Colorado to Columbus opened a shop hired a few men moved the height of the pipe up to 1 8 m 6 ft and went into business In the first two years of operation they sold only 19 systems The early designs were finicky and few farmers understood the systems Zybach kept improving his designs and focused on making his machines better rather than attempting to sell systems with problems 6 Zybach saw success with modified designs which improved the systems operational efficiency In 1954 he licensed his patent to Robert Daugherty and his company Valley Manufacturing Daugherty s engineers spent the next decade refining Zybach s innovation making it sturdier taller and more reliable and converting it from a hydraulic power system to electric drive Daugherty s company went on to grow into Valmont Industries with Valley Irrigation being its subsidiary 7 Overview Edit Pivot irrigation in progress on a cotton farm Center pivot irrigation is a form of overhead sprinkler irrigation consisting of several segments of pipe usually galvanized steel or aluminum with sprinklers positioned along their length joined together and supported by trusses and mounted on wheeled towers 1 The machine moves in a circular pattern and is fed with water from the pivot point at the center of the circle 8 For a center pivot to be used the terrain needs to be reasonably flat but one major advantage of center pivots over alternative systems that use gravity flow is the ability to function in undulating country This advantage has resulted in increased irrigated acreage and water use in some areas The system is used in parts of the United States Australia New Zealand Brazil 8 and in desert areas such as the Sahara and the Middle East Center pivots are typically less than 500 meters 1 600 ft in length circle radius with the most common size being the standard 400 meter 1 4 mi machine which covers about 50 hectares 125 acres of land 8 Center pivot irrigation nozzles Rotator style pivot applicator sprinkler End Gun style pivot applicator sprinkler Originally most center pivots were water powered These were replaced by hydraulic systems and electric motor driven systems usually driven by a motor mounted at each tower The outside set of wheels sets the pace for the rotation The inner sets of wheels are mounted at hubs between two segments and use angle sensors to detect when the bend at the joint exceeds a certain threshold When the angle is too large the wheels rotate to keep the segments aligned Typical periods for a full rotation include three days 8 while other sources have the outer edge of the structure moving at 2 to 3 m 6 6 to 9 8 ft per minute which would equate to 14 to 21 hours for one full rotation of a 400 meter radius 1 4 mi system 9 To achieve uniform application center pivots require an even emitter flow rate across the radius of the machine Since the outer most spans or towers travel farther in a given time period than the innermost spans nozzle sizes are smallest at the inner spans and increase with distance from the pivot point Aerial views show fields of circles created by tracings of quarter mile or half mile 400 or 800 m radial irrigation pipes which consume up to several thousands of gallons per minute 10 Center pivot irrigation at Irkhaya Farms in Al Rayyan Qatar Most center pivot systems now have drops hanging from a U shaped pipe called a gooseneck attached at the top of the pipe clarification needed with sprinkler heads that are positioned a few feet at most above the crop thus limiting evaporative losses and wind drift There are many different nozzle configurations available including static plate moving plate and part circle Pressure regulators are typically installed upstream of each nozzle to ensure each is operating at the correct design pressure Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops This type of system is known as LEPA Low Energy Precision Application and is often associated with the construction of small dams along the furrow length termed furrow diking dyking Crops may be planted either in straight rows or in circles to conform to the travel of the irrigation system Linear or lateral move irrigation machines Edit A small center pivot system from beginning to end Irrigation equipment can also be configured to move in a straight line where it is termed a lateral move linear move wheel move or side roll irrigation system 11 12 In these systems the water is supplied by an irrigation channel running the length of the field The channel is positioned either at one side or in a line through the center The motor and pump equipment are mounted on a cart by the supply channel The cart travels with the machine Farmers might choose lateral move irrigation to keep existing rectangular fields This can help them convert from furrow irrigation Lateral move irrigation is far less common relies on more complex guidance systems and requires additional management compared to center pivot irrigation Lateral move irrigation is common in Australia There systems are usually between 500 and 1 000 meters long Benefits EditCenter pivot irrigation uses less labor than many other surface irrigation methods such as furrow irrigation 8 It also has lower labor costs than ground irrigation techniques that require digging of channels Also center pivot irrigation can reduce the amount of soil tillage Therefore it helps reduce water runoff and soil erosion that can occur with ground irrigation 8 Less tillage also encourages more organic materials and crop residue to decompose back into the soil It also reduces soil compaction 8 In the United States early settlers of the semiarid High Plains were plagued by crop failures due to cycles of drought culminating in the disastrous Dust Bowl of the 1930s Only after World War II when center pivot irrigation became available did the land mass of the High Plains aquifer system transform into one of the most agriculturally productive regions in the world The crops are planted in circles for efficient irrigation Negative effects EditFossil water is a non renewable resource Groundwater levels decrease when the rate of extraction by irrigation exceeds the rate of recharge By 2013 it was shown that counterintuitively as the water consumption efficiency of center pivot irrigation improved over the years farmers planted more intensively irrigated more land and grew thirstier crops 10 This is an example of Jevons paradox In parts of the United States sixty years of the profitable business of intensive farming using huge center pivot irrigators has emptied parts of the Ogallala Aquifer also known as the High Plains Aquifer 10 One of the world s largest aquifers it covers an area of approximately 450 000 km2 170 000 sq mi in portions of the eight states of South Dakota Nebraska Wyoming Colorado Kansas Oklahoma New Mexico and Texas beneath the Great Plains in the United States 13 14 The total water extraction from center pivot irrigation in the area is estimated to be about 5 42 million acre feet of water per year 15 In 1950 irrigated cropland covered 100 000 hectares 250 000 acres With the use of center pivot irrigation nearly 1 2 million hectares 3 million acres of land were irrigated in Kansas alone At some places during maximum extraction the water table dropped more than 1 5 m 5 ft per year In extreme cases wells had to be greatly deepened to reach the steadily falling water table 10 In some places in the Texas Panhandle the water table has been drained dewatered Vast stretches of Texas farmland lying over the aquifer no longer support irrigation In west central Kansas up to a fifth of the irrigated farmland along a 100 mile 160 km swath of the aquifer has already gone dry It would take hundreds to thousands of years of rainfall to replace the groundwater in the dried up aquifer 10 Role in culture EditIn the 21st century recognition of the significance of the High Plains Aquifer has led to increased coverage from regional 16 17 18 and international journalists 19 A May 2013 New York Times article Wells dry fertile plains turn to dust 10 recounts the relentless decline of parts of the High Plains Aquifer System Writer Emily Woodson characterized the increased use of the center pivot irrigation system as part of a profound attitude shift towards modernism expensive tractors center pivot irrigation dangerous new pesticides and away from traditional farming that took place in the mid 1970s and 1980s in the United States A new generation chose high risk high reward crops such as irrigated corn or peanuts which require large quantities of groundwater fertilizer and chemicals The new family farm corporations turned many pastures into new cropland and were more interested in rising land prices than water conservation 20 21 See also Edit Agriculture and Agronomy portal Water portalIrrigation management Irrigation in Saudi Arabia Water management Fossil water HydrogeologyReferences Edit a b Mader Shelli May 25 2010 Center pivot irrigation revolutionizes agriculture The Fence Post Magazine Archived from the original on September 8 2016 Retrieved June 6 2012 ddr nal usda gov Archived 2011 10 09 at the Wayback Machine Center pivot irrigation system modification to provide variable water application depths a b Gray Ellen May 3 2012 Texas crop circles from space NASA Retrieved June 6 2012 a b Morgan Robert 1993 Water and the Land Cathedral City CA Adams Publishing Corp pp 35 36 ISBN 0935030026 Alfred Randy July 22 2008 July 22 1952 Genuine Crop Circle Maker Patented Wired Magazine Retrieved June 6 2012 Center Pivot Irrigation Systems Take over During the 1950s Valley Irrigation s History a b c d e f g Growing Rice Where it has Never Grown Before A Missouri research program may help better feed an increasingly hungry world College of Agriculture Food and Natural Resources University of Missouri July 3 2008 Archived from the original on September 17 2013 Retrieved June 6 2012 Pressurized Irrigation Techniques The center pivot irrigation systems PDF UN Food and Agriculture Organization 2007 Retrieved April 26 2020 a b c d e f Wines Michael May 19 2013 Wells Dry Fertile Plains Turn to Dust The New York Times Evans R O et al March 1997 Center Pivot and Linear Move Irrigation System PDF North Carolina Cooperative Extension Service North Carolina State University Archived from the original PDF on October 21 2012 Retrieved June 6 2012 Wheelmove Sprinkler Irrigation Operation and Management PDF Darton N H 1898 Preliminary report on the geology and water resources of Nebraska west of the one hundred and third meridian In Walcott C D ed Nineteenth Annual Report of the United States Geological Survey 1897 1898 Part IV pp 719 785 Dennehy K F 2000 High Plains regional ground water study U S Geological Survey Fact Sheet FS 091 00 USGS Archived from the original on July 23 2008 Retrieved May 7 2008 Cooley D J Maxwell R M Smith S M 2021 Center Pivot Irrigation Systems and Where to Find Them A Deep Learning Approach to Provide Inputs to Hydrologic and Economic Models Frontiers in Water 3 doi 10 3389 frwa 2021 786016 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Shrinking aquifer looms as big problem for farms Archived 2009 02 04 at the Wayback Machine Nancy Cole Arkansas Democrat Gazette September 24 2006 Last accessed October 24 2006 Column Mansel Phillips Too many thirsty industries not nearly enough water Archived 2013 06 15 at the Wayback Machine Mansel Phillips Amarillo Globe News October 4 2006 Last accessed October 24 2006 Another sign of long term water worries Lincoln Star Journal October 8 2006 Last accessed November 20 2012 Daily Telegraph UK Saturday Magazine Issue no 48 446 dated 5 March 2011 pp 26 32 High and Dry Report by Charles Lawrence Morris John Miller 2003 Sherry L Smith ed The Future of the Southern Plains Norman Oklahoma University of Oklahoma Press p 275 ISBN 0806137355 Rainwater Ken January 1 2004 Book Review The Future of the Southern Plains Great Plains Quarterly Great Plains Studies Lincoln Nebraska Center for Great Plains Quarterly Great Plains Studies University of Nebraska Additional sources EditSnyder Cindy January 18 2011 Center pivot irrigation systems cost big bucks Times News Twin Falls Idaho Retrieved June 6 2012 Becker Hank October 2 2000 Can Crop Temperature Guide Center Pivot Irrigation USDA Agriculture Research Service Retrieved June 6 2012 Garner Fay February 2008 Tuskegee Turf Farm Battles Drought With More Efficient Irrigation USDA Natural Resources Conservation Service Retrieved June 6 2012 Boyd Vicky February 16 2012 Valley Irrigation unveils tire sensor for center pivot systems The Grower Magazine Archived from the original on March 8 2013 Retrieved June 6 2012 External links Edit Wikimedia Commons has media related to Center pivot irrigation The Ogallala Aquifer Manjula V Guru Agricultural Policy Specialist and James E Horne President amp CEO The Kerr Center for Sustainable Agriculture Poteau Oklahoma USGS High Plains Regional Groundwater Study A Legal Fight in Texas over the Ogallala Aquifer Kansas Geological Survey information on the High Plains Ogallala Aquifer Rapid Recharge of Parts of the High Plains Aquifer Indicated by a Reconnaissance Study in Oklahoma Retrieved from https en wikipedia org w index php title Center pivot irrigation amp oldid 1123452328, wikipedia, wiki, book, books, library,

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