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Irrigation Assisted Rain-fed Agriculture A Sustainable Adaptation Strategy

Irrigation Assisted Rain-fed Agriculture A Sustainable Adaptation Strategy. Richard McNider John Christy University of Alabama in Huntsville Dennis Bragg Bragg Farms James Hairston Donn Rodekohr Auburn University SECC/WMO Orlando, FL. mcnider@nsstc.uah.edu.

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Irrigation Assisted Rain-fed Agriculture A Sustainable Adaptation Strategy

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  1. Irrigation Assisted Rain-fed AgricultureA Sustainable Adaptation Strategy Richard McNider John Christy University of Alabama in Huntsville Dennis Bragg Bragg Farms James Hairston Donn Rodekohr Auburn University SECC/WMO Orlando, FL

  2. mcnider@nsstc.uah.edu

  3. In the coming century the United States will be faced with three critical agricultural issues Food Security Can the US maintain its agricultural output in the face of potential declines in production due to water pressures in the West and High Plains? Energy Security Can the US expand its agricultural output to meet biofuel needs and not impact food supplies? World Food With the world as a whole still facing a calorie deficit can the U.S. provide leadership to increase food production in a sustainable fashion?

  4. Rain-fed Agriculture in the Eastern U.S. • At the turn of the 20th century most of the U.S food and fiber production was found in the East and Midwest based on rain-fed agriculture 100W Rain-fed Agriculture Precipitation>Evaporation

  5. Potatoes Cotton Vegetables This 1900 Eastern agricultural system was broad based Drought was a natural part of this system and drought losses were reflected in prices. Corn was grown in most every State.

  6. By 1980 with transportation improvements corn became concentrated in the deep water holding soils of a few states in the mid-west which insulated farmers from drought losses. Irrigation in the West removed drought losses. Potatoes Corn Cotton Vegetables

  7. ALABAMA

  8. Average Mid-west Yields Crop Model 180 Bushels per Acre In the SE with our shallow soils we are almost always in a drought. Energy, fertilizer and time wasted

  9. The next 50 years may be much different than the last 50 years. New pressures are now forcing a cost-accounting for Western irrigated-agriculture. In the long-term many observers feel this desert agriculture is not sustainable. • Ground water overdrafts from pumping in Ogallalah • Water demand from rapid urban growth • Salt and selenium surface poisoning • River restoration and endangered species initiatives

  10. Demand for water may not be the biggest issue facing the west. Rather, it may be supply. Recent reconstruction of climate indicate that the past 70 years may have been abnormally wet and future supply could be much less. The recent drought may be the norm. Abnormally Wet From Piechota et a. 2004

  11. Climate Change? IPCC Regional precipitation changes are uncertain. Dry areas likely to become drier and wet areas wetter.

  12. What is the solution to declining production in west and need for more land in production for bio-fuels? Put land in the East back into production! Sustainable Southeastern Model - Storage of Winter Surface Water Even in dry years crops need less than a foot of water.

  13. Run-off

  14. Even Year Withdrawal One million acre-ft withdrawn Alabama River 10 to 34 million ac-ft/yr Irrigation can be practiced in the Southeast with undetectable fractions of rivers withdrawn while in the West whole rivers are consumed

  15. Pure rain-fed agriculture in most areas is inefficient. Energy, fertilizers and time are wasted if rains don’t come at the right time. Irrigation solves these problems but it must be sustainable World should encourage irrigation where water is plentiful!

  16. Tools Developed to Determine the Economic Feasibility and Environmental Sustainability of Irrigation in the SE. We have embraced crop models (DSSAT) and long-term climate data to examine economic and environmental issues in the context of climatology.

  17. Water Run-off Irrigated Acreage Why haven’t more farmers in the East not irrigated? Is it not economically viable?

  18. Irrigated 250 Bushels per Acre Mid-west Rainfed

  19. Irrigated profit Rain-fed profit

  20. State investment would ensure that a choice for irrigation would be a “no-brainer” decision

  21. How large should on-farm reservoirs be? • Made detailed calculations of daily evaporative losses • E=C(eo- ea)(1+a*u) • Used dew points and wind speed from first order National Weather Service stations • Used DSSAT to determine irrigation amounts

  22. 1.8 acre ft of water needed in reservoir per acre Jan 1 Jul 31

  23. Figure 1. Example of Drought Monitor

  24. Example of the Lawn and Garden Index (LGI) for July 25, 2008.

  25. Developing Next Generation Agricultural Drought Index Using Crop Models and High Resolution Radar and Insolation • Incorporates both physical inputs and the physiological state of the crop • DSSAT run in a gridded mode • DSSAT driven by • High resolution (4km) radar derived precipitation • High resolution (4 km) satellite derived insolation • High resolution gridded tmin and tmax

  26. Satellite derived insolation Radar derived rainfall

  27. Dry Year Wet Year Water stress from DSSAT for corn simulation

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