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Oklahoma Agriculture in the Classroom

Agricultural Facts


  • Irrigation is the number one use of water in Oklahoma.
  • One inch of rain falling on a 160-acre field delivers 434,680 gallons of water or 13.3 acre feet. It would take just over 4 miles of 80,000 gallon capacity railroad tank cars to transport this amount of water, which would weigh more than 18,000 tons.
  • Water stress early in the life of crops results in limited growth and delayed development of cropping potential. Later, water stress can result in reduced yields and poor crop quality. Losses can also happen because of the indirect result of limited availability of nutrients because of soil moisture inadequate for optimal root growth and nutrient uptake.
  • The need for irrigation depends on geographic and seasonal variations. The cycle of water to and through the ground varies considerably from regions with high annual rainfall, such as the southeastern part of the state, to more arid regions such as the western part.
  • Annual average precipitation for the eastern part of the state averages between 35 and 57 inches. This compares with 37 for the state as a whole and between 15 and 35 inches for the western part of the state.
  • Ancient irrigation works have been found in the Oklahoma Panhandle.
  • Earth and clay moved from the channel of the canal was loosened by means of picks and gouges fashioned from bones of the elk and buffalo, shoveled into cariers of rawhide or wicker work with shovels shaped from the shoulder blades of the same animals and transported to the dump on the backs, shoulders or heads of men and women.
  • The purpose of this canal was to supplement the natural rainfall during the growing season by flooding an area of land under tillage, located around and immediately below the lower end of the artificial water course. As the course of the canal approached its end, its gradient was gradually reduced in order to deliver the water at the level of the adjacent soil surface, which was thus sure to be flooded and thoroughly soaked whenever there was a heavy shower in the hills where the small creek had its sources, regardless of whether there had been a shower on the land thus irrigated.