There is no doubt that irrigation has changed agriculture for the better. Irrigation is what makes farming in a large portion of the Great Plains possible on a large scale. Since the dawn of time farmers have been working to get water too their crops. Large ditches were dug in Mesopotamia to support civilization. Ancient Egyptians used the Nile River Valley to grow their crops. To this day states fight one another over water to be used for irrigation. Endless court battles are fought over water and who has a right to use it. Somewhere down the line, someone decided that it was more efficient to water crops with a center pivot sprinkler system than it was to keep digging ditches and flooding crop ground with water to help it grow.
United States (National)