Crop Response to Water
Crops needs water. There have been several studies that look at what happens to yields when the crop receives less water than it needs. We looked at a report done by Gary Hergert and others published in the Journal of Production Agriculture, Oct-Dec 1993, and another published by KState - Department of Economics by Dumler, and a third that was published in the American Society of Agricultural Engineers by Schneekloth, Kocke, Hergert, Martin, and Clark. If anyone wants to look at their research, just contact me and I can point you in the right direction.
Based on their data and research (and then I updated to reflect current yields), we have produced the Crop Response to Water chart. This chart is for corn. Click on the image to enlarge.
We place a line at average precipitation plus 8 inches because Dr. Martin of the University of Nebraska makes presentations telling people that corn only needs 8 inches of irrigation. He presents charts using the data that we look at to conclude that it doesn't make any economic sense to use more than 8 inches of irrigation in an average year.
He makes a lot of assumptions to reach that conclusion. Many do not hear the assumptions or consider if they are reasonable. Sometimes people hear only the headline. Dr. Martin works under contract and has signed a non-disclosure agreement with the Nebraska Department of Natural Resources. The DNR has hired Dr. Martin and others to help make the case that farmers can use much less water than they do now and still see the same profits.
We find many of the statements by the DNR and its agents to be different than what we experience in the field. So, we have decided to go back and look at the original data and see what it said. The chart we present here is a result of that research and is something that we think matches the real world.