Where does Jones get his facts on tile drainage as water quality culprit?

I read with interest Sunday’s article by Joy Mazur about tile drainage of farmland as it applies to water quality.

I agree that our water quality in Iowa is bad and getting worse. Chris Jones, formerly a hydrologist at the University of Iowa Department of Engineering was quoted as saying drainage tile is the “main delivery mechanism for nitrates from farm fields to the stream network.”

I have read a lot of Mr. Jones’ work in the area of water quality and agree with most of it. However, I am confused about this particular comment for two reasons. First, research at Iowa State done several years ago showed that the amounts of nitrates entering our water supplies from tiled fields was less than that of undrained fields.

Second, an Iowa farmer who spoke at a meeting I attended said he had worked extensively with the Iowa Soybean Association and Dr. Jerry Hatfield, former director of the USDA Soil Tilth Lab at Iowa State researching his regenerative farming practices. The ISA was monitoring the nitrates in water coming from the drainage tile from his field emptying into a creek that borders his farm. The results showed 3 ppm of nitrates in that tile water. 10 ppm is considered the acceptable level. They then tested the water in the creek and it measured over 10 ppm.

Based on the above, I question the comment by Chris Jones about tile drainage being the culprit. Where is his data coming from?

Larry Neppl

Marion