The carefully calculated and measured rate of glyphosate that goes in the spray tank is the same deadly dose that makes it to weed leaves, right?

Not necessarily, says Murray State University chemistry professor Scott Brown, who’s spent 4 years studying issues that surround the effectiveness of glyphosate.

Raised on a Kentucky farm, Brown began to investigate herbicide molecules and their activity while working on his degrees and managing his own farming operation.

He’s found that no-tillers with hard water may be losing some, or even most of their glyphosate activity before they even head for the fields — and those that think they’re already addressing the issue might still be missing the mark.

Essentially, no-tillers with hard water may be unknowingly spraying a lesser rate and getting a reduced response because of how glyphosate interacts with the minerals in the water, says Brown, who earned an undergraduate degree in chemistry and agriculture from Western Kentucky University and a doctorate from the University of Alabama.

Besides being a wasted herbicide investment, this interaction can be a recipe for weed disaster.

“The trend I’m seeing is that regions with hard water are having higher incidence of glyphosate-resistant weeds,” Brown told no-tillers at the National No-Tillage Conference earlier this year. “I’m not promising you that I can kill resistant pigweed or resistant marestail by addressing hard-water issues. But we’re losing activity right out of the gate.”

Brown became aware of the lack of knowledge about hard water, and its impact on the…