The photo below shows a patch of stunted corn July 7, amid a field of corn that’s reaching for 7 feet.
At first we thought it was herbicide carryover from soybeans in 2014.
Then the drainage pattern emerged. Runoff from a field of Roundup Ready crops across the road fans out into these stunted areas. And the residues accumulate. Soggy soils intensify the problem. Cultivating helped green up the corn, at least.
Wait — glyphosate just deactivates when it reaches the soil, right? Hardly. Also, soil can move. Especially when we had record rains in May and June, sluicing muddy runoff from about 25 acres of watershed which flows into a roadside ditch and then through a culvert and into our field.
When we pattern-tiled this field a few years ago, we should have mainstreamed the culvert drainage under our waterway, to protect from conflicting inbound chemicals. You can see the lay of the land in this photo. We won’t get much of a crop here, but we got a useful lesson.
That runoff lesson was also clear in another case a few years ago when we tried raising corn and soybeans on a rented 4-acre nearly level creek bottom field — just below a drive-in theatre. This is a couple of miles from our home farm. The drive-in operator saturated the parking area regularly with some kind of burn-down, probably glyphosate or paraquat, to block weed emergence through the gravel surface.
And the hard gravel in a four-acre parking lot was graded to shed water like a tin roof — directly onto our nearly level cornfield. Over several years, accumulated chemical residue made a decent crop very hard to achieve.
Finally the drive-in theatre was converted into an apartment complex with mandated storm drainage control.
Today, that little 4-acre flat field produces lush, non-GMO alfalfa.