Late last week, Brock Hansen and his father Curt were applying post-emergent herbicide to one of their cornfields just outside of Baxter in Central Iowa.
Hansen says there are a few reasons to apply herbicide just as the crop is poking through the soil. For one, he says weeds on farm field are a lot like crabgrass on a lawn; if not taken care of early, it can overtake the whole yard. Hansen says he subscribes to the philosophy of spraying early, and spraying often, as well as scouting early and scouting often, to make sure weeds don't pressure the corn.
But some worry the pesticides could show up in their food, Hansen doesn't think so.
"The pesticide no, it does not carry through at all it gets broken down over time and with rain." He says, "You know, we've got intervals in harvest time when we're supposed to stop spraying."
On his herbicide, Hansen says the preharvest interval, required so the plant can break down the herbicide naturally, is 45 to 50 days. After the applications last week, Hansen says no more chemicals will be applied to his field.
Up next for the field is a targeted application of nitrogen in each row just beside the crop, called side-dressing. Hansen says he's decided to apply nitrogen to his crop at different times, when the plant is best able to make use of it, a practice called split application.
Split-applying nitrogen by side-dressing corn is economic for farmers dealing with costly inputs, and as Hansen observes, is one way to make sure the fertilizer stays on the field, where it's needed.
"I guess that's part of our nutrient reduction strategy, we're putting a base down in the fall with a stabilizer. We do some with our pre-chemical stabilizer and then we'll come back and put some on." He says, "Kind of the way I look at feeding a corn plant, it's kind of like a teenage kid possibly or a kid when they're small they don't need it so much but they need to know it's there. And as the plant's growing they need to continue to eat and when they really start growing, boy, they just need to eat immensely."