"I've been doing this for 20 years now," Pat Wehr told us last week. We joined her and Greg Preston of the Indiana Ag Statistics Service as Wehr made actual visits to farm fields to do field checks. The information will feed into the first August crop report issued by USDA this season.
"Most of the farmers I work with are very cooperative," she explains. "Their farm is picked by a computer program at random. We come out in June with our aerial maps and ask for permission to work in their fields. If they agree, then we ask them to verify acreage and boundaries so that we know our maps are correct."
Once in a while someone will refuse to participate, Wehr says. "I had one refuse in Union County this year, but it doesn't happen very often. It's their choice."
Unfortunately, though, if a farmer chooses not to participate and doesn't let field enumerators, as they're called, on their farm to set up tiny check areas in a field or two, often a corn and soybean field on the same farm, then that data set is lost. It's simply not replaced, Preston says.
"We're basing our projections in Indiana on about 400 samples," he adds. "That amounts to two sampling locations in 100 corn fields and 100 soybean fields. The exact locations where we sample within fields is also picked by the computer at random. Once an enumerator marks off the sample area on the first visit in the summer, then they return to the same area twice more, always using the same spot for yield estimates."
One farmer that refuses means one less field to sample, maybe two if he was also chosen for both crops. That's either two or four sampling locations that will be lost.
The system works because everything is chosen at random, Preston says. If a location chosen by the computer turns out to be in a wet spot or dominated by a weed, enumerators still do their checks there. "We figure that represents all the other areas in Indiana where we might have the same conditions," he notes. "We instruct our field enumerators to go ahead and use that area, even if it's obvious that it won't be a good yielding spot."
The last visit to the field is just before harvest, Wehr says. Enumerators actually harvest the crop within their tiny check section, either soybeans or corn, and send total production from that spot to a central lab for tabulation. Don't worry - soybeans aren't hand-shelled, Preston reports.
"Many farmers let us know when they're going to be getting to those fields in a few days," Wehr says. "Sometimes someone forgets because they're so busy. But some value what we're doing so much that they'll actually leave the check strip - drive around it if they forgot to call us, so we can come get it later."