With tight margins, farmers may be rethinking their love affair with Roundup Ready (RR) soybeans, believes University of Missouri extension agronomist Don Null. Those technology fees look bigger and the convenience smaller with soybean prices sitting at historical lows. And then there's the whole biotech issue.

So Null contacted chemical company reps in his northwest Missouri area and asked them to come up with their best chemical package that would control the necessary weed spectrum and still compete with RR beans on cost.

"The basic premises of the situation were that the weed control had to be as efficacious as Roundup Ready soybeans, should be safe to the crop and offer the same flexibility," Null says.

Farmers in Null's area face significant weed pressure. The herbicide package recommended by the chemical companies had to control common waterhemp, lambsquarter, black nightshade, cocklebur, giant and common ragweed, velvetleaf, pigweed, sunflower, morningglory, jimsonweed, annual smartweed, marestail, venice mallow, giant foxtail, barnyardgrass, volunteer corn and shattercane.

The chemical combination that they needed to match, or exceed, was a single quart of Roundup applied to drilled soybeans under conventional tillage. Null figured the total cost for the Roundup program, including seed, herbicide and application charge, at $52.60/acre.

"Some might argue that you can't get by with a single Roundup application and control weeds," Null says. "But in a good stand of drilled beans with conventiona l tillage, our experience is that you can."

The recommended applications submitted by the different companies included combinations of both their own and other products for PPI, pre and post treatments. The chemical costs of the recommended programs, including application costs, are shown in the accompanying table. Add a ballpark number of $24/acre seed cost to figure total costs of seed and weed control per acre.

"You could knock $10-15 an acre off your seed costs if you used saved seed," says Null. "That's assuming it isn't patented, you saved it separately (not bin run) and you have it cleaned and treated before you plant. My experience has been that you usually lose 1-2 bu/acre in yield with saved seed."

Depending on the deals you can cut with your seed salesman and chemical dealer, you can argue that Null's numbers are high or low. The bottom line is, there are chemical programs that will control weeds that can compete with Roundup Ready soybeans.

But Null questions whether they meet all the criteria that he originally outlined. Flexibility is a big plus for RR soybeans. Most of the time you can be a week late and still get excellent weed control with Roundup. The same isn't true with many other postemerge herbicides.

You could also cut those costs by applying the chemicals yourself. That assumes you have a good sprayer and can calibrate it accurately. "That may or may not save you money," he says.

Null believes there is an unspoken advantage to custom application of chemicals. "If there's a problem, I think a chemical company is a lot more likely to listen to a dealer than to an individual farmer," he says.

"A conventional herbicide system requires a lot higher level of management," says Null. "But, if you don't do it right, you can spend $60/acre and still not control weeds."