Midwest grain harvest rolls along

Yield variability continues to dominate as Midwest farmers proceed with harvest.

“Remember that yield estimates are just that — yield estimates,” said Meaghan Anderson, Iowa State University field agronomist based in central Iowa.

The soybean yield formula is determined by plants per acre, pods per plant, seeds per pod and seed weight.

Soybean yield is tough to predict, Stephanie Porter, a certified crop advisor and outreach agronomist for the Illinois Soybean Association, said in a field advisor report.

“From my own experience, yield is virtually impossible to predict before harvest,” she wrote. “So far, yield reports from earlier-

planted soybeans are not bad but not as good as last year. Some farmers are reporting significantly low moisture despite soybeans still having green foliage, pods and stems.

“To add to that, significantly lower moisture levels, 11% to 8%, are causing header loss, shatter, mechanical damage and further yield reduction.”

According to Iowa State University, there is no yield loss at 13% moisture; 1.1% loss at 12%; 2.25% loss at 11%; 3.3% lost at 10%; 4.4 % loss at 9%; and 5.4% loss at 8%.

“Farmers in my geography are seeing significantly more yield variability this year in corn than they did last year,” Anderson said. “Fields are not necessarily as variable across the field, but the overall yield from one field to another seems much more variable.

“A number of issues are probably working together to create this issue — presence of significant southern rust and variability in fungicide application (whether it was applied, timing, product choice, etc.), significant rainfall in July followed by a relatively dry August for some farmers, and even warmer temperatures (particularly at night) during the month of July compared to 2024.”