The nice, dry weather this past week gave farmers a chance to start getting into fields, and as a result quite a few soybeans were harvested. The state has been able to avoid a killing frost so far, which has allowed late-planted crops to continue to develop.

The weekly crop and weather survey report, issued by Iowa Ag Statistics Service on October 6, shows soybean harvest has advanced to 37% complete in Iowa as of October 5. Iowa Ag Statistics, headquartered in Des Moines, is the Iowa field office of USDA's National Ag Statistics Service. Corn harvest also progressed in some areas, but the pace is much slower. Corn harvest is 3% complete as of October 5, well behind last year's 19% pace and the 5-year average of 15%.

Soybean harvest in Iowa for 2008 is running 4 days later than last year and 5 days later than the 5-year average. Soybean lodging is reported at 82% none, 15% light, 2% moderate and 1% heavy. Soybean shattering is rated at 82% none, 14% light and 4% moderate.

How are 2008 soybean yields turning out?

"We were surprised and impressed with the first field we harvested," says Ron Heck, who farms near Perry in central Iowa. "It was above-trend line yield. But each field we've harvested since then has been around one or two bushels per acre less. So we hope the trend turns around or we'll be below average in yield, if the yield keeps coming down as we harvest our later maturing soybeans."

Like many Iowans in 2008, Heck had some drowned out spots in some fields, due to heavy rain this past June. So far, his soybean yield average for 2008 is running 53 to 58 bushels per acre, which is pretty good, he notes.

"Iowa and other states aren't getting the soybean yields they were looking for in 2008," says Palle Pedersen, Iowa State University Extension soybean agronomist. "Bean yields are not only coming in lower than expected, but they are tremendously variable, not just in Iowa but throughout the Midwest."

Bean yields disappointing this year

A leading private forecasting firm, Informa Economics, is projecting 40.9 bushels per acre as this year's average U.S. soybean yield. Is that a number Pedersen thinks is high? "Yes, I do," says the ISU agronomist. "We've been harvesting our research plots in Iowa this past week. We're about 40% finished with our plots and we've seen yields anywhere from 5 bushels to 90 bushels per acre. A huge variation depending on whether the water got away last spring and in June."

"When I talk to colleagues in the Eastern Cornbelt, they see a lot of variation over there too," says Pedersen. "There's significant disappointment in bean yields in the Dakotas and elsewhere too. I just don't think we're going to get the bean yields everyone was hoping we would this year."

Is USDA's forecast still a little high? Pedersen thinks so. "The September USDA Crop Report estimated Iowa's average bean yield at 47 bushels per acre for 2008. We made an estimate at ISU just based on planting dates and come up with 43 bushels per acre as an average yield for Iowa. I think USDA's October Crop Report, due out on October 10, will revise Iowa's yield estimate downward from that 47 bushel per acre estimate in the September 12 report."

Later maturing fields will likely yield less

About 40% of Iowa's soybean acreage has been harvested, notes Pedersen, and many yields he's heard from farmers are in the low 50-bushel range. "People are surprised at how good those beans are," he says. "But we also have a lot of beans in the 30 to 40 bushel per acre range. Farmers anticipate that for the rest of the fields they will harvest this fall, the yields are going to go lower. These later maturing fields were delayed in planting and some were replanted."

It also depends on weather the next couple weeks. "Everyone was nervous about when the first killing frost was going to hit this fall, but it looks like most of Iowa's soybean fields are going to survive the frost threat," says Pedersen. "The frost has held off and many of the fields have matured. So that's good news."
A farmer from Warren County tells Wallaces Farmer he's never gotten higher yields on shorter beans. He's amazed at how many pods are on the shorter than normal plants. "Bean plants are shorter than usual this year," says Pedersen. "But height of the stalk is not correlated to yield. It is how many nodes that are on each stalk that makes the difference in yield."

Why beans have set pods so low this year

While there are some very short beans in Iowa this year, there are also tall beans in some areas of the state too. "In Mahaska County in southeast Iowa the beans are tall because they received so much rain earlier this summer and the water was able to get away," says Pedersen. "Those beans really grew."

Farmers need to be careful when harvesting the short soybeans this fall and set the combine header down low, as close to the ground as possible, he says. The pods are set low on the stalk, all the way down to the bottom this year. What is the reason for such low podding?

"What happened is we didn't get the canopy closure this summer," says Pedersen. "About half of Iowa's soybean acres are still planted in wide rows—30 inches or wider. When you have suppression of the canopy formation in a year like this, the sunlight is able to get down into the bottom of the canopy and you will get more pods developing closer to the ground than you normally do."

If you are using a drill to seed your beans in narrow row spacing or if you are using a planter with a 15 inch row width, which is a narrow width, you have the canopy closing faster and you don't get as much sunlight down in the bottom of the canopy, so the plants aren't going to set pods as low to the ground.

Some farmers are "digging their beans" as they are harvesting this fall, which is evidenced by the amount of dust surrounding the combines in the fields. They've got the headers set low enough to shave the fields, to try to capture those low-podded beans on the shorter than usual soybean plants.