Northern Illinois is not the first place you’d expect to see 100-bushel soybeans. But Peru, Ill., farmer Dan Arkels yielded 104 bushels per acre on his 30-acre Illinois Soybean Association Yield Challenge plot in LaSalle County, a 15-bushel increase above the previous Illinois record.

He credits good weather, excellent genetics, and keeping each and every plant healthy. “My top goal was to save as many blossoms and pods as possible,” he says. It must have worked, because he noticed an incredibly high number of pods and large seed size. “I’ve farmed for 35 years and have never seen seeds that large,” he says. His contest field had 80 to 128 pods per plant, compared to about 80 pods per plant in his non-contest fields.

Arkels planted a Group 3.4 maturity level variety (versus Group 2.8 on his non-contest acres) to capture more of the season’s sunlight.

It was a banner season for Illinois soybeans. “High sunlight and moderate July temperatures were great for crops, and there was enough soil moisture going into the month that the crop never went under stress,” says University of Illinois Crop Sciences Professor Emerson Nafziger. “Then it rained in August, which is the critical month for soybeans.”

Extra preplant phosphorus and potassium and 15-inch rows served him well in 2012, when he was one of three farmers topping 80 bushels per acre. He repeated that strategy for 2014, along with foliar nitrogen, zinc, manganese, iron and sulfur at V3-V4 growth stages (Harvest Max). For the past three years, if a sprayer crossed a field, he added Harvest Max micronutrient and slow-release nitrogen treatment.

His contest field also received a second pass of fungicide and Stoller Bio-Forge biologic growth promoter.

Arkels used his contest plot to learn “what’s going to really move my soybeans to the next level,” he says. His non-contest acres averaged 75 bushels this year.

Attempts to win the challenge in recent years taught him the value of narrow rows, foliar fertilizer applications applied at the 3-4 trifoliate stage and preplant fertilizer—all part of his standard program now.

If you want to break 70 bushels, you have to add some form of nitrogen, Arkels says. “Above that level, a soybean plant requires 4-5 pounds per acre nitrogen for every bushel of final yield. I also put down preplant chemical, using 32% nitrogen as carrier.”

Nitrogen also played a role in Arkels’s two previous wins in national corn yield contests. In 2012, Arkels won the National Corn Grower’s Association class AA corn yield contest with 277.3 bushels in the conventional tillage, non-irrigated category. Not bad considering it was a drought year, and with a CCCS rotation. In 2013 he won again with a 319-bushel yield.

Breaking the 100-bushel soybean barrier is “like winning the World Series,” he says. “Someone needs to prove it’s possible in Illinois, and with the right growing season, I know I can do it.” When this article went to press, there were about 20 additional 100-bushel Illinois contestants still waiting to harvest their test plots.

Perhaps best of all, his soybean yield contest field is profitable, he says.

Add nitrogen to soybeans?

The scientific community is less sold on the fact that soybeans lack the ability to fix enough nitrogen to surpass a certain yield level. Most yield contest winners add N to their soybeans.

Nafziger saw no yield response at all in a multi-input Illinois study. “In 2013 we had some 90-bushel beans that didn’t respond to nitrogen,” he says.

“One of my big concerns with using nitrogen mid-season on soybeans is that in dry years, a lot of it may be left in the field at harvest, and be subject to loss before the next spring,” Nafziger adds. “Farmers could do this in strips and see for themselves, but so far we haven’t figured how to boost yields at all with nitrogen fertilizer, let alone how to make it pay out.” 

Similar thoughts come from University of Minnesota Extension Agronomist Seth Naeve and Purdue Agronomist Shaun Casteel. After the United Soybean Board “Kitchen Sink” study of high-input soybean systems in six states failed to show that soybeans responded to nitrogen, Naeve advises farmers to “not bother with nitrogen on soybeans. Even if it does work, the amount of nitrogen you need means your chances of an economic return are near zero,” he says.

Purdue’s Shaun Casteel has seen no consistency in soybeans’ response to N. “We overloaded the system to see if the genetic potential was limited by the nitrogen supply. Yield responses (about 10 to 12 bushels per acre) were promising, but not economical with Group 3 beans in Illinois and Indiana nor with Group 2 in Wisconsin and Minnesota,” he says.

Shawn Conley, Wisconsin Extension soybean specialist, disagrees that N is required to break 70 bushels per acre. “We have many whole fields in southern Wisconsin in the 70 to 80-bushel mark without additional N,” he says. “Good genetics, good weather and a sound fertility and pest-management program, coupled with a conducive environment, are the big keys.”