For someone who grew up at a time when “good” soybeans made 50 bushels per acre and if yields topped 60 bushels per acre, you checked to make sure the weigh tickets were right, a final yield hovering in the high-50-bushel-per-acre range sounds acceptable. But 50 bushels was good for beans as far back as the early 1980s, when Indiana’s average soybean yield was typically in the 40s. This year, the average is projected around 60 or more bushels per acre.
The results are in, and the Soybean Watch ’20 field averaged in the mid-50s or slightly above on about 57 acres. However, Steve Gauck, a regional agronomy manager for Beck’s based near Greensburg, Ind., says that’s misleading. Nearly a third of that acreage was “dry corners,” not reached by irrigation. The dry corners were underlain with sand and gravel at about 3 feet deep, and from late August until harvest was very dry. Beck’s sponsors Soybean Watch ’20.
The best indication of how the field performed is more likely from passes in the field that were weighed in the grain cart. These passes, totaling 1.9 acres each, were irrigated. One variety yielded just over 61 bushels per acre, and the other yielded about 57.5 bushels per acre. The operator irrigated as often as necessary late in the season, keeping it going until leaves were yellowing and dropping, with the soil still moist, Gauck says. Pods on both varieties in irrigated areas were filled to the top.
The yield-limiting factors in the field included:
Planting date. Overall, across 80% or more of Indiana, spring 2020 was nothing like 2019, when rain dominated. Unfortunately, this field is in the 20% where the spring still bore a resemblance to last year, although not as severe. These soybeans were no-tilled into corn residue on June 5.
Then it turned dry for a spell. In fact, the grower irrigated the field to help beans emerge as uniformly as possible.
“A few fields planted in early June still hit 70 bushels per acre or more, but we’re aware of many that topped out in the 50s and 60s,” Gauck says. “Planting soybeans as timely as you can is always important. In Beck’s Practical Farm Research studies, the long-term data says that while it’s important to plant both corn and soybeans early, it may help soybeans even more than corn.
“On top of that trend, it seems like early-planted beans really excelled in 2020. We may not know all the reasons yet, but we will continue to look.”
Less-than-ideal soils. Besides the droughty soils, most of the rest of the field had a large hill running across it, with long slopes on both sides. Back when fields were plowed, it would have classified as a “red clay” hill, because a lot of topsoil washing away would leave the reddish-tinted subsoil at the surface.
Pest pressure. Another problem in the Soybean Watch ’20 field was feeding by voles or moles. “They can clean out a spot entirely once they establish their burrows,” Gauck says. “There were several different spots within the field, but they were all fairly small. They looked ugly in pictures taken from the air with a drone, but they probably didn’t drop yield that much.”
For example, if total area affected was half an acre, the damage may have dropped average yield about 0.5 bushel per acre. Even if the affected area was an acre, it would have only dropped yield by a bushel per acre.