The season finally began for the Soybean Watch ’20 field on June 5. Several varieties of soybeans were planted. While the purpose isn’t yield comparison among varieties and the field isn’t laid out as a yield plot, planting multiple varieties will allow the tracking of possible differences in timing and growth habits throughout the season.
“There was a difference of a few days in maturity in varieties a year ago,” recalls Steve Gauck, regional agronomy manager for Beck’s, based near Greensburg, Ind. Beck’s sponsors Soybean Watch ’20.
“One variety flowered slightly before others, and that can make a difference depending upon environmental conditions,” he says. “We will be looking at those kinds of differences again this year.”
While this year’s field has the capability for irrigation, it is comprised of different soil types. Not all of them are droughty. That is another factor Gauck will monitor during the season.
While early planting dates are preferable, this year’s field is within a streak that was almost as wet as 2019 during May. A year ago, the field was planted June 12, with the entire field averaging just under 60 bushels per acre. A weighed 5-acre section of one variety came in just under 64 bushels per acre.
“If we get a good stand and weather cooperates, there is still good yield potential,” Gauck says.
Gauck is a big believer in staging soybean growth according to a standard system during the season to improve management capability. So is Betsy Bower, a Ceres Solutions agronomist in west-central Indiana. She and Gauck are both members of the Indiana Certified Crop Advisers. Bower coordinates the Soybean Corner and Soybean Pest Beat columns for Indiana Prairie Farmer, and Gauck is a frequent contributor to the project.
Recently, Bower demonstrated how to stage growth on young soybeans on a field in her area. They were at the V3 stage. The Soybean Watch ’20 field should be at that stage soon, if not already, even though it was planted later.
“When you’re staging a young soybean plant, you start at the ground level,” Bower explains. “You can likely still see the cotyledons, which were the halves of the seed that split and emerged above ground. Then above them, you’ll find the unifoliate leaves.
“You don’t start counting yet to determine vegetative stage in young soybeans. What you’re looking for are trifoliate leaves that are open and unfurled.”
Technically, the Purdue University Corn & Soybean Field Guide classifies plants with cotyledons and unifoliate leaves fully expanded as the VC stage. Once the first set of trifoliate leaves are open and leaf margins don’t touch, it’s a V1 plant. A V2 plant has two sets of trifoliate leaves visible, with individual leaflets of the second trifoliate no longer touching.
“The plant we examined [see photo above] had three sets of trifoliate leaves fully expanded,” Bower says. “Leaf margins were no longer touching on the upper third set. That made it a V3 plant.
“The leaves for the fourth set of trifoliate leaves were visible, but they were still bunched tightly together. Plants go through several vegetative stages before they reach the first reproductive stage, which is R1. That is when a flower is visible at any node on the main stem.”