Soybeans: It’s not just a rotational crop anymore

CHAMPAIGN, Ill. — An east-central Illinois agronomist believes soybean producers rely too much on “the seed companies to bring the yield to them” rather than implementing additional practices on their own farms.

Kris Ehler, an agronomist with Ehler Brothers Co. in Thomasboro, was a keynote speaker at the Illinois Soybean Association’s Soybean Summit and has conducted extensive on-farm research to find ways to squeeze every bushel out of a soybean plant.

“We’re not delivering at the rate of increases that we need to be sustainable just through genetics and breeding. If you’re comfortable with a one-half bushel increase or three-tenths of a bushel increase per year, that’s not going to cut the mustard,” said the self-described “bean dork,” his Twitter handle, @Bean_Dork.

Another reason growers are slow to incorporate new products on their farm is their love for corn, according to Ehler.

“I think we missed the mark in an advertising campaign a couple of years ago when, let’s face it, soybeans were keeping the farm in the black, because we kept growing corn and we were losing money doing it, but we love corn because corn is sexy. We love growing it, and soybeans are the rotational crop,” he said.

“The marketing campaign during those years where soybeans were keeping the farm afloat could have been ‘Soybeans: It’s not just a rotational crop anymore.’

“We’re not doing on-farm evaluations or plots. These are our acres, our fertility, and our program, why don’t you evaluate those products on your acre to see what the return is on your acre, because everybody has something to sell you. They’re going to give you that magical five-bushel increase if you spray it on your soybeans. Put it into your program to see if you get a response and what is that response.”

Here are Ehler’s recommendations for a successful soybean program.

On The Givens

Fertility for a yield goal of 100 bushels per acre includes the need for 110 pounds of phosphorus, 230 pounds of potassium and 450 to 500 pounds of nitrogen.

Choose the best-yielding genetics within a herbicide platform that gives control of the weeds that you are fighting on your farm. If there’s a weed that another platform doesn’t cover that you’re not going to get control of, you can get pushed into a different platform.

Talk to other high-yield producers, find out what they’re doing and what’s working for them. It doesn’t necessarily mean it’s going to work on your farm, but if you keep hearing of a certain product, certain practice, that neighbors are using that’s increasing their yield, investigate.

On Maximizing Seed Real Estate

Growers have 8 ounces of opportunity per 100 pounds of seed. For every 100 pounds of seed, we can put about 8 ounces of product on it.

The standard fungicide and insecticide seed treatments are about 3.5 ounces per 100 pounds of seed and still allow room on the seed for other products.

For example, a nematicide with a really low-use rate — one-tenth of an ounce — is added. I’ve also thrown in Bio-Forge Advanced. If we don’t use inoculants, Bio-Forge Advanced has cobalt and molybdenum. Those are two micronutrients that are kind of signaling nutrients for nodulation. Bio-Forge is a 2-ounce product, so we still have plenty of room on that seed for maybe something else.

Do we want to use an SCS-type product? We’ve got room for it.

Products such as Saltro and ILeVO for protection against Sudden Death Syndrome can be added.

An inoculant treatment can also be added. Inoculate every acre every year.

On Sulfur

Sulfur is as important as nitrogen, phosphorus and phosphate. Options include applying ammonium thiosulfate with a pre-plant chemical, or broadcast-apply ammonium sulfate.

Proceed with caution as not a lot of the soybean herbicides are compatible with ATF. A compatibility agent is needed with a lot of the herbicides that are out there when using ATF.

AMS has a long, slow-release product that’s going to provide a little bit along the way throughout the entire growing season, and if we can give it a dump from the nitrogen in AMS later and make it available as the nodules slowdown in the mid to late reproductive phase, that’s not a bad thing.

Other options to provide sulfur are MicroEssentials or MESZ and elemental sulfur.

On Early Planting

April planting has out-yielded a May planting date in Ehler Brothers’ trials by six to 10 bushels per acre, averaging 6.4 bushels over the last 10 years of data.

On average, growers give up about one-half bushel per day when soybeans are planted after May 10. We’re giving up four-tenths to one-half bushel per day when we plant soybeans after April 25.

The goal is to have soybean initiate flowering the first week of June in preparation for the June 21 Summer Solstice. We want to build a bigger factory to withstand mid-season stress and the plant can recover faster because there’s more biomass there to do so.

On Micronutrients

Key soybean micros are iron, manganese, molybdenum, boron and zinc. If we’re making applications during the growing season, they are the micros that you should key-in on in a micronutrient foliar blend.

Starter is not just for corn. Field trials conducted at the Precision Technology Institute in Pontiac using NutriStart fertilizer applied with the Conceal system attached to the planter had a 3.4-bushel advantage at 10 gallons, 3 inches out, and one-half inch down, and five bushels at the 15-gallon rate. Those are positive returns on investment.

When we incorporate early planting, we need to recognize nutrient availability and what blend of starter would be best for our soybeans.

On Planting Rates

For conventional tillage, at 15-inch and 20-inch rows, Ehler uses a planting density 125,000 to 130,000 seeds per acre and 125,000 for 30-inch rows in conventional tillage. Seeding rates are 10% to 15% higher in no-till.

An additional 5% to 7% per week is added to the seeding rate after May 15.

Ehler recommended planting 2 inches deep before April 10, 1.5 to 1.75 inches between April 10 and April 20 and 1.25 to 1.5 inches April 20 or later.

On Yield Determination Stages

Soybeans determine the number of branches at V2 and V3. There have been growers using large rollers to do mechanical damage to get a response at V2, very early V3 to influence more branching. You can go late V3, but yields are going to be negatively impacted.

Manage the population based off of hormones and auxins to influence branching and less internode growth. If we make that plant, go out and it’s not going to go that far up there is less lodging.

Soybeans set the maximum number of nodes at V5. The number of nodes set at V5 can decrease, but not increase.

An application of auxin/hormone and nutrition can be done with the first post pass of weed control at V2 and V3 and may be able to influence the total number of nodes and total number of branches.

Everything you do in the growing season should attempt to influence the number of pods on a plant, which is also the number of nodes, and the seed size and weight.