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  • Writer's pictureWendell Koehn

Soybean populations as we plant later in the year? What rate for what date?

Updated: Jun 10, 2019

"The best way out of a difficulty is through it." -Will Rogers

Two soybeans push against the rain packed crust

The quote above is true for what farmers do best. With the excess rain across your fields, I hear a common thought: "This is a year like none other, but we will get through it." Unlike other industries, there is no strategy that can change many of the factors that affect growers. Thus, the mission and the focus of TOP Ag Services' updates is to: Help manage risk, reduce risk, and when that is not feasible move risk to a less vulnerable position. Today's topic is on soybean populations as we trend later.

Those that were at our meeting at the Rich Hill Lion's Club building last spring heard me talk on the results of our farm's population reduction studies. It is no secret that I am a fan of reducing seeding rates on soybeans. The results of these studies over the last view years when coupled with variable rate planting can be beneficial. Beck's PFR also bears out the benefits of lowered seeds/acre on soybeans. To quote Travis Burnett, Beck's PFR agronomist: "The improvement in seed treatments and the placement of the seed also enables soybeans to succeed at lower populations than previously believed." These results are positive if the following are true:

  • The soil type is MP-HP (think of soils in which soybeans easily establish themselves and have greater potential on yield)

  • Early Calendar Date

The calendar date is the widespread component that affects our decisions in a year like we have had so far. Since we are trending later into the growing season, we are changing to planting higher rates. Right now, in early June I would say 140-150k on most soils. If we get to the crop insurance date cutoff, I would tend to bump those 10-15k. After that date, 160-180k.

(A special note for bottom ground soils that bake hard in the warm June sun: adding a little to the above numbers for these especially ornery pieces of dirt can help emergence)

None of these numbers should be looked at verbatim. They are a guide to start. There are differences in equipment, soils, tillage, and cover that can change the plan of attack. The important thing is to be in contact with your "guy" you call for agronomic decisions to fine tune a seeding rate. As always, feel free to reach out to me anytime.

I am ending with something a little different today. It is a challenge that will cost you nothing in terms of inputs or equipment. Here it is:

-Make one round with your planter in a consistent part of one field planting soybeans between 1" and 2" this planting season.

Beck's PFR data for 4 years shows that the highest ROI on soybeans is at 1.5" planting depth. Going from ½" to 1" is a 4 year average of 5.3 bpa alone. Going to 1.5" adds an additional 1.8 bushel. The question I get, and rightfully so is: "What if they don't come up?" Let's consider the following:

  • Seedlings planted 1-2 inches have the root and stem infrastructure to support pushing the cotyledons through the rain packed crust.

  • The first ¾" of soil is the hot zone for your residual barrier. Soybean roots below that that chemical barrier are able to start nutrient scavenging and nodulation earlier and more quickly

  • Speaking of which, nodulation primarily occurs at the depth in which soybeans are planted. Nodulation does best in an environment of consistent temperatures and even moisture. Deeper seeds will experience less impact from the hot summer sun or hard drenching rains as the upper 1" is subject to greater swings in temperatures and moisture levels. (paraphrasing Luke Schulte, Beck's field agronomist)

Finally, there may be circumstances in which a ½" soybean will come up better than one planted deeper. However, 5.3 bpa extra to plant at 1" really gets my attention. Especially, when there is no cost to overcome its profitability. At $8.00 per bushel this returned in the PFR fields a whopping average $42.40 ROI with no upfront cost.

As with anything new on your farm, I recommend trying it, but sparingly. Observe the results, then expand implementation if it is verified. A wise old friend of mine once told me: "Research slowly, verify, then implement quickly!"

Article credits go to:

Josh Wallace, seed advisor for Beck's Hybrids in SW Missouri

Travis Burnett, PFR agronomist in Indiana

Luke Schulte, field agronomist in London Ohio

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