Soybean replanting decisions are almost always a tough call and a subjective decision. In 2023, favorable planting conditions in late March and early April have resulted in quite a few acres being planted. As we head into the month of May, let’s take a look at some objective factors that can help inform replant decisions.
Factors that will be discussed in this article:
- Planting Date
- Stand Counts
- Evaluation Methods and Growth Stage
- Do I Plant into my Existing Stand or Terminate and then Replant?
- Do I plant a Different Maturity Group?
Leave it as is and walk away? Plant into an existing stand? Terminate and start all over? These are the usual categories or questions surrounding soybean replant decisions each year. The best answer to “what should I do?” often depends on several factors. Throughout the soybean growing regions of the U.S., a substantial amount of work has been done to assess how to achieve and maintain maximum ROI in a replant scenario. So here’s my perspective on maintaining maximum ROI with soybean replant decisions in Tennessee.
- Planting Date
Replanted soybean is late(er) planted soybean. This is a good mantra to keep in mind since the replant date is always later than the initial planting date. Simple enough, but largely inconsequential as long as re-plant dates are prior to May 1. However, as we progress into mid and late April for an initial planting date, thereby pushing any potential replants into early and mid-May, the disparity in yield potential between planting dates begins to widen.
- Stand Counts
This may be the most visible and obvious way of assessing replant decisions. In our region, consider replanting into a stand when counts fall below 50,000 – 60,000 plants per acre. While this may seem like a drastic reduction in population, this is taking into account the total cost to replant.
- Evaluation Methods and Growth Stage
There are multiple ways of assessing final stand counts (plants per acre). Usually, the quickest and most accessible way is to measure 1/1000th of a row, count the total number of plants, and multiply by 1000. But when should you take these stand counts? I recommend waiting until soybean is at the VC growth stage. This is when both unifoliate leaves are completely unrolled. Soybean Growth Stages
Jumping the gun and evaluating a soybean stand as the cotyledons are coming out of the furrow will often lead to an underestimation of final plant stand, thereby potentially triggering a decision to replant that is unnecessary.
- Do I Plant into my Existing Stand or Terminate and then Replant?
Replanting into an existing stand, especially when stand counts yield > 50,000 plants per acre, is nearly always the right decision. Consider terminating the existing stand only in extreme circumstances.
- Do I plant a different/earlier Maturity Group?
In short, the answer is “no”. While some may reason that a different maturity group (an earlier one) is necessary for the replanted soybean to “catch up”, this isn’t the case. Staying with the same MG will result in a more uniform stand (with respect to growth/reproductive stage) later on in the season. However, replanting (if warranted) as soon as possible should be the goal.
Summary & Final Thoughts
Wait until VC to make your stand count determinations.
Consider replanting into the existing stand when stand counts yield a final plant population of 50,000 – 60,000 plants per acre. Yield may suffer slightly, ROI will not.
Replant the same or similar maturity group as the initial planting. If replanting in June into a determinate variety, replant a determinate variety as well.
Keeping ROI in focus, consider that thin or non-uniform stands may require an additional herbicide application since row-middles may never lap or will not lap until later in the season.
