Agronomy: Replanting Soybeans Decision

So when should you replant soybeans? This is not a common practice if you plant when soil conditions are right and don’t experience a late frost, drown out or crusting after a big rain followed by a hot dry wind blowing over tilled soils. However, nature throws us some curve balls and sometimes replanting is necessary or at least filling in the gaps when stands virtually disappeared.

If you find that your stand is less than desirable and all sorts of branching will not fill the gaps, growers need to consider the uniformity and density of stand before considering replanting. It all begins with a visual examination once the crop is up. Don’t get in too big of a hurry to replant until you can assess accurately the stand that you have.

Once the crop is up observe whether there are huge gaps in the stands such as from crusting or drown-out spots. Look for repeatable patterns that were probably man-made. Or are the gaps more isolated and smaller and spread throughout the field?  Do not do stand counts until all seed has emerged. Then get in the field and count the number of plants in one thousandth of an acre.  Use the following table to determine the row length to count plants per acre.

Before going to the field cut a length of rope to the appropriate distance and attach a stake at each end. Then count the number of plants in a row. University research suggests that a uniform final stand of 100,000 plants per acre is enough to optimize yield. Producers can determine their stand by counting the number of plants in a length of row equal to 1/1000th of an acre and multiplying by 1000.

If final stands are less than 75,000 to 80,000 or there are bare spots in a field, growers can easily fill in these areas. However, remember that the later planted seed will emerge later and those plants will never have the yield potential of the earlier planting. University research has shown that if stands have 65,000 to 70,000 plants per acre, adding more plants later does not increase yield. However, it may reduce an encroachment of weeds.

How do you decide to replant soybeans if there is a stand failure? Or do you just tear it all up and start again?

Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at djdavidson@agwrite.com.