If the soybean field where the beans didn't emerge as well as you would like is right in front of your landowner's house, or if it is right along a major road where everyone who passes by will see it, including perspective landowners you might rent to you in the future, then maybe you have other reasons to include factor sin your replant decision that just number of soybean plants remaining, date that you could replant, and cost of replanting. If it's a strictly economic, decision, however, odds are you will find it makes sense to leave stands where your first instinct is to tear up the stand and start over.
Consider these factors.
Soybeans compensate- Nearly 30 years ago Marv Swearingin, then a Purdue University Extension agronomist, demonstrated in trials that soybeans could produce well at much lower populations than most people gave them credit for. His work indicated that yield potential dropped little if any until stands dropped below 80,000 plants per acre, and didn't begin to drop significantly until you got below 60,000 plants per acre. His work assumed that the plants were fairly uniform in distribution, and that you could control weeds. Controlling weeds in Roundup Ready soybeans in thin stand sis much easier today than it was then, before Roundup Ready soybeans, when canopy closure still played an important role in reducing weed growth.
Planting date- If you're deciding today you don't like the stand and it's dry enough to replant, you may be more tempted if the economics are borderline to replant. If it's two weeks from now, the numbers would favor staying with even thinner stands. Soybean yields drop on average due to late planting just like corn- it just isn't as consistent and hasn't received as much press because people didn't use to plant soybeans early and have a baseline for comparison purposes.
There are still more factors to consider. Watch for more discussion in future articles.