Soybean Replants

Contributed by Robert Moloney, NK Brand Seeds

There are not a lot of soybean replants happening but there are a few fields (mainly planted in the Apr 30-May 2 timeframe) that are being replanted. This appears to be due to a combination of the beans just running out of steam and some level of crusting.

The key factors to look for if you are concerned about your field:
– if your beans have excessive swelling just below the crook of the seedling (i.e. it is swollen significantly just below the crook compared to the rest of the stem down to the root) this can indicate bean is trying to grow, but being stopped by a crust. Once the beans have a lot of this swelling they won’t be able to continue growing up.
– if your beans are starting to leaf out underground or the cotyledons are being snapped off as they try to push through the crust (bald beans) those plants are likely done.
– do you have a minimum 100,000 plants/acre? If you have this many healthy plants emerged you likely won’t increase yield enough by replanting to cover the cost of replanting.

To calculate your plant stand:

For 7” rows: in 7” rows it is easiest to use a hula-hoop and count the number of bean plants inside it. Below the factor to multiply the number of plants you count by to get a number per acre (based on the diameter of your hula-hoop). Make sure you check in a number of spots across the field and get an average population count.

EXAMPLE: if you have a 30” inside diameter hula hoop and you count an average of 12.5 plants inside it over a number of spots in the field, your plant stand is approximately 12.5 X 8,874 = 110,925 plants/acre and you are likely better off to leave the field than replant it.

For 15”, 20” or 30” rows: personally I prefer to count plants per foot of row on wider row spacings. There is too much variation depending where your hula hoop lands on the rows (even in 15” rows) with the hula hoop. You can use the factors below to get a plants per acre number. Make sure you check at least 10-15 feet of row in a number of places over the field.

EXAMPLE: if in your 15” rows beans you average 2.1 plants/foot so your stand is 2.1 X 34,848 = 73,180 plants/acre.  At this population you would want to re-plant or thicken the stand.

Make sure you do an actual plant count rather than just a visual assessment before deciding what to do. On a marginal stand appearances can be quite deceptive. It’s worth getting a 2nd opinion from your NK dealer if you have a field you are concerned with.

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