Stay with Corn? Switch to Beans
June 1 is this Sunday and some farmers that haven’t planted corn yet (or are replanting) may be thinking about switching to earlier maturing hybrids or to soybeans. Most agronomists agree that staying with a full season hybrid for southern and central IN and IL up until June 1 is a good decision based on the fact that late-planted corn can mature with less growing degree days than the same hybrid planted earlier in the spring. After June 1, however, there are many other factors involved and the picture gets a bit more fuzzy. It’s a complicated decision with no “one size shoe fits all” answer.
The following is a list of points to consider if corn or soybean planting is delayed past June 1. Use these to help with the decision process. Some of these points came from correspondence with Bob Nielsen (Purdue Corn agronomist) and a recent article by Emerson Nafziger (Univ. of IL Corn agronomist).
- Corn planted in early June may yield 20-25% less than optimum
- A uniform stand of soybeans planted in early June may yield around 10% less than optimum
- Late-planted corn probably does not need as much nitrogen (at planting or sidedress) because less of it will be lost from here on
- Summer weather is unpredictable, but early RM hybrids may pollinate during the hot/dry periods and soybeans may revive with a late rain in August
- Prices are still favoring corn
- Obviously, if a corn herbicide has already been applied – don’t plant soybeans. The risk is too high to plant beans following atrazine.
- The investment from applying nitrogen to the field ($75-100 or more/acre) will be lost if switching to soybeans
- Soybeans can be planted in a field that had nitrogen applied, but there will not be any significant yield boost from the nitrogen
- Having nitrogen already applied to the field still favors planting corn even if it is early June
- Is the soybean variety you want to plant available?
- Always use triple-stack or VT3 corn for replants or late planting (follow refuge requirements)
- Research shows that there is no need to increase the corn population above normal with late-planted corn
- Late-planted soybeans may benefit from higher seeding rates to promote more height and nodes/plant. Also, planting in narrow rows is preferred for the same reason.
- How will this decision affect my rotation in the future?
- Do I have contract commitments with my grain buyer?
There are many points to consider, but these will help get the decision process started.
Assessing Soybean Stands.
Get out the Hula Hoops! Many fields of soybeans were planted during the first few days of May – then came more rain and cold weather. The result has been less than perfect stands in several fields across the region. Use a Hula Hoop to count stands in drilled (7” row) fields. All the information you need to know for using a Hula Hoop to make stand counts can be found in the Purdue Corn and Soybean Field Guide. Example: for a 30” diameter hoop the factor is 8,878. Count the number of plants inside the hoop and multiply by 8878 to give you the population per acre. A hoop can also be used for 15” or 20” rows. For 30” rows, either count the number of plants in 17’ 5” of row (1/1000 of an acre) or the number of plants in one foot. Six plants per foot of row is about 104,500 plants per acre. If the plants have not yet emerged, and a crust is impeding their emergence, then a rotary hoe may help break up the crust or wait for a rain. Heritage-Diener has a good supply of different varieties for replants. Contact your local DSM for availability and further questions regarding replants.
Have a great weekend!
Dan Childs, Agronomist
