Farmers have asked Iowa State University Extension agronomist Roger Elmore several common questions this week in regard to planting corn in early to mid-May. In this article he shares his answers with us. Also, ISU Extension field agronomist Clarke McGrath has provided us with answers to some questions he's receiving.
Both Elmore and McGrath write columns in Wallaces Farmer magazine each month. Elmore's column is called "Corn Source"—since he's the ISU Extension corn agronomist. McGrath's column is called "CSI:Iowa"—for Corn and Soybean Initiative. McGrath is the partner program manager for this ISU Extension program.
Last week Elmore wrote an article in ISU's Integrated Crop Management newsletter titled "Progress of corn planting and corn emergence." It rained in several areas of Iowa last week. This week was drier and the corn planters started up again.
Has anything changed now that we are in the second week of May?
"No, I don't see any need for changes in the recommended approach to planting corn at this time," says Elmore. "I'd still plant corn if I wasn't finished planting yet. Certainly as the calendar moves forward, the window may be closing. That is, yield potential may be lower, if we have an average year for weather. But what are the odds of having that? We've had years where the best planting dates were the last ones of the season."
* It's May 9. Is there still a window to plant corn? "Yes, we're still within the window to plant corn," says Elmore. "I'd use the chart provided in the ICM article to give an idea of potential losses with the delay in planting to help your figure the economics of later planting dates. But as I alluded to in the above discussion, this may be the kind of year where late planting has little or no penalty. Remember, it is far better to wait for good soil conditions to plant the corn than to 'mud in' your seed."
* What about switching to an earlier maturity corn hybrid? Is there a "magic date" when farmers should consider switching hybrid maturities? Also, is there a "magic date" to switch from planting corn to soybeans on your acres that are intended for corn—but if it's getting late should you plant soybeans instead on those acres? "I usually start thinking about that in late May or early June. We've got time yet," says Elmore.
* How is your corn planter performing this spring? "It's been a frustrating couple of weeks here in western Iowa," reported Clarke McGrath on May 9. He is the ISU Extension field agronomist at Harlan. "We were planting and spraying the previous week in small windows between rains. Now, this week it looks like we're getting quite a bit of corn planted. Some farmers may finish planting corn and start on soybeans."
As farmers get the planting wrapped up and begin post emergence spraying, they need to carve out some time and evaluate how well their planter operated this spring, says McGrath. "As you scout your fields in the next few weeks, take notes on how your stand of corn looks in relation to planter performance. Did you come close to your target population? How is the plant spacing? Check for doubles, triples, skips and gaps. This can help tell you if the planter is performing at its best or if it could use a tune-up."
* Did your stand of corn come up pretty uniformly or was emergence uneven? Dig and check soil structure around the seed zone. Did your planter's openers, row cleaners, seed firmers, gauge wheels and closing wheels work like you wanted them to? Was the seed trench a nice "V" or more like a "W"? A "W" can indicate the need for new disc openers, says McGrath.
* Did you hit your target planting depths, or did the planter run shallow or deep? Again, problems can indicate the need for some work on your planter. Or if you see problems, this can give you hints as to what types of adjustments you need to make in the future, based on similar soil and crop residue conditions. "Planter maintenance and proper adjustment for the crop residue conditions are very important," says McGrath. "Work with the owner's manual and consult your implement dealer to ensure that your planter is operating at its best. The key is to get out in the field and scout your corn crop now and recognize any issues you can correct—to increase your future yields."