By Roger Elmore and Lori Abendroth, Department of Agronomy
Rain is forecast again for most of Iowa later this week. Little if any spring work has occurred because of cold weather and already saturated soils. More rain right now is not welcome for most of us corn growers!
We nervously look at the calendar and wonder how we can plant all our corn this year. We need to remember that although we are likely planting one million acres less in Iowa than we did in 2007, it is still more acreage than we’ve planted since 1992. And nationwide, we have to go back to 1949 to find more corn in the U.S., except again for 2007.
Hybrid cold tolerance, seed treatments, tillage systems, herbicide options and planter systems are technological improvements allowing early planting when conditions are good. For example, we had half of our 2006 corn planted nearly two weeks earlier than we did in the late 1970’s.
Our early planting trend was spoiled by wet cold weather in 2007 with half of the corn planted after the first week of May. We essentially had three planting dates last year in Iowa. One thing in common with all three sets of 2007 planting date was that it was wet every time! Yet we still had the third highest yield in the history of Iowa in 2007, 171 bushels per acre! Planting date is one of many management practices that relate to yield but it is not always the main factor.
Since 1981, the most corn we’ve ever planted in Iowa by mid-April was 6 percent; this was in 2006. In most years we have only had 3 percent or less of the corn acres in by then. By the end of the third week in April, only one in four years do we have more than 10 percent of Iowa’s corn planted (see Figure 1). In 2006 we again had the most with more than 25 percent planted. Usually we’ve had less than 5 percent of our corn planted by the third week of April.
Don’t worry! There is still plenty of time to plant corn. Remember that our best data shows that Iowa corn yield responses are relatively flat during April and only begin to decrease significantly as planting is delayed past May 10th. In addition, we can plant corn faster than ever before once the weather breaks.
We do not want to plant that precious seed into cold wet soils if there is no short-term promise that better days lie ahead. All sorts of problems arise such as poor germination, slow early-season growth, side-wall compaction and rootless corn.
The goal is to have all the corn come up at the same time with every plant looking like every other plant. It is far better to plant into cool, dry soils if the 7-day forecast calls for warming than to plant in warm soils knowing that temperatures will be dropping soon.
Patience is important when it comes to planting corn in April!
Roger Elmore is professor of agronomy with research and extension responsibilities in corn production. Lori Abendroth is an agronomy specialist with research and extension responsibilities in corn production.