By Roger Elmore and Lori Abendroth, Department of Agronomy
As of Sunday, April 19, six percent of Iowa's corn sits in Iowa's fields imbibing moisture and experiencing the beginning of the germination process. In our planting date research trials, corn planted during the first week of April has sprouted with a one-fourth inch root emerged. The season begins!
Six percent planted is similar to that of 2007 but is a little behind the five-year average, 10 percent. Yet, Iowa producers are further ahead than they were in 2008 when virtually no corn was planted. Remember though that the five-year average of 10 percent includes data from 2007 and 2008 which weights the average towards a slower start (see figure). For comparison, the five-year average for Iowa corn planted 2002 to 2006 — excluding both 2007 and 2008 data - was 18 percent planted during this same week. Depending on what years we include in the five-year average makes a difference on whether or not Iowa producers are considered "behind" in 2009.
As a point of reference, 2008 progress through May is like that of the five year average 1975 to 1979. That's more than 30 years ago! We typically plant corn earlier now than ever before, if conditions permit.
In spite of the slow planting progress in both 2007 and 2008, state-wide average yield for these two years tied for third in history at 171 bu/acre. These yields rank third behind 2004 and 2005 at 181 and 173 bu/acre, respectively. Some reasons for the high yields in 2008 were covered in the ICM News, 12-09-08.
We outlined recommendations for 2009 planting in a recent ICM News article, 4-8-09. Consider planting corn in mid- to late-April if:
• Seedbed conditions are good
• Soil temperatures are close to 50 degrees F and rising
• The forecast is for warm weather over the next five to ten days
All of these factors appear to come together this week. Seedbed conditions are good for planting across the state or they soon will be ready. Soil temperatures across the state are at or above 50 degrees F and rising. Both the short-term and 6 to 10 day forecast call for warmer and drier weather.
Although planting progress lags behind the different averages we calculate, yields in the last two years prove that excellent yields can result from 'slow' starts. All summed, this promises to be a great week to plant corn.
Figure Caption: Iowa Corn Planting Progress 2004 — 2008. Adapted from USDA-NASS data.
Roger Elmore is a 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. Elmore can be contacted by email at firstname.lastname@example.org or (515) 294-6655; Abendroth can be contacted by email at email@example.com or (515) 294-5692.