By Roger Elmore, Department of Agronomy
Corn spikes through fertile soil of early-planted fields in most parts of Iowa as I write. According to the May 4, 2009 USDA-NASS estimates, 2 percent of Iowa's corn is emerged compared to none last year and the five year average of 7 percent.
Amount planted varies widely in the state. Slightly more than a third of the corn is planted in East Central, South Central, and Southeast Iowa cropping districts; whereas, the remaining districts have over half of the corn planted with the most reported in Northwest, 78 percent. Some producers have completed planting.
Meanwhile, 40 percent of Iowa's corn crop remains unplanted. We are far ahead of last year, 84 percent unplanted; similar to 2005; but lag behind unplanted acreage estimates at this date in both 2004, 23 percent, and 2006, 29 percent. We are far ahead of states to our east. For example, 95 percent of Illinois' crop remains unplanted!
Emergence and early-season growth signal if the growing season has gotten off to a good start or not. Iowa's top corn producers walk their fields calculating plant populations, evaluating plant spacing variability, and examining seedling vigor and health much like a physician does during a newborn child's first physical. These early benchmarks serve for the rest of the corn growing season.
Evaluate crop stands as soon as possible, especially in fields where seedbed conditions were marginal at planting. If problems exist, often there is little chance of correcting many of the situations you find. But changes can still be made for the not yet planted crop — if any — and certainly it will produce good fodder for improving next year's planting season.
We can't always avoid planting into marginal conditions which result in poor stands, wild spacing variability, and poor plant vigor. Numerous causes exist. We summarized several of these in the Integrated Crop Management News, May 23, 2008. Some of these issues will undoubtedly reoccur this year.
Every growing season is different but one thing remains in common: high yields most likely occur when seed is planted into a good seedbed. Work at achieving this. Be aware that planting into marginal conditions brings about marginal returns. The goal for maximum yield is for every plant to look like every plant.
Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. Elmore can be contacted by email at firstname.lastname@example.org or (515) 294-6655.