McNay Research and Demonstration Farm
Producers continue to plant corn earlier each year. In 2006, 50% of the statewide crop was planted by approximately April 25. Earlier planting dates are attributed to several factors: larger acreage per producer, less spring tillage, advancements in hybrids, and seed treatments. Planting the crop during the optimum window is important to achieving high yields.
Iowa State University
Abendroth, Lori; Elmore, Roger W.; and Freehill, Leslie, "Corn Planting Date" (2007). Iowa State Research Farm Progress Reports. 884.