Soybean Planting Date Matters More than Most Believe

Palle Pedersen, Faculty, Agronomy

Problem Statement:

Most farmers in Iowa plant their soybean 2-3 weeks too late which cost us a significant amount of loss yield. The reason is that previous data from ISU developed in the early 1990s showed that very little if any yield loss would occur after May 15-20. However, new data show that planting on April 25 for the southern 2/3 part of the state and May 1 for the northern 1/3 of the state will increase the yield potential significantly. Growers have avoided early planting because of the perceived risks, such as cold and wet soil, and exposure to seedling diseases, which in certain years can reduce plant stands, seedling health, and yield. Planting early into cool wet soil delays emergence and may increase exposure to a late spring frost. Bean leaf beetles and its transmission of bean pod mottle virus is another problem associated with early planting.

Programmatic Response:

A major research and educational effort was implemented by ISU Extension through the soybean extension and research program in the Department of Agronomy to increase the awareness of Iowa farmers and agribusiness personnel of the issues related to soybean planting date recommendations and how it can help growers to increase their profitability. During this time, I had several hundreds of phone calls on soybean planting date, 2 tv interviews, 23 radio interviews, dozens of interviews with reporters from newspapers or farm magazines, and 53 presentations with a total of 4900 attendances. 


As a result of extensive information deliveries from the soybean extension and research program at ISU, many soybean farmers went to meetings and evaluated information from our research across the state. The economic impact is astounding. Based on just 3 years of data our results were so consistent that a new recommendation for planting date was proposed to the growers. Based on USDA NASS data it is predicted that 60% of the acres in Iowa get planted at least 3 weeks too late that will result in a loss of approximately $24 per acre. That will be a loss of approximately 127 million dollars per year. Without this information from ISU extension growers would have continued to use the old planting date recommendations and believe that delaying planting is not that costly for soybean as previous data have shown generated in the early 1990s.

July 1, 2007
100 Corn and Soybean Production and Protection


Page last updated: August 2, 2007
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