During the past week farmers in much of Iowa have made good corn planting progress. While the cold, wet weather kept farmers out of fields in April, many farmers have put in long days and some have even planted at night to get the corn in the ground during the first week of May.
As farmers finish planting corn, the question is: "Do I plant soybeans now or should I wait a week for the weather to warm up a little more?" John Holmes, Iowa State University Extension crop specialist at Clarion in north central Iowa, gives this answer: Plant soybeans if soil conditions are suitable.
Farmers are worried that soybeans will get Sudden Death Syndrome again this year, especially if soybeans are planted in early May, and yields will suffer. SDS was widespread in Iowa last year and caused some big yield losses in many soybeans fields. "Maybe I'm oversimplifying things but I try to remember that 2010 was unique," says Holmes. "Last year many soybeans were planted in mid-to-late April in absolutely perfect soil and weather conditions. Then cold, rainy conditions followed. We had record rains in parts of Iowa in June and July."
Deciding whether to plant beans in early May, watch forecast
The conditions last year were ideal for SDS infection: cold, wet soils shortly after planting, and we had such conditions in 2010, he notes. This year is more typical. Corn planting really didn't start this year in Iowa until April 20 at the earliest. It's now early May, which is a much more typical soybean planting period.
When you are trying to decide whether to plant beans in early May, the real question is: Do you expect cold, wet conditions the next week? The weather forecast as of May 6 was calling for warm weather conditions the week beginning May 9 and no rain—or at least not a lot of rain.
Plant beans as soon as you finish corn, if soil conditions allow
ISU agronomists in recent years conducted extensive planting date studies for soybeans. Those studies demonstrated that soybeans planted in early May develop more nodes per plant and have a higher yield potential. Those trials didn't have a lot of SDS infection and they were planted early. The bottom line is, over the years the soybeans that are planted early will obtain the highest yields.
"I also remind farmers that soil temperatures are rising and will continue to rise," says Holmes. "Last year was unique. The weather turned cold and wet after soybeans were planted. That's not typical. The bottom line is that I recommend planting beans as soon as you finish planting corn, if soil conditions are suitable."