By Palle Pedersen and Roger Elmore, Department of Agronomy
Excessive rainfall in Iowa over the last 2 months has challenged most farmers, agronomists, extension workers, and researchers. With another front of storms moving into Iowa today (June 11) we do not know when we will be able to get back into the fields. Our best estimate is that it will first be next week at the earliest.
Yield potential for both soybean and corn has dropped significantly in Iowa since we are more than a month after the optimum planting date for both crops. However, we still have a chance to get a crop but the yield may not be what we have experienced over the last few years. As of June 8, USDA predicted that only 86 percent of Iowa’s soybeans were planted and an estimated 6 percent of that was in need of replanting. Ninety-eight percent of the corn was planted while 7 percent was in need of replanting. These numbers will likely increase in the next report because of recent flooding.
When planting late we need to consider planting shorter season varieties and hybrids to insure they mature prior to the first killing freeze in the fall. Remember we had a killing freeze on September 15 throughout a large part of north central Iowa last year. For soybean it is recommended to plant the “original” full season variety until June 20 in northern and central Iowa and early July in southern Iowa. If planting occurs after these dates shorten the maturity group by 0.5 to 1.0. For corn, planting earlier-season hybrids was recommended in late May.
Many have asked if there are seeds available for replanting. We sent an email earlier this week to several major seed companies in Iowa. We asked them about their inventory for replanting. Responses from the different companies varied but over all we are in a good situation. The reason is that planting progress in more northern states has been easier than in Iowa this year and left over seed is being moved south into Iowa.
All companies have soybean and corn seed available. Here is a summary of the responses we received:
- Supply of soybean seed this year was down because of quality issues. Yet there is plenty of seed available in maturity group 2.
- Most companies’ seeds are conditioned. If more conditioned seed is necessary, the demand will easily be met.
- Soybean seed in maturity group 1 and 3 are less available than in maturity group 2.
- Seed quality varies across the companies from 80 to 95 percent germination.
- Corn seed is available. Many companies are positioning themselves by moving 90 and 100 day corn into Iowa.
- The open window for planting corn, however, is getting close to closing. Yield potentials for corn planted today might be 70 percent of normal. In two weeks, it may be down to 50 percent.
- Farmers will continue to plant corn until June 25 because of high prices, if nitrogen and/or herbicide have been applied, or just to be sure to qualify for the federal crop.
The best advice is to be calm, manage the planted fields and hope that we get some dry weather in the near future. More information on soybean and corn management decisions can found at www.soybeanmanagement.info and at www.agronext.iastate.edu/corn/
Palle Pedersen is an assistant professor of agronomy with research and extension responsibilities in soybean production. Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production.