Soybeans and sunflowers are two of the main crops that you can still plant in June and even July in the Dakotas and expect some pretty decent yields.
Soybeans can still be planted into mid-June in North Dakota and early July in South Dakota.
Nathan Mueller, South Dakota State University Extension agronomist, and Han Kandel, North Dakota State University Extension agronomist, offer the following advice on planting soybeans late:
•Select earlier maturing varieties. Reduce the maturity rating by 0.5 from normal as planting is delayed into mid-June (in North Dakota) and past mid-June (in South Dakota) and by as much as 1.0 if planting is delayed into early July. (in South Dakota).
•Increase seeding rates 10 to 15%.
•Solid seed or plant in narrow rows so that canopy closure occurs as quickly as possible, and to compensate for other yield components such as nodes per plant and pods per plant that can decrease when planting late.
•If you are planting soybeans on land that you had fertilized for wheat or corn, the extra nitrogen could increase the incidence of iron chlorosis deficiency. Also, if soils remain wet and cool, iron deficiency could be more of a problem. Therefore, select varieties with some IDC resistance. Soybeans will use the extra N that is available, but may not develop N-fixing nodules.
According to Larry Kleingartner, former executive director of the National Sunflower Association, common strategies agronomists and farmers have for working with late-planted sunflower include:
•Switch to an early maturing hybrid.
•Open or blacken the soil to warm it up for quicker emergence.
•Plant shallow, but into moisture, for faster emergence.
•Reduce some of the inputs to lower crop production costs.
•Plant slightly higher populations for quicker drydown.
•Minimize use of "stay green" hybrids to escape late-season drydown issues.
•Minimize use of "plant health" fungicides to avoid late-season drydown issues.
•Consider using a desiccant to aid drydown if it can be applied in time to be effective.
South Dakota and southern North Dakota farmers can plant sunflowers through early July. More-northerly locations commonly look at June 15 to June 20 as a last planting date, Kleingartner says.
The NDSU Carrington Research and Extension Center conducted a four-year date of planting study that used June 20 as the final planting date. The June 20 date in that central North Dakota location experienced a 25% yield reduction compared to a May 20 planting date, averaged across the four years.
The scenario is similar in South Dakota. Kathleen Grady, SDSU sunflower breeder, conducted a three-year date of planting study at multiple sites in that state's north and south crop insurance zones. Average yield (all locations) on a June 25 planting date in the north zone was 1,375 pounds per acre — 25% lower than the June 10 planting yield. The June 30 planting date in the southern zone yielded 1,350 pounds per acre on average — 32% lower than the June 15 planting date.
Yields for both of the South Dakota late-planting dates were still higher than the county average T-yields. Test weight and oil content declined with the later plantings, while harvest moisture increased.
"The key question is: Does a potential 25% yield reduction, compared to peak yield, still generate sufficient revenue compared to the risk of filing for prevent plant and leaving that land idle?" Kleingartner says.