Source: Ohio State University Extension
As prospects for a timely start to spring planting diminish, growers need to reassess their planting strategies and consider adjustments. Since delayed planting reduces the yield potential of corn, the foremost attention should be given to management practices that will expedite crop establishment. The following are some suggestions and guidelines to consider in dealing with a late planting season.
Although the penalty for late planting is important, care should be taken to avoid planting operations when soil is wet. Yields may be reduced somewhat this year due to delayed planting, but effects of soil compaction can reduce yield for several years to come.
If you originally planned to apply nitrogen (N) and herbicides pre-plant, consider alternatives so that planting is not further delayed when favorable planting conditions occur. Although application of anhydrous N is usually recommended prior to April 15 in order to minimize potential injury to emerging corn, anhydrous N may be applied as close as a week before planting (unless hot, dry weather is predicted).
In late planting seasons associated with wet cool soil conditions, growers should consider side-dressing anhydrous N (or UAN liquid solutions) and applying around 30 pounds N per acre broadcast or banded to stimulate early seedling growth. This latter approach will allow greater time for planting.
Similarly, crop requirements for phosphorus (P) and potassium (K) can often be met with starter applications placed in bands 2 inches to the side and 2 inches below the seed. Application of P and K is only necessary with the starter if they are deficient in the soil, and the greatest probability of yield response from P and K starter is in a no-till situation.
Planting into seedbeds that contain emerged weeds will make post-planting weed control critical. Herbicide-resistant corn, including Roundup Ready and Liberty Link hybrids, may offer definite advantages in these situations. Effective burndown applications will help minimize the potential for major weed problems developing later in the season.
Don't worry about switching hybrid maturities unless planting is delayed to late May. If planting is possible before May 20-25, plant full season hybrids first to allow them to exploit the growing season more fully. Research in Ohio and other Corn Belt states generally indicates that earlier maturity hybrids lose less yield potential with late plantings than the later maturing, full-season hybrids.
With no-till or reduced tillage, increase seeding rates 5-10% over those used with conventional tillage. Consult seed company recommendations for specific hybrid planting rates under reduced tillage. Lower yields in no-till can sometimes be related to sub- optimal plant populations at harvest.