A string of rainy days and colder than average temperatures has resulted in delayed corn planting for many farms in our area. As we approach mid-May the temptation is to do whatever it takes to get corn planted, even if that means “mudding” it in. We have all heard of the yield loss incurred for each day corn is planted after the end of April, but this is related to the maximum potential yield and planting date, while important, is only one of many yield influencing factors. Other important factors include insect and disease pressure, weather conditions during pollination, root development, soil fertility, nitrogen timing/availability and soil physical factors.
Peter Thomison, OSU Extension corn specialist provides the following advice regarding late corn planting:
Although the penalty for late planting is important, care should be taken to avoid tillage and planting operations when soil is wet. Yield reductions resulting from "mudding the seed in" are usually much greater than those resulting from a slight planting delay. Yields may be reduced somewhat this year due to delayed planting, but effects of soil compaction can reduce yield for several years to come.
Don't worry about switching hybrid maturities unless planting is delayed to late May. If planting is possible before May 20 to 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. Also remember that later May and June planting dates generally increase the possibility of damage from European corn borer (ECB) so planting ECB Bt hybrids is often beneficial.
As planting is delayed, seeding rates may be lowered (decreased to 3% higher than the desired harvest population) in anticipation of a higher percentage of seedlings emerging. Adjust seeding depth according to soil conditions and monitor planting depth periodically during the planting operation and adjust for varying soil conditions. Planting depth recommendations for corn in Ohio are 1.5 to 2 inches deep to ensure adequate moisture uptake and seed-soil contact. Deeper planting may be recommended as the season progresses and soils become warmer and drier.