2021 Corn Extended Growing Season in Kentucky

Note: the original article has errors regarding solar radiation for the past five years. That mistake was mine and not the source of the data. This revised article includes those corrections. The main point of 2021 being lower in solar radiation during key crop development stages is still correct.

Corn planting for 2021 was ahead of schedule, yet harvest and several other developmental stages were behind. Milk, dough and dent were all behind the 5-year average. (Thanks to USDA NASS for letting us use their graph. See Figure 1). Even with the slow emergence for some of the planted corn, these crop progress estimates suggest that the corn growing season was extended. An extension during seed fill of-ten means higher yields and the projected yields for Kentucky are record level. That extension of the seed fill also pushed a lot of corn into a fall that has been cool, cloudy and wet.

Once corn reaches physiological maturity (black layer) the drydown of the grain is simple physics and depends on air temperature, relative humidity (RH), windspeed and sunlight. Higher temperatures, low-er RH’s, higher windspeeds and more sunlight all contribute to faster drydown of the grain. This fall was just the opposite of those. The cool, humid, calm and cloudy conditions made for a very prolonged drydown (Figure 2). Each of the past five years at Fayette County have been cloudy relative to the last eleven (Figure 3). But, 2021 is the cloudiest.

Added to that delay in field drydown is larger kernel size. That extended seed fill period created some very deep kernels in some fields. Those deep kernels take longer to drydown (Figure 4).

Any farmer disappointed at how slow the corn dried down in the field SHOULD NOT BLAME THE HY-BRID this year! The slow drydown of corn is a function of the timing of corn maturity and weather. That timing allowed for excellent yields and for very slow drydown.

Perhaps farmers should look to improving grain drying systems and grain storage systems. For the past five years, simply relying on timely field drydown of corn has not worked very well.