Mid-April Soil Temperatures and Growing Degree Days

Jarrod O. Miller, Extension Agronomist, jarrod@udel.edu;Cory Whaley, Sussex Co. Agriculture Agent, whaley@udel.edu; Jake Jones, Kent Co. Ag Agent, jgjones@udel.edu; Dan Severson, New Castle Co. Ag Agent, sverson@udel.edu

In Georgetown, warmer days have kept soil temperatures a few degrees higher than in 2020, but cooler nights have kept temperatures below 60°F since last week. While 50°F is the baseline for corn germination, having soil temperatures above 60°F will allow emergence within 10 days. Over the next week we will continue to have mild days but cooler nights, so we can expect soil temperatures to remain about where they are. Based on 2020, soil temperatures did not begin to rise above 60°F consistently until early May.

Corn emergence takes up to 120 growing degree days (GDD) to emerge. Since April 15th, we have accumulated 15 GDD in Newark, 20 in Dover, and only 16 in Georgetown. The cooler weather in Georgetown can probably be attributed to the rainfall moving across lower Delaware, but not observed in the northern half of the state. At this time last year, Newark had 0 GDD, while Georgetown and Dover both had 6, so overall temperatures are a little warmer than last year.

Keep up with your regional conditions through DEOS (http://www.deos.udel.edu/).


Georgetown soil temperature chart, data explained in the above post