Amy Shober, Extension Nutrient Management and Environmental Quality Specialist, ashober@udel.edu; Jarrod O. Miller, Extension Agronomist, jarrod@udel.edu; Phillip Sylvester, Kent County Extension Agent, phillip@udel.edu; Cory Whaley, Sussex County Extension Agent, whaley@udel.edu.
Northeast Two Inch Soil Temperature, May 2, 2018
Soil temperatures need to stay above 50°F and we need to accumulate 100 to 125 growing degree days (GDD) in order for corn to germinate and emerge. From April 22 to May 1, soil temperatures have consistently stayed above 50°F from Georgetown to Newark, and most parts of the state have gotten some rainfall to keep the soil surface moist . Sussex County is a little bit ahead of Kent and New Castle Counties in terms of GDD (68 in Georgetown vs. 61 and 47 in Dover and Newark, respectively since April 22). A new online tool developed by Cornell University allows you to estimate growing degree days from planting for your own fields: http://climatesmartfarming.org/tools/csf-growing-degree-day-calculator/ With the end of this week temperatures topping out in the upper 80s, some of your fields that were planted last week may start to emerge.
We suggest going back and checking these earlier planted fields for emergence if time allows. Checking previously planted fields allows you to look for and identify any emergence issues, which may be related to lower soil temperatures due to surface residues, compaction, or planting depth. If you find that your calibrated seeding rate or depths were off, you have time to make adjustments now for fields you have yet to plant.
You might also consider completing stand counts on fields where corn has emerged to assess the potential for your field to achieve maximum yields. Early stand counts can also aid in decisions on whether or not to replant. Taking stand counts is relatively quick and easy; measure off the appropriate length (17.5 ft for 30 inch rows, 20 ft for 20 inch rows, or 35 ft for 15 inch rows), count the number of plants, and multiply by 1000, which will give you a stand count in plants per acre. Collect these counts for at least 5 locations in each field and take an average to get your final stand count. Even though you are likely busy planting other fields, taking a little bit of time to evaluate your early planted stands can help ensure that stand problems don’t affect your bottom line come harvest time.
