Emerging corn in a rye cover crop
While it may not seem much warmer than it was in 2020, having steady days above 50°F had provided much faster emergence than last year. In 2019 we were getting about 10 growing degree days (GDD) per day, while now we are seeing 15-20. The threshold for emergence is about 100-120 GDD, which we have reached for most fields planted between April 15 and April 22nd (Table 1). In 2020, we had only reached half of that (60-90 statewide) over the same time period.
Salts are a natural component of soils, including our soluble plant nutrients (Ca, NO3, ect). Excessive levels of any salt can be detrimental to both plant health and soil quality. On the Delmarva Peninsula, excessive salts can come through several sources, which include fertilizers, irrigation water, and salt water intrusion.
Fertilizer burn due to sidedress N applications.
Issues with fertilizers are related to seed germination and growth, where in-furrow recommendations of starter N+K fertilizers are limited to 10 lb/acre total due to salt effects. During sidedress applications, fertilizer burn (Figure 1) can damage leaf tissue, particularly UAN greater than 50lb/acre. As long as corn plants are younger, minimal tissue damage doesn’t affect yield. Considering the above recommendations, salt damage due to fertilizers should be easy to manage. Continue reading
Micronutrient deficiencies are commonly exhibited in agronomic crops grown on Delaware’s sandy, low organic matter soils. In 2018, University of Delaware researchers conducted a study at the Carvel Research and Education Center (Georgetown, DE) to examine corn response to manganese (Mn), zinc (Zn), and boron (B) in starter fertilizer. Two rates of Mn (0.25 and 0.5 lb/ac), Zn (0.5 and 1.0 lb/ac), and B (0.15 and 0.30 lb/ac) were applied as a liquid starter with the planter.
Amy Shober, Extension Nutrient Management and Environmental Quality Specialist, firstname.lastname@example.org; Jarrod O. Miller, Extension Agronomist, email@example.com; Phillip Sylvester, Kent County Extension Agent, firstname.lastname@example.org; Cory Whaley, Sussex County Extension Agent, email@example.com.
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.
Freezing Temperatures and Topsoil Compaction
Cold winters can actually help compacted soils
Last weeks polar vortex stuck around long enough to cause a pretty significant freeze on our soil surfaces. With our temperatures swinging from 0 to 60°F, we have certainly had the conditions for freeze/thaw in our soils, which is considered a physical weathering process. Continue reading