Delaware Agronomy Blog

University of Delaware Cooperative Extension

Category: Soil (page 1 of 2)

Grid Sampling Soils to Improve Understanding of Soil Variability

Jarrod Miller and James Adkins, University of Delaware

Variability in soil land landscape characteristics reduces yield response to management techniques, particularly regarding seeding rates and fertilizer additions. Yield maps provide a spatial map of yield, which can be associated with drainage issues, soil nutrient holding, or nutrient concentrations. One method to uncover soil variability and crop response is to use precision soil sampling, including either grid or zone methods. Both increase the cost of taking soil samples, and each have their value depending on the desired outcomes.

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A Warmer 2021 is Boosting Emergence

Emerging corn in a rye cover crop

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.

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Considering Fall Salt Remediation

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

Research Report: Mn, Zn and B Starter for Corn Production

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.

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Evaluate Corn Stands for Emergence!

Amy Shober, Extension Nutrient Management and Environmental Quality Specialist,; Jarrod O. Miller, Extension Agronomist,; Phillip Sylvester, Kent County Extension Agent,; Cory Whaley, Sussex County Extension Agent,

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: 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.

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