Delaware Agronomy Blog

University of Delaware Cooperative Extension

Category: Soybean (page 2 of 3)

Checking Vegetative Growth Stages

Corn at our research station is at V4, which means we will probably be sidedressing several fields next week. Anyone who planted prior to April 25th may be one leaf ahead, and plans for sidedressing should be done. If you are unsure of which stage you are at, one common method is to count leaves based on the presence of the collar (Figure 1a). While many leaves can be emerged from the whorl, only those with collars are considered fully developed. Continue reading

2021 Agronomy Day

January 20th, 2021

9am-4pm. 

You must register to attend and have access to the quizzes for credits: https://udel.zoom.us/webinar/register/WN_EVCIBMb_RvqoDjAOL3S0ww.

Current credit approval:

Nutrient Management : DE (2 credits), MD (2 credits)

Pesticide  Continuing Education: DE (4 credits Private and 1A).

CCA Credits (Full Day): 4PM, 1.5NM, 0.5PA.

The full schedule is below

Continue reading

Using Foliar Manganese Applications to Correct Deficiencies

Amy L. Shober, Professor and Extension Specialist, Nutrient Management and Environmental Quality, ashober@udel.edu; Jarrod O. Miller, Assistant Professor and Extension Specialist, Agronomy, jarrod@udel.edu; Mark Reiter, Associate Professor and Extension Specialist, Soils and Nutrient Management, Virginia Tech, mreiter@vt.edu

 

This image shows areas of the field where the soybeans that were growing in a field ditch (yellow arrow) showing less Mn deficiency symptoms than areas that have better tilth. Figure credit: Jarrod Miller, UD

Soybean is susceptible to manganese (Mn) deficiency, especially when grown on sandy, low organic matter soils like we have in Delaware. Soil Mn availability is a function of both Mn concentration and soil pH. Soil Mn converts to unavailable forms as soil pH increases. So when soil pH starts creeping above 6.2, we can start to see Mn deficiency symptoms. While Mn deficiency can be widespread across the field, we can also see Mn deficiency symptoms in small pockets in a field, often occurring after liming. Deficiency symptoms can be prevalent in areas where lime applications overlapped or where the soil is sandier than the general field; thereby changing pH more quickly and becoming higher than soils with more clay, loam, and/or organic matter. Manganese deficiencies may also reveal themselves with dry soil conditions like we have seen this summer (especially when soils were tilled soils) because soil Mn also becomes less available to plants. Interestingly, Mn deficiencies are less likely in areas of the field that stay wetter (e.g., compacted wheel tracks, field ditches) as wetter soils are less oxygenated, promoting plant available forms of Mn (as seen in the photo below). Continue reading

Early Cover Crop Termination vs Planting Green

Jarrod Miller, Jamie Taraila, and Amy Shober

Farmers must make several decisions when considering termination of cover crops. Early termination is typically the easiest option, since it reduces issues related to planting into a standing cover crop. In 2018, planting green decreased corn stands by 10,000 plants per acre in our Sussex County research plots. This type of stand reduction when planting green is not expected for all soil or cover crop combinations. Continue reading

Split Applied K for Soybeans

 

Summary: With a grant funded by the Delaware Soybean Board, we studied whether split application of K for soybeans would benefit yield on sandy soils. Yield increases through split application were not seen, although yield had a positive correlation with greater tissue K levels, and split applied plots had the highest leaf tissue K.

Discussion: With the lower cation exchange capacity of sandy soils, it is possible that some pre-plant applied K could leach below the root zone prior to crop uptake. We set up three treatments, no K, all pre-plant (70 lbs K2O/acre), and a 50/50 split. For the split applied treatment, the first half was applied pre-plant while the remaining amount was done just prior to reproductive stages. Potassium (0-0-62) was applied as dry granules with a Valmar spreader. Continue reading

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