Delaware Agronomy Blog

University of Delaware Cooperative Extension

Category: Precision Ag

Using NDVI to Determine Early Vegetative Growth and Nitrogen Needs

Jarrod Miller, Extension Agronomist, University of Delaware

Precision nitrogen (N) management through the use sensors has been used to improve nitrogen use efficiency (NUE) for field crops by estimating corn needs during early growth stages (Aula et al., 2020; Cao et al., 2017) Indices have been developed using specific wavelengths of light, such as the normalized difference vegetation index (NDVI) to estimate plant biomass and correlate it to N needs (Holland et al., 2012; Raun et al., 2005a; Dellinger et al., 2008). The use of NDVI has allowed for reductions in N application have been performed without reducing crop yield (Barker and Sawyer, 2012; Aula et al., 2020).

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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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Estimation of Cover Crop Nitrogen with Drones

Jarrod O. Miller, Assistant Professor and Extension Specialist, Agronomy, jarrod@udel.eduAmy L. Shober, Professor and Extension Specialist, Nutrient Management and Environmental Quality, ashober@udel.edu,  Jamie Taraila, Graduate Research Assistant; 

As part of a Northeastern SARE graduate student grant, we used a drone to predict the nitrogen (N) that may be present in cover crops prior to burndown. We flew fields in Laurel, Georgetown, and Harbeson with a readily available consumer drone (Phantom4) equipped with a standard (RGB) camera. Each of the fields were flown prior to cover crop burndown (late April to late May) resulting in 25-100 images per field that had to be stitched together into one image (Figure 1a). The camera captured different wavelengths of light (i.e., red, green, blue) that were reflected by plants which were transformed into the Visible Atmospherically Resistant Index (VARI). This allowed us to estimate plant biomass by comparing VARI values to cover crop biomass that was collected in the field. We collected 10 samples per field, which were dried, weighted, and then analyzed for N content by the UD soil testing lab.

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Using Drones for the 2019 Scouting Season

Jarrod Miller, Extension Agronomist, jarrod@udel.edu

 

Drones can be an excellent tool to assist with scouting this season. University of Delaware Extension has information on drone and camera types, which can be found at the following link: http://extension.udel.edu/factsheets/types-of-drones-for-field-crop-production/ Continue reading