Browsing by Author "Taraila, Jamie"

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    Assessing relationships of cover crop biomass and nitrogen content to multispectral imagery
    (Agronomy Journal, 2024-02-29) Miller, Jarrod O.; Shober, Amy L.; Taraila, Jamie
    Cover crops provide valuable roles in sustainable agriculture, provided they produce enough biomass. To accurately measure their services to field management, spatial estimates would be useful to producers. This study used multispectral drone imagery to produce maps of normalized difference vegetation index (NDVI), normalized difference red edge index (NDRE), and a digital surface model (DSM) of cover crop plots on sandy, Mid-Atlantic soils. Cover crops included cereal rye (Secale cereale), mixtures of rye and crimson clover (Trifolium incarnatum), and mixtures of rye and hairy vetch (Vicia villosa). Their biomass was sampled in the spring of 2019, 2020, and 2021, dried, weighed, and analyzed for total nitrogen (N) content. Measurements of NDVI became saturated (i.e., reached a linear plateau) at 3.86 Mg biomass ha−1, NDRE at 5.72 Mg biomass ha−1, and the DSM at 5.11 Mg biomass ha−1. The measured N content became saturated at 80.9, 139.1, and 75 kg N ha−1 for NDVI, NDRE, and the DSM, respectively. Based on log transformations, NDVI was a stronger predictor of biomass and N, but not C:N. The NDRE was important for biomass, N, and C:N, while the DSM interactions with cover crop species helped predict both the N content and C:N of cover crop tissues. Accumulated growing degree days was important as an individual variable for biomass and N and as an interaction with cover crop species. Abbreviations DSM digital surface model GDD growing degree days NDRE normalized difference red edge index NDVI normalized difference vegetation index
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    Evaluation of cover crop termination timing, soil nitrate availability and crop emergence
    (University of Delaware, 2021) Taraila, Jamie
    Implementing cover crops into farm management plans can prove to be an important tool in limiting nutrient leaching, providing a green manure nitrogen (N) source, preserving soil moisture and many other ecosystem services; however efforts are needed to understand the effect of management decisions on the cover crops overall performance and their effect on the cash crop’s yield and profitability. We assessed the effects of two termination timings on four cover crop treatments on a soybean cash crop at sites in northern and southern Delaware. Although cover crops appeared to have inconsistent effects on soybean yields, we did observe that control plots (no cover crop) had higher subsurface inorganic nitrogen, which demonstrated that any cover crop was better than none in preventing leaching from the surface. Lower levels of inorganic nitrogen was present in late terminated rye plots which indicated that it was best at scavenging for N. In terms of biomass production, late terminated clover/rye mix plots had the highest biomass, however late terminated vetch/rye mix plots had the highest N Mg ha-1. Plots with any legume mix were more successful at producing higher levels of N than monoculture rye plots. The vetch/rye mixture had a lower C:N, which may aid in supplying additional N through mineralization to the soybean cash crop. This work highlights the need to continue research on cover crop management techniques to provide insight on how to maximize the performance of cover crops to benefit yields and profitability for farmers.