Browsing by Author "Brooks, Keren"

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    Edamame Yield and Quality Response to Nitrogen and Sulfur Fertilizers
    Brooks, Keren; Reiter, Mark S.; Zhang, Bo; Mott, Joshua (MDPI, 2023-07-14)
    As United States farmers adapt soybean (Glycine max) production methods from oilseed to vegetable (edamame), key management practices will need to be considered. The key objective of this study was to determine the optimal nitrogen (N) rate and N application timing for edamame in the mid-Atlantic coastal plain system. The study was conducted for three years in Painter, VA, USA on sandy loam soils. A factorial arrangement of four N rates was applied with two application timing strategies: at-planting, and split application. Leaf tissue samples were collected and analyzed at R1. At harvest, the Normalized Difference Vegetation Index (NDVI) was measured, whole pods were mechanically collected, and yield was recorded. Additionally, pod and bean physical and chemical quality were assessed. Nitrogen fertilization significantly increased pod yield in two out of three years. R1 leaf N and sulfur (S) concentrations correlated to the yield, and R1 leaf and R6 whole-plant N concentrations correlated to the total N uptake. None of the tested parameters indicated that N fertilizer decreased yield or quality. In conclusion, we found that N fertilizer applied at planting may aid edamame yield and profit for sandy loam soils in the mid-Atlantic, USA.
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    Soybean Yield Response to Sulfur and Nitrogen Additions Across Diverse U.S. Environments
    Brooks, Keren; Mourtzinis, Spyridon; Conley, Shawn P.; Reiter, Mark S.; Gaska, John; Holshouser, David Lee; Irby, Trent; Kleinjan, Jonathan; Knott, Carrie; Lee, Chad; Lindsey, Laura; Naeve, Seth; Ross, Jeremy; Singh, Maninder Pal; Vann, Rachel; Matcham, Emma (Wiley, 2022-09)
    As soybean [Glycine max (L.) Merr.] yields reach record highs, more nutrients are required to maintain these production levels. This study was conducted to evaluate the effect of sulfur (S) and nitrogen (N) on soybean yield in diverse environments across the US. Data were collected from a total of 52 sites in ten states over two years (2019 and 2020) for this study. A factorial arrangement of three S rates (11, 22, and 33 kg S ha−1) utilizing two sources (ammonium sulfate and calcium sulfate) were broadcasted by hand at planting. Additionally, to examine the impact of N on soybean yield, urea was applied at 10, 20, and 29 kg N ha−1 to equal that supplied by ammonium sulfate. A zero-fertilizer control treatment was also included. Soil samples prior to fertilization as well as grain yield at R8 were collected and analyzed to understand what environmental conditions favor soybean response to S additions. Results indicated that soil and environmental factors are poor indicators of yield response to S and N additions. Yield responses to S and N additions were observed in yield environments averaging > 3,643 kg ha−1, but S did not limit yield in most environments (n = 49). Partial profit analysis was conducted at two soybean grain prices ($0.32 and $0.55 kg ha−1). Yield increases were only profitable at two site-years at the tested soybean grain prices. Overall results suggest that use of N and S fertilizers are rarely justified across diverse growing environments.