VTechWorks staff will be away for the Thanksgiving holiday beginning at noon on Wednesday, November 27, through Friday, November 29. We will resume normal operations on Monday, December 2. Thank you for your patience.

Browsing by Author "Knott, Carrie"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Foliar fertilizers rarely increase yield in United States soybean
    Matcham, Emma G.; Vann, R. Atwell; Lindsey, Laura E.; Gaska, John M.; Lilley, Dylan T.; Ross, W. Jeremy; Wright, David L.; Knott, Carrie; Lee, Chad D.; Moseley, David; Singh, Maninder; Naeve, Seth L.; Irby, J. Trenton; Wiebold, William J.; Kandel, Hans; Lofton, Josh; Inman, Matthew; Kleinjan, Jonathon; Holshouser, David L.; Conley, Shawn P. (2021-09-25)
    Farmers have been interested in using foliar-applied nutrient products to increase soybean [Glycine max (L.) Merr.] yield since at least the 1970s, despite limited evidence that these products offer consistent yield increases when used prophylactically. Recently, interest in foliar fertilizer products for soybean production has been renewed, likely related to elevated soybean prices. Over the 2019 and 2020 growing seasons (46 site-years), agronomists in 16 states collaborated to test six foliar nutrient treatments (commercial mixtures of macro- and micro-nutrients) on soybean grain yield and composition. Soybean grain yield and composition differed among sites but not among foliar fertilizer treatments. Results show that prophylactic foliar fertilization is likely to decrease the profitability of soybean production. Foliar fertilizer products tested in this study and similar products should not be recommended to U.S. soybean farmers in the absence of visual symptoms of nutrient deficiency.
  • Thumbnail Image
    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.