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 "Nafziger, Emerson D."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Neonicotinoid seed treatments of soybean provide negligible benefits to US farmers
    Mourtzinis, Spyridon; Krupke, Christian H.; Esker, Paul D.; Varenhorst, Adam; Arneson, Nicholas J.; Bradley, Carl A.; Byrne, Adam M.; Chilvers, Martin, I.; Giesler, Loren J.; Herbert, D. Ames Jr.; Kandel, Yuba R.; Kazula, Maciej J.; Hunt, Catherine; Lindsey, Laura E.; Malone, Sean M.; Mueller, Daren S.; Naeve, Seth; Nafziger, Emerson D.; Reisig, Dominic D.; Ross, William J.; Rossman, Devon R.; Taylor, Sally V.; Conley, Shawn P. (Springer Nature, 2019-09-09)
    Neonicotinoids are the most widely used insecticides worldwide and are typically deployed as seed treatments (hereafter NST) in many grain and oilseed crops, including soybeans. However, there is a surprising dearth of information regarding NST effectiveness in increasing soybean seed yield, and most published data suggest weak, or inconsistent yield benefit. The US is the key soybean-producing nation worldwide and this work includes soybean yield data from 194 randomized and replicated field studies conducted specifically to evaluate the effect of NSTs on soybean seed yield at sites within 14 states from 2006 through 2017. Here we show that across the principal soybean-growing region of the country, there are negligible and management-specific yield benefits attributed to NSTs. Across the entire region, the maximum observed yield benefits due to fungicide (FST = fungicide seed treatment) + neonicotinoid use (FST+NST) reached 0.13 Mg/ha. Across the entire region, combinations of management practices affected the effectiveness of FST+NST to increase yield but benefits were minimal ranging between 0.01 to 0.22 Mg/ha. Despite widespread use, this practice appears to have little benefit for most of soybean producers; across the entire region, a partial economic analysis further showed inconsistent evidence of a break-even cost of FST or FST+ NST. These results demonstrate that the current widespread prophylactic use of NST in the key soybean-producing areas of the US should be re-evaluated by producers and regulators alike.
  • Thumbnail Image
    Soybean response to nitrogen application across the United States: A synthesis-analysis
    Mourtzinis, Spyridon; Kaur, Gurpreet; Orlowski, John M.; Shapiro, Charles A.; Lee, Chad D.; Wortmann, Charles; Holshouser, David L.; Nafziger, Emerson D.; Kandel, Hans; Neikamp, Jason; Ross, William J.; Lofton, Josh; Vonk, Joshua; Roozeboom, Kraig L.; Thelen, Kurt D.; Lindsey, Laura E.; Staton, Michael; Naeve, Seth L.; Casteel, Shaun N.; Wiebold, William J.; Conley, Shawn P. (2018-01-01)
    The effects of supplemental nitrogen (N) on soybean [Glycine max (L.) Merr.] seed yield have been the focus of much research over the past four decades. However, most experiments were region-specific and focused on the effect of a single N-related management choice, thus resulting in a limited inference space. Here, we composited data from individual experiments conducted across the US that examined the effect of N fertilization on soybean yield. The combined database included 207 environments (experiment x year combinations) for a total of 5991 N-treated soybean yields. We used hierarchical modeling and conditional inference tree analysis on the combined dataset to establish the relationship and contribution of several N management choices on soybean yield. The N treatment variables were: N-application (single or split), N-method (soil incorporated, foliar, etc.), N-timing (pre-plant, at a reproductive stage, etc.), and N-rate (from a 0 N control to as much as 560 kg ha−1). Of the total yield variability, 68% was associated with the effect of environment, whereas only a small fraction of that variability (< 1%) was attributable to each N variable. Averaged over all experiments, a single N application and the split N application were 60 and 110 kg ha−1 greater yielding than the zero N control treatment, respectively. A split N application with more than one method (e.g., soil incorporated and foliar) resulted in 120 kg ha−1 greater yield than zero N plots. Split N application between planting and reproductive stages (Rn) resulted in greater yield than zero N and single application during a Rn; however, the effect was not significantly different than N application at other growth stages. Increasing the N rate increased the environment average soybean yield; however, 93% of the environment-specific N-rate responses were not significant which suggested a minimal effect of N across the examined region. A large yield variability was observed among environments within the same N rates, which was attributed to growing environment differences (e.g., in-season weather conditions, soil type etc.) and non-N related management (e.g., irrigation). Conditional inference tree analysis identified N-timing and N-rate to be conditional to irrigation, and to seeding rates >420,000 seeds ha−1, indicating that N management decisions should take into account major, non-N related management practices. Overall, the analysis revealed that N management decisions had a measurable, but small, effect on soybean yield. Given the growing pressure for increasing food production, it is imperative to further examine all soybean N decisions (application method, timing, and rate) in environment- and cropping system-specific randomized trials in important agricultural regions.