Input‐based Stress Management Fails to Increase Soybean Yield in Kentucky

Abstract

Soybean producers have recently adopted management systems that attempt to manipulate plant stress throughout the growing season in an effort to increase yield. The purpose of this study was to determine if management systems that utilize crop inputs to manipulate soybean stress can increase soybean seed yield. Inputs designed to affect soybean stress were applied to early‐maturity (2.8 relative maturity [RM]) and full‐season (4.5 RM) soybean at three locations in Kentucky throughout the 2013 and 2014 growing seasons. Treatments consisted of a single application, sequential applications, or combined applications of the following inputs: lactofen, lambda‐cyhalothrin with thiamethoxam, pyraclostrobin, and N,N’‐diformyl urea. The full‐season soybean yielded greater (19%) than the early‐season soybean, resulting from an increase in mainstem node, pod, and seed numbers. Lactofen decreased early season light interception in all environments but did not affect soybean yield. None of the stress‐management inputs investigated increased yield compared to untreated soybeans. Soybean stress management through prophylactic input application does not appear to be a viable strategy to increase soybean yield.

High‐Input Management Systems Effect on Soybean Seed Yield, Yield Components, and Economic Break‐Even Probabilities

“…Similarly, this study did not observe increased seed yield with the defoliant. These findings support recent studies which also did not observe increased seed yield with defoliant use (Gregg et al, 2015; Orlowski et al, 2016; Mangialardi et al, 2016). Finally, increased seed yield was not observed for N,N’‐diformyl.…”

“…Finally, increased seed yield was not observed for N,N’‐diformyl. A lack of seed yield response to N,N’‐diformyl was also reported by Gregg et al (2015).…”

“…It has been suggested that lactofen applied at early vegetative growth kills the apical meristem, leading to increased branch node development and subsequently increased seed yield. Early studies examining lactofen for weed control purposes failed to observe seed yield increases for early season lactofen application (Kapusta et al, 1986; Harris et al, 1991; Wichert and Talbert, 1993), while more recent work has shown that lactofen does not affect soybean branching or seed yield (Gregg et al, 2015; Mangialardi et al, 2016; Orlowski et al, 2016).…”

Comparing High- and Low-Input Management on Soybean Yield and Profitability in Michigan

“…Henry et al (2011) and Orlowski et al (2016) observed soybean yield increases of 3.5 and 4.6% from pyraclostrobin applications, respectively, in the absence of disease. In contrast, Swoboda and Pedersen (2009), Gregg et al (2015), and Ng et al (2018) found no differences in soybean grain yield from fungicide applications within an environment lacking disease pressure.…”

“…During this same time, soybean yield and total acres planted in Michigan increased by 8 and 28%, respectively (USDA‐NASS, 2017). Increased prices paid and commercial marketing have encouraged soybean producers to adopt high‐input management in which a greater number of agronomic inputs are applied to maximize yield and profitability (Gregg et al, 2015; Marburger et al, 2016; Orlowski et al, 2016). Additionally, increased adoption of intensive soybean systems combined with the introduction of new genetics have some individuals questioning older (>20 years) university nutrient recommendations (Vitosh et al, 1995; Fulford and Culman, 2018).…”