Agronomic Maximization of Soybean Yield and Quality: Variety x Management Interactions.

Variety selection is the most important management decision that soybean producers can make each year.  New varieties, possessing various trait/genetic backgrounds are continuously being introduced into the market.  In addition, the use of multiple inputs (e.g. seed treatments, biological compounds, foliar fungicides and insecticides, etc.) has increased.  However, it is not yet well understood how intensive management (i.e. multiple input use) interacts with variety selection.  Therefore, the objective of this study was to evaluate current, high-yielding varieties under both high input and standard soybean management practices across the U.S. to better understand how management interacts with variety choice.  Research was conducted in nine states (AR, IA, IL, IN, KS, KY, MN, WI) as part of a three-year, multi-state project initiated in 2012.  Six varieties representing high-yield potential optimal for each location were produced under 3 levels of management: (1) untreated check (UTC), (2) “SOYA” (seed treatment fungicide, insecticide, and inoculant; Ratchet®; Task Force 2®; nitrogen fertilizer; BioForge®; Headline®; Warrior II®), and (3) “SOYA” minus Headline®.  Preliminary yield results from 2012 indicate no variety by management interaction (P = 0.96) across all locations.  A difference in managements across all locations was observed (P = 0.004).  Managements 2 and 3 yielded 3.4 and 2.9 bushels acre^-1 better than management 1, respectively.  When separated into regions, differences in managements were observed in the north (IA, MI, MN, and WI) and central (IL, IN, and KS) regions; however, no difference was observed in the southern region (KY, AR).  Yield component measurements (seeds m^-2, pods plant^-1, and seeds pod^-1) indicate the yield response was due to an increase in seeds m^-2.