Systematic Optimization of Soybean Yield and Quality: Input Interactions.

In an effort to maximize yields, many soybean growers across the country have begun moving to intensive, input-based soybean management systems.  These intensive management systems often combine the use of inputs such as seed treatments, foliar fertilizers, growth promoters, stress reducers, defoliants and sub-threshold use of foliar insecticides and fungicides.  The purpose of this study was to evaluate the effect of individual inputs and combinations of inputs as part of high yield management systems on soybean seed yield.  Small plot studies were established at two or more sites in Michigan, Minnesota, Wisconsin, Iowa, Illinois, Indiana, Kansas, Kentucky and Arkansas.  The studies were conducted in a randomized complete block arrangement and were maintained weed-free.  Individual treatments included a fungicide only seed treatment consisting of pyraclostrobin at 0.26 ml kg^-1 and metalaxyl at 0.52 ml kg^-1, a fungicide and insecticide seed treatment that included both fungicides as well as imidacloprid at 2.8 ml kg^-1, clothianidin and Bacillus firmus at 0.13 mg ai seed^-1 and a seed treatment consisting of both the insecticide and fungicide treatments and a combination of lipo-chitooligosaccharide (LCO) and Bradyrhizobium japonicum at 1.83ml kg^-1 followed by foliar LCO applied at 290 ml ha^-1 between V4 and V6.  Individual post-emergence treatments consisted of lactofen applied at 870 ml ha^-1 at V4, nitrogen applied at 168 kg ha^-1 at V4,  foliar fertilizer applied at 4.68 L ha^-1 at R1, pyraclostrobin applied at 440 ml ha^-1 at R3, lamda-cyhalothrin applied at 57 ml ha^-1 R3, N,N’-diformyl urea applied at 1.16 L ha^-1 at R3.  These treatments were combined to create combinations of management treatments.  Significant management x location x year interactions were observed.  When data were averaged across all locations, treatments that included the foliar insecticide showed a significant yield advantage compared to the untreated control in certain northern locations in both 2012 and 2013.