Earlier soybean [Glycine max (L.) Merr.] planting coupled with increasing seed costs and higher commodity prices has led to a surge in the number of hectares planted with seed treatments (Esker and Conley, 2012). Furthermore, recent studies have suggested that growers should consider lowering seeding rates to increase their return on investment (De Bruin and Pedersen, 2008; Epler and Staggenborg, 2008). Ultimately, growers would like to know the value proposition of combining seed treatments with lowered seeding rates. Therefore, the objectives of this study were to quantify the effects of seed treatments and seeding rates on soybean seed yield and assess the economic risk and profitability of seed treatments and seeding rates, including the calculated economically optimal seeding rate (EOSR) for each seed treatment.
Trials were conducted at nine locations throughout Wisconsin during the 2012 and 2013 growing seasons, totaling 18 site-years. Syngenta brand S20-Y2 ($50 unit-1) soybeans were treated with either no seed treatment (UTC), ApronMaxx ($5 unit-1) (mefenoxam + fludioxonil at 0.0094 mg ai seed-1), or CruiserMaxx ($12 unit-1) (mefenoxam + fludioxonil + thiamethoxam at 0.0858 mg ai seed-1) at six seeding rates of 40000, 60000, 80000, 100000, 120000, and 140000 seeds acre-1. The analysis used a soybean grain sale price of $12 bu-1.