Three-year (2011-13) results from the 4-factor study at Carrington include:
• Early-planted soybean (May 5, 2011 and April 30, 2012) emerged 10 days earlier, flowered 5 days earlier, and yielded 3 bu/acre (6.2%) higher compared to the later-planted soybean (May 19, 2011 and May 15, 2012). Due to the late start to planting in 2013, the first planting date was May 28, which had 14 additional days of growth from planting to maturity and tended to have higher yield compared to the late planting date of June 12.
• Yield was similar across years between tillage systems: conventional tillage = 45.1 bu/acre, directseed = 44.3 bu/acre. • Response to broadcast- vs. bandapplied fertilizer was similar each year and averaged 0.6-0.7 bu/acre greater than the untreated check.
• In 2011, yield increased 6.5 bu/acre (14.5%) with foliar fungicide compared to the untreated check. Fungicide application was made several days after significant hail damage to the trial. In 2012 and 2013, yield did not increase with fungicide. Across years, yield with fungicide averaged 45.1 bu/acre compared to 44.4 bu/A with the untreated check.
This database would indicate the greatest potential for increasing soybean yield is with early planting.