Effect of Planting Date and Starter Fertilizer on Soybean Quality and Yield.

Variability in Ohio weather patterns has caused soybeans (Glycine max) to be planted earlier or later than what is recommended. In Ohio, soybean planting may begin in April and continue through early July. Soybean growth, quality, and yield may differ significantly depending on when they are planted in this relatively large window. Earlier planted soybeans may be subjected to cooler and wetter soils, which may slow down early growth on a per day basis. However, they may be able to reach canopy closure earlier in the growing season to maximize light interception. Later planted soybeans may have more rapid early growth on a per day basis, but be limited by an overall shorter growing season. The objectives of this study were to (i) evaluate the effect of planting date on soybean growth (canopy closure) and quality (protein and oil content); and (ii) determine the effect of planting date on soybean yield. These objectives were evaluated at one location in 2013 (South Charleston, OH) and two locations in 2014 (South Charleston and Hoytville, OH). There were four soybean planting dates at South Charleston and three at Hoytville beginning the first week of May and every two to three weeks thereafter. A maturity group 3.2 soybean was used at both locations and planted in 76 cm rows at a rate of 359,000 seeds ha^-1. Results from 2013 indicated that yield and oil content significantly increased with earlier planting dates. Protein content was lowest at the earliest planting; however, there were no significant differences among later plantings. Canopy closure occurred at a rate of approximately 1.5% per day across all treatments in the study.