Influence of Planting Date On Soybean in Rotations with Barley and Wheat.

Plant growth and yields of soybean [Glycine max (L.) Merr.] are affected by planting date. The objective of this study was to evaluate the influences of planting date on maturity group (MG) VII soybean following barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.). The research was conducted at Clemson University, Edisto Research and Education Center (REC) located near Blackville, South Carolina from 2008 to 2011. Wheat and barley were planted in the fall of 2008, 2009, and 2010. Soybean was planted every week for five weeks following barley and wheat harvest in 2009, 2010, and 2011. Compared to May/June planting, the time from planting to R6 stage (full size seed) was about one month shorter than June/July planting dates. Moreover, later planting dates decreased plant leaf area index (LAI) and plant normalized difference vegetation index (NDVI). Soybean yields decreased following mid-June planting in two out of three yr. Previous crop did not affect soybean yields.