Effects of Soybean-Corn Rotation On Seed Composition in Soybean.

The objective of this study was to investigate the effect of crop rotation on seed composition in soybean (Glycine max L. Merr.). Soybean variety DBK4651 was grown in Stoneville, MS, from 2005 through 2008 with eight different cropping sequences.  Following three years of rotation, higher seed protein (8%) and oleic acid (69%) but lower total oil (6%) and linoleic acid (12%) were found in a soybean/corn rotation compared to continuous soybean. Higher protein and oleic acid in a corn/soybean rotation compared to continuous soybean was also found in 2008, but oil, linoleic or linolenic acids in seed did not decrease.  Yield in 2008 followed the same pattern of protein and oleic acid. The results suggest that including corn in soybean production system increases protein and oleic acid, and this increase may not occur at the expenses of oil, oleic or linolenic acid. There was no consistent correlation between yield and seed composition constituents was found. Our preliminary results showed that the increase of protein and oleic and linoleic acids were accompanied with higher nutrient concentrations of N, K, P, B, Zn, and Mg in leaves and seed. The mechanisms controlling seed composition in a crop rotation sequence are not understood and need further investigation.