Influence of Manganese Nutrition On Soybean Yield and Seed Composition.

As grain prices rise, producers are beginning to search for methods to improve yields and grain quality in soybean (Gycine max [L.] Merr.). Soybean are the most popular oil seed crop in the United States and most of the oil is destined for human use. The fatty acid composition of the oil has important implications for human health, and hence has been a topic of considerable research.  In 1982, D.O. Wilson provided evidence that soybean seed protein, oil and fatty acid makeup are correlated with tissue manganese (Mn) concentration. However, this correlation has not been verified on newer higher yielding cultivars of soybean. A three-year experiment was initiated in 2011 at the Bradford Research Center in central Missouri on a Mexico silt loam (fine, smectitic, mesic Vertic Epiaqualf).  MorSoy RT3930N soybean (MG 3.9) were sown in 38 cm rows and grown as part of a typical cropping system that includes rotation with corn (Zea mays L.) and pre- and post-emergent herbicide applications. Manganese treatments of  1.12 kg ha^-1, 3.36 kg ha^-1, 5.60 kg ha^-1, and 7.85 kg ha^-1 MnSO₄ applied in-furrow were established at planting. Another four Mn treatments consisted of 247g ha^-1, 494g ha^-1, 741g ha^-1 and 988g ha^-1 of MnSO₄ were applied foliarly during late vegetative growth stages. Yield was determined on five 6.1 m long rows.  Protein and oil concentration was determined on a 100 g subsample by NIR spectroscopy.  Yield did not differ among treatments and averaged 3.88 Mg ha^-1. Protein and oil concentrations were not affected by Mn applications and averaged 398 and 212 g kg^-1, respectively across treatments. Yield, oil, and protein differed between years but no year by treatment interactions were observed.

.