Comparison of Soybean Grown On Raised Beds Vs. a Flat Surface.

A long standing assumption is that irrigated soybean (Glycine max L. Merr.) grown on raised beds have greater seed yields than crops grown on flat surfaces, though research confirming this is limited.  Two soybean cultivars were grown at Stoneville, MS in 25 cm twin-rows, spaced 102 cm between centers on raised beds and flat surfaces in 2009 and 2010.  Seeding was done in mid-April at 20, 30, 40, or 50 seeds m^-2.  Raised beds were furrow irrigated while flat seed beds were flooded.  Raised beds had a 0.3 Mgha^-1 yield increase for both cultivars in 2010 and 0.8 Mgha^-1 for one cultivar in 2009.  More plants m^-2 became established in raised beds in 2009 than 2010.  Due to early drought stands in 2010 were less than 2009. Pods per plant were greater in 2010 (69 to 76) than 2009 (49 to 58) but seed weights in 2010 (116 to 142 mg) compared to 2009 (159 to 181 mg) were lower and resulted in less yield in 2010 (3.1 to 4.1 Mgha^-1) than 2009 (3.8 to 5.1 Mgha^-1).  Raised beds had at least a 0.2 Mgha^-1 increase in yield for all seeding rates except at the highest level (50 seeds m^-2) which did not differ between bed types.