Organic Soybean Official Variety Trials (OVT) were planted on organically managed land at research stations over the last three years.  These trials are providing good information on non-GM soybeans performance under organic conditions.  Organic soybean seed is not available in varieties (or Maturity Groups) that perform well in the southeast, and organic farmers in the state are limited to choosing conventional (non-GM) varieties. Plots were planted in 36 to 38 inch rows at a population of 165,000 seed/acre.  All sites had a history of amendment with either chicken litter or compost and lime.  All soils before planting for a sufficiency of macro and micronutrients and pH.  The only amendment added during soybean growth was manganese sulfate at the Kinston location where deficiencies are routine.  Weed management at each site included two rotary hoe passes in the first two weeks after planting, cultivation 2 to 4 times, and hand rouging 0 to 2 times.  At all sites, weed competition was substantial and intentional.  We waited to rogue plots until some yield decline was expected so that competitive ability of the soybeans could be tested.

Maturity Group 5 Early

Maturity Group 5 Late

Maturity Group 6

Maturity Group 7-8

Varieties of note: Group V, early Osage (released from Arkansas in 2007):  resistant to several important diseases in the mid-South, including southern stem canker, sudden death syndrome, soybean mosaic virus, and frogeye leaf spot Jake (released from Missouri in 2006):  some resistance to soybean cyst nematode and root knot nematode Group V, late NC-Miller (released from NC in 2012):  large seed-size, good yields Group VI NC-Roy (released from NC in 2001) Group VII and VIII Woodruff (released from GA in 2008) NC-Raleigh (released from NC in 2002)

What to plant?  What Maturity Group (MG) is best? In theory, we should expect the higher maturity groups to have higher yield because later maturing beans grow for more days and capture more sunlight.  However, we see huge fluctuations each year on which maturity group yields the best due to which maturity groups had sufficient water during pod fill.  For organic production, we do not recommend soybeans in maturity groups lower than five (V) because the plants start to lose leaves so early that summer weeds are able to jump up and fill those light gaps.  These late weeds can make harvesting difficult.  However, early Group V beans may reduce corn earworm damage.  It is probably best to plant a variety of Maturity Groups to reduce risk since each will reach pod fill at different times.  If soybeans are double cropped behind wheat, plant at least a Group VI or higher so that plants have time to put on adequate biomass before flowering, therefore reaching higher yield potential.