Double Cropping of Soybean and Sorghum after Winter Small-Grain Crops in Virginia.

Double cropping soybeans (Glycine max L.) after winter small-grain crops is common in the mid-Atlantic region.  Grain sorghum (Sorghum bicolor L. Moench) can also be doublecropped after small grain and this practice is increasing due to greater local demand for feed grains.  The objective of this experiment was to evaluate and compare yield and agronomic characteristics of grain sorghum planted full season or double-cropped after wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) or triticale (x Triticosecale) with soybean in the same rotations.  A total of six field experiments were conducted in Virginia at the Southern Piedmont Agriculture Research and Extension Center (AREC) (Appling sandy loam) and Tidewater AREC (Nansemond loamy sand) in 2012-2014.  Experimental design was a split-plot with 14 treatments and four replications.  Main plot was winter crop (barley, triticale or wheat) and the subplot either soybean or sorghum.  In 2012, there was limited rainfall in July and August and doublecrop treatments were not harvested at Southern Piedmont.  Two-year average yield of barley, triticale and wheat was 3411, 2557, and 3404 kg ha^-1 respectively at Southern Piedmont and 4424, 3569 and 3764 kg ha^-1 at Tidewater.  At Tidewater, full season sorghum and soybean yielded 3225 and 1936 kg ha^-1 in 2012 and 8906 kg ha^-1 and 3763 kg ha^-1 respectively in 2013.   In 2013 at Tidewater full season sorghum yielded 7652 kg ha^-1 and soybean yielded 2831 kg ha^-1.  At Tidewater in 2013, doublecrop yields were 5896 and 4099 following barley, 4510 and 2218 following triticale, and 4600 and 2016 kg ha^-1 following wheat, for grain sorghum and soybean, respectively.