Sorghum-Sudangrass Production Guide Dakota Boren, Matt Yost, LuRee Johnson, Tina Sullivan, Earl Creech, Grant Cardon, Corey Ransom, Randall Violett, Cheyenne Reid, Cody Zesiger, Kalen Taylor, Jacob Hadfield, Michael Pace, and Jody Gale
Introduction
forage sorghum, so Sudex falls in the middle range for toxic levels.
Sorghum-Sudangrass, or “Sudex,” is a hybrid of forage sorghum (Sorghum bicolor) and sudangrass (S. bicolor var. Sudanese). Both are high-producing, rapidly growing, warm-season, annual summer crops. While most annual and perennial grasses grown in Utah are cool-season crops, sorghumsudangrass grows best under high temperatures. In addition to forage production, this crop can also increase soil organic matter, control weeds, fight against nematodes, loosen compacted subsoils, and enhance drought tolerance (Bowman et al., 2012).
This fact sheet provides information to producers about using Sudex and best production practices. Much of the information may also apply to forage sorghum (Figure 1) and a few of the major differences will be noted throughout.
Site Selection Sudex grows in conditions similar to sorghum and corn, performing best in climates with daytime temperatures regularly reaching above 90 F during the growing season. Sudex needs about 45 days for each harvest, so allow at least 90 frost-free days for the entire growing season when taking multiple cuttings (Hale, 2016). Sudex does not grow well on poorly drained soils. Although the crop will grow in most soils, it does best in loam soils with a neutral soil pH, albeit pH ranges of 5.5–9.0 have produced acceptable yields (Bowman et al., 2012). An Oklahoma study showed that highly acidic soils (pH below 4.4) significantly reduced Sudex biomass and plant vigor, whereas soils with a pH above 5.5 showed no decrease in yield (Butchee et al., 2012). In Utah, most soils have a pH around 7.5–8.0 and thus are well suited for Sudex.
Using Sudex on dairies has increased in recent years, particularly the brown midrib (BMR) cultivars. BMR varieties have a higher leaf-to-stem ratio and a lower lignin content, making them more digestible and providing more energy for heifer growth and milk production (Bernard, 2019). For many members of the Sorghum genus, there is concern for hydrocyanic (prussic acid) and nitrate poisoning. However, there are cultural practices and management techniques like ensiling, haying, and diluting by mixing high-containing forage with one that tests low to mitigate these concerns. Generally, sudangrass has less prussic acid than
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