Forage Sorghums

Forage sorghums are technically warm-season, annual grasses. However, these forage types have grown so much in popularity in recent years they have been given their own category. They are grown for grazing, hay and silage all over the U.S.

Forage Sorghums

Seed companies often include three species into the forage sorghum category – forage sorghum, sorghum x sudan hybrid, and sudangrass. Sorghum x sudan hybrids are created by crossing forage sorghum and sudangrass. Sudangrass products are less used than in the past with the rapid development of sorghum x sudan hybrids.

Forage sorghum is usually used in a one-cut system for silage, as regrowth is slow or non-existent. The one cut can produce yields comparable to corn silage yields. Sudangrass is used for hay and grazing since its stalks are thinner and regrowth can be fast. Sorghum x sudan combines the benefits of both, with thinner stalks and fast regrowth, but also with huge forage yields.

Forage sorghums have historically been used only as emergency crops because of their heat and drought tolerance but low forage quality. However, with the development of brown midrib (BMR) varieties (lower lignin content), the forage quality is now outstanding – rivaling cool-season grasses, legumes and corn silage in digestibility and animal performance.

BMR forage sorghums can, and should, be utilized more throughout the U.S. for summer grazing and hay and very affordable silage (often much more affordable than corn).

Forage Sorghum

Forage sorghum in a summer annual often used for silage in arid climates because it has excellent drought and heat tolerance (better than corn). Newer, higher-quality varieties called BMR (brown mid-rib), are exceptionally good forage quality, and when used for silage, it has very similar quality to corn silage. BMR varieties contain less lignin, which is the undigestible component in plants that gives them standability. BMR varieties maintain enough lignin for standability. There are three BMR traits, 6-, 12- and 18-gene. Generally speaking, the lower the number, the higher the forage quality. In poorer soils or more arid conditions, forage sorghum can out-yield corn in a one-cut silage system, and total production seed and costs are much lower. Forage sorghum has poor regrowth after harvest. Conventional (non-BMR) forage sorghum is still popular, but if it’s being used for animal feed, BMR varieties are a much better investment.  

  • Seeding Rate (Pure Stand): 5-10 lbs/acre
  • Seeding Depth: ½ to 1 inch
  • Forage Quality (BMR  6-gene): Excellent (comparable to corn silage)
  • Forage Quality (Conventional): Poor-Medium
  • Longevity: Summer Annual
  • Winter Hardiness: N/A
  • Drought Tolerance: Excellent
  • Heat Tolerance: Excellent

Sudangrass

Sudangrass is a summer annual that has a similar appears to johnsongrass and shattercane (which it is related to). It has much thinner stalks than forage sorghum, along with having excellent regrowth after harvest, making it more popular for summer pastures or hay. Sudangrass is similar to forage sorghum in its heat and drought tolerance. A few BMR sudangrass varieties have been developed, but they are only 12-gene varieties. The 12-gene varieties are very high quality (and superior to conventional sudangrass varieties), but 6-gene sorghum x sudan hybrid varieties offer more advantages.

  • Seeding Rate (Pure Stand): 40-50 lbs/acre
  • Seeding Depth: ½ to 1 inch
  • Forage Quality (BMR  12-gene): Excellent
  • Forage Quality (Conventional): Medium
  • Longevity: Summer Annual
  • Winter Hardiness: N/A
  • Drought Tolerance: Excellent
  • Heat Tolerance: Excellent

Sorghum x Sudan Hybrid

Sorghum x sudan hybrid is a cross between forage sorghum and sudangrass, giving it some of the best characteristics of each parent. Sorghum x sudan has the regrowth capability of sudangrass but the yield potential of forage sorghum. While sorghum x sudan generally has larger stalks than sudangrass, BMR 6-gene varieties provide much better forage quality than conventional sudangrass and equal to or better quality than BMR 12-gene sudangrass, all while generating higher forage yields and lower seed and production costs. BMR 6-gene varieties, when used for grazing, have shown to add up to 3 lbs/day of weight gain on beef cattle and exceptional milk production in dairy cows. Beef cattle weight gains when grazing on conventional sorghum x sudan are often around 1.5 lbs/lb. Even when cut at a mature stage, hay samples of 6-gene varieties can have a protein content 60% higher and TDN nearly 20% higher than conventional sorghum x sudan. While conventional sorghum x sudan is more widely sold (primarily because it is cheaper per pound of seed, but only slightly cheaper per acre because of higher required seeding rates), BMR sales are rapidly increasing because it is a much better investment and overall more profitable. Yields from the top BMR varieties are similar to the popular conventional sorghum x sudan varieties.

  • Seeding Rate (Pure Stand, BMR 6-gene): 15-30 lbs/acre (lower seeding rates in arid regions)
  • Seeding Rate (Pure Stand, Conventional): 25-50 lbs/acre (lower seeding rates in arid regions)
  • Seeding Depth: ½ to 1 inch
  • Forage Quality (BMR  6-gene): Excellent
  • Forage Quality (Conventional): Poor-Medium
  • Longevity: Summer Annual
  • Winter Hardiness: N/A
  • Drought Tolerance: Excellent
  • Heat Tolerance: Excellent