Sorghum Sudan crosses are a warm season or C4 grass. Warm season grasses process sunlight into sugars (photosynthesis) differently than do cool-season (C3) grasses. The rami-fications are that C4 grasses 1) must be planted after soil temperatures reach 60°F and are rising, 2) grow very little at less than 60°F, 3) grow best at 77°F and higher and 4) will produce a ton of silage at 1/2 the rain or irrigation than will corn silage. Hot and dry is their ideal environment after germination. C4 grasses die soon after a freeze. These forages produce quick tons of highly digestible (high energy) silage or pasture. They are an excellent source of pasture for the hottest months. Other C4 grasses include all Sorghum and Sudans, plus Millet, Teff, Bermuda and Bahia grasses.
BMR (brown mid-rib) is a natural trait (not GMO) that indicates low levels of lignin in the plant. BMR Gene 6 is the highest level of BMR, meaning it contains the lowest level of lignin of any sorghum or sudan. This trait transforms sorghum products from heifer feed, to the highest quality dairy cow feed. All Byron sorghums are from Alta and all are BMR Gene 6. This is a non-GMO trait.
Sorghum Sudan will be harvested for baleage or haylage in 45 days after planting. Grazing is usually initiated a week to 10 days earlier. The taller varieties (AS6401, AS6501) are mowed when they reach 38" to 40" tall and the dwarf (AS6402) when it reaches 32". Residue heights are also important. The taller versions must be mowed at 5-6" residue (above the 2nd growth node) to allow for rapid regrowth. AS6402 can be mowed at 3" and is one reason for its popularity. These cutting heights are essential as regrowth can be almost zero if the residual is too short.
Fertilizer needs are 1 to 1 1/4 units of N per growing day, i.e. 45 to 50 units for first cut and 30-35 units for each cut thereafter. Potassium, phosphorous and sulfur are also needed on most farms. All fertilizer needs are the equivalent of the needs for 100 bushel corn. Manure can be used for the original application; however, commercial N is the best source after a cutting. If manure will be used after the first cut, choose AS6401, due to its superior disease package. Nitrogen needs for grazed sorghum Sudan are reduced proportionally so that cows can be brought in to graze earlier without danger of nitrate (NO3) poisoning. (See article on sorghum nutrition for more on NO3 and Prussic acid plus management of the crop after freezing weather.)
Brachytic Dwarfism: AS6402 is a brachytic dwarf. This trait (natural, not GMO) provides these plants with three advantages. Already mentioned was the shorter residual cutting height. Second is the shorter intermodal distance or space between leaves. The plant will then have a shorter stalk, but with more leaves which is always a quality improvement. Third is the higher tillering capacity of the Brachytic plants (also included in the Brachytic category would be AF7401 Forage Sorghum and AS9301 Sudan Hybrid which is a semi dwarf variety)
Sorghum Sudan will usually need about ten days to emerge, and then can grow 3" to 6" per day. A conventional or no-till drill is used for the seeding and planting depth should be 1" to 1 1/2". Planting after a small grain crop (e.g. rye or Triticale) requires dealing with the allelopathic effects from the dying grain plants (minimum tillage or heavy liquid manure application). Weed management should be dealt with pre-planting as there are no herbicides available for Sorghum-Sudan grasses.
AS6503 is a photoperiod sensitive sorghum-sudan with a better disease package than AS6501 plus higher levels of sugar. Since sorghum sudans (SS) need about 1 to 1 1/4 units of N per growing day, this must be accounted for in your planting time fertilization. Sugar levels will be highest when plant is 40" tall as opposed to the delayed harvest. SS are typically high in sugar, a valuable energy source for cattle, however AS6503 will be several percentage units higher than standard SS.