Forage sorghum

Forage sorghum is a good summer annual grass for silage.

ORANGE CITY, Iowa — A wet fall, unusually cold temperatures, excess rain and, in some cases, flooding, have cattle and sheep producers wondering how to manage forage shortages this summer and lay in forages for next winter.

“The good news is there are haying, grazing and silage options,” Beth Doran, beef specialist for Iowa State University Extension, said in an Extension news release. “But, before a final decision is implemented, producers should check with their crop insurance agents about their alternative plans.”

According to Brian Lang, Extension field agronomist with Iowa State University, most short-term forages are fast-growing annual crops. Sorghums and millets are traditionally grown for summer forage, whereas cereal grains and forage brassicas are popular cover crops for fall or early spring grazing, depending upon the forage species.

Each forage species has unique characteristics, such as growing season, size, regrowth potential, feed value, presence or absence of anti-quality components, yield and suitability for haying, grazing or silage. An Iowa Beef Center fact sheet of short-term and supplemental forages descriptions is available for download from the IBC website at https://bit.ly/2QDh7I4.

Prussic acid may be present in Sudangrass, sorghum-Sudangrass hybrids and forage sorghum when the plants are grazed or green-chopped at short heights (less than 18 inches for Sudangrass; less than 24 inches for sorghum-Sudangrass hybrids; less than 30 inches for forage sorghum), during a severe drought or if grazed too soon after frost. Remember that all annual forages can be high in nitrates if the season turns dry.

Sorghums and millets are usually planted once soil temperatures are 65 degrees Fahrenheit and increasing, up to early July, and used during the summer and autumn. They will be ready for first harvest or grazing about 50 days after emergence.

Pearl millet and Sudangrass are best suited for grazing due to their rapid rate of regrowth. Do not cut or graze shorter than a 5- to 6-inch stubble height to encourage good regrowth. For an emergency hay crop, foxtail millet would be the forage of choice due to rapid dry-down, but plan for only one hay harvest. If harvesting silage, forage sorghum and corn are best based on yield and feed quality.

Teff is a relatively new forage species that has very fine stems, rapid regrowth in mid-summer and a high leaf-stem ratio. It can be harvested 45 to 55 days after planting and is most often used for hay. To encourage good regrowth, the cutting height should be 4 to 5 inches.

Teff stores its regrowth-reserves in its lower stems, and a cutting height under 4 inches can be devastating to its regrowth ability. Grazing is not recommended due to its shallower rooting, especially early in the growing season.

“The species of choice for fall grazing cover crops is highly dependent on how early they can be planted,” said Joel DeJong, field agronomist with ISU Extension.

“For fall grazing, most cover crop species such as cool-season annual grasses, cereals and brassicas yield more forage when planted mid-summer. If planted after early September, cereal rye and triticale, which is a cross of wheat and rye, are better suited for the shorter growing season.”

Doran said there are a couple of advantages for cereal rye — it will overwinter and is one of the earliest cover crops to appear in the spring. Because of this, it is often used for early spring grazing and a clean, green area for cow-calf pairs after calving.

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