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A Growing Interest in Forage Sorghum

25 March 2015
Uni Kansas State

US - Continued research on sorghum could help cattle producers diversify their feedstuffs.

As winter soon comes to a close, it is never too early to start planning feedstuffs production for cattle next winter. Forage sorghum offers a variety of benefits that help secure its place as one of those major feedstuffs.

“Interest in forage sorghum is definitely on the rise,” said John Holman, K-State Research and Extension agronomist based in Garden City. “There is a lot of interest in general to supply cow-calf, feedlot and dairy industries in the region.”

The growing interest is in part due to the versatility of forage sorghums, he said. Other advantages of sorghum include that it uses less water than some other traditional forage crops and, when managed correctly, contains high-quality nutrients for cattle.

“Depending on what the producer’s goal is, with sorghum we have the ability to graze, hay or put it into silage,” Holman said. “It’s one of the advantages of sorghum, with all of the different sorghum types that are available. Once a producer identifies what his or her goal is, then we can select a sorghum type and variety to match the grower’s needs.”

Sorghum has better heat and drought tolerance than corn or alfalfa, and requires less irrigation than corn silage, Holman said.

“Particularly in the Ogallala Aquifer region, there are advantages of sorghum over corn when we are working with limited irrigation wells or dryland,” Holman said. “Sorghum has good drought tolerance and high water use efficiency.”

However, for producers who have adequate water, corn silage may suit their forage needs better than sorghum.

“If you are able to fully irrigate, you will obtain higher quality forage with corn silage due to its grain production, but if you are working with limited irrigation, sorghum silage is an excellent choice,” Holman said. “Sorghum grown under limited irrigation can produce more biomass, and by selecting the right variety, can produce good feed quality.”

Producers may view sorghum tonnage as the most important factor, he said, because they are paid on tons produced, like any biomass crop. But, feed quality is also important.

“When we evaluate feed quality, we measure components such as crude protein, fiber content, energy and digestibility of that forage,” Holman said. “There are several things to consider when it comes to feed quality.”

Sorghum Types and their Benefits

Brown midrib, or BMR, forage sorghum has been around for many years, but it has become more common in the last 5 to 10 years, Holman said.

“When you look at the midrib on the plant’s leaf, or if you cut open the stalk, it’s going to be brown in color versus white in color,” Holman said.

BMR sorghum can be useful to producers when it comes to lignin content. Lignin helps provide the plant rigidity, but it also reduces fiber digestibility and thus energy content in forages.

“The brown midrib trait has between 20 and 50 percent less lignin content,” Holman said. “Lignin is indigestible by the animal and protects plant fiber from being digested. So with reduced lignin, we have better fiber digestibility and, as a result, increased energy content in the forage.”
However, this isn’t always true.

“Not all BMRs meet that,” he said. “Some BMRs just don’t live up to what other BMRs can. Just because it is a BMR does not make it necessarily a good variety. Producers need to look at university performance test data and select a variety with good feed quality and yield potential.”
Photoperiod-sensitive (PPS) forage sorghum is another type of sorghum producers can consider utilizing.

“It remains vegetative until day length decreases to less than 12.5 hours a day,” Holman said. “So it remains vegetative long into the growing season.”

PPS forage sorghum does not produce seeds in Kansas, which extends the harvest window for hay production.

“It will not make seed or grain in our region, because we do not have a long enough growing season,” he said. “The advantage is it can produce high tonnage and gives a longer window of opportunity for haying in the fall, because it is not going to be maturing.”

But, PPS sorghum is not best for all types of production.

“(PPS) is not going to be a good choice as a silage crop, but it would be a good hay crop,” Holman said. “There are other crops that have better forage quality, but it can be a good hay choice.”

Sorghum-Sudan grass has been on the market a while and can be used for grazing, he said. It is typically grown when a producer is looking for grazing potential or, more recently, as a good fit for a cover crop.

“(Sorghum-Sudan grass varieties) have good regrowth potential and are a good fit for grazing,” Holman said. “Their feed quality drops off later in the season, whereas forage sorghums’ quality can stay quite high.”

Sorghum-Sudan grass varieties also fit a variety of difficult situations. “They tend to be a little more drought tolerant and more tolerant of high pH soils than forage sorghum,” Holman said.

Continuing Research

As with all crops, having a good nutrient management program is highly important.

Over-applying nitrogen can be hazardous, which has been shown in work Holman and others at K-State have done the last several years that examined nitrogen response with these sorghum crops.

“Sorghum requires a good nutrient management plan, not just for yield but to minimize the risk of high nitrate also,” Holman said.

“Producers should soil sample and make sure all of the macronutrient needs are met. Make sure to not over-fertilize with nitrogen. Otherwise, we run the risk of elevating nitrate in the plant.”

K-State is adding a forage testing program for producers to aid them in their variety selection decision-making.

“Years ago, K-State had a forage variety testing program, but we are reinitiating it this year,” Holman said. “There isn’t a good university-wide testing program anywhere in our region, and we have producers asking for that information. We will have five sites across the state (Garden City, Hays, Hutchinson, Mound Valley and Scandia) where we will be evaluating both corn and sorghum silages, as well as sorghum and millet hay types. The success of this program is going to be based on the industry’s desire to enter varieties.”

“I would encourage producers and county agents to make sure that their seed supplier is entering the test, so they can see how varieties they are interested in compare to everyone else’s out there,” he added. “In addition, we’ve had a lot of cropping systems research projects that include forage sorghum over the last several years, because it is such an important crop for producers in the state.”

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