Sorghum gaining ground as a forage

“Interest in forage sorghum is definitely on the rise,” says John Holman, a 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.”

Some of the advantages of forage sorghum include less water usage than for other forage crops, higher heat and drought tolerance, versatility, and high-quality nutrients for cattle (with proper management.) 

“Depending on the producer’s goal, with sorghum we have the ability to graze, hay, or put it into silage,” Holman says. “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.”

Corn silage vs. 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.”  

Like any biomass crop, farmers are paid by tons produced. While that is a major factor to consider, a sorghum crop's forage feed quality – crude protein, fiber content, energy, and digestibility – is equally important from a business perspective.

Laying out the sorghum types

Brown midrib (BMR) 

BMR as a forage sorghum has gained popularity in the past five to 10 years. BMR sorghum as a forage can be beneficial to producers when it comes to lignin, a substance that reduces fiber digestibility and, in turn, energy content in forages. 

“The brown midrib trait has between 20% and 50% less lignin content,” Holn 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.”  

But that isn’t true of all BMR varieties. Holman suggests producers look at university performance test data to select a BMR variety with good feed quality and yield potential.

Best use: Silage 

Photoperiod-sensitive (PPS) sorghum

Plant maturity and seed development reduces the nutrition value and opportunity to hay. PPS remains vegetative until day length decreases to less than 12.5 hour per day, explains Holman. Due to the shorter growing season, Kansas PPS sorghum doesn’t produce seeds, so the harvest window for hay stays open longer.

“The advantage is it can produce high tonnage and give a longer window of opportunity for haying in the fall because it won't be maturing,” he adds.

Best use: Hay crop.

Sorghum-sudan grass 

With good regrowth potential and better drought tolerance than forage sorghums, sorghum-sudan grass fits great into a grazing operation. While other feeds’ quality drops off late in the season, the quality of forage sorghum stays high, says Holman.

Best use: Grazing

Nutrient management with sorghum

Holman and others at K-State conducted research over the last several years looking into nitrogen response of sorghum. Key finding: Over-applying nitrogen can be hazardous. 

“Sorghum requires a good nutrient management plan, not just for yield but to minimize the risk of high nitrates, also,” Holman said. “Producers should soil sample and make sure all of the macronutrient needs are met. Make sure to not overfertilize with nitrogen. Otherwise, we run the risk of elevating nitrate in the plant.”