It’s time to take inventory of the current state of sorghum species as a forage resource in more humid regions of the United States. Of course, sorghums will always be a go-to crop in semi-arid areas, even with sugarcane aphid as a major new deterrent.
In the more humid regions, there’s no question that the use of forage sorghum, sorghum-sudangrass, and sudangrass has become more popular as a warm-season annual forage resource. That said, there are still many farmers unwilling to try it or who have had bad experiences and are not inclined to give it a second chance.
Last year, with a lot of unplanted or late-planted acres, more than the usual amount of sorghum species were planted and harvested. It was also a year where sorghums didn’t perform up to expectations in many cases because of persistent cool, wet weather conditions.
In the same way that our cool-season annual and perennial forages don’t perform to peak levels under dry, hot conditions, warm-season sorghums are not well adapted to cool temperatures. However, they can offer exceptional performance and forage yields under normal summer conditions, even in our Northern states.
This variation in performance has left our world full of sorghum lovers and haters and opinions ranging from undependable to forage savior.
Jeff Jackson is the national forage sorghum product manager for Croplan by Winfield United. He’s not an office dweller but rather a “boots on the ground” forage agronomist with lots of experience in the world of growing sorghum species in the Upper Midwest. He’s seen plenty of forage sorghum successes and also a lot of disasters. I recently was able to pick his brain on what he thought some of the factors were that separated success from failure, sans uncontrollable weather.
When selecting seed genetics and feeding for dairy or beef performance, Jackson highly recommends that sorghum growers look to the more highly digestible brown midrib options. “It may cost a little more, but you’ll easily make that up with more milk or animal gain, palatability, and less feed waste,” Jackson said.
Get a good start
“You can’t rush the planting date,” Jackson said. “You need consistent soil temperatures above 60°F at 8 a.m. before you should think about planting. If you don’t heed this rule, germination and seedling vigor will be compromised. Patience is a virtue with sorghum planting. If planting pearl millet, hold off until morning soil temperatures are 65°F or above,” he added.
Jackson explained that the recommended seeding rates have changed as new genetics have entered the market.
“Genetics have improved for fiber digestibility, which allows us to plant less seed per acre while improving standability and producing excellent yields,” he said. “Many older genetic styles of single-cut forage sorghum have been planted at 10-plus pounds per acre to decrease stem diameter and improve palatability. Today, genetics have the potential to yield as well or better planted at as little as 4 pounds per acre for single-cut forage sorghums.”
Sorghum-sudangrass hybrids can be successfully established at a seeding rate of 15 to 25 pounds per acre. “It’s not like the ol’ adage of ‘plant a bag per acre,’” Jackson said. “The optimum rate will vary with local rainfall patterns, soil types, and planting methods.”
Fertilization of sorghum species is another area where the Kansas City-based agronomist sees a lot of mistakes being made.
“It’s a myth to think that you shouldn’t fertilize to avoid high nitrates,” Jackson said. “Proper fertility is actually needed to reduce nitrate potential. I tell growers to apply nitrogen and sulfur at a 5-to-1 ratio, having 1 to 1.2 pounds of nitrogen per day of growth is the standard.”
If using a multi-cut crop such as sorghum-sudangrass, Jackson recommends split-applying nitrogen for each harvest sequence; this helps to prevent luxury consumption of nitrogen and high nitrates in first cutting. For a crop growing over 90 days, there should also be 50 to 60 pounds per acre of phosphorus and 80 to 90 pounds of potassium applied for optimum growth.
It’s not corn silage
Weather volatility and the lack of a harvest plan have made sorghum harvests a challenge in recent years. “This is not like corn silage that dries down uniformly and only temporarily takes on moisture following a rain event,” Jackson said. “Sorghum has a tendency to take on multiple points of moisture and holds it much longer before it is dissipated.
“In order to control moisture for sorghum silage or baleage, growers should consider swathing, wilting, and using a pick-up head when chopping. This will help manage risk for harvest timing and moisture content. If a custom chopper or baler is coming on Wednesday, start swathing on Monday,” he noted.
For producers not willing to cut and wilt the crop, Jackson said they will likely have to depend on a killing frost event for dry down. The problem with such a strategy, he explained, is that the risk of lodging is enhanced, and feed quality suffers. Also, this reduces the time available to apply manure and get a fall-seeded cereal crop in for winter cover.
Forage sorghum, sorghum-sudangrass, or sudangrass are receiving more interest and use than ever before in the humid regions of the U.S. They offer a lot of value in both grazing and conventional-harvest systems, but their use needs to come with a firm understanding of how these species grow, develop, and can be harvested.