By Tom Kilcer
Sorghum can produce a much lower-cost forage for dry cows and heifers.
With some corn varieties topping $350 a bag, or $140 an acre, BMR sorghum at 10 pounds of seed per acre is only about $20 an acre, a savings of $120 an acre before the crop is even planted.
Nitrogen is like a good corn crop, and with seed treated by a safener, the proper herbicide can control the weeds.
Heifers will get fat on BMR sorghum because the slow rate of passage allows a very high amount of digestion.
Our research (Northeast SARE study) showed the same rate of gain in beef cattle on sorghum as it did with corn silage.
If you have higher-quality haylage, utilize a non-BMR-type sorghum to fill them up, yet reduce the chance of them getting over conditioned. In any case, sorghum is less expensive per ton than corn silage.
You can learn more by watching the video “Why Sorghum in the North” below.
Now’s the time to plant
The off-peak planting period (early June) and harvest window (end of August, beginning of September) can also balance the workload on the farm.
But keep these factors in mind. While sorghum is easy to grow, if you plant in cool soils — less than 65 degrees F — and delay herbicide, weeds will overrun the field.
Corn rootworm isn’t a problem since the worms die if they feed on sorghum. Also, the adult rootworms do not lay eggs in it, so corn will not be economically threatened.
But armyworm could be a problem, and deer will hide in sorghum and come out to eat the corn.
As you move further south into Pennsylvania, the potential for the crop increases even more. Sorghum thrives in areas that frequently turn hot, dry or both. Corn silage stops growing at temperatures over 85 degrees, while sorghum will continue growing up to 105 degrees.
Conversely, in cooler climates sorghum will stand still and corn will yield much better.
This year is forecasted to be slightly warmer than normal across the Northeast. Under dry conditions, sorghum will produce twice as much dry matter on 1 inch of water than corn silage. When there is excessive water it hyperhydrates, and then you have to wait for it to metabolize the excess moisture out of its system.
For more information on sorghum varieties, watch the video “Selecting Sorghums For The North” below.
Potential replacement for wheat straw
An experimental use of sorghum is a replacement for scarce and expensive wheat straw as a fiber source in rations for dry cows. Wheat straw has a uNDFd-240 dry matter percentage of 35.6. In a trial, the non-BMR sorghum had a uNDFd-240 dry matter percentage of 22.3. So, in theory it would only supply two-thirds of the effectiveness of wheat straw.
A non-BMR sorghum or sorghum-sudan can be chopped long — 1 inch minimum — and ensiled. Thus, you will not need to chop straw each week, nor will you need to wet it so that it mixes in the ration. The fibers are very slowly digested and will remain in the rumen longer, providing an effective rumen mat.
In 2017 a non-BMR variety yielded over 32 tons an acre of 35% dry-matter silage and stood like a tree. In one experiment I chopped a BMR-type at 22 millimeters, the longest the chopper would go, and opened the processor all the way. It produced a very interesting shredded product. We have learned that, as a fiber source, it would have been better if it had not been a BMR type and if it would have been cut longer.
In Texas, Brent Bean, agronomist with the sorghum checkoff, has done research showing farmers routinely chop their sorghum at 1 inch to 1.3 inches. He says that the animals will clean up everything in front of them.
An ideal rotation
Where sorghum fits in a rotation is to plant it in early to mid-June as a setup for next year’s legume seeding. Harvest it by the end of August or the beginning of September. This will maximize the NDFd 30 of the sorghum while optimizing yield potential of the winter forage triticale.
Harvest the winter forage next spring and use a no-till seeder to plant the alfalfa in early June. You will get better seedings, balance the spring workload and still harvest 3 to 5 tons of dry matter from that acre in the seeding year.
Both sorghum and sorghum-sudan can be harvested as a one-cut system that will double the yield over a multicut while reducing harvest costs. We suggest a male sterile BMR sorghum as it has given us maximum yield with minimum lodging. The energy is stored in the plant cells and digestible fiber, not the seeds.
Drilling in 15-inch rows is preferred to optimize yield and shade the ground. The most critical step in establishing sorghum is to wait until the soil is warm enough — 62 to 65 degrees at 1-inch planting depth. Plant at three-quarters to 1-inch depth and fertilize like corn. A safener-treated seed allows you to use a herbicide.
For organic farms we suggest sorghum-sudan drilled at 60 to 65 pounds into a stale seed bed.
Because of its high sugar content, sorghum can be ensiled at higher moisture if a proper inoculant is used.
With the proper varieties and good management, silage yields have equaled or exceeded corn silage in tests over multiple years.
Kilcer is a certified crop adviser in Kinderhook, N.Y.