Forage sorghum silage is an alternative to corn silage due to its drought tolerance, but management is key to making the silage valuable, according to a Texas A&M AgriLife Extension Service specialist.
Jourdan Bell, Ph.D., agronomist jointly appointed to both AgriLife Extension and Texas A&M AgriLife Research, Amarillo, planted 92 sorghum hybrids along with some corn for a side-by-side silage comparison in her research trials northeast of Bushland.
In general, if water is not limited, corn will yield better, which is why corn silage is often the silage of choice, Bell said. But, corn loses yield and quality when water is limited. If the crops are drought stressed, sorghum will “shut down” at peak water demand periods, while tasseling corn will lose quality more quickly than with sorghum.
Bell and a graduate student, in a collaborative research study sponsored by the Texas Grain Sorghum Board, evaluated forage sorghum silage quality. The silage study included two harvest stages – soft-dough and hard-dough, with and without a kernel processor, and four ensiling durations: 0, 30, 60 and 120 days.
“We wanted to evaluate how ensiling duration affects silage quality,” Bell said. “Ideally, producers should harvest forage sorghum at a soft-dough grain stage when the forage moisture is 65%-70% and use a kernel processor to optimize forage quality. But many challenges can delay harvest such as equipment breakdowns, precipitation and even delayed forage dry down due to the stay-green trait.
The study data confirmed that silage stabilizes quicker when harvested at soft-dough, Bell said. Silage harvested at a more mature grain stage took 120 days to stabilize. She said a fermentation analysis can give producers an indication of silage quality.
“Because ensiling is a fermentation process, we want the pH of the silage to drop quickly,” Bell said. “If the drop in pH is slow, spoilage can occur as a high pH environment favors the growth of bacteria and molds. Silage pH is also related to protein breakdown in the pit. When the pH of silage is greater than 4.2, protein will break down to ammonia resulting in nitrogen and protein losses.”
Through the application of science-based knowledge, AgriLife Extension creates high-quality, relevant continuing education that encourages lasting and effective change.