High feed prices motivate dairymen to evaluate every aspect of their nutrition program including their homegrown forages. Forages are typically the cornerstone of a dairy’s feeding system with corn silage as the standard by which most other forages are measured due to its consistency in combining high yield and high quality. Other common forages offer niches when compared to corn silage such as alfalfa’s superior protein content or agronomic advantages of winter small grains in cropping rotations. So where does brown midrib (BMR) brachytic forage sorghum fit in?
A warm season annual like corn, BMR brachytic forage sorghum grows in much the same seasonal window. It is more efficient than corn in water and nitrogen use, requiring less of both. Dr. Chris Teutsch of the Southern Piedmont AREC showed establishment cost for forage sorghum was almost $40 per acre less for seed and $50 per acre less for fertilizer compared to corn. Additionally, it is more drought and heat tolerant than corn. Like traditional sorghums, these new varieties possess many of the same attributes including the possibility of nitrate and prussic acid poisoning, but these issues are manageable.
What makes these new BMR brachytic varieties unique? First, the BMR trait results in lower lignin content, which increases forage digestibility. Second, brachytic refers to the dwarfing trait resulting in less stalk and more leaf area. Combining greater leaf:stem ratio with less plant lignin, and adding the seedhead at harvest results in forage quality that compares quite well with corn. Dr. Teutsch observed DM digestibility of BMR forage sorghum at 74%. Data on nutritional quality is still limited, and may vary by variety.
Given BMR forage sorghum’s attractive quality traits, establishment costs, and its ability to handle hotter, drier and slightly more acidic growing conditions, these newer varieties offer two distinct opportunities for consideration in your forage program.
1. An emergency crop. Forage sorghum typically requires warmer soil temperatures for germination compared to corn, so it is often planted later. Research studies have planted sorghum as late as early July with acceptable results. Though they may not have time to develop a full seedhead, they will still produce a significant amount of quality forage. In the drought of 2012, Dr. Chris Teutsch’s research at the Southern Piedmont AREC showed 4 varieties yielded 12 to 19.5 tons/acre (adjusted to 35% DM) when corn plots only yielded 6.1 tons/acre. Drought-prone fields may be good places to consider BMR dwarf forage sorghums.
2. Double crop alternative. In western Virginia, cooler climates lend themselves to less stressful growing conditions for corn most years compared to hotter areas of the state. In the cooler regions the greater need may be the added option to increase total forage yield per acre using a double-cropping system. Corn can be used in rotation with harvestable winter small grain crops, but it can be a challenge to get corn planted on time. With its later planting date, BMR dwarf forage sorghum may be advantageous following a spring small grain silage harvest.
In conclusion, BMR dwarfing forage sorghum is relatively new to the scene. While there appears to be justification for its use in dairy forage systems, remember to consider it as part of an overall forage management strategy. I do not recommend a whole farm conversion to forage sorghum away from corn silage, but it may be another tool to consider. Diversity in your farm’s cropping and feeding plan reduces risks for crop failure and can help break disease and pest cycles. Consider all these factors, and seek trusted advice as you decide what forages to include in your cropping and dairy herd feeding plans.
—Kevin Spurlin, Virginia Cooperative Extension Agent, Grayson County