Comparison of forage growth of multi-cut (left) and single-cut (right) harvest sorghum plots in late September.
Sorghum shows promise in the North by Matt Akins and Liz Remick
F
ORAGE production on dairies often focuses on optimizing forage quality and yield for lactating cows; however, this can cause a shortage of moderate-quality forage for dairy heifers, especially bred heifers. Dairy heifers are often fed high-forage diets with corn, alfalfa, or grass silages. Corn silage is high energy (70 to 75 percent total digestible nutrients [TDN] on a dry matter [DM] basis), which exceeds the needs of 900 to 1,200pound heifers that require 60 to 62 percent TDN. These high-quality forages are also lower in fiber and cause higher feed intakes. Sorghum and sorghum-sudangrass hybrids are forage options that have a moderate nutritive quality (higher fiber, lower energy) and could control feed intake and weight gain. Also, sorghums have a lower cost of production, reduced seed costs, and lower nutrient and irrigation needs, which help reduce heifer-raising costs. New sorghum types (photoperiod sensitive) are now available as forage options. These are being utilized in the
6 | Hay & Forage Grower | January 2018
southern United States but also have potential in the North. Photoperiod-sensitive hybrids stay vegetative until daylight shortens to 12 hours and 20 minutes, allowing the plant to accumulate greater yields and have lower energy due to their lack of grain production. The potential to grow this forage using similar management to corn (direct chopping at desired moisture) makes it easier to incorporate the crop into current production systems. Research we are conducting is looking at photoperiod sensitive, conventional, and brown midrib (BMR) types of sorghum and sorghum-sudangrass. This article will provide an overview of our completed research on planting date optimization and harvest strategies along with recommendations for growing sorghums in cooler climates.
Better single-harvest yields We established plots at the Marshfield and Hancock Agricultural Research Stations as these locations have stark differences in soil types and management. At Marshfield, the
clay-based soil is heavier, which makes growing sorghums more challenging. Hancock is in the Central Sands region and a more ideal soil because sorghum is better able to deal with lower soil moisture. We evaluated two planting dates (early and mid-June) and harvest schedules (one or two harvests) with the two harvests taken in early August and after a killing frost in the fall (usually early October). The single harvest was taken according to forage maturity or after a killing frost for the photoperiod-sensitive hybrids. Overall, later planting had a negative impact on yield with 1 to 2 tons of DM per acre lower yields. The exception was
MATT AKINS AND LIZ REMICK Akins (pictured) is an extension dairy scientist with the University of Wisconsin based at the Marshfield Agricultural Research Center. Remick is a graduate research assistant.