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OSU Extension

College of Food, Agricultural, and Environmental Sciences

June 2, 2016 - 6:56am -- lewandowski.11@...

          No one knows for certain what the weather is going to do, but we do know that in a typical summer cool season forages in our pastures and hayfields have reduced growth and production.  For anyone looking for some extra forage production during the summer months, consider planting a warm season annual crop during June.  Warm season annual forages thrive in summer heat, are drought tolerant, and can be used for either grazing or as a stored feed.  Summer annuals include forage sorghum, sudangrass, sorghum x sudangrass hybrids, millet, teff, and corn.  With adequate soil fertility and a minimum of moisture, these species are capable of producing three to five tons of dry matter over the summer months.  Most of these species can provide two to three grazing passes or cuttings beginning 30 to 45 days after planting.

            Plant summer annuals when the soil temperature is 60 to 65 degrees F.  Plant forage sorghum at 5-7 pounds/ acre, millet, sudangrass and sorghum x sudangrass hybrids at 25 to 40 pounds/acre, teff grass at 4 to 5 pounds/acre and corn used as forage can be planted at about 80,000 kernels/acre and seeded with a grain drill.  Soil pH should be in the 6.0 to 6.5 range, soil phosphorus should be at least 15 ppm and soil potassium in the 100 to 125 ppm range.  All summer annuals respond to nitrogen and best yields will be obtained when 50 pounds of actual nitrogen/acre is applied before or at planting, followed by 30 to 35 pounds/acre after each cutting or grazing pass.  For dairy farmers looking for a place to summer apply manure, summer annuals provide a good option. 

            Summer annuals grow fast and mature quickly.  Forage quality is good at young vegetative growth stages but declines rapidly once the plant enters reproductive growth.  Summer annuals best suited to grazing include millet, sudangrass and sorghum x sudangrass hybrids.  The brown mid-rib (BMR) varieties of sudangrass and sorghum x sudangrass are recommended because they have superior digestibility compared to non-BMR varieties.  While corn has also been used for grazing, this is a single pass forage.

          Graze sudangrass and sorghum x sudangrass hybrids when plants are 18 to 30 inches tall. Approximate forage quality at this growth stage is 17 to 19% crude protein, 58-60% Neutral Detergent Fiber (NDF), 0.69 Mcal net energy of lactation or 66-68% a total digestible nutrient (TDN) content.   Leave a stubble height of 6 to 8 inches to insure fast regrowth.  Millet should be grazed beginning at 12 to 18 inches in height and livestock removed to leave a 6 inch stubble.  Sudangrass and sorghum x sudangrass hybrids can go from a high quality feed to a mediocre or even poor quality feed in about 7-10 days under good growing conditions.   Plan your grazing or harvest timing with this in mind.   If grazing was uneven and old stems remain, clip the stubble to a uniform 8 inches after the grazing pass.

            All of the summer annual species can be mechanically harvested for stored feed.  This is the best option if forage sorghum or teff grass is planted.  With the exception of teff grass, baleage and silage are the best harvest and storage options for summer annuals because they have a high moisture content, produce a lot of tonnage, and they are difficult to dry.  Typically, forage sorghum, sorghum x sudangrass hybrids and sudangrass are harvested at 36 to 48 inches in height while millet and teff grass are harvested at the boot stage or approximately 36 inches in height.

            One note of caution is that summer annual crops can accumulate nitrates in the lower portions of the stems under drought conditions.  Reduce nitrogen fertilization and manage grazing to make sure livestock do not graze lower than 8 inches to reduce the risk of nitrate toxicity.  In addition, sorghum, sorghum x sudangrass hybrids and sudangrass all have varying levels of potential for prussic acid poisoning if plants are consumed when they are under stress conditions.

            For more information about the use of summer annuals as a supplemental pasture or stored feed crop, contact the Wayne County Extension office at 330-264-8722.