Switchgrass for a bioenergy crop and livestock feed

Switchgrass can be used as either a bioenergy crop or livestock feed as it has good persistence and a decent forage quality.

In recent years, switchgrass received attention from farmers and the general public due to skyrocketing fuel and oil prices. Although switchgrass is a warm-season grass, it can be grown even in the Upper Peninsula’s climatic and soil conditions (wide range of soil pH 5.5 – 7.0). Once switchgrass is established well, it can last more than 15 years with very low maintenance. Switchgrass can also be used as livestock feed (either hay or pasture) during summer while most cool-season grasses experience summer slump. Do not feed switchgrass to horses since switchgrass can cause photosensitization in horses. Following is the technical information on stand establishment and management of switchgrass.

Stand establishment

  • Late May to mid-June planting using 8 to 10 lbs of PLS/acre (PLS; pure live seed based on germination rate and purity). Since there is a very wide range of germination rate in switchgrass (6 to 80%), it is very important to buy a high quality seed having very high germination rate.
  • Upland ecotype variety (i.e., Cave-in-Rock, Carthage, Pathfinder, and Blackwell) is winter hardier than lowland ecotype variety (i.e., Alamo and Summer).
  • Need a firm, level, weed-free seedbed.
  • Calibrate drill.
  • 1/4 to 1/2 inch seeding depth.
  • Seed to soil contact is critical.
  • Pre-planting herbicide application: Roundup and 2,4-D.
  • Post-emergence: 4 oz of Pursuit/acre (4 leaves stage).
  • Alternative method: Clipping (when weeds reach 6 to 10 inches tall).
  • No nitrogen fertilizer or manure during the seeding year due to heavy weed pressure.
  • It is very important to have clean, weed-free seed bed during establishment year. Once the stands of switchgrass are established well, weed issues in switchgrass will be minimal due to massive rhizomes and tall plant characteristics. This results in suppressing the weed pressure either from annuals or perennials.

Management in production years

  • After three years of production, test the soil (P & K).
  • Begin grazing when switchgrass is 18 to 22 inches tall and stop grazing when there are 8 to 12 inches of stubble left.
  • Harvest two to three weeks after a killing frost.
  • Moisture content of switchgrass should be 15% or less for bioenergy crop.
  • Finish cultural weed control before switchgrass is 12 inches high.
  • Leave a 6-inch stubble when harvested to protect crown and lower stem, collect snow, and provide birds’ habitat.

Based on a four-year research trial at the UP Research Center in Chatham, the average yield of switchgrass was 3 – 3.5 dry matter tons per acre per year. Cave-in-Rock variety appears to be the best.

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