Growing Biomass: Switchgrass

Introduction to the Crop:

Switchgrass is a native perennial grass, most commonly    seen in grassland ecosystems. This species has seen increased use in bioenergy crops due to their fast growth, success as a crop species, and the high content on lignins and cellulose that the plant produces.  The lignins and cellulose produced are the main attributes that go into production of bioenergy sources such as cellulosic ethanol. Little research has been done on Switchgrass in the Upper midwest, with the majority of research and successful harvest being completed in the southern states.  In these areas Switchgrass has shown to survive and thrive on sites too poor for conventional crops where access to nutrients and water would normally be limiting factors.

Production from this crop can be variable especially in the early years of production depending on harvest timing and nitrogen content (fertilizers).  Harvest does not normally occur during the first year of production due to the need to properly establish root systems. Along with this, the second year?s harvest will also be below average with only two-thirds of the yield being reached. During the third year, the full potential harvest should be reached. Once the full root system is established, the plant can produce a harvestable crop consistently.  The crop yield has a high variability depending on site conditions with a range of 0.9 to 34.6 tons of dry mass per hectare annually.

Site Selection:

Switchgrass is grown similarly to conventional crops with respect to planting, growing, and harvesting methods. All the attributes normally selected for field crops are easily in the bounds of what switchgrass requires. Fields that would normally not be considered for field crops due to poor soils or water availability can most likely support healthy switchgrass growth. Soil pH requirements range from 4.9 to 7.6, meaning these soils are moderately acidic to slightly neutral. One component that should be avoided is an area where flooding can occur, as this grass is only moderately tolerant to flooding and will grow poorly in wet areas.

Site Preparation:

When preparing a site for switchgrass, much of the same procedure for field crops is required. Tillage of the site is only needed for the first year for seeds to establish. After the first successful growing season, individual plants will survive as a perennial and will re-seed itself prior to harvest (late season harvest) requiring only the addition of fertilizer to reach high yielding harvests.

End Result:

Beyond the potential dry mass produced by switchgrass, the use of this crop as habitat and cover by animals (deer and upland game birds) can provide landowners with multiple use goals. However, a major drawback to growing this crop is the lack of a market for Switchgrass in the Upper Peninsula as a biofuel. Even though the markets may exist closer to the Wisconsin border with ethanol plants located in central Wisconsin, the only current market for this is as a hay replacement. Regardless, this crop has potential to be planted in the Upper Peninsula with successful growth rates and the potential for bioenergy utilization and should not be overlooked.

Pros:

  • Easily planted
    • Does not require conversion of cropland
  • Quick harvest
    • First strong yield after third year, then every year after
  • High yields on poor soils
  • Productive crop for  ten years, or more

Cons:

  • No market exists within reasonable distance
  • Requires fertilizing to be economically viable
  • Requires three years to reach full capacity

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Development Status of Perennial Energy Crops

Farm Scale Production Cost of Switchgrass