Oklahoma State University

Misconceptions and Facts

Misconceptions and Facts

MISCONCEPTION: Switchgrass grows well in dry areas with shallow, infertile soils and does not require fertilization or irrigation.

  • Alabama switchgrass yields approached 15 tons/acre. Nitrogen was applied at 100 lbs N/acre and there was abundant rainfall.
  • Switchgrass production in Iowa uses the same nitrogen recommendation.
  • Oklahoma does not currently have specific nitrogen recommendations, but switchgrass does not appear to be responsive to more than 50 lbs N/acre.
  • In Oklahoma, the highest yields (8 tons/acre) occurred with 40 inches of precipitation; lower yields (6 tons/acre) occurred with 30 inches of precipitation, both on deep, fertile soils. Old stands of inferior varieties do not yield 6 tons/acre. Average yields of only 1 to 3 tons/acre should be expected on marginal sites.


MISCONCEPTION: Fifteen percent of the U.S. agricultural land is unsuitable for farming. If all of it were planted to switchgrass, we could replace every gallon of gasoline with ethanol.

  • Currently, much of this land is in CRP, which is not highly productive for agriculture with poor soil conditions, steep slopes, shallow, etc.
  • Yields are much less than 6 to 8 tons/acre on steep, shallow soil with low fertility.


MISCONCEPTION: In the future (10 to 20 years), switchgrass yields will increase beyond their current potential.

  • Switchgrass is a perennial and should be resown every 10 to 15 years.
  • Yields are currently dependent on differences in environmental conditions with average yields of between 5 to 10 tons/acre on good soils. Marginal sites yield much less.
  • Historically, there has been little success with increasing biomass yields in herbaceous crops.
  • Little research has been devoted to increasing switchgrass yields (compared to many of our row crops) and no research yet indicates substantially higher yielding cultivars will be available.


MISCONCEPTION: Switchgrass is cheaper to produce as a feedstock than corn for producing ethanol.

  • The processes for conversion of cellulose in switchgrass stems to a usable clean fuel have not been proven on a large scale; thus, the economics remain unknown.
  • Consideration must be given to: 
    • Fuel prices 
    • Yield (higher yields have cheaper production costs per unit of production.) 
    • Transportation costs. Switchgrass is bulky and expensive to haul.
  • Overall it may be more than, less than, or equal to corn-based ethanol.


MISCONCEPTION: Switchgrass is good for the environment because it adds organic matter and carbon to the soil.

  • Switchgrass captures great amounts of carbon from the air and converts it to organic matter as it grows; however, this last only as long as the plants are alive.
  • When a stand is destroyed and the land is plowed, the organic matter quickly breaks down and the carbon is released into the atmosphere as carbon dioxide.
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