Switchgrass yield on reclaimed surface mines for bioenergy production

Area of Science:

• Agricultural Science
• Bioenergy Research
• Environmental Science

Background:

• Rising fuel costs and environmental concerns drive demand for renewable bioenergy.
• Switchgrass (Panicum virgatum) is a high-potential bioenergy feedstock due to its adaptability and biomass yield.
• West Virginia's reclaimed surface mines offer potential land for switchgrass cultivation.

Purpose of the Study:

• To assess dry matter yields of three switchgrass varieties over three years on reclaimed mine sites.
• To compare switchgrass productivity on different soil types of reclaimed surface mines.
• To evaluate the feasibility of switchgrass as a bioenergy crop in West Virginia.

Main Methods:

• Established two research sites on reclaimed surface mines in southern West Virginia (Hobet and Hampshire).
• Cultivated three switchgrass varieties (Cave-In-Rock, Shawnee, Carthage) from their second to fourth production years.
• Measured and compared dry matter yields (kg/ha) across varieties, sites, and years.

Main Results:

• Hampshire site (topsoil and sludge amended) averaged 5760 kg/ha, exceeding the 5000 kg/ha economic threshold.
• Hobet site (sandstone material) yielded significantly lower at 803 kg/ha.
• Highest yields reached 9222 kg/ha (Cave-in-Rock at Hampshire, year 3), while regional agricultural land averaged 12,000 kg/ha.
• Multiple harvests per year did not significantly impact fourth-year yields compared to a single harvest.

Conclusions:

• Reclaimed surface mine lands, particularly those amended with topsoil and organic matter, can support economically viable switchgrass production.
• Switchgrass cultivation on suitable reclaimed lands presents a sustainable bioenergy option.
• Site preparation and soil amendment are critical factors for successful switchgrass biomass yield on marginal lands.