You are here: Home / Research Topics / Research Highlights / Individual Highlight

Research Highlights

Individual Highlight

Water quality effects of switchgrass intercropping on pine forests in coastal North Carolina

Photo of Research site with loblolly pine and intercropped native switchgrass plants. Research site with loblolly pine and intercropped native switchgrass plants. Snapshot : Six recent years of data from site preparation to full growth of switchgrass, as a celluolosic bioenergy crop, suggest that planting switchgrass between loblolly pine tree beds improved downstream nutrient water quality when compared to a traditional managed pine forest at a North Carolina Coastal Plain site. However, a switchgrass only treatment yielded higher nitrogen levels than the intercropped site.

Principal Investigators(s) :
Amatya, Devendra M.  
Research Location : North Carolina
Research Station : Southern Research Station (SRS)
Year : 2017
Highlight ID : 1314


A large amount of land is under pine production in the U.S., with loblolly pine (Pinus taeda L.) widely used for timber and other wood products. Intercropping switchgrass (Panicum virgatum L.), as a celluolosic bioenergy crop in loblolly pine stands is hypothesized to provide bioenergy feedstock without competing for land currently in food production. Switchgrass is a native perennial grass that uses water efficiently and prevents soil erosion. However, in order to recommend this novel intercropping practice to forest managers and landowners, there is a critical need for information about its impacts on water quantity and quality. Accordingly, six recent years (2009-2014) of data from a watershed-scale field experiment conducted on Weyerhaeuser's managed pine forest in coastal North Carolina suggest that fully grown switchgrass between pine tree beds improved downstream water quality by reducing nitrate and phosphate concentrations and loads compared to the traditional pine forest. However, the watershed planted only with switchgrass yielded higher nitrate concentration and loads than the intercropped site, possibly due to greater outflow from the former site. Pine-switchgrass intercropping may thus be a viable method of producing a sustainable bioenergy crop on pine forest lands while improving water quality, except for its site preparation period.

Forest Service Partners

External Partners

  • CatchLight Energy
  • North Carolina State University
  • University of Georgia
  • Weyerhaeuser Company