Intercropping

Intercropping is a practice of planting different crops in the same field to optimize output economics. Current timber plantation management practices emphasize large-diameter saw timber productivity through frequent thinning and relatively large row spacing. Intercropping Switchgrass between rows, for example, allows for significantly higher biomass output while maintaining consistent saw timber productivity. Harvesting of energy grasses intercropped with actively managed saw timber plantations provides both a source for low-cost biomass as well as increased revenue to the plantation owner.

Over the next year, the Biofuels Center of North Carolina plans to establish trial plots to test intercropping on the Oxford Biofuels Campus. The plots will be designed with trees (Pine and Sweetgum) planted in rows spaced at 10, 20, and 30 feet. Perennial grasses (Switchgrass and Giant Miscanthus) will be planted between the rows of trees. The effect of the shading from the trees on the grasses and the competition from the grasses on young tree seedlings will be observed and evaluated. The observation and evaluation will occur over the next 12 years, which is the projected productive lifespan of intercropped perennial grass. The row spacing/competition and grass harvesting equipment will be evaluated to determine a logical row spacing of trees for intercropping.