Biomass Production Potential of Miscanthus, Switchgrass, and Willow in the Northeastern United States.

The Northeastern United States has suitable growing conditions for the biomass crops shrub willow (Salix spp and hybrids), a C₃ plant, and miscanthus (Miscanthus × giganteus) and switchgrass (Panicum virgatum), both C₄ plants. The objective of this research is to estimate the potential biomass achievable by these crops in the region. We simulated biomass production for 30 years in soils with no nutrient limitations. We summarize results for Central Pennsylvania near State College, which is particularly suitable for both crop types. The critical crop parameters were: radiation use efficiency (solar radiation)of 1.2 and 2.3 g biomass/MJ, and water use efficiency of 5.5 and 8.1 g biomass/kg water at 1 KPa of vapor pressure deficit, for willow and the C₄ crops respectively. No less than 25% of the biomass produced in a single day was allocated to belowground organs, a conservative assumption. Willow and the two C4 crops harvestable biomass averaged 10.7 and 15.4 Mg/ha; approximately 5 Mg/ha were destined to belowground organs. Mature stands of willow may divert a fraction of this allocation to aboveground growth. The crops intercepted 40% of the yearly solar radiation, and transpired 430 mm, with 250 mm of direct evaporation from the soil during the growing. An earlier and faster crop cover can translate in more plant radiation interception and water use. If 100 mm of the 250 mm of water evaporated were destined to transpiration, the biomass production could increase by 25%. In conclusion, the biomass potential of these crops is between 13 and 18 Mg/ha. Experiments with these crops are useful to explore the extent to which this potential is realized in the varied soils of the northeast. The high realized transpiration indicates abundant water supply during the growing season, a key component to secure a study supply of biomass from perennial crops.