Coupling of Carbon and Nitrogen Cycles Critical for Biomass Sustainability
A multi-component plant-soil biogeochemical model for the herbaceous energy crop switchgrass was developed and evaluated using data from a long-term bioenergy plantation in the southeastern United States. DOE scientists at Oak Ridge National Laboratory used the model to simulate biomass production, nitrogen dynamics, and carbon sequestration in soils beneath switchgrass over a 30-year period, revealing a strong coupling of carbon and nitrogen dynamics, both above- and below-ground. The lead scientist concluded that the extent to which biogeochemical cycles are coupled is a critical determinant of sustainability in systems where biomass growth and removal occurs annually. More efficient use of nitrogen in the production of biomass deserves further investigation. Based on model simulations, researchers believe that reductions in nitrogen fertilization are possible given rates of organic matter decomposition and soil nitrogen mineralization. Overall, the model simulations reveal a suite of feedbacks and tradeoffs in the production of feedstock for transportation fuels, but the author suggests that long-term production and removal of biomass from switchgrass fields for transportation fuels is possible.
Garten, C.T., Jr. 2011. “Review and Model-Based Analysis of Factors Influencing Soil Carbon Sequestration Beneath Switchgrass (Panicum virgatum),” BioEnergy Research, DOI: 10.1007/s112155-011-9154-2.