Development and evaluation of a crop specific soil bio-geochemistry model (CropCent) to assess greenhouse gas benefits of growing miscanthus as a second-generation biofuel feedstock

Background/Question/Methods

Miscanthus can potentially meet US biofuel goals (offsetting 20% of gasoline consumption by ethanol) using only ~9.3% of agricultural acreage. High annual productivity (~ 25 Mg/ha), ability to recycle nutrients, and sustained perennial yield over long periods (>10 yr) contribute to miscanthus being an ideal energy crop. Assessing Impact of land use change due to miscanthus on GHG balance requires development of a mechanistic model that can predict biomass productivity and GHG emissions over a large spatial area covering a wide range of soil types and climatic conditions. The goal of this work is to establish a common modeling framework for second-generation biofuel feedstocks that can make predictions about biomass yield and GHG emissions from plot to regional scales. We have developed modules based on the description of bio-geochemical dynamics of DayCent to simulate changes in soil organic carbon and greenhouse emissions. These modules are used to establish two-way coupling between a bio-physiological crop growth model (BioCro) and bio-geochemistry model (DayCent).

Results/Conclusions

Here, we are describing development and evaluation of a crop-specific model (CropCent) for simulating soil bio-geochemistry and GHG emissions. Simulations are performed for miscanthus. Model performance is evaluated against the following variables: (1) biomass yield, (2) soil carbon, (3) N₂O  emissions, and (4) nutrient losses in leachate, measured from 2008 to 2012 at the energy farm site of the University of Illinois, Urbana-Champaign, IL. Advantages of the new model (CropCent) over parent models (BioCro and DayCent) are also discussed.