Taras E. Lychuk1, Roberto C. Izaurralde1, Robert L. Hill2
1 Joint Global Change Research Institute,
Pacific Northwest National Laboratory and the University of Maryland
 2 Department of Environmental Science and Technology, University of Maryland

Simulations of crop productivity under climate change suggest an increased vulnerability of crop yields to elevated temperature, water availability, nutrient stresses as well as a deterioration of soil functions. Biochar is viewed as a potential technique to adapt / mitigate climate change because of its positive effects on crop productivity, greenhouse-gas emissions, soil physical properties, and soil carbon sequestration. The objectives of this paper are to (a) describe new algorithms developed in the EPIC (Environmental Policy Integrated Climate) model to quantify the influence of biochar additions on crop productivity and selected soil properties (e.g. cation exchange capacity [CEC], pH) and (b) report on the ability of EPIC to reproduce observations reported in the literature of a 5-yr experiment performed on an Amazonian Oxisol amended with biochar at rates of 0, 8, and 20 Mg ha-1. Short- and long- term responses included crop yield and CEC, pH, bulk density, and organic carbon.  Concurrent with observations, simulated yields of biochar amended treatments were significantly different than control yields at p<0.05. Soil pH increased from 3.9 to 4.17 after 5 years of biochar application in the field study while EPIC simulated a final soil pH of 4.19.  Soil CEC increased from 9.76 to 10.9 cmolc kg-1 in the field with biochar addition of 20 Mg ha-1. The corresponding CEC simulated by EPIC was 11.5 cmolc kg-1. EPIC simulations also reproduced observations of increased soil organic carbon and decreased soil bulk density. In conclusion, the algorithms introduced in EPIC contributed to satisfactorily capture the observed effects of biochar additions on crop productivity and soil properties of an Amazonian Oxisol. Further tests of the biochar algorithms in EPIC will be conducted as results of ongoing biochar studies become available.