Fifteenth International Conference on Environmental, Cultural, Economic & Social Sustainability

Abstract

Carbon footprint from agriculture is directly proportional to the amount of fertilizer applied and indirectly proportional to agricultural management practices such as use of cover crop and tillage. Soil Carbon-Nitrogen ratio (C:N) is important because it provides an overview of change in carbon and nitrogen stock due to change in land use. Existing databases that model agriculture have high levels of uncertainty associated with processes such as bacterial denitrification and nitrification, application of synthetic fertilizers, tillage and crop residues; we hypothesize that the use of scaling factors to estimate carbon footprint underestimate nutrient management in a watershed. Therefore, in this study on-farm CO2 emissions for the crop rotation were simulated using a watershed-scale biogeochemical model called SWAT. Simulated physical processes were then coupled with IPCC guidelines for C-footprint estimation. A biological agricultural scenario was considered with a continuous corn–soybean–oats rotation using alfalfa and cereal rye as cover crops, conservation tillage using lemken cultivator, and a mix of conventional and biological fertilizers while conventional scenario used no cover crop, intensive tillage and conventional fertilizers. Biological agricultural practice, showed 25% reduction in carbon footprint than conventional practice. C-footprint from bio-based practice could be further reduced to 27% and 33% by adopting strip till and no till practice respectively. Results concluded soil C:N was rich in nitrogen indicating residual nitrogen as the major source of N2O emissions. Bio based approach had higher soil C:N ratio than conventional baseline scenario. The result showed that with the increase in soil C:N ratio, on-farm emission decreased.