Energy and Carbon Budgets in Transitional Cropping Systems in Minnesota.

Energy and carbon budgets were constructed for a wide range of cropping systems during the transition from conventional cropping practices. Cropping system treatments included factorial combinations of: conventional and organic systems (CNV and ORG), conventional tillage and strip tillage (CT and ST), corn-soybean and corn-soybean-wheat/alfalfa-alfalfa rotations (2YR, 4YR), with fertilizer/manure applied at recommended rates or no fertilizer/manure (YF, NF). Carbon-equivalent emissions associated with production activities and input use were highest for the CNV-2YR-YF with either CT or ST (184 and 183 kg ha^-1, respectively). Despite higher diesel fuel use, carbon-equivalent emissions for the ORG systems were at least 30% lower than for the highest CNV system, due to reductions in emissions from pesticide and fertilizer manufacture and transport. Soil carbon changes can be linked to carbon inputs from biomass and biological indicators of soil quality.  The relationships between direct and indirect energy use and total carbon balance in plant and soil will be defined.