Globally, biofuel production is growing by about 15% per year even though the environmental and economic costs of current biofuel systems may exceed the benefits. Much of the debate centers on the net greenhouse gas emissions (GHG) of biofuel production. Fertilizer and pesticide manufacture and transport, farm machinery operation, and processing of biomass into fuel all lead to carbon dioxide (CO₂) emissions, but the largest GHG sources for biofuel systems are often nitrous oxide (N₂O) emissions from soils associated with nitrogen (N) inputs from fertilizer application and legume cropping and loss of organic carbon as a result of land use change. Recent papers suggest that full accounting of N₂O emissions using a top down approach negates the benefits of biofuels and that CO₂ emissions from land use change exceed the CO₂ savings from displacing fossil fuel.

Results/Conclusions

Our analysis shows that converting abandoned cropland to ethanol production in the central USA does not lead to CO₂ emissions if conservation tillage is employed and that full accounting of N₂O emissions does not nullify the GHG benefits of biofuel cropping if precision nitrogen management is used. Further analyses need to be conducted to account for the impacts of biofuel cropping on other environmental factors such as water quality, non-GHG emissions and biodiversity, but from a GHG perspective, biofuel cropping can be beneficial when improved land management practices are implemented.