Background
The authors write that "recently, the prospect of biofuel production on a large scale has focused attention on energy efficiencies associated with different agricultural systems and production goals," but they note that "few empirical studies comparing whole-system multiyear energy balances are available." In fact, they say that insofar as they are aware, "there are no studies that directly compare food vs. fuel production efficiencies in long-term, well-equilibrated cropping systems with detailed descriptions of fossil energy use."

What was done
To initiate the filling of this data void, Gelfand et al., as they describe it, "used 17 years of detailed data on agricultural practices and yields to calculate an energy balance for different cropping systems under both food and fuel scenarios," comparing one forage and four grain systems in the U.S. Midwest that included "corn-soybean-wheat rotations managed with (1) conventional tillage, (2) no till, (3) low chemical input, and (4) biologically based (organic) practices, and (5) continuous alfalfa," where they "compared energy balances under two scenarios: all harvestable biomass used for food versus all harvestable biomass used for biofuel production."

What was learned
Overall, the three researchers report that "energy efficiencies ranged from output:input ratios of 10 to 16 for conventional and no-till food production and from 7 to 11 for conventional and no-till fuel production, respectively."

What it means
Gelfand et al. say that their analysis "points to a more energetically efficient use of cropland for food than for fuel production," and that the large differences in efficiencies attributable to the different management techniques they evaluated suggest that there are "multiple opportunities for improvement." Thus, as the debate over the desirability of using good cropland for biofuel production continues to rage, it is becoming ever more evident that food should be the world's priority.