This result suggests little hope for alternatives in the US Corn Belt for people heavily invested in the promise of non-food bioenergy crops. Yet opportunities do exist: we found that annual grain crop rotations can remain profitable when incorporating a 2G crop as a winter cover crop, which could help improve the environmental performance of corn production. In addition, high-yielding woody crops may become a profitable perennial feedstock if more economically efficient harvest methods are developed, or if biomass prices approach $80 Mg−1 – a situation that is not inconceivable.

Despite the many environmental benefits associated with 2G crops, their implementation across the US corn-belt landscape hinges on their economic performance relative to grain crops. It's not that the environmental benefits don't matter. Indeed, in future economic analyses of these cropping systems our team will explore the potential for incorporation of ecosystem service values to close the profitability gap between 2G and food crops. Rather, it’s that the people who will adopt and manage alternative crops are farmers, and farmers are business people – ensuring the profitability of their enterprise is key to their decision-making processes.

Our economic analysis was based on an ongoing experiment, referred to as the Landscape Biomass Project, in central Iowa. The main goals of this project are to develop, refine and implement a portfolio of sustainable bioenergy feedstock production systems that together (1) contribute significantly to reducing dependence on foreign oil; (2) have net positive social, environmental, and rural economic impacts, and (3) are compatible with existing agricultural systems. Our research team is collecting a vast set of data on the ecological impacts of five novel cropping systems across a series of agricultural landscapes in an effort to reach these goals.

• This article was updated on 23 October 2013, following author feedback.

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