Integrating Food and Fuel: How to Manage a 2G Crop Portfolio.

Sustainable intensification of existing agricultural systems has been suggested as a means to increase agricultural output of food, feed, fuel and fiber to meet 21^st century demands. Here we describe three primary means of agricultural intensification – conventional intensification, temporal intensification and spatial intensification – and how they can be used to manage integrated food and second-generation (2G) crop portfolios. While each has individual merits, strategically combining intensification approaches to meet case-specific targets may achieve optimum results. Multiple experiments and case studies from the USA and EU illustrate the potential of combining these approaches for agroecological intensification that can provide ecosystem services while maintaining or increasing economic output, thus striking a balance between ‘land sparing’ and ‘land sharing’. Management strategies will vary by the types of markets available, e.g., food, fuel and/or ecosystem services, and the scale of markets supplied, e.g., small heat and power vs. large cellulosic ethanol. Future research should holistically evaluate the trade-offs between different management strategies. Physical and policy infrastructures must be developed and streamlined to facilitate integration of 2G fuel crops and ecosystem services with traditional food, feed and fiber production.