Charles Kwit, h* Madhugiri Nageswara-Raoha and
C. Neal Stewart Jr. U2

Introduction

Providing food and energy to an ever-increasing world population is arguably the most challenging issue we face today. Exactly how to proceed on the agricultural side of this challenge, in conjunction with worldwide economic growth forecasts, is the subject of intense interest (see Tilman et al. 2011). Indeed, food and energy production comprise top priorities in the U. S. President’s Council of Advisors on Science and Technology’s recent report on agricultural research (Executive Office of the President 2012), and they are primary components of the U. S. Department of Agriculture’s current priority areas and challenges (through Authorization—7 U. S.C. 450i). One seemingly simple way to successfully address this challenge is through increases in agricultural crop biomass. Historically speaking, these challenges, or at least portions of them, are not new. The ‘Green

department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA. “Email: mnrao@utk. edu; mnrbhav@yahoo. com

2BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Email: nealstewart@utk. edu ^Corresponding author: ckwit@utk. edu

Revolution’ of the 1960s is often heralded for its resultant increases in agricultural biomass and crop yields through traditional and technological improvements in breeding, mechanization, and promotion of irrigation, fertilization, and pest control (see Borlaug et al. 1969; Hesser 2006). At its core, the Green Revolution was primarily focused on food (particularly grain) production, and though its efforts did result in increased yields, biomass for energy production was not emphasized.

The current push for the use of biomass (and other non-biomass renewable energy sources) for energy production is being driven by desires to lessen dependence on foreign oil, and to promote rural development and climate change mitigation. Interest in this area can be found worldwide, as bioenergy crop production comprises a top priority of numerous countries and governments (Sang and Zhu 2011; Nijsen et al. 2012). In the U. S., in the liquid transportation fuel sector alone, recent government mandates put forward in the Energy Policy Act of 2005, the Energy Independence and Security Act of 2007, and the Food, Conservation, and Energy Act of 2008 call for up to 36 billion gallons (> 136 billion liters) of fuel being produced from domestic biomass sources by 2022. This amount would displace 30% of current demands from foreign petroleum sources (U. S. Department of Energy 2011), and may indeed promote rural economic development in certain geographic locations (Leistritz and Hodur 2008). Exactly how to sustainably accomplish such lofty energy-related goals and still provide food and fiber for an ever-increasing human population will indeed prove challenging. Many would agree that one place to start is to ensure that biomass for energy does not compete with biomass for food. This concern is complemented by the need to ensure sustainable practices in bioenergy crop production to reduce carbon emissions, promote environmental stewardship, and conserve biodiversity.