||Will biofuels help to wean the US off of oil, or at least off of foreign oil supplies? While politicians and the press answer with a resounding ``yes’’, the answer is not so simple. First, we need to understand what is meant by the term ``biofuel’’. All biofuels are organic, energy-storing materials. Although they are widely perceived as new forms of energy, many biofuels are of ancient origin; crop residues, wood, and dried manure have been used for centuries as solid fuels. What is new is our attempt to make use of uniform feedstock to create liquid fuels, such as diesel, ethanol, and oil, on a large scale. The cultivation of crops like corn, oil palms, and switchgrass to provide such feedstock creates high-input low-diversity (HILD)agricultural systems. HILD systems are characterized by large-scale monocultures subject to large inputs of fertilizer, irrigation water, and pesticides.