Sustainable energy crop production

Biofuels currently supply a small portion of the world's energy needs but this is increasing due to mandates intended to reduce use of fossil fuels and the associated environmental impacts. However, the potentials of plant based feedstocks to substitute for fossil fuels and mitigate environmental impacts are uncertain. Much of the uncertainty is related to the quantification of nitrous oxide (N2O) emissions from feedstock production and the extent to which use of grain and biomass for biofuel feedstocks leads to land use conversion for compensatory cropping (indirect land use change). Current consensus is that sugar cane, perennial cellulosic crops, and waste biomass provide clear benefits while corn ethanol and oil seed crops may provide benefits if indirect land use change is assumed to be negligible and if recommended crop management practices, such as use of enhanced efficiency fertilizers and minimal tillage, are employed. Future research should better quantify N2O emissions from different feedstocks grown in different regions, the ability of best management practices to mitigate these emissions, and the potential for marginal lands and increased crop yields to supply biomass.