Integrating Perennial Bioenergy Crops into Agricultural Landscapes for Biomass and Soil and Water Quality Benefits.

Mitigating impacts of climate change and meeting nutritional, energy, and other basic needs of future human population as well as making agricultural production resilient requires innovative approaches to manage our limited land and water resources. Increased use of second generation biofuels and other low-carbon sources of energy is one of the solutions to decrease future greenhouse gas emissions and thereby mitigate impacts of climate change. On the other hand, more productivity is expected from agricultural lands, but production intensification could further impact the integrity of our finite land and water resources. With their perennial growth habit and distinct physiological features (e.g., deeper rooting system, higher water and nutrient efficiencies, etc.), incorporating second generation bioenergy crops in a predominantly agricultural landscape could provide feedstock for biofuels and address sustainability issues associated with commodity crop production. Results of a study at a site in central Illinois, USA showed that careful placement of a bioenergy crop like shrub willow (Salix spp.) can passively reuse excess nutrient from adjacent continuous cornfields and thereby reduce off-site nutrient loss with a beneficial reuse of the fugitive nitrogen. Willow biomass production per ha was comparable to a non-fertilized willow monoculture of the same age, nitrogen use efficiency was increased by up to 18.8%, and annual reduction in soil water nitrate concentrations were found to be up to 87% (p = 0.007) compared to adjacent corn without negative impacts on major soil nutrient concentrations including soil organic carbon. This significant nitrate reduction could be a critical tool to cost-effectively address excess nutrient from agricultural production in the U.S. Midwest and therefore large scale problems such as the Gulf of Mexico’s hypoxia.