Groundwater Recharge Characteristics and Subsurface Nutrient Dynamics Under Alternate Biofuel Cropping Systems in Wisconsin

Background/Need: High yielding cropping systems such as perennial switchgrass and hybrid poplar trees have been proposed to supply feedstock to the latent cellulosic ethanol industry. Maintaining or expanding acreage in perennial crops and some pastures (or even idle Conservation Reserve Program (CRP) lands) will reduce acreage devoted to corn. While these systems are well known for producing large quantities of aboveground biomass, an important consideration is their relative sustainability in a variety of agroecological settings. The potential for widespread introduction of non-traditional agronomic cropping systems and management for cellulosic biofuel production has generated concerns about associated unintended environmental consequences. Knowledge gaps exist with regard to water and nutrient dynamics when alternative cropping systems are used in the context of meeting the needs for biofuel production. Few studies have investigated subsurface drainage from cellulosic biofuel crops under continued biofuel cropping management within the same environmental conditions.
Objectives: The major goal of this project was to further understanding of water and nutrient dynamics associated with biofuel cropping systems. The specific objective was to measure subsurface (below the root zone) drainage and nutrient (N, P, C) fluxes for continuous corn (CC), monoculture switchgrass (SG) and hybrid poplar (HP) cropping systems.