MULTIFUNCTIONAL LANDSCAPES AND WATER QUALITY IN THE MIDWEST

High nutrient loadings in aquatic and terrestrial ecosystems due to runoff and nutrient leachate from agricultural systems has led to research interest in the value of multifunctional landscapes to improve resilience of ecosystems. This six-year study introduced shrub willows (Salix miyabeana SX64), an energy crop, on marginal (low-yielding and environmentally susceptible) areas within a 6.5-ha continuous corn field in east-central Illinois to quantify their impact on the environmental ecosystem services. The primary focus has been on the extent of nutrient interception from an upland corn field as well as evaluating the influence of energy crop placement on the agricultural landscape. Nutrient cycling at the field scale was measured by sampling soil, soil water, groundwater, and vegetation for nutrient loss and uptake. Additional field measurements included soil moisture, groundwater elevation, greenhouse gas flux, transpiration, and biomass. Results show that since willow establishment in 2013, willows significantly reduced concentrations of nitrate leachate compared to corn crop cover. Additionally, willows were comparable to corn in terms of rates of water use and soil N reserve utilization.

Our research has shown that shrub willows could be cost-competitive, when compared on a nitrogen removal basis, to mainstream conservation practices, because the value of the biomass generated compensates for part of the costs of implementation. The recovered nutrients reduce the need for fertilizers, and land is used more efficiently in an annual and perennial double cropping system. Converting “marginal land” to perennial crops may provide biomass feedstock and substantial water quality benefits whose value may exceed that of the costs of production. By intercepting nitrates in the subsurface, willows can efficiently self-serve for their nutrient requirements. This provides yield and water quality improvements at little to no additional cost.