Innovative approaches to agricultural land management are needed to address the future challenges of climate change; meet the nutritional, energy, and other basic needs of future populations; and improve agricultural sustainability and resiliency. The use of second-generation biofuels and other low-carbon energy sources is one solution to reducing greenhouse gas emissions, thereby mitigating the impacts of climate change. Their use is also proving to have a beneficial impact on environmental problems related to excess nutrients from agricultural production.
The productive capacity of agricultural lands is highly variable. Even at the field level, some areas are highly productive, while others are low-yielding. Coincidentally, these less productive or marginal areas usually exhibit water stress (too wet or dry for commodity crops) and susceptibility to environmental degradation, such as high nitrate leaching, soil erosion, etc. Perennial bioenergy grasses and short rotation woody crops (SRWCs), such as shrub willow (Salix spp.), are better suited to these marginal areas because of their perennial growth habit and distinct physiological features (e.g., massive and deeper rooting system, dense aboveground biomass growth, and higher nutrient and water efficiencies).
As part of the U.S. DOE-funded project entitled "Biomass Production and Nutrient Recovery," an on-going field study is being conducted in east-central Illinois. In this study, shrub willow is planted within marginal areas and buffer zones of a 6.5-ha continuous corn field. Under this cropping system, corn is managed under business-as-usual practices. The shrub willows do not receive fertilization, but instead are expected to draw leached nutrients from the adjacent corn fields. Producing biomass while intercepting excess nutrients maximizes the use of and economic return for an expensive production input. This approach maximizes biomass production while minimizing off-site nutrient leaching losses, having the added benefit of protecting nearby surface water and groundwater resources. We are currently evaluating the environmental, economic, and ecosystem services benefits of implementing this and other bioenergy buffer systems through modeling analyses with the goal of scaling up to larger regions.
Results of the Illinois study have shown that careful placement of a bioenergy crop like shrub willow can reduce off-site nutrient loss from corn fields through passive reuse of excess nutrients (fugitive nitrogen). Emissions of nitrous oxide (a greenhouse gas) from soils under shrub willow plots were also significantly reduced compared to areas under corn. Soil water nitrate concentration in willow areas was reduced by 87% relative to the adjacent corn. This significant reduction in nitrate could be a critical and cost-effective way to address the problem of excess nutrients from agricultural production in the U.S. Midwest. This in turn could have a beneficial impact on large-scale environmental problems like hypoxia in the Gulf of Mexico (that results from the discharge of excess nitrate via the Mississippi River).
Growing Shrub Willow as Bioenergy Buffer on Corn Production System | Conservation Matters from SWCS Events.
Jules Cacho provides a two-minute summary of his work on bioenergy crops for the SWCS "Conservation Matters" video series. Recorded at the 2017 72nd SWCS International Annual Conference in Madison, Wisconsin. Presentation: The viability of growing shrub willow as bioenergy buffer on intensively managed agricultural fields of U.S. Midwest.
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