Andy VanLoocke is an Agricultural Meteorologist in the department of Agronomy at Iowa State University. He conducted his doctoral studies including significant portions of this article in the department of Atmospheric Sciences at the University of Illinois Urbana-Champaign. His research interests are focused on assessing the impacts of land-use and crop management on carbon, water and nitrogen cycling. His group uses a combination of agro-ecosystem and hydrology models with micrometeorology and crop physiology measurements in both perennial and annual cropping systems.
As societies and technologies have developed, the ways we use the sun’s energy to grow crops has dramatically expanded. So has the expectation that we produce energy in ways that have minimal impacts on the environment.
Many of the acres that are in cropland today were once home to perennial plant species — predominantly grasses, shrubs and trees. These perennials formed nutrient-rich, self-sustaining ecosystems that lasted millennia.
However, the vast majority of crops produced today are annual species — like corn and soybeans. This has provided us with great resources and opportunities. But in an annual system, it is difficult to synchronize the timing of nutrient availability and uptake by plants. This leads to challenges in retaining soil and nutrients in the field.
One research-supported strategy is to integrate more perennial plants into current cropping systems. Perennial ecosystems have many characteristics that make them beneficial as bioenergy feedstocks and their ability to prevent nutrient losses are an added ecosystem service.
My research has assessed how transitioning some of the cropland in the Mississippi River Basin into perennial crops would impact regional water quality. We developed a model to simulate two perennial grasses used to produce biofuels, Miscanthus and switchgrass, using regional soil, climate and cropland data.
The model indicates that in some locations, nitrate losses went down more than 70 percent. These decreases in lost nutrients have a direct benefit to the quality of water that eventually reaches the Gulf of Mexico.
Our results suggest that perennials should have a prominent place in our portfolio of strategies to address crop production and environmental needs. Also, our scenarios illustrate what’s physically possible, but did not include important social and economic factors that will have a major impact on any future outcome.
Like most complicated scientific challenges, we do not have a silver bullet in perennial bioenergy crops. Instead, we have more evidence of a promising strategy that can contribute to an important local, regional and national issue.