The negative effects of anthropogenic greenhouse gas emissions on the Earth’s climate system urged efforts on a global scale to accelerate the transition from fossil fuels to renewable energy sources. Bioenergy sources are an important component of the strategy to reduce the dependency of the energy sector on fossil fuels while potentially meeting climate change mitigation goals. In this presentation, I will discuss the results of an experiment where water and radiation-use efficiencies (i.e., WUE and RUE) of corn and a perennial grass grown for bioenergy (i.e., miscanthus) were evaluated in a marginal land site in the Coastal Plain region of North Carolina, USA. Miscanthus used more water and intercepted more radiant energy than corn, but that did not translate to greater WUE and RUE. Results suggested that marginal land features such as low fertility and high air temperatures may constrain productivity even if soil water and radiant energy are non-limiting. Lastly, I will discuss some of the research topics I plan to pursue as I begin my appointment at the University of Manitoba.