The phrase “a double-edged sword” describes something that is beneficial in some ways but problematic in others. One example is removing maize stover (the husks, stems and leaves of corn plants) from fields. Maize stover is used to make cellulosic ethanol, a renewable biofuel. And renewable biofuels are beneficial to the environment. However, removing the stover can harm the environment because it can cause the soil to erode and lose nutrients.