This is a problem biofuel crops share with food crops, gardens and lawns worldwide. All of these plants grow better when given fertilizer. But those fertilizers can have harmful effects on the surrounding environment, and expanded biofuel production could mean a major pollution threat to sources of fresh water.
Many fertilizers contain nitrogen and phosphorus. While both of these additives promote rapid and hearty growth in many crops, they have a downside. Overuse or inappropriate application can leave excess fertilizer in the soil, which then washes through regional watersheds and into streams, rivers, lakes and underground aquifers. And once the chemicals are in the water supply, bad things can happen.
Phosphorus has been implicated as a trigger of localized algae blooms: The tiny aquatic plants feed off it and rapidly reproduce, often killing other plants and aquatic animals by reducing the amount of oxygen in water or by releasing toxic chemicals. Nitrogen in drinking water can lead to a host of health problems, including methemoglobinemia, a condition that prevents infants from utilizing the oxygen in their blood [source: Rosen and Horgan]. Careful fertilizer application can help prevent widespread pollution problems, but expanding biofuel production to meet the world's demand opens the door for more mistakes in this realm.