Last week an OpEd in the New York Times called attention to the agricultural activities damaging the Ogallala aquifer, both depleting the aquifer by using water faster than it is replaced, and polluting it with fertilizer and pesticides.
Sprinkler irrigation in the High Plains (Texas AgriLife Research photo by Kay Ledbetter)
The Ogallala provides water to over a quarter of irrigated farmland in the United States, and sprawls 174,000 square miles across eight states from South Dakota to Texas. That water helps farmers grow a lot of corn, and 40 percent of that corn is used to fuel our cars. It takes about 8 ounces of ethanol to move an average car one mile, but using irrigated corn from Nebraska to produce that small glass of ethanol can take 30 gallons of water. Looks to me like that’s a car with a serious drinking problem.
Corn farming is a leading cause of water pollution
Pollution from corn farming is a leading cause of water quality problems across the country, but particularly in the corn-growing Midwest. High fertilizer application rates means nitrogen and phosphorous are running off into nearby waters. In the areas where it’s grown, particularly in the Upper Mississippi River watershed, it pollutes drinking water and produces toxic lake algae that attacks U.S. Senators during their vacations.
Downstream, the fertilizer-turned-pollutant feeds more algal blooms that contribute to the ever- expanding Gulf of Mexico “dead zone” (a large aquatic area deprived of oxygen). That spells big problems for the Gulf economy and some nationally important fisheries, which the National Marine Fisheries Service says produced 1.3 billion pounds of fish and shellfish valued at $661 million in 2008 (which was, admittedly before That Oil Spill, which didn’t help either).
Ethanol is a leading cause of corn farming
Farming in Iowa without stream buffers. Photo Courtesy of the Natural Resources Conservation Service
I’ve written a paper that goes into great detail on the water quality problems of corn ethanol, which you can read here. I talk about how current farming practices often leave fields bare for long stretches of the year, so there aren’t plants to “hold” the fertilizer on the land, and the widespread use of tile drainage, which increases crop yield but also dramatically speeds the flow of pollutants into surface waters.
Demand for corn to make ethanol – driven by government policies – encourages more corn production and thus contributes to this problem of fertilizer “spilling” into our waters. We can do better, and my paper touches on some ways to do so: cover crops, better crop rotation and returning perennial grasses to the agricultural landscape, which would also offer a viable biomass source for clean, cellulosic biofuels. As I argued here last summer, if we want to protect water quality while also reducing U.S. oil dependence, biofuel production must move beyond corn to more diverse and environmentally friendly crops and waste materials.