Nixing Nitrate Flow from the Farm

When early settlers arrived in the Midwest, they began constructing an underground network of tile drains to channel water away from the soggy prairies, which then became some of the most fertile crop fields in the country. But now when nitrate from soils and fertilizers leaches out of those flourishing fields, the subsoil engineering also facilitates the discharge of nitrates into nearby streams and rivers. Because these local waterways are part of the vast Mississippi River Watershed, the nitrates are eventually transported into the Gulf of Mexico, where they can feed the development of oxygen-deficient “dead zones.” But nitrate management isn’t just an issue for the folks downstream. The U.S. Environmental Protection Agency has mandated that nitrate concentrations in drinking water—obtained either from surface water or ground water—cannot exceed 10 parts per million. Minimizing nitrate loss can also help producers obtain the greatest economic returns from the application of expensive fertilizers. So everyone benefits when nitrates are stopped from contaminating local water supplies