Agricultural Research Service (ARS) scientists are finding ways to stem the flow of nitrates that are washed out of crop fields into regional surface and groundwater sources. These nitrates come primarily from nitrogen fertilizers that are not taken up by crops. After the nitrates are flushed out of the soil, they flow into subsurface tile drains that channel excess water away from crop fields.
But these underground drains can facilitate the eventual passage of nitrate-laden runoff into the Gulf of Mexico, the Chesapeake Bay and other water bodies. When the runoff enters these areas, it can intensify the development of oxygen-deficient "dead zones," a condition called hypoxia.
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