Agricultural runoff generally refers to what leaves a farmer’s field when it rains, as opposed to what stays there. When more nutrients can stay in the field, we avoid harmful outcomes such as eutrophication—algae blooms in water systems that are fed by nitrogen and phosphorous runoff from fertilizers. Here is some US agricultural data to help you size up the situation:
About 300 million acres of land are used for crop farming in the US.
US conservation practices implemented from 2003 to 2006 lowered edge-of-field nitrogen losses by 3.8 billion lbs annually and edge-of-field phosphorus losses by 584 million pounds annually.
That’s nearly enough per year to fill 21,000 train cars stretching 237 miles.
That’s an annual nitrogen fertilizer savings worth $927 million when held in field.
One Ohio farmer who uses cover crops and no-till practices reports soil losses of under 100 pounds per year.
In the Chesapeake Bay region in the mid-Atlantic US, conservation practices used by farmers in 2011 reduced nitrogen and phosphorus farm runoff to rivers and streams by 44% and 75%, respectively.
Cropland conservation across the US’s Western Lake Erie basin in 2012 reduced farm runoff of phosphorus and nitrogen into Lake Erie by 41% and 17%, respectively.
About 46% of US rivers and streams have excess nutrients, and 21% of US lakes have high levels of algal growth.
Nearly 21% of US coastal waters have high nutrient levels.
– Source: US Department of Agriculture, Environmental Protection Agency