A woman shops in the produce section at Whole Foods in New York City. The company recently announced it would prohibit produce farmed using biosolids in its stores. Stephen Chernin/Getty Images hide caption
fertilizer
Fertilizer runoff causes toxic algal blooms. This one covered a third of Lake Erie in 2011. © Peter Essick/National Geographic hide caption
Thick jets of processed sewage arc out 30 to 40 feet from giant moving spreaders at Birmingham Farm in Kansas City, Mo. Frank Morris for NPR hide caption
A tractor spreads fertilizer at a dairy farm in Morrinsville, New Zealand. Sandra Mu/Getty Images hide caption