Environmental hazards from field crop production

Massive concentration of cattle production has taken place in the United States, with a subsequent concentration of feed grain production. The environmental impacts thus far include increased runoff from fertilisers and pesticides in the U.S. grain belt ending up in the Mississippi River, which could be responsible for a growing offshore "dead zone" in the Gulf of Mexico. Concentrated feedlots also contribute to negative air quality problems, such as increased methane production from manure.