Threats to the Natural Environment
The natural environment also suffers in many ways from factory-farming practices. Sometimes the damage is sudden and catastrophic, as when a ruptured lagoon causes a massive fish kill. At other times, it is cumulative -- for example, when manure is repeatedly overapplied, it runs off the land and accumulates as nutrient pollution in waterways.
Either way, the effects are severe. For instance, water quality across the country is threatened by phosphorus and nitrogen, two nutrients present in animal wastes. In excessive amounts, nutrients often cause an explosion of algae that robs water of oxygen, killing aquatic life. One toxic microorganism, Pfiesteria piscicida, has been implicated in the death of more than one billion fish in coastal waters in North Carolina.
Manure can also contain traces of salt and heavy metals, which can end up in bodies of water and accumulate in the sediment, concentrating as they move up the food chain. And lagoons not only pollute groundwater; they also deplete it. Many factory farms use groundwater for cleaning, cooling and providing drinking water.