Why Worms (and Microbes) Are Catching on As a Manure Pollution Solution

Anthony Agueda, a third-generation California dairy farmer, pulls a rake through a bed of dark, wet wood chips on his family’s land in Hickman, a tiny town in the state’s agricultural heartland.

He reaches down with both hands and pulls up a clump of muck, turning it over to reveal a half-dozen squirming red earthworms. There are likely hundreds of thousands more wriggling just under the surface of the three-foot mound of wood and crushed river rock before us, which stretches across the equivalent of six football fields. These natural materials form a biofilter that may dramatically cut the methane, nitrous oxide, and water pollution generated by the massive amounts of manure that hundreds of Holstein cows produce each day.