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.…