Cultures and communities that still live close to the land as our ancestors once did - farmers and ranchers, tribal people, rural neighbors - all know the wisdom of allowing the land to lie fallow. Even the neighborhood horse co-op that I belong to rotates our herd of horses from one mountain pasture to the next during the growing season. "Leave enough biomass above the ground," traditional wisdom advises, "so that the sun may feed the roots below the ground."

The golden grasses are dormant now -...