The heavy tillage—heavier than in a conventional field—destroys the tilth of the soil and reduces its biological activity as surely as chemicals would; frequent tilling also releases so much nitrogen into the air that these weed-free organic fields require a lot more nitrogen fertilizer than they otherwise might. In a less disturbed, healthier soil, nitrogen-fixing bacteria would create much of the fertility that industrial organic growers must add in the form of compost, manures, fish emulsion, or Chilean nitrate—all inputs permitted under federal rules.
