Dairy cows that produce USDA-certified organic milk also produce manure that may gradually replenish soil nutrients and potentially reduce the flow of agricultural pollutants to nearby water sources, according to findings by Agricultural Research Service (ARS) scientists and colleagues.
Cows on organic dairy farms generally consume forage feeds cultivated on soils that are fertilized with manure and compost rather than manufactured fertilizers. This organic management, in turn, may significantly affect how easily nutrients are converted in soil into forms readily taken up by crops.
ILRI Clippings 