When properly managed, raising animals on pasture instead of factory farms is a net benefit to the environment. To begin with, a diet of grazed grass requires much less fossil fuel than a feedlot diet of dried corn and soy. On pasture, grazing animals do their own fertilizing and harvesting. The ground is covered with greens all year round, so it does an excellent job of harvesting solar energy and holding on to top soil and moisture. Grazed pasture removes carbon dioxide from the atmosphere more effectively than any land use, including forestland and ungrazed prairie, helping to slow global warming.
It’s a different story in a confinement operation. Here, the animals are crowded into sheds or kept outdoors on barren land and all their feed is shipped to them from distant fields. On those fields, the crops are treated with fossil-fuel based fertilizers, sprayed with pesticides, and planted, tilled, and harvested with heavy equipment. Each of these operations requires non-renewable fuel. Then the feed is shipped to feed manufacturers where it is dried, flaked or pelleted, and mixed with other ingredients and then, finally, shipped to the waiting animals, using yet more fossil fuel.
There is also a night and day difference in “manure management” on the two systems. On well-managed pasture-based farms, the animals spread their manure evenly over the soil where it becomes a natural source of organic fertilizer. The manure improves the quality of the grass, which increases the rate of gain of the animals. It’s a closed, sustainable system.
On factory farms, the excrement builds up in the feedlots and sheds where it fouls the air and releases ammonia and other gasses to the eco-system. The fumes stress and sicken the animals and farm workers, and they lower the quality of life of people in nearby homes. To get rid of the waste, it is shipped to nearby fields where it overloads the land with nutrients. The excess nitrogen and phosphorous pollute the soil and ground water and drain off into streams, rivers, and estuaries where it can create “dead zones” that threaten the fish population.