Grass requires little besides sunlight to grow.
Fertilizer and pesticides aren't needed. Cows
trample decaying matter into the soil, which helps
keep carbon dioxide (CO2)
underground and out of the air. The cows' food
(grass) and the grass's fertilizer (manure) are made
right where they are needed.
contrast, the production of fertilizer for feed
crops can emit 41 million metric tons of CO2
a year. Big farms guzzle fossil fuel and
feed-crop demand has turned vast swaths of rain
forest into farmland. Feed transport, spanning
lengthy trade routes around the world, adds to the
greenhouse-gas tally. The EPA links the jump in
methane emissions to factory farms and their
liquefied-manure systems. Compared with feedlot
cows, grass-fed ones produce more methane but have
lower net emissions.
ŠTime Magazine June 2006