1/4 earths terrestrial surface for grazing, 1/3 arable land and 40% of cereals for livestock feed
"A quarter of the earth’s terrestrial surface is used for ruminant grazing, and a third of global arable land is used to grow feed for livestock, accounting for 40% of total cereal production. Animal agriculture uses far more land resources than any other human activity."
Food and Agriculture Organization of the United Nations (UN FAO), "World Livestock 2013: Changing disease landscapes" (Rome, 2013), 2, accessed October 2, 2014, http://www.fao.org/docrep/019/i3440e/i3440e.pdf.