 The <unk> is the outermost layer of Earth 's continental surface and is composed of soil and subject to soil formation processes . The total arable land is 10 @.@ 9 % of the land surface , with 1 @.@ 3 % being permanent cropland . Close to 40 % of Earth 's land surface is used for cropland and pasture , or an estimated 1 @.@ 3 × 107 km2 of cropland and 3 @.@ 4 × 107 km2 of pastureland . 
