Earth as an apple

I sometimes wonder how much we can take from the earth? Often, keynote speakers at international conferences explain this principle by using an apple. First, you pretty much cut the apple in half or more to remove the oceans (70%, unsuitable for land based farming). Then you further cut down the apple to remove the desert areas, swamps and mountains, also not very suitable for growing crops or building farms. What is left is just a very small piece (some say 1/32nd) of the apple, that we can us