this is a quick read, informative, a solution that combines organic and synthetic to meet world food needs
In 1898, the chemist and physicist William Crookes devoted his presidential address to the British Association for the Advancement of Science to ?a life and death question for generations to come.?
At existing rates, he argued, the world?s wheat crop would cease to be able to feed the world?s wheat-eating people within a few decades. Crookes based his forecast on an estimate of the amount of nitrogen available for the growth of wheat crops.
For centuries, farmers had observed that land would become less productive when it was planted year after year. With the advent of modern chemistry, scientists came to understand that these declining yields resulted from dwindling levels of nutrients in the soil as these substances were taken up by crops and removed from the land at harvest.
http://www.inexactchange.org/blog/20.../unlikely-fix/