There is a finite quantity of naturally occurring potash, or potassium carbonate, in the Earth's crust. You can manufacture it by burning down forests of broad leaf trees – let's not go there. Digging it out of the ground is the agri-business-preferred option. Meanwhile, to produce the nitrogen for fertiliser you need to burn an awful lot of – er – crude oil. Yep, the world is going to look like a perforated airflow golf ball by the time we've finished with it.

http://www.telegraph.co.uk/foodanddrink/fo...y-food-is-costing-us-the-earth.html

/S

/ES

.s

^D