I remember a story on TV years ago about a father and son farmers in the Midwest. The son came home from WWII and used all the modern techniques - fertilizers, herbicides, pesticides. His dad gave him some land to work, and he was excited.

Then it turned out that his yields weren't much better, and he was spending waaay more money than the old man. So he dropped it and went back to the old ways - natural fertilizer, crop rotation, etc.