In the eighties, my best friend's father was into organic farming in the following manner : he'd squish the slugs he happened to find while walking through his crops and that was his pest control over the top of great land husbandry in the tenth generation. My friend taught himself turbo pascal then vb and the farm tax deduction provided a 286 of my unfulfilled dreams. The son was shortly trading in commodity supplies and even derivatives and taking delivery of GPS equipped combines. But I doubt he could have been successful had he not grown up with his father's wisdom.

I would say the biggest challenge of this kind of field is it is so big so no one actually know everything. The rule also varies between countries. For example, the construction rule in England may be different from the rule in the US