You speak as if industrial farming is the only way to grow food, but of course that's false.[1] In fact after subtracting out government subsidies (including subsidies on chemical inputs) industrial farm fields are a net loss. TL;DR industrial ag is a way of funneling your tax dollars to chemical companies.

Chemical use can be eliminated (yes, even to grow cereals!) by cultivating healthy living soil. The easiest way is with green mulches/cover crops, which serve the same thermodynamic functions but using sunlight instead of fossil fuel.

* Legumes fix nitrogen. Yep, solar powered.

* Insect predators eat pests. They're part of the food chain, so they're solar powered.

* Deep rooted plants[2] bring up minerals (essentially micro-scale mining on site in response to mineral deficiencies) and make soil. Photosynthesis, natch.

You get the idea.

I don't really have to say that an erosive food system that compromises humanity's only closed-loop habitat is a bad value, do I?

[1] http://www.rand.org/pubs/occasional_papers/OP179.html

[2] e.g. Symphytum