Trust a headline with the words "pig manure" to get readers rock-and-rolling in the comments threads. Lots of good stuff, but I was taken with this post by IaintBacchus that manages to combine a progressive, optimistic sensibility with a mandate for sustainable agriculture.
...We can't go back to preindustrial times, we'd all starve and ruin every bit of arable land in the process. Preindustrial agriculture, by and large, was harder on the soil than agro-industry. Why should we anyway? We've learned a lot about growing food since then. Low energy, low input doesn't mean primitive or stupid, it means exactly the opposite. When crop rotation was found to work back in the late 1500s or early 1600s farmers didn't know why it worked or how to improve on it. It just worked. They didn't know about trace minerals, plant symbiosis, soil conservation, nitrogen-fixing or deep cultivation. We can grow a lot more and healthier foods on the same amount of land than anyone could have even 100 years ago. And it can be done without chemical fertilizers. Whether the energy input is human, animal or fossil fuel doesn't change that.
But you have to close the system on trace minerals, which we haven't had to do in a long time and largely because of petroleum. To do that you either crush and transport mineral bearing rock to use as a soil amendment, use hard well water (if you're lucky and it has the right mineral content) for irrigation, or till your own composted waste back into the soil. And then you still have to use compost or green manure to keep the soil built up.
I agree with you that industrial farming has to go. But we have to [move] forward, not back.