Super awesome!
I imagine that most of the time, you don't even need to dig giant trenches, though.
Sepp Holzer grows citrus in the freezing alps above ground. Their average temp is 5C.
Think about that for a second -- your garage is housing the equivalent of 120 horses. How much "labor" is that?
Now, we don't really notice that when everything is working well and the gasoline keeps flowing. There are calculations that figure a gallon of oil has something like two weeks of 8-hour/day manual labor embedded in it, energy-wise (using the cute term "energy slaves"). Synthentic fertilizer is basically spending a crap-ton of energy to fix nitrogen -- google "haber bosch energy".
Especially with the covid supply chain disruptions going on now, though, I've been rethinking what "scale" means or if it's even the right metric to be going for. Permaculture has been really interesting to me last few weeks because it doesn't try to go for "scale" per se (though there are claims that properly done it's more productive per acre), but rather it tries to cycle as many energy flows as possible.
So if your yardstick is "how many bushels of corn per acre can I grow?" then yeah, permaculture doesn't 'scale'. But if your yardstick is "how do I get the most output while minimizing energy inputs" and accept that outputs aren't necessarily a monocrop but can be complementary outputs (corn + legumes + animals + fertilizer), then it starts to get really interesting.
I'm a developer not a farmer, but the systems-level thinking I've seen in the permaculture community is extremely fascinating. There's 'labor' embedded everywhere, the question is are you counting it.
No one who does this thinks it's efficient. It's just a fun hobby.
Erm ... clearly you have not met true believers of the movement ..
Not it is not. A horse needs food, also if it is idle. A car does not.
And labour does not equal energy. The advancement of humanity did happen, because we found other energy sources and apply them, so machines can do the hard labour.
(now it is a struggle to adjust that system, but I believe globally the sun is excessively shining to provide all the energy we need)
"I'm a developer not a farmer, but the systems-level thinking I've seen in the permaculture community is extremely fascinating"
And to this I agree very much, but I would still rather bet on more traditional ways of feeding the world.
That said, I think there is a lot of interesting stuff in permaculture design. But in a lot of cases it is a bit of a pyramid scheme / agile consultancy feel going on.
Definitely, Sepp Holzer is sadly a prominent example of this as well. There was a case of a new project, where a naive women, a true believer of permaculture, invested all her money in a permaculture school project under the guidance of Holzer, where all the ordinary farmers could learn how much more efficient permaculture is. And it failed spectacular and ended in court. [german wikipedia for more, english version is very small]
He has a book Restoration Agriculture you can find on Amazon, etc.
Permaculture is nice and I would like to see more of it adopted, but I don't see at all, how we could feed the current world population with it. With general ecologocal farming, yes.