In Germany the "primary sector" (this one includes farming, forestry, fishery and mining) consumes roughly 1% (one percent) of the primary energy.
This does not include processing and transportation of the food and producing fertilizers, pesticides or tractors...
So if we eat less meat, if we stop throwing away roughly 50%(!) of our food, if we stop transporting potatoes from North Germany to South Italy for washing and processing and than back again, if farmers use more organic fertilizers and less or no pesticides, would it really be impossible to feed our population easily and still use tractors and machinery? Those can also run on biofuels, a few years ago the use of biodiesel from rapesead was quite common and this rapeseed could have been processed in small local oil mills. (todaqy it is taxed like fossil fuel so the farmers switched back to the still cheaper fossil options)
Fertilizer is made from methane and if you still need a bit of it, why not use biomethane or even RE-methane? ( http://www.solar-fuel.net/
I would like to see more organic farming (I try to buy that stuff today) and I would like to see an end to meat that is produced in "animal factories".
Of course this will come at a cost, but today Germans use only 11% of their income on food (and lots of this money goes to processed food which is way more expensive than tha basic stuff). People are used to it, that they can buy 2-3 pounds of meat or 5 pounds of butter or 20l milk at the price of one our of work at an average salary, so I assume that it will take some time for people to realise that the food of the future might be a bit more expensive than today.
On the other hand people spend 2,50€ on a frozen "ready-to-heat"-pizza while it would take 0,20€ of organic flour, 1,50€ of some pieces of organic ham and cheese, 0,30€ for some mushrooms, 0,05€ for yeast, 0,05€ for sugar, salt and spices and some organic tomatoes at 0,40€ (or window grown) = 2,50 Euro altogether to get a way, way, way more superior pizza with mostly organic grown stuff.
In Germany the by far most expensive "organic" stuff is meat, even eggs are affordable (conventional= 0,10€/egg, organic = 0,20€/egg). But not so many years ago it was common to eat large portions of meat only on Sundays, so maybe 20-30kg meat per person and year would be ok and affordable even at 3-5 times higher prices than meat from "animal factories".
Today the average German eats 83kg meat per year, the average US American 127kg. The average person in Bangladesh on the other side eats 3kg meat/year. http://www.vgt.ch/news/100903-fleischko ... tional.htm
So in my opinion Europe can easily feed its people in a world with rare oil. The farming machinery and the farms do not really use so much oil and most of it could be substituted with biodiesel that can be produced locally from rapeseed.
If some would try permaculture with more labour and less machines, why not. If you can find a market for it and make a living of it. (so far the permaculture people seem to make the money mainly from selling books and tickets to permaculture events, not from selling food, but maybe I'm not up to date here)
In my opinion it would have lots of benefits of farming would become more organic and if animals would be treated like living things again. I assume that this system will be less productive (so far organic farming has lower yields compared to conventional farming and animals take a lot longer to grow), but we do not need todays productivity if we would throw away less food and eat less meat.
It's quite easy for everyone to help this process NOW. Buy organic food and buy less meat, but "organic" meat. It will cost more (1,5x to 5x times more here in Germany) but you could save this money if you don't throw away some of your stuff and if you buy the basic materials instead of processed fast food. Maybe you can even grow some vegetables or spices for yourself.
Just talking in message boards will not change the farming system.