Requiring calorie-heavy diets to carry out their punishing workloads, [the Irish impoverished tenant farmers] were soon consuming between 40 and 60 potatoes every day.
I'd imagine how much actual calories that is depends on the size of the potatoes. When potatoes fail, they often do so by producing tiny tubers. The smallest I personally ate were less than an inch in diameter.
Also,people who don't do any farming don't realise how much effort goes into pest/disease control. Especially with potatoes the main pest around here(central Europe) is Colorado Potato Beetle (if that is the correct name for it in English). It is an extremely resilient organism. It very quickly starts tolerating all insecticides that are allowed around here. And between seasons it gets into the ground half meter deep. So unless you want to destroy your soil there is no getting rid of it once it establishes itself somewhere. The only option is to take the crop elsewhere.
It is such a pain in potato growing, during communist times it was used as a propaganda piece. There was (very likely fake) news that US was dropping that beetle from spy planes to ruin the crop. Of course the association of the beetle with one of the US's states didn't help.
Another way to deal with such infestation is to pick it up by hand and lots of people did that back then and now. You can imagine how unpleasant that is. Also you end up with 5l jars full of these bugs...
When I was growing up, in eastern Europe, we had a small potato plot and every few days during the growing season, we would go to the plot, scrape the little red eggs from the leaves, and hand-pick the larva and adult beetles, then crush everything with our feet. I'm guessing this wouldn't scale too well for larger producers, but seemed to be working well for us.
The brought-in-for-some-purpose, escape-to-bush, become-feral, become-pest worked also for cats, dogs, horses ... up-to camels.
I am not aware of Australian Feral Elephants but it may exist.
Would it help to switch crops around between plots or would these beetles stay in the ground for years even if they couldn't find any potato plants to feed on?
There’s a general rule in amateur gardening that you rotate the location of your potatoes on something like a 4 year schedule. In wider agriculture you’re looking at “crop rotation”. I don’t know how this affects specific beetles etc.
It depends a lot on how poor one was. Some had extreme diets of potatoes and milk or buttermilk with rare variations. Others incorporated oats and other vegetables and meat when they could afford it. But the best stuff was taken for sale in Britain.
Imagine 6-12 lbs potatoes and a cup or two of milk, day in, day out!
Selective breeding of potatoes started in the beginning of the 20th century; growing potatoes long to be very large increased the risk of crop failure due to blight (and other problems).
Given that, combined with the lack of modern farming equipment/resources, I think it's fair to say that the average farmer didn't come close to eating 6000 calories a day. Even at very high energy expenditure levels, that would bump you way over a 100kg bodyweight.
Also,people who don't do any farming don't realise how much effort goes into pest/disease control. Especially with potatoes the main pest around here(central Europe) is Colorado Potato Beetle (if that is the correct name for it in English). It is an extremely resilient organism. It very quickly starts tolerating all insecticides that are allowed around here. And between seasons it gets into the ground half meter deep. So unless you want to destroy your soil there is no getting rid of it once it establishes itself somewhere. The only option is to take the crop elsewhere.
It is such a pain in potato growing, during communist times it was used as a propaganda piece. There was (very likely fake) news that US was dropping that beetle from spy planes to ruin the crop. Of course the association of the beetle with one of the US's states didn't help.
Another way to deal with such infestation is to pick it up by hand and lots of people did that back then and now. You can imagine how unpleasant that is. Also you end up with 5l jars full of these bugs...