Sometimes, that means I get a little focused on little things. And often enough, those are stupid little things. Like this time:
It was now Harvest, and our Crop in good Order; it was not the most plentiful Encrease I had seen on the Island, but however it was enough to answer our End; for from our 22 Bushels of Barley, we brought in and thrashed out above 220 Bushels; and the like in Proportion of the Rice, which was Store enough for our Food to the next Harves... (208)I know what you're thinking: "Okay, they harvested enough."
But I was listening to a couple audio books recently, one a history of medieval Europe, the other a history of the crusades (from a European point of view), and both texts talked about some important changes in food production during the middle ages. From my poor memory (which is a big disadvantage with audio books), there are changes from a two field system of crop rotation to a three or four field system of crop rotation, which led to greater production. There's also the introduction of the horse collar, which means greater plowing production, and so more land can be cultivated. And so on.
But by the late middle ages, if memory served, the ratio of seed to harvest had gone from 1:2 (which means you then have to hold half the harvest to reseed next year) subsistence farming to 1:3 or 1:4 not-quite subsitence farming.
But ol' Crusoe isn't doing crop rotation, and he's working in imaginary tropical fields (which in real life aren't suited to barley production at all, though apparently in literature they sometimes are, on which, more later).
But by the 1720s when the book is published (as opposed to 1659, when he supposedly got shipwrecked on the island), Jethro Tull (the agriculture guy, not the band) had done some serious agricultural work to increase production. And other rotation practices (and potatoes!) were being introduced around.
Anyway, I was getting my geek on about this, and look what I found! It's a database of three centuries of crop yields in England!
You have to sign in, which I did, and then play around a bit to find an estate for which there's data for the years and crops you've chosen, but it's just way cool! And if you were a real geek, you'd start looking for somewhere that the database covers AND that has good parish records, and you'd go to town wildly looking at food production and birth/death/wedding information.
In Kent, for example, at a manor called Westerham (owned by Westminster Abbey), in 1312-13, the yield for wheat is 4.46 (that's the ratio, again) and for barley it's 7.56. The next year the barley ratio is above 8. But in 1304-5, the ratio for wheat is 1.32 and for barley 1.25. (That had to be a BAD year.) 1348-9 is even worse (1.27 and 1.19), and then there's apparently a 12 year gap in the records.
I've only explored a bit, but the 8 fold increase seems exceptional, and an increase of 2-4 fold seems typical. (You can explore yourself! It's fun and entertaining!)
What does this tell me about Robinson Crusoe? I think it suggests that someone more 18th century than I should figure out if something similar is available for 18th century crop yields. But I suspect what it tells us is that Defoe doesn't actually know much about farming, and so is at best overestimating yields (especially in a tropical context). At any rate, Crusoe is basically doing BAD medieval agriculture (and not using clover in his rotation, as was being introduced into England in the 18th century, or any crop rotation or fallow field rotation), so he probably shouldn't count on the 10 fold yield. On the other hand, it's a neat little thing in the text that they're willing to wait 6 months so that they can get another crop in before bringing over the Spaniards from where they were captives.
Other than that, well it's more entertaining to look at a database of medieval crop yields than to think about teaching an 18th century novel, but I suppose that says more about me than about the novel.
Anyone have crop yield information for the 16th, 17th, or 18th centuries in England?
Sources (because the geek is strong in me!)
Campbell, Bruce M. S. (2007), Three centuries of English crops yields, 1211‑1491 [WWW document]. URL http://www.cropyields.ac.uk [November 21, 2011.]
Daileader, Philip. The Teaching Company: The High Middle Ages. 2001. Audiobook.
Defoe, Daniel. Robinson Crusoe. Ed. Thomas Keymer. Oxford: Oxford UP, 2007. Print.
Harl, Kenneth W. The Teaching Company: Era of the Crusades. 2000. Audiobook.