I use this resource for developing settings for DMing various games:
http://www222.pair.com/sjohn/blueroom/demog.htmIt's pseudo-intellectual, but easily applicable.
I also did a JSTOR search on my university's account for medieval crop yield information. Here are a few estimates for wheat production:
5.68-15.92 bushels/acre for "low productive lands" (maybe badlands in BM?), 10.26-22.98 bushels/acre in better/moderately fertile lands.
Cleaning the Medieval Arable
David Postles
The Agricultural History Review , Vol. 37, No. 2 (1989), pp. 130-143
(this is an article about WEEDING PRACTICES in Medieval England. God I love academics.)
9 bushels/acre in English fields primarily
Convertible Husbandry vs. Regular Common Fields: A Model on the Relative Efficiency of Medieval Field Systems
Harry Kitsikopoulos
The Journal of Economic History , Vol. 64, No. 2 (Jun., 2004), pp. 462-499
5-36 bushels/acre, depending on the year
Crop Failures on the Winchester Manors, 1232-1349
G. H. Dury
Transactions of the Institute of British Geographers , New Series, Vol. 9, No. 4 (1984), pp. 401-418
Somewhere in the low teens seems about right for bushels per acre.
Of course, that's an annual measure. That's crop yield in wheat for a WHOLE YEAR. And arable land probably isn't even close to 100% of the land of any BM continent.
So for yield probably assume arable land is somewhere between 15% and 50% of a region's area (depending on type and specific geography maybe). Then figure out how many acres there are (simple conversion I think). Then multiply by some value that strikes your fancy in the ranges given, again, probably adjusted for region type. That supplies you the total ANNUAL yield, if we want to be historically correct.
PS- I'm still in favor of adopting a 1-harvest-a-year model... pretty pretty please?
