Medieval Crop Yields

Question

I'm the DM for a D&D campaign, set in a sort of "realistic-fantasy" setting. There's monsters and magic and stuff, but there's not enough of that for the average medieval community to see much more than the odd zombie attack or passing griffin.

Last session, one of the PCs came into possession of a large manor, which covers 2000 acres of good farmland, 500 acres of meadowland, and a nearby woodland that they have permission to harvest timber and the like from.

I was wondering if someone can help me figure out the yields of the following crops per acre; bear in mind, this would be medieval European technology, toward the later end of the High Middle Ages, specifically. Geographically, the region is similar to Maryland, Delaware or New Jersey.

• wheat
• barley
• oats
• rye
• maize (see note)
• peanuts (see note)
• potatoes (see note)
• flax
• hemp
• wild walnuts (kinda mixed in with the forest)

I've decided to include peanuts, maize, and a few other new-world nightshade crops (e.g. tomatoes and potatoes) in the world for flavor, and so that the peoples inhabiting more southerly climates could still rotate in a pulse crop of some kind (i.e. peanuts) during the growing season instead of wasting a third of their cropland letting it go fallow.

Also, for the grains that can do it, I'd also like to include an increased yield for the winter planting (e.g. planting in October vs. planting in March).

Problem is, Google has been supremely useless in finding a satisfying answer to this question, it's only interested in modern yields.

Edited to provide additional clarity, and to remove dice discussion.

Answer 1

I am not an expert but I did find a few things. Everything I found is about grains, specifically wheat, rye, barley, and oats. I tried to find things on the other plants you asked about, but could not find anything I deemed of use. I don't know if what I found will be of any use, but here it is:

The most common means of calculating yield was the number of seeds harvested compared to the number of seeds planted. On several manors in Sussex England, for example, the average yield for the years 1350–1399 was 4.34 seeds produced for each seed sown for wheat, 4.01 for barley, and 2.87 for oats. https://en.wikipedia.org/wiki/Agriculture_in_the_Middle_Ages#Fields

The average yield of an acre of farming in the Middle Ages was eight to nine bushels of grain (291-327 Liters). http://www.thefinertimes.com/Middle-Ages/farming-in-the-middle-ages.html

Rye = seven-fold render (7 bushels on one acre) (629 Liters per Hectare); does better in poor soil Wheat = 5-fold render (5 bu/acre) (435 Liters/Hectare) in poor soils.. https://www.ibiblio.org/london/agriculture/general/1/msg00070.html

For more info on grain planting: http://www.fao.org/3/y5146e/y5146e07.htm

• They knew that wheat would yield 250 to 300 liters of grain per acre -
• Barley would bring 700-720 liters per acre. (The higher yield for barley was partially the nature of the plant, plus the fact that you put 72 liters of seed into each acre of wheat and 144 liters per acre of barley.)
• Oats yielded 360-400 liters an acre, for 108 liters of seed.
• Peas, an important diet supplement and protein source, gave 300-340 liters per acre, for 108 liters of seed.
• Flax and hemp was also grown, to provide raw material for linen and rope.

Depending on the nature of the land, the size of the farmers holdings, local weather conditions, and drinking habits, about half the land would be sown in barley.
In ale drinking areas (most of England and large parts of France), barley would be needed for making ale.
Barley was also a more productive grain, even though it produced a less tasty meal than wheat.
A third (or more) of the land would be planted in wheat. The remainder would go for peas and oats.

Grain yields of slightly under four times seed grain sown were the norm until the 18th century.(So take your yield and divide by four of under)
There, another burst of innovation brought productivity to ten times seed sown.. In the 20th century, this rose to twenty times. http://www.hundredyearswar.com/Books/History/Agricult.htm

Answer 2

Potatoes are a total game changers.

"Many researchers believe that the potato’s arrival in northern Europe spelled an end to famine there" according to a piece in the Smithsonian*. It is even argued that the far greater productivity gave rise to the age of empires.

If you have the climate - like Ireland - you can get rid of the labor-intensive business of cerial cultivation and get all your carbohydrate from something that it easy to grow, easy to harvest, requires little preparation (none of that threshing and grinding and baking - just boil 20 mins). Like the Irish, your people could live on just potatoes far, far more easily than cereals.

Organic farming - no modern pesiticdes etc -can yield over 10 tons an acre, which blows wheat (3 tons an acre) out of the water. This requires just two hundredweight of seeds, so yield is a factor of 100 which is awesome compared to seed. When a head of wheat gets too heavy, the plant topples; when a potato crop grows well, you get big potatoes.

England had 17 major famines in the century after 1623, but after the potato was introduced famine all but disappeared. Obviously total reliance can lead to total disaster when potato blight strikes.

This depends completely on having high-yield varieties available...but then the same is true of wheat anmd other crops.

• "How the potato changed the world" https://www.smithsonianmag.com/history/how-the-potato-changed-the-world-108470605/

This is a good 1920s source which reckons you can plants less than 10 bushels per acre and get more than 200 back -- https://smallfarmersjournal.com/how-to-grow-an-acre-of-potatoes/

Answer 3

If your players are just trying to figure out their profit that's a bit easier than crop yields.

Throughout D&D systems, land was valued at the profit it could produce in a 5 year period. Typically farmland is valued at 50 gp/acre, meadow land is similar. So 2500 acres x 50 gp / 5 years is 25,000 gp/year or 68.5 gp/day.

(note that this is the profit and it's assumed that the upkeep costs are built into the evaluation of the profit)