Well, I did say that the spare could go to chickens

Part of the excess that I mentioned in the previous post, you'll note, I reduced by 2/3rds - effectively seed, waste etc.
I have also been reading a bit more of Astill & Grant's
The Countryside of Mediaeval England, ISBN1-0904490-01-8 - It is part of the BBC History Magazine Classics range and I would say a must for the research library!
Any-hoo, they note that crop yields were 10-20 bushels per acre for wheat. The Harn yields are at the low end of this range.
A&G note various interesting extra considerations.
• that problems were wastage, weeds, the need for seed etc.
• Harn manors will likely have a corn/cereal mix, but most mediaeval manors had a prime crop and lesser amounts of other crops. Oats in the north, Spelt Wheat in Wales and the South. Barley was fairly ubiquitous.
• Wheat was for bread, Oats as fodder and oatmeal, Barley for ale/beer (allocation was 1 gal/day! in one record, but it was small beer 1 1/2% alcohol) and Rye for bread, which was not as nice as wheat bread, and for wattle and daub and thatching.
But, yes I did try to account for seeds in a sense - the 10 acres cereal should feed over the average of a household, especially as a child requires less than an adult - I would assume the remainder would go to wastage and seed.
BTW, Sophia's quoted number of 4 acres per person would work if you take the standard of HarnManor that 45% of cleared land is cereal crops. An average household is 4.5 persons. 10 acres means that 2.2 acres supports 1 person = 4.9 acres assuming 45% cereal. You can reduce the amount as the extra acreage alos produces fruit and veg.
rgds nick