Here's a quick table I've put together from various sources showing optimistic "million calories per acre" (MCPA) and "percent protein" (PP) estimates, not really adjusting for NH's climate:
Some of those numbers are pretty disappointing. Buckwheat is one of the healthiest foods in the world, especially for people at risk for diabetes. Beans are also very healthy, but less agriculturally efficient than I had hoped.
Note that sources differ quite a bit due to the decade when the study took place, location, variety of crops, planting methods, yield success, etc, etc, etc. Another significant margin of error comes from differences between crop weight (as listed in the
NDSU page) vs edible weight. For example, when it says 50 tons of pumpkin per acre, how much of it is edible? If all of it,
according to WolframAlpha it would be 13.5 MCPA!
Protein percentages are also approximate. You can find this number out by looking at a food label (ex.
WolframAlpha.com) and calculating P*4/C*100 where P is protein in grams (i.e. 0.05 if 50 mg) and C is the total number of calories. A vegetarian diet becomes unhealthy if it drops below about 25% protein, so eating a lot of legumes, mushrooms, lean veggies, etc and less fruit is very important.