When in a food shortage- it is not important just to get food- but also what kind of food.
For example 2 cups of lettuce only have 20 calories! The average daily intake for a woman is 1,500 calories. So, to even make 1/15 of a woman's daily intake she'd have to eat 10 cups of lettuce. Not a good thing to grow or ship to a country in need.
Well, when planting, surface area- its not just about how much land you
have to plant, its also about how many calories and nutrients come from
that plant. When making decisions on what to plant, not only
climate/ability/soil type must be taken into consideration...the area
it takes and the caloric value of a particular food is also important.
Like beef takes alot of area but provides only so much calories per
that area. It makes it inefficient because per square foot (or whatever
area you want to measure by) the calorie output is low.
From the above website, I looked up some caloric dense foods.
Avacado's -- the most caloric dense fruit there is!
Penuts & penut butter- very dense, provides both fat and protien
Also from: http://www.livestrong.com/article/32630-list-high-calorie-high-fat/
mentions seeds and their high caloric properties.
So, when facing a food shortage it is important to know what would be good to plant...immediately, and then turn it over to whatever other crop after sustainabiltity has been reached. Just some things to think about :)
Japan is interesting because it is such a looong island chain. It spans a wh*** bunch of different climates based on if you are in the north or the south of the country. It means there is alot of opperunities to grow different foods and maximize intake for its people.