Size of plot for subsistence farming

["Thatcher, Drew" <dht0303@hub.doh.wa.gov>]

Does anyone have any information on the size of a plot necessary to grow 
an individual's or family's food requirements in a subsistence or rural 
residential setting?  I seem to recall an NRC document estimating the 
size but cannot locate the reference.  I'm currently planning on using 
the estimated crop yield (kg/mư) in relation to standard ingestion rates 
per age groups to approximate the land requirements.  

Any insights/references would be appreciated.  Please send your replies 
directly to me.

Sincerely,
Andrew H. Thatcher, MSHP, CHP
Washington Department of Health
360-586-8715 voice
360-753-1496 fax
dht0303@hub.doh.wa.gov