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Staging  Hypothetical     Food          Area of        Area of cornfields
area        crane      requirement    cornfields        (103 ha)available
          population  (103 kg corn)   (103 ha)           assuming fall
          (thousand)                   required            tillage is*
                                     assuming corn
                                      removed is
                                    ______________    _____________________
                                    100%  75%  50%    75%   50%   25%   0%

1            207           609      3.0   4.0  5.9    8.8  14.9  21.0  27.1 
             276           813      4.0   5.3  7.9
             345          1016      5.0   6.6  9.9    
             414          1219      5.9   7.9 11.9

2             39           112      0.5   0.7  1.1    3.0   5.0   7.0   9.1
              52           150      0.7   1.0  1.5
              65           187      0.9   1.2  1.8
              78           224      1.1   1.5  2.2
              
3             54           155      0.8   1.0  1.5    1.6   2.7   3.8   4.9
              72           206      1.0   1.3  2.0
              90           258      1.3   1.7  2.5
             108           310      1.5   2.0  3.0

Combined     300           876      4.3   5.7  8.5   13.4  22.6  31.8  41.1
             400          1169      5.7   7.6 11.4   
             500          1461      7.1   9.5 14.3
             600          1753      8.6  11.4 17.1

*Assumes that tillage reduces corn availability by approximately 90%
(Frederick 1979:50-52).