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In the primary research, from which this paper is derived,
income is expressed as the production value per acre (or amount
the farmer could afford to pay per acre for land, based upon
its production). The value is obtained through the capitaliza
tion formula:
Return per acre
7%
x 100
Production Value
Where: 7% represents the interest rate prevailing for the
farmer's land mortgage.
A very troubling assumption to many who have reviewed
this work is the modeling of individual farm productivity by
using average production values. This may account for some
of the errors found, however it is assumed that the efficient
farmer will not just have high yields, but will also have
more acreage in high return crops as compared to the poorer
farmer. It should also be noted that usually the difference
in output between two crops (for example hay and corn) is
much greater than the difference within a given crop.
With this very simplistic outline of what is a rather
complex system one may use the aerial photograph and apply
the new methods suggested here.
APPLICATION OF THE METHOD
The method used to interpret the photographic image
requires one to be able to differentiate agricultural crops on
1:15840 mid-summer imagery and to be able to determine the type
of farm. All further contacts with the image require measure
ments only.
Experiments at the University of Waterloo showed that
117 of 120 geography students who were studying their first
course in aerial photographic interpretation, could interpret
crops with an accuracy of 82 to 100 per cent. The top one-
quarter of the class achieved an average accuracy of 95 per
cent.
Farm type may be identified by using the Crop Triangle
developed in earlier work (Ryerson & Wood 1971) (and computer
ized for this work) and careful analysis of buildings.
Table II provides an indication of the method's built
in complexity. The interpreter then uses crop acreage and
building size to determine the number of livestock and the
total output of livestock and crop products for each farm.
All further calculations were done using a high speed digital
