COMMISSION X V2 
Appendix to the INT. ARCHIVES or 
PHOTOGRAMMETRY, Vol. XIL:4, 1956. 
  
  
Aerial Photo-Interpretation and Analysis for Soilsurvey and 
Landclassification purposes 
by Dr. J. S. VEENENBOS, Lecturer in Soil Science, International Training Centre 
for Aerial Survey, Delft — The Netherlands. 
Introduction. 
One of the occupations of the Soil Section of the I.T.C. is the application of airphoto- 
interpretation to agriculture in general and to soil science, land classification, soil and 
water conservation in particular. Besides training of students, its task is to develop such 
methods as to make airphoto-interpretation a reliable means for mapping. Many ex- 
periments have already been carried out in this field, but so many of them have met with 
serious criticism (Kellog 1954, Buringh 1955) that until recently soil scientists viewed with 
great scepticism the possibilities of airphoto-interpretation and were loth to apply them. 
Only as a fieldmap is the value of the aerial photo generally recognized (Stephens 1953, 
Soil Survey Manual 1951) in particular for territories of which no good topographic maps 
exist. This use of the aerial photo represents already — for many reasons which need not 
be discussed here — a great step forward (Simonson 1950) compared with surveys executed 
without the application of the aerial photograph. However, the fact that the photo 
sometimes contains indications with regard to the course of important boundaries of map- 
ping units is considered only as a welcome circumstance. 
A more efficient use can be made of aerial photographs by applying the new techniques 
developed by Buringh (1954) former lecturer in the Section of Soils at the ITC and at 
present working as a soil expert in Iraq. As a soil scientist Buringh was not only aware 
of the possibilities of aerial photography, but also of its limitations. The new methods 
contribute considerably to the speeding up of regional surveys. The need for these surveys 
is obvious since everywhere large agricultural development schemes have been projected 
which require maps of various detail at short notice. The new techniques are in particular 
of importance for surveys on scales 1 : 50.000 and smaller, and mean a considerable saving 
of time and manpower. 
Working methods. 
The application of aerial photo-interpretation for soil survey purposes is subject to 
many limitations. The photo images only show the physical conditions of the earth’s 
surface but not the soil itself: the physical and chemical properties of the different soil 
horizons, their thicknesses, the depth of the whole profile and other characteristics. 
Moreover, in many cases the soil is covered by the vegetation. 
The methods developed therefore cannot be based on direct photo-interpretaion sensu 
stricto. They are limited to an analysis of those differences in terrain conditions which may 
be expected to correlate with the differences in soil conditions. In this way a map can be 
produced on which already are indicated mapping units and boundaries important for the 
purpose of the survey, but which is not yet a soil-, land class or land capability map. 
It is only a so-called photo-analytical map for certain purposes, without any pretention to 
completeness. 
The photo-analytical map can only be converted into a soil map or land capability map 
by means of control in the field, necessary corrections and the addition of further terrain 
data, profile descriptions, sample data, etc. When analyzed in a proper way by an expert 
in soil science, soil survey and soil conservation practices, the photo-analytical map is of 
great help to actual field work. À great part of the time-consuming boundary plotting 
becomes superfluous. From the analysis it is known which boundaries need much control 
and which little; which mapping units deserve much attention and which are of less