It can be stated that soil science occupies a central position in the agricul 
tural development plan. However, many factors in this plan which are of the 
utmost importance for the cost-benefit ratio of the project are beyond the 
scope of the soil scientist. 
The only conclusion the soil scientist can, and is allowed to draw from pure 
pedological reasoning is whether or not the soil has certain agricultural poten 
tialities. The soil scientist can give and has to give a classification of soil 
potentialities, but he cannot give a complete land classification. 
Land classification and priority for development of certain areas can only 
be given when there has been teamwork in a broad field by a group of experts. 
Each of these technicians will have to study the aerial photographs for 
his own purpose, and in many cases the most accurate methods of photo- 
grammetry will hardly be sufficient. In all cases, a large part of the investiga 
tions must be carried out in the field. 
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
Topography 
The topography or morphology of the landscape is a property used by 
every soil surveyor in composing his soil map, and more especially when photo 
interpretation is applied. From the engineering point of view, such a topograph 
ical interpretation in the soil work - no matter how it is adapted to engineering 
needs - has great disadvantages. The soil surveyor is working with relative 
topographical differences, whereas the project engineer has to base his calcula 
tions on exact and absolute figures and differences. The soil surveyor is unable 
to give these figures, and consequently it is impossible to give a picture of the 
realisation of a drainage or irrigation system, even when one is working with 
good quality aerial photographs. The relationships between technical require 
ments and the external factors, such as lift of a pumping station, height of 
dykes and so on, cannot be given, so that it is not justified to draw conclusions, 
based only on soil survey. 
Discussion 
Several of those present expressed their agreement with the ideas put forward by the speaker. 
From questions and remarks by Messrs. Maignien, Pascaud (both of France), Curtis (U.K.) 
and Kux (U.S.A.) and the answers given by the speaker, it became apparent that the formation 
of an integrated team of scientists is always desirable. However, lack of funds or of capable 
scientists frequently make its formation impossible. Under these circumstances, the soil 
scientist is often asked for advice that is beyond the scope of his field of science, but in which 
he may have some practical experience. It may also happen that data furnished by him are 
used for applications for which they were not intended. None of these is desirable, and should 
be avoided by the formation of a team of scientists, as indicated by the speaker.