4. THE INTERPRETATION OF SOIL SURVEYS FOR PRACTICAL ...

Interpretation of soil survey1. Soil classification2. Soil quality classification3. Soil crop response classification4. Soil use classification5. Soil suitability classification6. Advisory land classification7. Administrative land classification.Soil classijìcation is the grouping of soils according to their inherent characteristics. It isthe fundamental grouping of the soils themselves from the pure view of natural scienceand is the foundation for all the other groupings mentioned.Soil quality classijìcation looks at the grouping of soils from a technical standpoint, that isthe technical qualities important for a certain use of the soils or for their improvement.This may be permeability, ploughability, erosion hazard, occurrence of an impermeablelayer, indications about hardpan, about drainage, about solidity, and many other of thesame kind. Sucha classification is extremely useful for the man who needs only a few indicationsof the soil map in a very definite sense. It is in general necessary for him to havethese indications. For instance a land consolidation engineer cannot be expected to knowall about soil science, so the soil scientist must help him to the essentials needed for thistechnical job. He may sometimes have to discuss these questions with the soil scientistbefore the latter can make a sufficiently useful classification for him.Soil crop response classijìcation gives the response of a crop on a certain soil type for acertain management procedure. This may be for instance the application of variousamounts of one or more artificial fertilizers. It may also be the response to drainage. Theeffect of growth of new varieties on various soils also falls in this category.Soil use classijication, or as it is more generally called, land use classijication, is the registeringof the present use of the soils. In this field we have the special World Land Use Surveyof which Prof. L. DUDLEY STAMP is the eminent leader. This land use classificationcan also be carried out on the basis of the use of the soil type or soil series, in which casewe call it soil use classification. This kind of classification is extremely useful becausethere often is an astonishing lack of knowledge about the actual way soils are used, notonly in so-called developing countries, but also in the middle of our Western so-calledcivilized and very intensively used countries. We consider the soil use classification, however,as an auxiliary classification. We do not think it possible to give accurate predictionson the potential use of soils by studying only this kind of data. For this it is necessary tohave more knowledge about the suitability of soils in general and especially, of course,about the particular soils themselves.47