ABSTRACTbility arises mainly from the limitations of the discrete data model and from the polygon-based mapping prac- A geographical information system (GIS) or expert knowledge-tice employed in conventional soil surveys.based fuzzy soil inference scheme (soil-land inference model, SoLIM) is described. The scheme consists of three major components: (i) a Zhu (1997a,b), Zhu and Band (1994), Zhu et al.model employing a similarity representation of soils, (ii) a set of Zhu et al. (1997) survey approach are first discussed to provide a context for the SoLIM, which is followed by an overview of the SoLIM. The assessment of the SoLIM for soil survey D etailed soil spatial and attribute information is through two case studies is described in the third part required for many environmental modeling and of this paper. land management applications

Thomas S. Kuhn developed the paradigm theory of science. The soil survey is an example of paradigm‐based science. The soil‐landscape model, on which the soil survey is based, is an operative paradigm. An extreme reliance on tacit knowledge, the knowledge gained by experience, creates serious inefficiencies, both in learning the soil‐landscape paradigm and in disseminating the information resulting from its application. This article introduces concepts important to understanding paradigm theory and the nature of tacit knowledge. Among these are elements of Gestalt psychology, the theory of natural families, maps as conveyors of knowledge, and the linguistic nature of human perception. Students and field soil scientists should be provided explicit instruction concerning the paradigm on which soil mapping and interpretation are based. I also recommend that more of the soil geographic relationships discovered while making detailed soil maps be described and published so that the knowledge can be communicated to others.

No abstract

Polynov (1937) calculated the relative mobilities of important elements in landscapes: Cl > SO4 > Ca > Na > Mg > K > Si > Fe > Al. This series depicts a general weathering sequence that is essential to understanding many aspects of soil genesis and soil geography. It is argued on tbeoretical grounds that Ca and Na are out of proper sequence in Polynov's series. Polynov estimated ion mobilities by comparing the average content of elements in igneous rock to the average content of the same elements in river waters. However, an estimated 80% of the rocks at the earth's surface, which supply most of the leachate to rivers, are sedimentary. Accordingly, Polynov's mobility series was recalculated after adjusting rock chemical composition for the dominance of sedimentary rock types at the earth's surface. By using the elemental composition of igneous rocks in his calculations, Polynov greatly overestimated the amount of Na relative to Ca in rocks providing leachate to rivers. As a result, he significantly underestimated the mobility of Na relative to Ca. It is recommended that Polynov's ion mobility series be modified to the following: Cl > SO4 > Na > Ca > Mg > K > Si > Fe > Al. This study showed that Na is much more mobile (relative mobility 18.0) than Ca (8.1), Mg (5.4), or K (3.5). Therefore, it is recommended that Na be placed in a distinct mobility phase (II) second in relative mobility to Cl and SO4 (I).

No abstract