Soil Distribution and Classification

Abstract

This chapter describes the main soil types and their geographical distribution based on the soil map of the Atlas of Spain's National Geographic Institute, at a scale of 1:1,000,000. It was written according to the guidelines of the Soil Survey Manual and the methodology of Soil Taxonomy. Spanish soils are developed under a wide range of temperatures and moisture regimes–cryic, mesic, and thermic in the first case, and udic, ustic, xeric and aridic (or torric) with an occasional aquic regime in the second. Entisols (39.9 %) and Inceptisols (37.9 %) comprise more than three-quarters of Spain’s surface, while Alfisols (12.3 %) and Aridisols (5.6 %) account for only a bit more than one-sixth of the land. The remaining orders do not reach 5 % of the total land (Vertisols 2.4 %, Mollisols 1.5 %, Ultisols 0.2 %, Spodosols 0.1 %, Andisols 0.1 %, and Histosol 0.02 %). In this chapter, special attention is paid to the description of soil properties related to land management. Furthermore, their relationship with soil-forming factors is indicated. For each order, hectares and distribution of soil groups are indicated, down to the Spanish province scale. The text is accompanied by tables and maps, displaying the distribution of soil orders in Spain, including the synonyms of equivalent units in the WRB system.

Appendix

See Tables 2.12 and 2.13.

Table 2.12 Correlations between Soil Taxonomy (USA) and WRB (FAO)

Table 2.13 Main equivalences between the U.S. Soil Taxonomy and the WRB systems