Interpretability Comparison between Soil Taxonomic and Fertility Capability Classification Units: A Case of Some Major Cassava Soils in Northeast Thailand

Abstract

               A comparison between two classification systems in the context of interpretability for soil management recommendations was undertaken on nine soils growing cassava across the northeast region of Thailand. Study methods included field investigation and laboratory analysis, both based on standard methods. Results showed that all soils were classified as Typic Paleustults, based on the Soil Taxonomy system, whereas their fertility capability classification (FCC) was different, mainly in modifiers. The limitation of the Soil Taxonomy system, which provided only a Typic subgroup for use in Paleustults, created a difficulty in interpreting this group of soils for agronomic uses. FCC units tended to be more
interpretative and clearly indicated major soil constraints for cropping.

               It is strongly recommended that the taxonomy unit of these particular soils needs modification at the subgroup level, in order to distinguish the soils and to offer more meaningful interpretation for guidelines on soil management. Modification of FCC units could also improve the interpretability of the system by adding new modifiers indicating the presence of some soil constraints at the Type or Substrata level to reflect a priority on soil management.