Reference soil Ecuador 04: Alisol

EC004

Alisols occur in the tropics and subtropics, and in the warm temperate regions of the world in relatively young landscapes. The high level of exchangeable aluminium in these soils is caused by rapid weathering of secondary high-activity clays such as vermiculite and smectite.

Characteristics

Soils having an argic horizon (a subsurface horizon with distinct higher clay content than the overlying horizon), which has a cation exchange capacity of 24 cmolc per kg clay or more, and which starts either within 100 cm from the soil surface, or within 200 cm from the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout. They have "alic" properties (high content of exchangeable aluminium) in the major part between 25 and 100 cm from the soil surface; moreover, only such diagnostic horizons as an ochric, albic, andic, ferric, nitic, plinthic, or vertic horizon are present.

Distribution of Alisols (rough estimation supplied by soilgrids)

 

Reference soil EC004: Alisols

Natural vegetation is nearly completely overtaken by introduced species. Dominant species are Lantana accumulata, introduced 2 years ago and Guajaba introduced about 20 years ago(verbal information). The weather station El Progreso at an altitude of 200 meter is connected to this site. Source of data is FAO (1985) Plant Production and Protection Series no.24 "Agroclimatological data for Latin America". An altitude correction of about 300 meter should be applied. Note that the meteo station of Puerto Baquerizo localized at sealevel is not representative. According an approximate precipitation-altitude correlation for San Cristobal island the precipitation at an altitude of 500 meter is in the range of 1500 to 2000mm. It is assumed that the soil was frequently enriched with volcanic ash. The soil has many chemical properties of an Andosol, and would be classified as Oxic Dystrandept, however the bulk density is too high.

 

Classification

WRB 2006WRB 1998
Cutanic- Alisol (Alumic Humic Clayic)Cutani-Rhodic- Luvisol (Hyperdystric)
12-142 cmargic horizon
0-12 cmochric horizon
12-142 cmargic horizon
FAO-UNESCO-ISRIC 1988FAO-UNESCO-ISRIC 1974
Humi-Haplic AlisolHumic Acrisol
0-12 cmochric A horizon
12-142 cmargic B horizon
-strongly humic
0-12 cmochric A horizon
12-142 cmargillic B horizon
-high organic matter content in the B horizon