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Previous Soil Surveys

The earliest soil survey known for the area is the pioneering reconnaissance of the Canal Zone and its environs by Bennett (1926 & 1929).  He mapped the whole of BCI as the Frijoles red clay, with a topographic subdivision for the central plateau.   He admitted that the separation of the moderately fertile red clays derived from intermediate lithologies in Panama was problematic.  He noted that the clastic sedimentary formations contain much volcanic material and that their soils – the Gatun clays – are morphologically similar to the Frijoles clays, as are the Arraijan clays derived from calcareous sedimentaries.

BCI is covered by a soil survey of the Canal area (Catapan, 1970) for the Comision de Reforma Agraria (CRA) of the Ministerio de Desarollo Agropecuaria (MIDA).  The general map (1:100 000) shows the whole of BCI as ‘Red Mountain Soils’, where ‘mountain’ presumably means upland and non-alluvial rather than montane.  BCI is also covered by 1:20 000 soils maps from the same study.  These are held at the Comision’s office in Santiago, and were made readily available by MIDA staff for inspection and copying.  We have lodged hard copies of the Catapan 1:20 000 sheets covering BCI with STRI and the University of Potsdam.

The Catapan maps appear to be based mainly on the interpretation of aerial photography of unknown scale and dating from the mid-1960’s, with limited field checking. The mapping units are parametric compilations that incorporate: topsoil and subsoil diagnostic horizon designations according to the USDA Seventh Approximation (Soil Survey Staff, 1960); profile drainage; textual class; depth class; parent material group; slope gradient class; erosion class; stoniness class; and an evaluation of the land’s potential capability using a system similar the eight class hierarchy then employed by USDA (Klingebiel & Montgomery, 1961). The Catapan mapping units are therefore of land sensu lato, rather than just soils.

The boundaries generally accord with our findings, and clearly separate the dipslope plateau from the more rugged Bohio scarp terrain, the sedimentary, and volcanic lowlands. Other similarities include the recognition of the subsoils on the Bohio scarplands as cambic, compared to the oxic subsoils elsewhere.  Differences from our mapping and characterisation include their omission of smectitic mineralogy and impeded drainage on the Caimito marine facies, designation of the Bohio scarpland soils as having worse drainage than the rest of the island, and differentiation of umbric (dark) topsoils on the plateau compared with ochric (lighter coloured and less organic) topsoils elsewhere.

Other pedospatial data

Although not primarily pedological, investigations in several disciplines have collected data that contribute to understanding of the soil cover of BCI.  The soils interest was tangential and primary soils data were zero/slight in many studies.

Those with more substantial soils data or discussions are summarised in Table 3.1. The list is incomplete and we welcome information on omissions and errors.

Previous data on soil cover of BCI


Location on BCI

Data & findings relevant to soil cover



General physical environment

Whole island

Pits and augerings

Some our soil classes are presaged in brief descriptions.  Soil shallowness stressed.

Dietrich et al., 1996;
Windsor, 1990


Whole island

13 plots identified as on Frijoles clay, 3 on gleys

Tree spp distributions appear to be fairly indiscriminate with respect to soil type

Knight, 1975

Flora of BCI

Whole island

Identifies Frijoles clay, gleys & possible ‘fragipan’

‘Fragipan’ may refer to the pale swelling clays

Croat, 1978

Soil water potential in gaps & on slopes

Andesite dipslope/plateau & slopes

Slope soils are better watered > plateau

Possibly due to lateral inflows by throughflow from plateau upslope.

Becker et al., 1988;
Daws et al., 2002

Uptake of soil moisture in dry season

Available moisture depleted from surface down.  Uptake by evergreens continues +/- same through dry season & from deeper than deciduous.  Soil moisture fairly constant below ca 1 m.

Jackson et al., 1995;
Meinzer et al., 2004;
Andrade et al., 2005

Clay mineralogy of stream sediments

Whole island

Clays are mainly kaolinitic on andesite & Caimito volcanics; smectitic on Caimito marine sedimentary & Bohio.

Johnsson & Stallard, 1989

Fine root biomass

Gigante Peninsula (on mainland)

Profile description & some analyses of red clay

The study soil appears to be equivalent to Ava

Cavalier, 1992


Location on BCI

Data & findings relevant to soil cover



Secondary phytochemical variation in Quararibea asterolepis

Distinction between Oxisols on andesite cap and Alfisols on slopes along southern Ava Trail

Soils not significant factor in phytochemical variation

Brenes-Arguedas & Coley, 2005

Nutrient dynamics on three soil parent materials

Topsoil N, P & S at 15 m intervals along 200 m transects on andesite, Bohio & Caimito marine

Some parent material differences for P, but very slight for N & S

Yavitt, 2000; Yavitt & Wieder, 1988; Yavitt & Wright, 1996

5 years dry season irrigation experiment

Caimito marine sedimentaries, Poacher’s Peninsula

Control (=non-irrigated) monitoring of soil water & O2

Wright, 1990 & 1992; Wright & Cornejo, 1990; Kursar et al., 1995

Litter decomposition on control plots

Wieder & Wright, 1996

Litter nutrients

Yavitt et al.,2004

Nutrient dynamics

Control plots give detailed chemical analyses of top- & upper subsoil.

Yavitt et al., 1993,

Soil charge characteristics

Yavitt & Wright, 2002