FRANCE SOIL PROFILES

PROFILE EUR17 - FR
Buron du Perle. - june 2001

Soil Climate:  Udic soil moisture regime; Mesic soil temperature regime

Topography: Mountainous

Landform:

Land element: Slope

Position: E-W

Slope: 15-20% Midslope of Mountain of Perle

Form: Concave slope as a result of mass movement (colluvium, mass slip)

Microtopography: Terracettes

Landuse/Vegetation: Altitude meadow with broom

Human influences:

Parent material: Colluvium of dark trachyandesitic parent rock with feldspar crystals

Rock outcrops:

Effective soil depth:

Erosion:

Drainage Class: Well drained

Internal drainage: Moderate

External drainage: Rapid

Moisture conditions: Moist throughout

SOIL HORIZON DESCRIPTION:

Ah1:   0-8 cm; dark brown (10YR 3/3) moist. Silt loam, few very fine crumb, friable, no gravel, very many fine roots, very porous, clear wavy boundary.

Ah2:   8-32 cm; dark brown (7.5YR 3/2) moist. Silt loam with few gravel (trachytic basalt), moderate fine and medium subangular blocky structure, high biological activity, very few roots and many fine roots, very porous, gradual to diffuse smooth boundary

Ah3:   32-50 cm; dark brown (7.5YR 3/3) moist. Silty clay loam with some gravel of trachytic basalt (some gravel totally oxidised with phenocrystal relic structures and some fresh gravel), weak to moderate and medium subangular block structure, friable, common fine roots, few coarse dead roots, large patches of charcoals, highly porous, high biological activity, clear and wavy boundary

2Bw:  50-90 cm; dark brown (7.5YR 3/4) moist. Clay loam with common gravel and stones (altered to partially altered trachytic basalt), moderate, medium to coarse subangular blocky structure, very porous, friable, few clay skins along roots channels, few dead roots and few fine roots, gradual smooth boundary

2Bt:    below 90 cm; dark brown (7.5YR 3/2). Clay with gravel and stones (altered to partially altered trachytic basalt), moderate medium angular blocky structure, firm, tubular pores, very few fine roots, many clay skins, decomposing orange roots (fungal activity?)

WRB (2001): umbric horizon (0-50 cm); aluandic horizon (0-35cm); silandic horizon (35->90 cm); ECEC < 2.0 cmol kg^-1 fine earth between 70 and 100 cm:

ST (1999): umbric epipedon (0-50 cm); andic soil properties (0->95 cm); KCl-extractable Al > 2.0 cmol(+) kg-1 between 0 and 50 cm; mean Si_o 0.89%, mean Feo 1,23%, both between 0 and 100 cm; 8x Sio + 2x Feo > 5, 8x Sio > 2x Feo: