Reference soil Colombia 09: Acrisol

CO009

Acrisols occur dominantly in the wetter parts of the tropics and subtropics and the warm temperate regions in relatively young landscapes.

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 less than 24 cmolc per kg in some part, either starting 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 a base saturation (total amount of Ca, Mg, K and Na with respect to the cation exchange capacity) of less than 50 percent in the major part between 25 and 100 cm from the soil surface

Distribution of Acrisols (rough estimation supplied by soilgrids)

Reference soil CO009: Acrisols

PHYSIOGRAPHY: Local relief: 100 m. CLIMATE: Available climatic data of the Araracuara area are incomplete. The rainfall is estimated between 3000-3500 mm/year (closer to 3000 mm) with a minimum in January between 150-200 mm (closer to 150 mm). A maximum is recorded in July between 200-250 mm (closer to 250 mm). The evaporation is estimated to be about half of the precipitation, e.g. about 1600 mm/year. The relative humidity is more than 75% with a minimum in January and February. VEGETATION AND LAND USE: Area was cleared from tropical rainforest 50 years ago and was put under pasture; extensive grazing. PARENT MATERIAL: Precambrian. EROSION: Severe in places.

Classification

WRB 2006

WRB 1998

Haplic- Acrisol (Alumic Humic Clayic)

Alumi-Humic- Acrisol

10-130 cm

argic horizon

0-35 cm	ochric horizon
10-130 cm	argic horizon
-	strongly humic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Haplic Acrisol

Humic Acrisol

0-35 cm	ochric A horizon
10-130 cm	argic B horizon
- cm	argic B horizon
- cm	umbric A horizon
-	strongly humic

0-35 cm	ochric A horizon
10-130 cm	argillic B horizon
-	ferric

Other classification

USDA-SCS (1975)

Tropohumult udic isohyperthermic

Physical characteristics

Particle size distribution

Depth (cm)	Gravel % v/v	very coarse sand % w/w	coarse sand % w/w	medium sand % w/w	fine sand % w/w	very fine sand % w/w	Total sand % w/w	coarse silt % w/w	fine silt % w/w	Total silt % w/w	Clay % w/w
0-10	-	2.3	8.1	11.3	17.0	11.7	50.4	6.8	6.4	13.2	36.4
10-20	-	1.7	5.0	9.0	16.0	11.9	43.6	7.5	6.6	14.1	42.4
20-35	-	1.9	4.5	7.8	15.1	11.9	41.2	7.3	6.6	13.9	45.0
35-55	-	1.8	4.5	6.8	13.3	11.3	37.7	8.3	5.9	14.2	48.2
55-95	-	1.9	5.2	7.0	12.4	10.9	37.4	8.1	4.8	12.9	49.9
95-130	-	2.0	4.8	6.7	12.7	11.9	38.1	8.4	6.5	14.9	47.1

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-10	-	-	-	12.5	36.4
11-17	1.130	-	-	-	-
10-20	-	-	-	17.9	42.4
58-65	1.230	-	-	-	-
20-35	-	-	-	20.9	45.0
115-121	1.220	-	-	-	-
35-55	-	-	-	6.9	48.2
55-95	-	-	-	0.0	49.9
95-130	-	-	-	0.0	47.1

Other physical data

Depth (cm)	Bulk density kg/dm³	pF 0 % v/v	pF 1.0 % v/v	pF 1.5 % v/v	pF 2.0 % v/v	pF 2.3 % v/v	pF 2.7 % v/v	pF 3.4 % v/v	pF 4.2 % v/v
11-17	1.130	54.0	53.1	47.6	42.1	40.0	37.8	33.3	30.8
58-65	1.230	49.5	47.4	44.1	41.2	40.0	38.9	36.9	34.9
115-121	1.220	48.7	48.1	44.9	40.6	38.9	37.4	33.1	31.6

Chemical data

Depth (cm)	pH H2O	pHKCl	EC 1: 2.5 dS/m	CaCO3 % w/w	C % w/w	N %	C / N	Exch. Acid cmol(c)/kg	Exch. Al cmol(c)/kg	Ca cmol(c)/kg	Mg cmol(c)/kg	K cmol(c)/kg	Na cmol(c)/kg	Sum Cations cmol(c)/kg
0-10	3.8	3.7	0.44	-	3.11	0.23	14	5.9	5.1	0.0	0.0	0.0	0.0	0.0
10-20	4.4	3.9	0.09	-	2.11	0.15	14	5.5	4.7	0.0	0.0	0.0	0.0	0.0
20-35	4.7	3.9	0.04	-	1.07	0.09	12	4.4	3.6	0.0	0.0	0.0	0.0	0.0
35-55	4.9	3.9	0.04	-	0.75	0.07	11	4.3	4	0.6	0.0	0.0	0.0	0.6
55-95	4.6	3.9	0.03	-	0.38	-	-	3.5	3.3	0.0	0.0	0.1	0.1	0.2
95-130	4.5	3.9	0.04	-	0.28	-	-	3.0	2.9	0.0	0.0	0.0	0.0	0.0

Depth (cm)	Base sat. %	CEC soil cmol(c)/kg	CEC clay cmol(c)/kg	CEC org cmol(c)/kg	ECEC cmol(c)/kg	Al sat. %	ESP %
0-10	0	17.3	48	10.9	-	29	0
10-20	0	15.4	36	7.4	-	31	0
20-35	0	10.7	24	3.7	-	34	0
35-55	6	9.4	20	2.6	-	43	0
55-95	4	4.5	9	1.3	-	73	2
95-130	0	5.5	12	1.0	-	53	0

Depth (cm)	pH NaF	P Retention %	ODOE	Al o % w/w	Si o % w/w	Fe d % w/w	Al d % w/w	Fe p % w/w	Al p % w/w	C p % w/w	Fe o % w/w
0-10	-	-	-	0.25	0.01	1.11	0.45	-	-	-	0.25
10-20	-	-	-	0.31	0.01	1.35	0.52	-	-	-	0.28
20-35	-	-	-	0.26	0.01	1.38	0.49	-	-	-	0.19
35-55	-	-	-	0.23	0.01	1.59	0.49	-	-	-	0.10
55-95	-	-	-	0.16	0.01	1.65	0.51	-	-	-	0.03
95-130	-	-	-	0.17	0.02	1.54	0.43	-	-	-	0.02

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-10	-	-	-	-	-	-	very strong	medium to strong	-	-	-	medium to strong
10-20	-	-	-	-	-	-	very strong	medium to strong	-	-	-	medium to strong
20-35	-	-	-	-	-	-	very strong	medium to strong	-	-	-	medium to strong
35-55	-	-	-	-	-	-	very strong	medium to strong	-	-	-	medium to strong
55-95	-	-	-	-	-	-	very strong	medium to strong	-	-	-	weak
95-130	-	-	-	-	-	-	very strong	medium to strong	-	-	-	weak

Profile description

Ah 0-10 cm	very dark greyish brown (10YR 3/2, moist)sandy clay loam slightly gravelly,weak fine subangular blocky to crumb,slightly hard friable slightly sticky slightly plastic,many fine tubular pores and many tubular pores,gradual wavy boundary to,
10-20 cm	dark brown (10YR 3/3, moist)sandy clay loam,moderate fine subangular blocky to crumb,slightly hard friable slightly sticky slightly plastic,patchy thin unspecified in root channels and pores cutans,many fine coarse tubular pores,frequent charcoal fragments,few pedotubules,gradual wavy boundary to,
20-35 cm	(dark) brown (10YR 4/3, moist)sandy clay loam slightly gravelly,moderate fine subangular blocky,slightly hard friable slightly sticky slightly plastic,patchy thin unspecified in root channels and pores cutans,common fine medium tubular pores,few pedotubules,gradual wavy boundary to,
Bt1 35-55 cm	(dark) brown (7.5YR 4/4, moist)clay loam,moderate fine and medium subangular blocky to angular blocky,slightly hard friable sticky plastic,broken thin unspecified cutans,common fine medium tubular pores,frequent pedotubules,gradual wavy boundary to,
Bt2 55-95 cm	strong brown (7.5YR 5/6, moist)clay,weak to moderate fine and medium angular blocky,hard friable very sticky very plastic,broken moderately thick unspecified cutans,many fine medium tubular pores and many medium vesicular pores,few lithorelict fragments,very frequent pedotubules,gradual wavy boundary to,
95-130 cm	reddish yellow (5YR 6/8, moist)clay,very weak fine angular blocky to porous massive,friable very sticky very plastic,patchy thin unspecified cutans,very frequent pedotubules,abrupt wavy boundary to,
C 130-150 cm	gravelcoarse gravel sandstone coarse gravel sandstone fragments,

Kind 1 (parent material) ; Parker (eds), 1984	sandstone
Mode of accumulation or deposition of parent material	colluvial
Remarks on Parent Materials	with clayey lenses
Texture of parent material	stony

Land use or vegetation in the immediate vicinity of the site	semi-natural grassland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Cleared tropical rainforest; nowmainly grass, some herbs and shrubs LANDUSE: 50 years ago and put under pasture; now used for extensive grazing

Altitude	290m
Physiographic Unit	footslope, associated plateau
Physiographic position of the site	lower slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	piedmont
Slope	30%
Slope Aspect	east
Form of the slope surrounding the site	straight

Drainage class ; FAO (2006) - Guidelines for soil description	well
Moist From - To	0-150cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline

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Reference soil Colombia 09: Acrisol

Characteristics

Reference soil CO009: Acrisols

Classification