Reference soil Colombia 01: Acrisol

CO001

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)

<div class="table-responsive"><p> </p><h2>Reference soil CO001: Acrisol</h2> A field opposite the HIMAT station Libertad GEOLOGY: Quarternary sedimentary rocks VEGETATION AND LAND USE: The original savanna vegetation characterized by Melinis minuti flora has been cleared at the site and replaced by Kikuyu grass. Land is exclusively used for grazing. CLIMATE: Soil temperature at 50 cm depth is 31 °C, the air temperature is 25 °C. ADDITIONAL NOTES ON PROFILE DESCRIPTION: Ap - few fecal pellets; AB - few fecal pellets; Bt1 - below 150 cm the profile has been observed by augering; BC - below 150 cm the profile has been observed by augering; C - mottles, colour also 2.5YR 4/8, weathered gres. The soil has a "nitic" appearance below 100 cm depth. This soil developed on so called "older alluvial terraces". Is widespread and exhibits good physical properties. It is associated with poorly drained clayey soils in the valley bottoms (ground water laterites).<p> </p></div>

Classification

WRB 2006

WRB 1998

Cutanic- Acrisol (Alumic Humic Profondic)

Profondi-Humic- Acrisol (Alumic)

100-150 cm	nitic horizon
47-150 cm	argic horizon

0-47 cm	ochric horizon
100-150 cm	nitic horizon
47-150 cm	argic horizon
-	strongly humic property

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

HumiHaplic Nitisol

Humic Acrisol

0-47 cm	ochric A horizon
47-150 cm	argic B horizon
- cm	argic B horizon
- cm	umbric A horizon
-	nitic property
-	strongly humic property

0-47 cm	ochric A horizon
47-150 cm	argillic B horizon
-	ferric property
-	high organic matter content in the B horizon property

Other classification

USDA-NRCS (1999)	Ustic Palehumult
USDA-SCS (1975)	Ustic Palehumult ustic kaolinitic isohyperthermic

Location:

Departamento del Meta, 28km E of Villavicencio on road to Puerto Lopéz, in field opposite the HIMAT station Libertad

Physical characteristics

Particle size distribution

Depth (cm)	Clay % weight/weight	coarse sand % weight/weight	coarse silt % weight/weight	fine sand % weight/weight	fine silt % weight/weight	Gravel % volume/volume	medium sand % weight/weight	Total sand % weight/weight	Total silt % weight/weight	very coarse sand % weight/weight	very fine sand % weight/weight
0-24	42.1	4.3	6.5	18.3	9.0	-	12.8	42.4	15.5	0.0	7.0
24-47	34.0	4.1	8.9	17.3	15.0	-	12.4	42.0	23.9	0.5	7.7
47-74	46.1	3.3	6.7	16.1	9.4	-	10.4	37.9	16.1	0.7	7.4
74-100	47.5	3.5	8.1	15.3	7.1	-	9.9	37.2	15.2	0.8	7.7
100-150	48.1	3.5	8.3	14.1	8.4	-	9.3	35.2	16.7	0.6	7.7

Chemical characteristics

Depth (cm)	C % weight/weight	Ca cmol(c)/kg	CaCO3 % weight/weight	C / N unitless	EC 1: 2.5 mS/cm	Exch. Acid cmol(c)/kg	Exch. Al cmol(c)/kg	K cmol(c)/kg	Mg cmol(c)/kg	N %	Na cmol(c)/kg	pH H2O unitless	pHKCl unitless	Sum Cations cmol(c)/kg
0-24	2.57	0.0	-	18	0.07	2.8	2.4	0.2	0.1	0.14	0.3	4.8	4.0	0.6
24-47	1.87	0.0	-	21	0.05	2.9	2.4	0.1	0.0	0.09	0.3	4.8	4.1	0.4
47-74	1.05	0.0	-	18	0.12	2.4	2.1	0.1	0.0	0.06	0.2	4.7	4.1	0.3
74-100	0.56	0.0	-	11	0.04	2.2	1.9	0.0	0.0	0.05	0.1	4.7	4.0	0.1
100-150	0.48	0.0	-	10	0.03	2.1	1.8	0.0	0.0	0.05	0.1	4.7	4.1	0.1

Depth (cm)	Al sat. %	Base sat. %	CEC clay cmol(c)/kg	CEC org cmol(c)/kg	CEC soil cmol(c)/kg	ECEC cmol(c)/kg	ESP %
0-24	16	4	35	9.0	14.8	-	2
24-47	18	3	39	6.5	13.2	-	2
47-74	20	3	23	3.7	10.6	-	2
74-100	20	1	20	2.0	9.7	-	1
100-150	19	1	20	1.7	9.6	-	1

Depth (cm)	Al sat. %	Base sat. %	CEC clay cmol(c)/kg	CEC org cmol(c)/kg	CEC soil cmol(c)/kg	ECEC cmol(c)/kg	ESP %
0-24	16	4	35	9.0	14.8	-	2
24-47	18	3	39	6.5	13.2	-	2
47-74	20	3	23	3.7	10.6	-	2
74-100	20	1	20	2.0	9.7	-	1
100-150	19	1	20	1.7	9.6	-	1

Clay mineralogy

Depth (cm)	Chlorite unitless	Feldspar unitless	Gibbsite unitless	Goethite unitless	Halloysite unitless	Hematite unitless	Kaolinite unitless	Mica / illite unitless	Mixed-layer unitless	Quartz unitless	Smec unitless	Vermiculite unitless
0-24	-	weak	-	medium to strong	-	-	very strong	-	medium to strong	-	-	-
24-47	-	weak	-	medium to strong	-	-	very strong	-	medium to strong	-	-	-
47-74	-	weak	-	medium to strong	-	-	very strong	-	medium to strong	-	-	-
74-100	-	weak	-	medium to strong	-	-	very strong	-	medium to strong	-	-	-
100-150	-	weak	-	medium to strong	-	-	very strong	-	medium to strong	-	-	-

Rare clay minerals

Depth (cm)	Amphibole unitless	Augite unitless	Calcite unitless	Lepidococrite unitless	Pyrophillite unitless	Pyroxene unitless	Weddelite unitless
0-24	-	-	-	-	weak	-	-
24-47	-	-	-	-	weak	-	-
47-74	-	-	-	-	weak	-	-
74-100	-	-	-	-	weak	-	-
100-150	-	-	-	-	weak	-	-

Profile description

Ap 0-24 cm	dark brown (7.5YR 3/2, moist) clay loam,weak fine subangular blocky to granular,slightly hard friable slightly sticky plastic,common fine pores,few coprogenic elements,gradual smooth boundary to,
AB 24-47 cm	dark brown (7.5YR 3/4, moist) clay,weak to moderate fine subangular blocky,slightly hard friable slightly sticky plastic,common fine pores,few krotovinas,gradual smooth boundary to,
Bt1 47-74 cm	(dark) brown (7.5YR 4/4, moist) clay,moderate to strong fine and medium angular blocky,slightly hard friable slightly sticky plastic,patchy thick unspecified cutans,few fine pores,few krotovinas,diffuse smooth boundary to,
Bt2 74-100 cm	strong brown (7.5YR 5/6, moist) clay,moderate to strong fine angular blocky,slightly hard friable slightly sticky plastic,patchy thick unspecified cutans,few fine pores,diffuse smooth boundary to,
BC 100-180 cm	yellowish red (5YR 5/8, moist) clay,moderate to strong fine angular blocky,slightly hard friable slightly sticky plastic,patchy thick unspecified cutans,few fine pores,few krotovinas,
C 180-180 cm	clay many mottles (5YR 5/8) and (10YR 4/6),

Remarks on Parent Materials	weathered Quaternary gres arenisca
Texture of parent material	clayey
General characterization of the status of weathering of solid rock	partially or moderately
Weathering Resistance	moderate
Kind 1 (parent material) ; Parker (eds), 1984	sedimentary rock
Mode of accumulation or deposition of parent material	colluvial

Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	secondary
Land use or vegetation in the immediate vicinity of the site	semi-natural grassland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Kikuyu grass. Original savanna vegetation characterized by Melinis minuti flora has been cleared at the site and replaced by Kikuyu grass. LANDUSE: Land is exclusively used for grazing

Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating
Physiographic Unit	structural terrace
Slope	0%
Form of the slope surrounding the site	straight
Altitude	336m
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	piedmont
Physiographic position of the site	flat

Moist From - To	0-180cm
Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
Estimated run off (class)	very slow
Estimated permeability (class) of least permeable part of the profile	moderate
Kind of ground water table (USDA, 1979)	no groundwater table observed

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

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Reference soil Colombia 01: Acrisol

Characteristics

Classification