Reference soil Bhutan 01a: Andosol

BT001a

Andosols occur throughout the world where volcanic activity is common, especially in the circum-Pacific region and along the mid-Atlantic Ridge.

Characteristics

Soils with a vitric or andic horizon (slightly to moderately weathered horizons in pyroclastic deposits dominated by short-range-order minerals, notably allophane and imogolite) starting within 25 cm from the soil surface. In addition, they may have a histic, fulvic, melanic, mollic, umbric, ochric, duric, or cambic horizon. Other diagnostic horizons (unless buried deeper than 50 cm by volcanic deposits) are absent.

Distribution of Andosols (rough estimation supplied by soilgrids)

Reference soil BT001a: Andosol

Classification

WRB 2014
Aluandic-Eutrosilic-Dystric- Andosol

Local classification:	Yellow Hill Soil

Location:

Lame Goempa Research Forest, Jakar (Bumthang dzongkhag), Bhutan

Physical

Particle size distribution:

Depth (cm)	very coarse sand % w/w	Gravel % v/v	Total silt % w/w	medium sand % w/w	fine silt % w/w	fine sand % w/w	Clay % w/w	Total sand % w/w	coarse silt % w/w	very fine sand % w/w	coarse sand % w/w
0-10	0.561	-	50.4	1.818	35.94	2.781	34.814	14.8	14.5	8.539	1.086
10-23	0.817	-	43.5	11.138	31.127	10.025	19.642	36.9	12.4	13.931	1.113
23-45	0.138	-	57.8	3.282	36.884	4.954	19.547	22.7	20.9	13.084	1.154
45-95	0.517	-	49.1	4.396	35.857	6.562	23.097	27.8	13.2	14.385	1.853
95-145	2.877	-	36	7.172	26.561	10.614	25.489	38.5	9.4	12.392	5.384

Other physical data

Depth (cm)	Spec. Surf. Area m²/g	Water disp. clay %	Clay % w/w	COLE cm/cm	Bulk density kg/dm³
0-10	-	-	34.814	-	-
10-23	-	-	19.642	-	-
23-45	-	-	19.547	-	-
45-95	-	-	23.097	-	-
95-145	-	-	25.489	-	-

Chemical characteristics:

Depth (cm)	pHKCl unitless	Exch. Acid cmol(c)/kg	Na cmol(c)/kg	Sum Cations cmol(c)/kg	Ca cmol(c)/kg	EC 1: 2.5 dS/m	K cmol(c)/kg	Mg cmol(c)/kg	pH H2O unitless	C / N unitless	Exch. Al cmol(c)/kg	N %	C % w/w	CaCO3 % w/w
0-10	3.95	-	0	1.6	1.127	0.213	0.336	0.24	4.53	19.496	7.347	0.403	7.86	-
10-23	4.61	-	0	0.9	0.514	0.023	0.257	0.14	5.21	16.262	4.114	0.258	4.196	0.116
23-45	4.46	-	0	-	0	0.012	0	0	5.33	16.919	2.057	0.104	1.756	0.121
45-95	4.8	-	0	0.02	0	0.018	0.047	0	5.48	15.846	-	0.127	2.014	0.132
95-145	4.33	-	0	0.1	0.072	0.011	0.048	0	5.5	9.029	1.648	0.062	0.555	0

Depth (cm)	pH NaF unitless	P Retention %	Si o % w/w	Al d % w/w	Fe o % w/w	Al p % w/w	Al o % w/w	ODOE unitless	C p % w/w	Fe p % w/w	Fe d % w/w
0-10	-	88	0.033	0.907	1.883	-	0.875	0.469	-	-	3.615
10-23	10.63	98	0.1	1.582	3.861	-	1.443	0.456	-	-	5.85
23-45	11.43	93	0.364	1.172	1.149	-	1.478	0.156	-	-	2.6
45-95	11.43	99	0.572	1.592	2.328	-	2.202	0.21	-	-	3.842
95-145	-	61	0.065	0.532	1.168	-	0.489	0.125	-	-	2.534

Depth (cm)	CaSO4.2H2O %	P Bray mg/kg	P Olsen mg/kg	pH CaCl2 unitless
0-10	-	-	-	4.29
10-23	-	-	-	4.65
23-45	-	-	-	5
45-95	-	-	-	5.2
95-145	-	-	-	4.67

Profile description

Ah 0-10 cm	pH field values appear too high;soil pH field kit was probably not working properly.; subangular blocky; very friable; none; none (0%); high (15-40%); common; none; none (0%); common; 6.5; smooth; nearly plane surface
Ah 0-10 cm	pH field values appear too high;soil pH field kit was probably not working properly.; subangular blocky; very friable; none; none (0%); high (15-40%); common; none; none (0%); common; 6.5; smooth; nearly plane surface
B1 10-23 cm	yellowish brown; subangular blocky; very friable; none; none (0%); high (15-40%); few; none; none (0%); other insect activity; 6.5; smooth; nearly plane surface
B1 10-23 cm	yellowish brown; subangular blocky; very friable; none; none (0%); high (15-40%); few; none; none (0%); other insect activity; 6.5; smooth; nearly plane surface
B2 23-45 cm	yellowish brown; subangular blocky; friable; none; none (0%); high (15-40%); few; none; none (0%); none; 7; smooth; nearly plane surface
B2 23-45 cm	yellowish brown; subangular blocky; friable; none; none (0%); high (15-40%); few; none; none (0%); none; 7; smooth; nearly plane surface
B3 45-95 cm	yellowish brown; subangular blocky; firm; none; none (0%); medium (5-15%); very few; none; none (0%); open large burrows; 7; smooth; nearly plane surface
B3 45-95 cm	yellowish brown; subangular blocky; firm; none; none (0%); medium (5-15%); very few; none; none (0%); open large burrows; 7; smooth; nearly plane surface
BC 95-145 cm	yellowish brown; subangular blocky; firm; none; very fine (< 2 mm); low (2-5%); very few; soft; weathered; none; 5.5; smooth; nearly plane surface
BC 95-145 cm	yellowish brown; subangular blocky; firm; none; very fine (< 2 mm); low (2-5%); very few; soft; weathered; none; 5.5; smooth; nearly plane surface
CB 145- cm	yellowish brown; subangular blocky; firm; none; none (0%); low (2-5%); none; weathered; none; 5.5;
CB 145- cm	yellowish brown; subangular blocky; firm; none; none (0%); low (2-5%); none; weathered; none; 5.5;

Age of the land Surface	older pleistocene, with periglacial influence, commonly the recent soil formation on younger over older, preweathered materials.
Kind 1 (parent material) ; Parker (eds), 1984	marl
Remarks on Parent Materials	Mica schists of Thimphu Formation

Intensity of the soil erosion type	slight
Soil erosion type	water erosion or deposition
Classification of total area affected by erosion and deposition	0%-5%

Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	vegetation moderately disturbed
Land use or vegetation in the immediate vicinity of the site	selective felling
Remarks on Land Use / Vegetation	Blue pine (P. wallichiana) with a.o. Rhododendron sp., Daphne sp., Vaccinium sp. and ferns in understorey
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	closed forest (continuous tree layer, crowns overlapping, large number of tree and shrub species in distinct layers)

Altitude	3009m
Hierarchy of major landforms	high-gradient mountain
Physiographic Unit	middle slope (back slope) in undulating to mountainous terrain
Physiograpy description	Roadcut on hillside
Slope	09%
Slope Aspect	north
Form of the slope surrounding the site	concave
Slope gradient %	35.0%

Drainage class ; FAO (2006) - Guidelines for soil description	moderately well drained
Flooding	none
Depth to groundwater table	> 1000cm
Drainage class - intergrade; FAO (2006) - Guidelines for soil description	well drained

Surface stoniness class (FAO (2006) - Guidelines for soil description)	few (2-5%)
Average size of stone	stones (6-20 cm)

You are here

Reference soil Bhutan 01a: Andosol

Characteristics

Reference soil BT001a: Andosol

Classification