Reference soil Bhutan 03: Umbrisol

BT003

Umbrisols occur mainly in regions where precipitation exceeds considerably the evapotranspiration. They are dominantly associated with acid parent materials.
Characteristics

Soils having an umbric horizon (deep, brownish or blackish surface horizon with a significant accumulation of organic matter and low base saturation). They have no diagnostic horizons other than an anthropedogenic horizon less than 50 cm thick, or an albic or cambic horizon

Distribution of Umbrisols (rough estimation supplied by soilgrids)

Reference soil BT003: Umbrisol

Classification

WRB 2014
Umbrisol

Local classification:	Brown Hill Soil, kamsa (forest soil)

Location:

Close to road above Gogona village, Phobjikha Valley (Wangduephodrang dzongkhag), Bhutan

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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	-	0.015	0.307	2.018	6.053	7.792	16.2	12.3	39.259	51.6	32.158
10-40	-	0.312	0.635	1.928	4.992	8.657	16.5	12.7	39.939	52.6	30.86
40-70	-	0.506	0.818	1.841	4.544	9.088	16.7	13.7	41.448	55.1	28.18
70-85	-	0.634	0.634	1.717	4.157	7.953	15.1	13	41.714	54.7	30.166
85-95	-	0.737	0.822	2.263	5.156	7.002	16	11.9	42.033	53.9	30.122
95-120	-	0.241	0.994	2.366	4.595	7.327	15.5	11.8	43.236	55	29.496
120-140	-	0.135	0.851	2.419	4.464	7.432	15.3	12.6	42.708	55.3	29.375
140-150	-	0.227	0.909	2.282	4.687	7.723	15.8	11.8	38.999	50.8	33.362

Other physical data

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-10	0.43	-	-	-	32.158
10-40	0.75	-	-	-	30.86
40-70	0.7	-	-	-	28.18
70-85	0.78	-	-	-	30.166
85-95	0.85	-	-	-	30.122
95-120	0.86	-	-	-	29.496
120-140	1.09	-	-	-	29.375
140-150	1.15	-	-	-	33.362

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	4.81	4.05	0.219	-	14.91	0.991	15.05	-	6.311	2.64	1.224	0.984	0	4.8
10-40	4.83	4.49	0.063	-	4.12	0.356	11.57	-	6.145	0.095	0.119	0.62	0	0.8
40-70	4.99	4.71	0.031	-	2.84	0.25	11.376	-	3.05	0	0	0.195	0	0.2
70-85	4.64	4.49	0.061	0	3.404	0.24	14.198	-	3.851	0	0	0.16	0	0.2
85-95	5.08	4.26	0.031	0.156	2.411	0.198	12.171	-	3.4	0	0	0.183	0	0.2
95-120	5.21	4.18	0.016	0.026	1.306	0.156	8.374	-	2.954	0.121	0	0.242	0	0.3
120-140	5.37	4.38	0.012	-	0.99	0.114	8.719	-	2.288	0	0	0.177	0	0.2
140-150	5.43	4.31	0.011	-	0.77	0.124	6.25	-	2.184	0	0	0.239	0	0.2

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	9	51.176	-	-	11.1	57	-
10-40	4	21.11	-	-	6.9	88	-
40-70	1	16.316	-	-	3.2	94	-
70-85	1	19.848	-	-	4.1	95	-
85-95	1	16.362	-	-	3.6	94	-
95-120	2	12.34	-	-	3.3	91	-
120-140	2	11.669	-	-	2.5	92	-
140-150	2	12.759	-	-	2.4	92	-

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	-	73	0.605	0.891	0.06	2.323	1.001	-	-	-	1.021
10-40	-	86	0.293	1.097	0.102	3.308	1.113	-	-	-	1.381
40-70	-	81	0.271	0.952	0.093	3.362	0.94	-	-	-	1.419
70-85	-	80	0.318	0.881	0.038	3.505	0.857	-	-	-	1.536
85-95	-	81	0.234	0.799	0.036	2.928	0.871	-	-	-	1.663
95-120	-	76	0.193	0.667	0.036	3.668	0.851	-	-	-	1.552
120-140	-	78	0.281	0.782	0.092	3.069	0.907	-	-	-	1.153
140-150	-	71	0.113	0.687	0.094	2.544	0.837	-	-	-	0.939

Depth (cm)	CaSO4.2H2O %	P Bray mg/kg	P Olsen mg/kg	pH CaCl2	clay_noncarbonate % w/w	clay_carbonate % w/w	phosphorus4 mg/kg	phosphorus1 mg/kg	total_sulfur % w/w
0-10	-	-	-	4.14	32.158	-	897.232	36.382	0.079
10-40	-	-	-	4.63	30.86	-	799.608	6.228	0.019
40-70	-	-	-	4.76	28.18	-	697.884	5.241	0.01
70-85	-	-	-	4.53	30.166	-	550.507	4.029	0.009
85-95	-	-	-	4.59	30.122	-	367.167	0.741	0.01
95-120	-	-	-	4.53	29.496	0	376.897	0.978	0.007
120-140	-	-	-	4.71	29.375	-	412.472	2.381	0.005
140-150	-	-	-	4.63	33.362	-	336.021	2.024	0.003

Profile description

Ah 0-10 cm	dark brown(10YR 3/3, moist) ; silt moderate medium ; friable ; no cutans; few (2-5%) prominent fine (2-6 mm) mottles; very high (> 40%) pores; common fine common very fine common very fine roots; none ; few (2-5%) fresh or slightly weathered medium artefacts (6-20 mm) ; common ; diffuse (> 15 cm) smooth; nearly plane surface boundary to
Ah2 10-40 cm	dark brown(10YR 3/3, moist) ; moderate medium ; friable ; no cutans; common (5-15%) prominent fine (2-6 mm) mottles; very high (> 40%) pores; common fine common very fine common very fine roots; none ; few (2-5%) fresh or slightly weathered coarse artefacts (> 20 mm) ; few ; diffuse (> 15 cm) smooth; nearly plane surface boundary to
Ah3 40-70 cm	dark yellowish brown(10YR 3/4, moist) ; friable ; no cutans; common (5-15%) prominent strong brown fine (2-6 mm) mottles; very high (> 40%) pores; common fine common very fine common very fine roots; none ; few (2-5%) fresh or slightly weathered coarse artefacts (> 20 mm) ; few other insect activity ; diffuse (> 15 cm) smooth; nearly plane surface boundary to
2Ah4 70-85 cm	dark brown(10YR 3/3, moist) ; friable ; no cutans; common (5-15%) prominent fine (2-6 mm) mottles; very high (> 40%) pores; common fine common very fine roots; none ; very few (0-2%) fresh or slightly weathered fine artefacts (2-6 mm) ; few other insect activity ; gradual (5-15 cm) wavy; pockets less deep than wide boundary to
2AB 85-95 cm	dark yellowish brown(10YR 4/4, moist) ; friable ; no cutans; common (5-15%) prominent fine (2-6 mm) mottles; high (15-40%) pores; common fine common very fine roots; none ; few (2-5%) fresh or slightly weathered ; few other insect activity ; gradual (5-15 cm) wavy; pockets less deep than wide boundary to
2B1 95-120 cm	yellowish brown(10YR 5/6, moist) ; fine/thin ; friable ; no cutans; no (0%) mottles; high (15-40%) pores; common fine common very fine roots; none ; few (2-5%) fresh or slightly weathered ; few other insect activity ; diffuse (> 15 cm) smooth; nearly plane surface boundary to
2B2 120-140 cm	yellowish brown(10YR 5/6, moist) ; moderate medium ; firm ; no cutans; very few (0-2%) prominent fine (2-6 mm) mottles; medium (5-15%) pores; few fine few very fine roots; none ; few (2-5%) fresh or slightly weathered ; few other insect activity ; diffuse (> 15 cm) smooth; nearly plane surface boundary to
2BC 140-150 cm	yellowish brown(10YR 5/6, moist) ; moderate medium ; firm ; no cutans; very few (0-2%) distinct very fine (< 2 mm) mottles; low (2-5%) pores; very few very fine roots; few ; no rocks (0%) ; no biological activity ;

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	MA3
Remarks on Parent Materials	Loess, Chekha Formation

Land use or vegetation in the immediate vicinity of the site	selective felling
Remarks on Land Use / Vegetation	Blue pine (P. wallichiana), with Rhododendron sp., ferns and Yushania sp. in the understorey
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	coniferous forest

Altitude	3197m
Physiographic Unit	middle slope (back slope) in undulating to mountainous terrain
Hierarchy of major landforms	medium-gradient mountain
Physiograpy description	Front of dissected slope
Slope	08%
Slope Aspect	east-south-east

Drainage class ; FAO (2006) - Guidelines for soil description	well drained
Depth to groundwater table	> 1000cm
Drainage class - intergrade; FAO (2006) - Guidelines for soil description	well drained

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Reference soil Bhutan 03: Umbrisol

Reference soil BT003: Umbrisol

Classification