Reference soil Philippines 01: Andosol

PH001

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 PH001: Andosols

A fine-textured soil, situated at upper slope of piedmont plain of Mount Isarog (gradient 2-5 %). The parent material is derivedfrom reworked pyroclastic allophane materials. Sheet, rill and gully erosion are apparent in this cultivated land (corn, sorghum, beans, coconuts, sugar cane) that is fertilized and irrigated (BMS project). Moreover, worm casts and krotovinas can be found. Apart from the first and the last horizon, there is illuviated organic matter and clay material on root channels.

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
0-27	-	0.1	0.2	1.6	5.6	4.3	11.8	15.6	30.3	45.9	42.2
27-52	-	0.1	0.2	0.9	3.7	3.4	8.3	8.3	35.2	43.5	48.3
52-85	-	0.2	0.3	1	3.6	3.6	8.7	10	40.2	50.2	41.1
85-121	-	0.1	0.2	0.8	2.9	2.8	6.8	11.2	40	51.2	41.9
121-157	-	0.1	0.4	1	3.2	2.7	7.4	7.6	43.9	51.5	41.1

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-27	0.536	-	-	-	42.2
27-52	-	-	-	-	48.3
52-85	0.527	-	-	-	41.1
85-121	-	-	-	-	41.9
121-157	0.447	-	-	-	41.1

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
0-27	0.536	74.8	74.8	71	66	64	61.8	443	39.5
52-85	0.527	80	80.1	78.6	74.4	72.4	70.4	58.9	55.1
121-157	0.447	81.2	81.2	79.3	74.7	72.9	71.2	56.7	50.9

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
0-27	5.6	4.6	0.04	-	10.98	-	-	-	-	1.2	0.3	0.2	0.2	1.9
27-52	5.8	5.1	0.03	-	4.73	-	-	-	-	2.6	1.4	0.2	0.3	4.5
52-85	6.3	5.2	0.02	-	2.29	-	-	-	-	3.2	1.0	0.2	0.3	4.7
85-121	6.4	5.1	0.02	-	1.86	-	-	-	-	1.6	0.7	0.2	0.3	2.8
121-157	7.2	5.2	0.01	-	1.88	-	-	-	-	1.6	0.7	0.2	0.3	2.8

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 %
0-27	2	93.7	222	38.4	-	-	-
27-52	7	67.7	140	16.6	-	-	-
52-85	7	66.8	163	8	-	-	-
85-121	4	72.7	174	6.5	-	-	-
121-157	4	76.6	186	6.6	-	-	-

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
0-27	10.8	99	-	9.43	3.18	2.31	2.72	0.45	1.42	-	1.41
27-52	10.6	99	-	8.51	4.64	2.47	2.27	0.03	0.44	-	1.23
52-85	10.3	99	-	10.9	4.53	2.34	2.29	0.02	0.28	-	1.18
85-121	10.3	100	-	9.29	5.34	2.63	1.97	0.02	0.29	-	1.75
121-157	10.2	100	-	9.74	5.67	2.93	1.64	0.02	0.31	-	1.49

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-27	-	strong	very weak to weak	-	weak	-	-	very weak to weak	-	-	very weak to weak	-
52-85	-	strong	very weak to weak	-	weak	-	-	weak	-	-	very weak to weak	-
121-157	-	strong	very weak to weak	-	weak	-	-	weak	-	-	very weak to weak	-

Profile description

Ah 0-27 cm	black (10YR 2/1, moist)silt loam,massive parting to weak medium prismatic,very friable non sticky non plastic,clear smooth boundary to,
BA 27-52 cm	dark yellowish brown (10YR 3/4, moist)silt loam,strong fine and medium subangular blocky,friable non sticky non plastic,clay and humus cutans,few fine pores,few worm channels,diffuse wavy boundary to,
Bw1 52-85 cm	(dark) brown (7.5YR 4/4, moist)silt loam,strong fine and medium subangular blocky,friable slightly sticky slightly plastic,clay and humus cutans,few fine pores,few worm channels,diffuse wavy boundary to,
Bw2 85-121 cm	(dark) brown (7.5YR 4/4, moist)silt loam,moderate fine and medium subangular blocky,friable slightly sticky slightly plastic,clay and humus cutans,few fine pores,diffuse wavy boundary to,
Bw3 121-157 cm	(dark) brown (7.5YR 4/4, moist)silt loam,moderate fine and medium subangular blocky,

Kind 1 (parent material) ; Parker (eds), 1984	ejecta ash
Mode of accumulation or deposition of parent material	ejecta ash

Land use or vegetation in the immediate vicinity of the site	mixed farming
Remarks on Land Use / Vegetation	Research area with diversified crops

Altitude	140m
Physiographic position of the site	upper slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	piedmont
Slope	5%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	well
Kind of ground water table (USDA, 1979)	no groundwater table observed
Estimated run off (class)	medium

Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	no surface slaking/crusting observed
Rock outcrop class (FAO (2006) - Guidelines for soil description)	none
Surface stoniness class (FAO (2006) - Guidelines for soil description)	none

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Reference soil Philippines 01: Andosol

Characteristics

Reference soil PH001: Andosols

Classification