Reference soil Brazil 22: Solonetz

BR022

Solonetzes occur where a sodium source supplies the clay-rich subsoil with exchangeable Na, causing peptization of clay and organic substances and deterioration of the topsoil.

Characteristics

Soils having a natric horizon (a subsurface horizon with distinct higher clay content than the overlying horizon and more than 15% exchangeable sodium) within 100 cm from the soil surface.

Distribution of Solonetz (rough estimation supplied by soilgrids)

Reference soil BR022: Solonetz

Moderately deep; imperfectly drained, sandy clay derived from gneiss; abruptly overlain by a sandy topsoil. The transition of E to B horizon is tongued. The columns of the B-horizon have prominent rounded tops, which are locally called "cabeca de gato" (literally: "cat head"). Classification: the abrupt textural change (duplex) from sandy topsoil to sandy clay subsoil consisting of rounded columnar structure are pointing to a "solodized solonetz". Boa Vista has a slightly higher rainfall than Cabeceiras. The annual precipitation of Boa Vista=370mm, the annual precipitation of Cabaceiras=217mm (1931-1960). The soil moisture regime is ustic to aridic. Slides no 9834-9854.

Classification

WRB 2006

WRB 1998

Stagnic- Solonetz (Albic Abruptic Magnesic)

Stagni-Magnesic- Solonetz (Albic)

18-30 cm	albic horizon
30-70 cm	natric horizon
-	abrupt textural change
-	reducing conditions

0-18 cm	ochric horizon
18-30 cm	albic horizon
30-70 cm	natric horizon
-	stagnic
-	abrupt textural change

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Abrupti-Stagnic Solonetz

Gleyic Solonetz

0-18 cm	ochric A horizon
18-30 cm	albic E horizon
30-70 cm	natric B horizon
- cm	natric B horizon
- cm	ochric A horizon
-	stagnic
-	abrupt textural change

0-18 cm	ochric A horizon
18-30 cm	albic E horizon
30-70 cm	natric B horizon
-	abrupt textural change
-	hydromorphic

Local classification:	Solonetz solodizado

Other classification

USDA-NRCS (1999)	Grossarenic Paleustalf
USDA-SCS (1975)	Grossarenic Paleustalf ustic loamy isohyperthermic

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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
0-18	-	5.4	7.6	16.9	36.2	17.1	83.2	9.4	3.5	12.9	4.0
18-30	30	8.9	12.9	22.7	32.6	11.2	88.3	6.1	2.2	8.3	3.4
30-51	20	3.7	12.1	21.6	19.0	6.3	62.7	5.1	2.0	7.1	30.3
51-70	-	2.1	8.8	20.6	21.8	7.9	61.2	5.7	3.3	9.0	29.8

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
5-10	1.433	-	-	-	-
0-18	-	-	-	1.8	4.0
18-30	-	-	-	2.9	3.4
30-35	1.720	-	-	-	-
30-51	-	-	-	28.1	30.3
51-70	-	-	-	26.7	29.8

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
5-10	1.433	39.9	36.5	29.4	17.0	11.5	10.2	4.4	4.3
30-35	1.720	37.2	35.6	34.4	32.8	30.2	29.0	27.6	26.9

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
0-18	4.8	4.1	0.26	-	0.56	0.06	9	0.3	0	1.4	0.7	0.1	0.3	2.5
18-30	5.9	4.4	0.12	-	0.23	-	-	0.1	0	0.4	0.8	0.1	0.5	1.8
30-51	5.8	4.2	0.28	-	0.38	-	-	0.4	0	1.4	5.0	0.1	2.8	9.3
51-70	7.5	6.0	0.85	0.7	0.16	-	-	-	-	2.0	7.0	0.1	4.0	13.1

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 %
0-18	132	1.9	48	2.0	-	0	16
18-30	95	1.9	56	0.8	-	0	26
30-51	85	11.0	36	1.3	-	0	25
51-70	112	11.7	39	0.6	-	-	34

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
0-18	-	-	-	0.00	0.00	0.10	0.00	-	-	-	0.00
18-30	-	-	-	0.00	0.00	0.10	0.00	-	-	-	0.00
30-51	-	-	-	0.00	0.00	0.40	0.10	-	-	-	0.10
51-70	-	-	-	0.10	0.00	0.20	0.00	-	-	-	0.00

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-18	-	-	-	-	-	-	medium to strong	medium to strong	-	-	medium to strong	-
18-30	-	-	-	-	-	-	medium to strong	medium to strong	-	-	medium to strong	-
30-51	-	-	-	-	-	-	very strong	weak	-	-	medium to strong	-
51-70	-	-	-	-	-	-	strong	weak	-	-	strong	-

Profile description

Ah 0-18 cm	(dark) brown (10YR 4/3, moist)Description sand,structureless single grain,very friable non sticky non plastic,many very fine interstitial random pores,clear wavy boundary to,
E 18-30 cm	(10YR 6.5/2, moist)Description sand gravelly,structureless single grain,loose non sticky non plastic,many very fine interstitial random pores,abrupt irregular boundary to,
Btn1 30-51 cm	greyish brown (10YR 5/2, moist)sandy clay loam slightly gravelly,strong very coarse columnar,extremely firm sticky very plastic,common medium prominent clear mottles (5 YR 4/6),few fine inped tubular random pores,gradual wavy boundary to,
Btn2 51-70 cm	grey (10YR 5/1, moist)sandy clay loam,strong very coarse columnar,extremely firm sticky very plastic,few medium faint diffuse mottles,few fine inped tubular random pores,very few medium gravel weathered calcite fragments,clear wavy boundary to,
Btn2 51-70 cm	dominant medium gravel weathered calcite+gneiss fragments

Kind 1 (parent material) ; Parker (eds), 1984	gneiss
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	gneiss with calcite veins
Soil Depth	70cm
Texture of parent material	loamy
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

Intensity of the soil erosion type	slight
Intensity of the soil erosion type (second entry)	slight
Soil erosion type	sheet
Soil erosion type (second entry)	rill

Land use or vegetation in the immediate vicinity of the site	shrubland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Caatinga hiperxerófolia LANDUSE:
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	degraded
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	extremely xeromorphic shrub

Altitude	500m
Physiographic Unit	moderately dissected denudational plain
Physiographic position of the site	middle slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plain
Slope	5%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Lower limit of a slow permeable or stagnating layer in the profile	70cm
Drainage class ; FAO (2006) - Guidelines for soil description	imperfect
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-90cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	rapid
Upper limit of a slow permeable or stagnating layer in the profile	30cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	slightly alkaline
Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	surface slaked; sorted sand/silt, some clay films
Rock outcrop class (FAO (2006) - Guidelines for soil description)	fairly rocky
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline
Surface stoniness class (FAO (2006) - Guidelines for soil description)	very few stones

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Reference soil Brazil 22: Solonetz

Characteristics

Reference soil BR022: Solonetz

Classification