SOIL PROFILE DESCRIPTIONS
SOIL PROFILE DESCRIPTIONS
The following profile descriptions cover the major classes of soil distinguished in A Place Against Time (see Chapter 10). You may jump to:
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Explanation and Definitions
The soils come from the survey of soil sites that I conducted in the west of the Kerewa-Giluwe region, and are taken from my field description schedules. The profile descriptions follow the method of theSoil Survey Field Handbook (Soil Survey of England and Wales Technical Monograph No. 5), used in the field during the survey. The colours match the standard soil colour charts of the Japanese Ministry of Agriculture and Forestry. The grid references locating the pit sites refer to the Papua New Guinea 1:100,000 map series, Kutubu sheet (number 7585); the place names are the Wola names for small locales (see Chapter 5).
HAEN HOK ARRESTED SOIL
Soil Survey Profile No. 11
(USDA suborder: Rendoll; FAO soil group: Rendzina)
Location: Waishaenk, Was valley (grid ref. 612215)
Elevation: 1750 m.
Aspect: 45
Slope: 35
Parent material: limestone
Local relief: valley side, middle slope; straight slope broken by large outcropping rocks into steps.
Drainage status: normal
Land use/vegetation: sweet potato garden, recently cleared (2 months) from secondary regrowth in which sword grass, stinging trees and chenille common.
| Horizon | Depth (cm) | Description |
|---|---|---|
| H | 0-2 | Very moist, very dark reddish brown (7.5R 2/2), loose to very friable organic silt loam with a moderate fine to medium granular structure; low packing density; few small chert and large limestone stones; many very fine to coarse roots;merging smooth boundary. |
| Ah | 2-36 | Very moist, brownish grey (7.SYR 4/1), friable to firm, slightly sticky and very plastic silty clay with a moderate medium to very coarse angular blocky structure; medium packing density; many medium chert and very large limestone stones; very fine to coarse roots common; merging discontinuous boundary. |
| C | 36-80+ | Unconsolidated limestone blocks of various sizes, which have powdery white surfaces. The spaces between them packed with very moist, yellowish brown (10YR 5/6), friable, sticky and very plastic gritty clay with a strong medium to coarse granular structure; medium packing density; very few roots (none below 43 cm.) |
HUNDBIY CLAY SOIL
Soil Survey Profile No. 2
(USDA great group: Humitropept; FAO soil group: Cambisol)
Location: Hogray, Was valley (grid ref. 618211)
Elevation: 1900 m.
Aspect: 55
Slope: 36
Parent material: limestone
Local relief: valley side middle slope; fairly even surface, straight slope.
Drainage status: normal site, moderately well drained
Land use/vegetation: sweet potato garden, long established (20+ years)
| Horizon | Depth (cm.) | Description |
|---|---|---|
| Ap | 0-4 | Slightly moist, dark brown (7.5YR 3/3-4), very friable, non-sticky & non-plastic sandy silt loam with a moderate fine to medium granular structure; low packing density; common very fine & fine roots; sharp wavy boundary. |
| B1 | 4-26 | Slightly moist, bright brown to orange (7-5YR 5-6/8), firm, sticky & moderately plastic silty packing density; few medium angular chert stones & few medium to coarse, moderately firm, dark reddish brown (2.5YR 3/6) concretions; few fine roots; merging straight boundary. |
| B2 | 26-40 | Moist, bright yellowish brown (10YR 7/6), firm,sticky & very plastic clay with a medium to coarse angular blocky structure; medium packing density; common medium angular chert stones & few medium to coarse, moderately firm, dark reddish brown (2.5YR 3/6) concretions; few fine roots (to 30cm); merging straight boundary. |
| BC | 40-60+ | Extremely abundant, large angular chert stones, packed between with bright yellowish brown (10YR 7/6), firm, sticky & very plastic clay, structureless. |
TIYPTIYP VOLCANIC ASH SOIL
Soil Survey Profile No. 68
(USDA subgroup: Typic Hydrandept; FAO soil unit: humic Andosol)
Location: Sabim, Ak (Augu) valley (grid ref. ~532254)
Elevation: 1725 m.
Aspect: 80
Slope: 22
Parent material: volcanic ash overlying lava & tuft breccias & conglomerates
Local relief: valley side, lower slope; fairly even surface, straight gentle slope to river terrace.
Drainage status: receiving site, some run-off; moderately well drained.
Land use/vegetation: sword grass regrowth predominating, ferns and some small trees.
| Horizon | Depth (cm) | Description |
|---|---|---|
| F | 0-5 | Moss covered mat of dense, tangled fine roots |
| A | 5-13 | Moist, brownish black (7.5YR 3/2), very friable, very slightly sticky and moderately plastic silty clay loam with a weak fine to medium granular structure; low packing density; abundant very fine through medium roots; clear smooth boundary. |
| B | 13-50+ | Moist, orange (7.5YR 6/6), friable to firm, sticky and very plastic sandy clay with common, distinct, fine and medium, bright brown (2.5YR 5/8) mottles; moderate, fine to coarse angular blocky structure; medium packing density; common, small to large, dark mineral stones (some weakly cemented); few very fine roots (to 43cm). |
IYB DOR TILAI ALLUVIAL SOIL
Soil Survey Profile No. 82
(USDA great group: Tropofluvent;FAO soil unit: dystric Fluvisol)
Location: Kopa, Kopako creek (grid ref.~538049)
Elevation: 1125 m.
Aspect: –
Slope: 0
Parent material: volcanic breccias and conglomerates overlain by alluvium
Local relief: flat to very gently undulating valley floor; floodplain of Kopako creek
Drainage status:receiving site, no run-off
Land use/vegetation: overgrown taro and banana garden (~2 years old, nearing abandonment) with herbaceous regrowth and saplings predominating over crop
| Horizon | Depth (cm) | Description |
|---|---|---|
| L | 0-<1 | Fresh litter of dead leaves and plant stems. Loose and plant structures little altered. |
| A | 1-9 | Moist, brown (7.5YR 4/3), very friable, slightly sticky and moderately plastic sandy silt loam with a moderate fine to medium granular and angular blocky compound structure; medium packing density; many very fine through coarse roots; merging smooth boundary. |
| C | 9-50+ | Moist, brown to dull brown (7.5YR 4-5/4), very friable, slightly sticky and moderately plastic sandy loam with a fine to medium granular and angular blocky compound structure (verging on structureless); medium packing density; common decreasing to few, very fine to coarse roots (to 46cm). |
IYB MUW SANDY SOIL
Soil Survey Profile No. 26
(USDA great group: Tropopsamment; FAO soil unit: dystric Arenosol)
Location: Saela, Was valley (grid ref. 636206)
Elevation: 1850 m.
Aspect: 10
Slope: 20
Parent material: sandstone
Local relief: narrow flat-topped ridge; slope straight and even.
Drainage status: good, shedding site
Land use/vegetation: primary woodland in which chestnut oaks predominate, some sword grass.
| Horizon | Depth (cm) | Description |
|---|---|---|
| F | 0-2 | Litter layer of dead leaves, stems, twigs and so on, enmeshed in a mat of fine roots; sharp smooth boundary. |
| Ah | 2-12 | Slightly moist, brown (10YR 4/4), very friable, sticky and very plastic sandy clay loam with a strong fine to medium granular structure; medium packing density; few very small and small weakly cemented pieces of sandstone; many very fine through coarse roots; sharp smooth boundary. |
| B | 12-27 | Slightly moist, greyish olive (5Y 6/2) streaked orange (5YR 6/8), very firm, non-sticky, very fine loamy sand with a moderate coarse angular structure; high packing density; few very fine to medium roots (to 23cm); merging smooth boundary. |
| C | 27-70+ | Slightly moist, greyish olive (5Y 6/2) streaked orange (5YR 6/8) fine sand, with some fine reddish black (7.5R 2/1) weakly cemented concretions; massive and structureless, extremely firm and weakly cemented. |
PA TONGOM GLEY SOIL
Soil Survey Profile No. 23
(USDA subgroup: Typic Tropaquept; FAO soil unit: dystric Gleysol)
Location:Pa, Was valley (grid ref. 634206)
Elevation: 1850 m.
Aspect: 338
Slope: 0
Parent material: mudstone/siltstone
Local relief: flat, valley bottom with even surface, stream running along centre.
Drainage status: poor, receiving site
Land use/vegetation: sword grass predominating, a few trees and some short grasses
| Horizon | Depth (cm) | Description |
|---|---|---|
| F | 0-<1 | Some dead grass stems and leaves |
| Ahg | 1-12 | Wet, dark brown (10YR 3/2-3), sticky and moderately plastic silty clay with common fine and medium prominent bright reddish brown (5YR 5/8) mottles;weak fine and medium granular structure;medium packing density; many very fine to medium roots; merging smooth boundary |
| B | 12-70+ | Wet, grey (N 4/0) and greenish grey (10GY 5/1) [in ~ equal proportions], very sticky and very plastic clay with many medium and coarse prominent bright reddish brown (5YR 5/8) mottles; weak adherent angular blocky structure (verging on structureless); high packing density; common decreasing to few very fine to medium roots (to 62cm). |
IYB UW DAMIY PEAT SOIL
Soil Survey Profile No. 78
(USDA great group: Tropohemist; FAO soil unit: eutric Histosol)
Location: Pega valley (grid ref. 591211)
Elevation: 1810 m.
Aspect: 135
Slope: 3
Parent material: organic over limestone with inwashed mineral sediment
Local relief:bowl-like feature subject to ponding in heavy rains
Drainage status:poor, receiving site
Land use/vegetation:swamp and cane grasses with some trees
| Horizon | Depth (cm) | Description |
|---|---|---|
| F | 0-2 | Tangle of rotting leaves and dead grass stems |
| Oh | 2-5 | Moist, dark reddish brown (10R 2/2) friable silt loam with weak medium granular structure; porous; abundant fine to coarse roots; merging smooth boundary. |
| Ah | 5-38 | Very moist, brownish black (7.5YR 3/2), slightly sticky and non-plastic organic silty clay loam with few fine distinct reddish brown (2.5YR 4/6) mottles and weak subangular blocky structure; many fine-medium pores; many fine to coarse roots and rotting plant remains; merging smooth boundary |
| A01 | 38-66+ | Wet, brownish black (7.5YR 3/2), slightly sticky and non-plastic organic silty clay loam; structureless with many dead roots and some pieces of rotting wood |
WAIP PEAT SOIL
Soil Survey Profile No. 88
(USDA subgroup: Tropofolist;FAO soil unit: Histosol)
Location: Seblaenda, Was valley (grid ref. 615208)
Elevation: 2000 m.
Aspect: 300
Slope: 30
Parent material: organic over limestone
Local relief: valley side, middle slope; convex surface, fairly straight
Drainage status: normal site, moderately well drained
Land use/vegetation: dense fern brake, a few cane grass clumps.
| Horizon | Depth (cm) | Description |
|---|---|---|
| L | 0-11 | Relatively fresh, loose litter of dead fern fronds and stems; plant structures little altered; many fine roots, merging smooth boundary |
| Of | 11-71 | Moist, dark reddish-brown (10R 3/3) fibrous layer of decayed leaves and tough stems, loosely packed and structureless, with many fine roots; merging smooth boundary |
| Oh | 71-73 | Moist, very dark reddish brown (10R 2/3), slightly sticky and non-plastic friable organic loam of fine to medium granular structure; low packing density and many fine roots, with clear smooth boundary. |
| Ah | 73-98+ | Moist, greyish red (2.5YR 5/2), friable to firm slightly sticky and slightly plastic organic silty clay with few fine and medium distinct redmottles (10R 5/8) and moderate medium angular blocky structure; medium packing density, and few fine roots. |
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