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Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P2-3 – Acid Sulfate Soils Contract: LTN/6/31/2003(10)

R.W. Fitzpatrick, W.S. Hicks, G.J. Grealish and A.J. Ringrose-Voase

CSIRO Land and Water Science Report 06/08 February 2008

1st Revision

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Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report 2-3 – Acid Sulfate Soils

Contract: LTN/6/31/2003(10)

R.W. Fitzpatrick, W.S. Hicks, G.J. Grealish and A.J. Ringrose-Voase

CSIRO Land and Water Science Report 06/08 February 2008

Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report 2-3 – Acid Sulfate Soils Page ii

Contacts:

Project Director Dr Chris Smith, CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601

Tel: +61-2-6246 5960; e-mail: [email protected]

Project Coordinator Dr Anthony Ringrose-Voase, CSIRO Land and Water, GPO Box 1666, Canberra ACT 2601

Tel: +61-2-6246 5956; e-mail: [email protected] Other project staff:

Project Management Mr Edward A’Bear, URS Australia Pty Limited, Adelaide, SA

Soil Surveyor Mr Gerard Grealish, URS Australia Pty Limited, Perth, WA

Soil Taxonomy Dr Rob Fitzpatrick, CSIRO Land and Water, Adelaide, SA

Soil Fertility Dr Mike Wong, CSIRO Land and Water, Perth, WA

Tropical Crops Mr Ted Winston, URS Australia Pty Limited, Mission Beach, Queensland

Acid Sulfate Soils Mr Warren Hicks, CSIRO Land and Water, Canberra, ACT

GIS/Database Ms Tania Laity, Bureau of Rural Sciences, Canberra, ACT

Remote Sensing Mr Alan Marks, CSIRO Land and Water, Canberra, ACT

Laboratory analysis Mr Adrian Beech, CSIRO Land and Water, Adelaide, SA

Quality Control/Assurance Mr Bernie Powell & Dr Phil Moody

Queensland Department of Natural Resources and Water, Brisbane, Queensland

mailto:[email protected]

mailto:[email protected]

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Acknowledgements This work was funded by the Department of Agriculture Negara Brunei Darussalam.

Adrian Beech, Janice Trafford, John Gouzos, Jane Richards, Michelle Smart and Aimee Walker of the CSIRO Land and Water Analytical Chemistry Unit provided soil chemical analyses. Mark Raven provided x-ray diffraction (mineralogical) analyses. Sam Grigg, URS Pty Ltd, provided assistance in the field.

Bernie Powell, Queensland Department of Natural Resources and Water, thoroughly reviewed this report and suggested many improvements.

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Executive Summary This report:

• Assesses the potential for occurrence of acid sulfate soils.

• Determines the properties and hazards of acid sulfate soils including suitability for agricultural development.

• Develops recommendations for the sustainable management of acid sulfate soils and identifies mitigation strategies for identified hazards.

We examined all 29 Agricultural Development Areas (ADAs) for the occurrence of acid sulfate soils (ASS). We found a wide range of ASS in 9 of these ADAs. In these ADAs, we inspected 27 sites and sampled 7 for detailed analysis. Thirty samples were collected and analysed for chemical, mineralogical and physical properties.

These samples provided an adequate baseline for soil condition in the ADAs in Brunei. Recorded locations and long-term storage of the oven dried samples and air dried / moist samples kept in chip trays will allow for future re-sampling and analysis, if required.

ASS of the flat floodplain areas are already acidic, and appear to have been so for a long period of time. Much of this condition may be attributable to a lowering of the shallow water table by drainage. The key to management and sustainable production on these lowland soils both for soil fertility and environmental protection is an understanding of their complex hydrology so that the water table can be managed appropriately (Melling 2002). Unless properly managed, the economic usefulness of these soils will be short lived.

Management of ASS is intimately linked to the overall management of the hydrology. Poor management of the water table will result in increased acidification, poor production, environmental degradation and ultimately the loss of the soil resource itself. Acidification or occurrence of sulfuric materials is considered to be a risk because all the sulfide containing wetland soils we examined have little acid neutralising capacity. In soils, acid neutralising capacity is provided by carbonate minerals and clays. In Brunei, as in all high rainfall, highly leached acid tropical soils, carbonate contents are low; however some locations in Brunei have high (>30%) clay contents which provide some buffering.

The user-friendly “Soil Identification Key” developed for the soils of the ADAs incorporates the acid sulfate soils to allow the easy identification of the various Acid Sulfate Soils (ASS). Similarly to other non-ASS, the key is based on the comprehensive data set of soil properties acquired across the ADAs. The soil identification key uses non-technical terms to categorise ASS and other soils in terms of attributes that are important for charactering the soils and their fertility. The key describes practical, surrogate methods to assist extension officers and farmers to recognise and manage ASS. All ASS contain either a sulfuric horizon or sulfidic material. The following 4 soil groups: (i) Organic; (ii) Cracking Clay; (iii) Sulfuric; and (iv) Sulfidic have been identified. These are further divided into 2 sub-groups based on pH and lastly on consistency (Appendix A, Table A2).

The main risks to the development of ASS for agricultural production are:

• Lowering the water table and exposing the remaining sulfidic material to further oxidation and acidification;

• Subsidence due to oxidation of the organic soils (peats) and loss of the soil resource.

Unless well managed and controlled, the development of ASS will result in decreased production due to the toxicity and plant nutrition effects of the low pH. The discharge of acid drainage water will cause offsite environmental degradation from acidic discharges into waterways affecting aquatic life and fisheries. There will also be cumulative global effects

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due to greenhouse gas emissions from the release of fossil carbon currently stored in the soils.

The most effective management of ASS to minimise risk is avoidance, i.e. do not develop ASS. If their development is absolutely necessary, then minimise disturbance.

On lowland acid sulfate soils:

• Identify the depth to sulfidic material;

• Maintain the watertable above the sulfidic material and at the highest practicable level for the crops grown;

• Treat sulfuric horizons with lime;

• Use mineral layers and treated sulfuric layers to construct raised beds;

• Treat drainage water with hydrated lime to prevent off site effects on infrastructure such as concrete drains and bridges and degradation of stream water quality.

On upland soils affected by pyritic sedimentary rock:

• Control erosion to prevent the exposure of pyritic rocks;

• Treat sulfuric layers with lime;

• Treat drainage water with hydrated lime to prevent off site effects on infrastructure such as concrete drains and bridges and degradation of stream water quality.

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Table of Contents 1. Introduction.............................................................................................................. 1

1.1. Background.......................................................................................................................... 1 1.2. Objectives and Outputs of this Study................................................................................... 3

1.2.1. Acid Sulfate Soil Risks ..................................................................................................... 3 1.2.2. Awareness and Economic Impacts.................................................................................. 4

2. Methodology ............................................................................................................ 5 2.1. Field Survey ......................................................................................................................... 5 2.2. Definitions: Soils, Materials, Conditions............................................................................... 5

2.2.1. Organic and Mineral Soils................................................................................................ 5 2.2.2. Sulfidic Materials and Sulfuric Horizons .......................................................................... 6 2.2.3. Aquic Conditions .............................................................................................................. 7 2.2.4. Soil Cracks, Slickensides and Cracking Clay Soils ......................................................... 8 2.2.5. n Value ............................................................................................................................. 8 2.2.6. Monosulfidic Black Ooze Material in Drain Sediments .................................................... 8 2.2.7. Sulfate-Containing Salt Efflorescences ........................................................................... 8

2.3. Laboratory Analyses ............................................................................................................ 9 2.3.1. Laboratory Soil Analysis Methods.................................................................................... 9

3. Soil Classification.................................................................................................. 11 3.1. Soil Classes Identified........................................................................................................ 11 3.2. Soil Identification Key......................................................................................................... 11

4. Major Characteristics of ASS ............................................................................... 16 4.1. Morphology ........................................................................................................................ 16

4.1.1. Field Description and Morphology ................................................................................. 16 4.1.2. Sulfidic Material.............................................................................................................. 16 4.1.3. Sulfuric Horizons............................................................................................................ 16 4.1.4. Tests to Identify Sulfidic Material and Predict the Consequences of Disturbance ........ 16

4.2. Chemistry ........................................................................................................................... 17 4.2.1. Soil pH and Electrical Conductivity (EC)........................................................................ 18 4.2.2. Sulfur.............................................................................................................................. 18 4.2.3. Carbon ........................................................................................................................... 19 4.2.4. Acid–Base Budget ......................................................................................................... 20 4.2.5. Arsenic and Cadmium.................................................................................................... 20

5. Management of ASS for Soil Fertility, Agricultural Production and Environmental Protection ..................................................................................... 22

5.1. Management Options......................................................................................................... 22 5.1.1. Avoiding Disturbance ..................................................................................................... 22 5.1.2. Minimising Disturbance.................................................................................................. 22 5.1.3. Rehabilitation ................................................................................................................. 23

5.2. Acid Sulfate Soil Classification and Management Options................................................ 24 5.2.1. ASS Hazard Maps ......................................................................................................... 27

References ........................................................................................................................... 34 Appendices .......................................................................................................................... 37

Appendix A Data Tables.................................................................................................................... 38 Appendix B: Photographic Reference for Brunei Acid Sulfate Soils ................................................. 63

Tables Table 1: Soil Taxonomy classifications of surveyed Agricultural Development Areas in Negara

Brunei Darussalam. ............................................................................................................ 11 Table 2: Summary soil identification key for major acid sulfate soil types in surveyed Agricultural

Development Areas of Negara Brunei Darussalam............................................................ 13 Table 3: Soil identification key for acid sulfate soil subtypes in surveyed Agricultural

Development Areas of Negara Brunei Darussalam............................................................ 14 Table 4: Soil rating scale for the pHFOX test. ......................................................................................... 17

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Table 5: Thresholds indicating the need for an ASS management plan based on texture range and chromium reducible sulfur concentration (SCr) and amount of soil material disturbed (Dear et al., 2002). .............................................................................................. 19

Table 6: Potential management options based on the soil characteristics of acid sulfate soil types.................................................................................................................................... 24

Table 7: Management and treatment class of acid sulfate soil types in surveyed ADAs...................... 25 Table 8: Acid Sulfate Soil Hazard Classes............................................................................................ 27 Table 9: Acid Sulfate Soil (ASS) Hazard of the map units of Agricultural Development Areas

(ADAs) where ASS occur.................................................................................................... 29 Table A1: ASS site descriptions. ........................................................................................................... 38 Table A2: Description of soil profiles ..................................................................................................... 42 Table A3.1: Results of laboratory analyses for soil samples – EC, pH, organic C, N, S, reduced

inorganic S (RIS) and titratable actual acidity (TAA)........................................................... 52 Table A3.2: Results of laboratory analyses for soil samples (exchangeable cations, Al and Mn). ....... 54 Table A4: Results for laboratory analyses of selected soluble salts in soil samples. ........................... 56 Table A5: Acid base accounting. (* When pH1:2.5 <5.0 then ANC=0).................................................... 58

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1. Introduction This document is Report P2-3 – Acid Sulfate Soils for the project Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam. The objective of this report is to define the nature and extent of acid sulfate soils recognised in Phase 1 of the project (Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-2 – Soil Properties and Soil Identification Key, Grealish et al. 2007a); to discuss the problems associated with them and to recommend management strategies for acid sulfate soil areas.

1.1. Background Acid Sulfate Soils (ASS) are all soils in which sulfuric acid may be produced, is being produced, or has been produced in amounts that have a lasting effect on major soil characteristics (Pons 1973). This general definition includes potential, active (or actual), and post-active acid sulfate soils: three broad genetic kinds that continue to be recognized (e.g. Fanning et al. 2002).

ASS form from the interaction of sulfates, usually from seawater, iron from sediments and abundant organic material under permanently waterlogged or saturated conditions. These conditions lead to the formation of sulfide-containing minerals, predominantly iron pyrite (FeS2). Sulfide minerals may also be present in sedimentary rocks (e.g. Setapi shale) as a result of similar processes in the geologic past.

Soil that contains sulfides is called sulfidic material (Soil Survey Staff 2003) and can be environmentally damaging if exposed to air by disturbance. Exposure results in the oxidation of pyrite with each mole of pyrite yielding 4 moles of acidity (i.e. 2 moles of sulfuric acid). This process transforms sulfidic material to a sulfuric horizon when, on oxidation, the material develops a pH of 3.5 or less (Soil Survey Staff 2003). When ASS become strongly acidic (pH <3.5) acid drainage water is produced (Figure 1). This acid, together with toxic elements that are leached from sediments, can kill fish, contaminate shellfish, drinking water and groundwater, and can corrode concrete and steel in buildings and underground pipes, unless it is adequately neutralized by the receiving environment. These impacts can be measured in terms of:

• Loss of agricultural production with poor water quality (Figure 1), damage to water environments and reduction of wetland biodiversity.

• Additional maintenance of community infrastructure affected by acid corrosion (Figure 2).

• The need for rehabilitation of disturbed areas to improve water quality and minimize impacts.

ASS are widespread in Brunei. Blackburn and Baker (1958) identified ASS beneath peats and Phase 1 of the present evaluation (Grealish et al. 2007b) noted ASS in nine Agricultural Development Areas (ADAs). Apart from the work of Mohamad Yussof bin Haji Mohiddin (1982) little work has been done on the properties, distribution and types of ASS in Brunei. This work concentrated mainly on Al toxicity and P status on two soils from Mulaut Agricultural Station. According to Mohamad Yussof bin Haji Mohiddin (1982), land near Mulaut Agricultural Station was too acid for rice production and other agriculture and the station was subsequently closed.

Brunei contains a wide range of different types of organic and mineral ASS in various physical settings, which can oxidise and produce acid because of changing hydrological and biogeochemical conditions. This occurs in two broad situations:

i) Drained/partly drained conditions, which develop in natural tidal, intertidal and supratidal zones, and fluvial floodplains or when watertables are artificially lowered for agriculture.


ii) Drained conditions, which develop during the excavation and construction of drains; buildings and other infrastructure; or when erosion of sulfide-rich sediments or weathered pyritic sedimentary rocks occurs.

In general terms, these ASS occur in association with lowland peat domes where specific characteristics such as clay and organic carbon contents depend upon their topographic setting within the peat dome. Exceptions are ASS in which the sulfuric horizon has been formed as a result of acid leachate from the weathering of pyritic shale.

An environmental risk is present because, if river or wetland systems are drained, sulfidic material that has not previously been in contact with the oxygen in the atmosphere is disturbed. During the lowering of the watertable or drying of subaqueous soils, sulfidic materials may be exposed, and sulfides within the subaqueous soil horizons will begin to oxidise because they are exposed to air. This produces sulfuric acid and releases toxic quantities of iron, aluminium and heavy metals. The acid, aluminium and heavy metals can leach into waterways, kill fish, other aquatic organisms and vegetation, and can even degrade structures made from concrete or steel to the point of failure.

However, appropriate management of ASS during development can improve the quality of discharge water, increase agricultural productivity and protect infrastructure and the environment. Such improvements can generally be achieved by applying low-cost land management strategies based on the identification and avoidance of ASS materials; slowing or stopping the rate and extent of pyrite oxidation, and by retaining existing acidity within the ASS landscape. Acidity and oxidation products that cannot be retained on-site may be managed by other techniques such as acidity barriers or wetlands that intercept and treat contaminated water before it is finally discharged into rivers or estuaries.

The selection of management options will depend on the nature and location of the ASS materials, and their position in the landscape. This is why reliable ASS risk maps, at appropriate scales, and characterizing ASS landscapes are so important (Table 1). All management options recommended in this report comply with the above principles.

Figure 1: Recently cleared land and excavated drains in the Betumpu Agricultural Development Area showing: (a) good pineapple growth on the higher mounded areas and stunted growth on the lower areas adjacent to the drains with precipitates of iron oxyhydroxysulfate minerals (schwertmannite) on the edges of the drain / wetland margin (pH 3.5–4.2), and (b) close-up view of a sulfuric horizon in spoil bank of a drain showing bright yellow jarosite mottles (pH 3.5) and clear reddish coloured water in the drain (pH 3) with patches of oil-like bacterial surface films.


Figure 2: Damage to road infrastructures by erosion and corrosion of concrete and road material (pH 3.5 - 4.2) from the exposure (oxidation) of pyrite contained in the pyrite-rich shale at Tungku.

1.2. Objectives and Outputs of this Study This study presents results of literature studies, fieldwork and laboratory analysis, and provides recommendations for management strategies in areas identified as likely to have acid sulfate soil. The report objectives are to:

• Assess available information on these critically important soils in Brunei;

• Assess the potential for occurrence of acid sulfate soils as identified in Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-2 – Soil Properties and Soil Identification Key for Major Soil Types (Grealish et al. 2007a) and mapped in Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-1.2 – Soil Maps (Grealish et al. 2007b);

• Determine the properties and hazards of acid sulfate soils including their suitability for agricultural development; and

• Develop recommendations for the sustainable management of acid sulfate soils.

1.2.1. Acid Sulfate Soil Risks ASS are stable and environmentally benign if undisturbed. However once the sulfidic materials are disturbed through drainage, excavation or suspension in the water column, conditions change from anoxic (reducing) to oxidising. Oxidation of sulfides commences, resulting in a number of potential environmental risks. Disturbance can be natural such as isostatic rebound in areas of the Baltic coast, uplift in the case of the Bangkok Plain, or disturbance can be the result of drainage and reclamation for urban development (e.g. coastal Australia), aquaculture and agriculture (e.g. coastal Australia, Mekong Delta). Risks include:

Acidification and elevated metal concentration: In addition to lowering pH, activation or oxidation of sulfidic materials can lead to significant increases in dissolved metal concentration in surface water, including toxic species such as aluminium, iron and other metals (e.g. arsenic or cadmium). The increase in the solubility of metals under acidic conditions may be more harmful to biota than the low pH itself.

Water column deoxygenation: When sediments rich in monosulfides are resuspended, they will rapidly oxidise, potentially removing most of the oxygen from the water column (Sullivan et al., 2002). This can lead to fish kills, especially in enclosed areas such as fish ponds. In coastal acid sulfate soil regions of eastern Australia, resuspension of sulfidic sediments during the flushing of drains by high runoff events has been linked to deoxygenation of waterways (Sullivan et al., 2002). However, little information on this issue is available outside Australia. In addition, not all deoxygenation events can be safely attributed to sulfides. “Blackwater” events – the flushing of particulate and


dissolved organic matter during high runoff events following dry periods – can also induce deoxygenation.

1.2.2. Awareness and Economic Impacts It is vital for all farmer groups and government agricultural extension officers to be aware of the many impacts that result from disturbance of sulfidic materials. These impacts are important from an environmental, engineering, economic, and quality of life perspective. Because of the extensive level of existing ASS occurrence and planned development in Brunei this could be a critical natural resource management issue for many areas. This is understandable when one adds up the documented potential for disturbed sulfidic materials to destroy wetlands, acidify and deoxygenate waterways and estuaries, increase the incidence of fish kills and disease, contaminate valuable groundwater resources, facilitate the accumulation of heavy metals, corrode, attack and destabilise roads, concrete and steel infrastructure, stimulate blooms of marine blue-green algae, decrease the agricultural productivity of land, and increase mosquito and arbovirus incidence.


2. Methodology

2.1. Field Survey The field observations and sampling for this study were confined to the Agricultural Development Areas (ADAs). The rationale for site selection, the number of sites and samples chosen for analysis are given in Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-1.1 – Laboratory Analysis of Soil Chemical and Physical Properties (Beech et al. 2006) and in Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-2 – Soil Properties and Soil Identification Key for Major Soil Types (Grealish et al. 2007a). GPS (geographic positioning system) locations of sampling sites are provided in the project database. Samples for ASS specific analyses were confined to ADAs within Brunei Muara. All soils were described and classified according to Soil Taxonomy. For detailed operational standards and general approach see Grealish et al. (2007a).

2.2. Definitions: Soils, Materials, Conditions The purpose of this section is to briefly explain: (i) the nature of organic and mineral soils, (ii) the nature of sulfidic materials and sulfuric horizons, (iii) the risks they pose to the environment under certain conditions and (iv) awareness and economic impacts of ASS.

2.2.1. Organic and Mineral Soils Mineral Soil Material

Mineral soil material is defined in the Keys to Soil Taxonomy (Soil Survey Staff 2003) as soil material which:

either (i) is saturated with water for less than 30 days (in total) per year;

or (ii) contains: <18% organic carbon if the clay content is >60% <12% + 0.1 x clay%) if the clay content is <60%

Organic Soil Material

Soil material that contains more organic matter than described for mineral soil material (including litter) is called organic soil material.

Organic and Mineral Soils

Most soils are dominated by mineral soil material but may have horizons of organic material. In this case the relative importance of the mineral and organic materials is based on the type, depth and thickness of the organic material. Generally a soil is classified as organic if more than half of the upper 80 cm of the soil is organic soil material or any thickness if it rests on rock. Detailed criteria are contained in the Keys to Soil Taxonomy (Soil Survey Staff 2003).

All Organic Soils have a histic epipedon (i.e. diagnostic surface Organic horizon) and hence classify as Histosols according to Soil Taxonomy (Soil Survey Staff 2003). These Histosols often contain sulfidic materials (see definition below).

Sapric, Hemic and Fibric Materials

Histosols in Brunei can be distinguished according to their fibre content. Sapric organic soil materials are defined as having less than 17% fibre by volume; hemic organic soil materials between 17% and 40% fibre and fibric organic soil materials more than 40% fibre (Soil Survey Staff 2003). Hence horizons that contain predominantly sapric material have a high degree of decomposed organic matter and are given the horizon suffix “a” (e.g. Oa1). Hemic materials contain moderately decomposed organic matter and are given the horizon suffix “e” (e.g. Oe1).

Acid sulfate soils in Brunei have predominantly sapric materials at depth (e.g. Oa2, Oa3 and C) and have the following characteristics:


i) The fibre content after rubbing is less than one-sixth (17%) (by volume), excluding coarse fragments; and

ii) The colour of the sodium-pyrophosphate extract on white filter paper is a dark brown colour (Figure 3) whose Munsell value/chroma falls below or to the right of a line drawn on a page of a Munsell colour book to exclude value/chroma blocks 5/1, 6/2, and 7/3 (Munsell designations as defined in Soil Survey Staff 2003).

The sapric material identified in these soils is more finely divided and reactive than the coarser, “fibric” materials commonly observed in other tropical mangrove areas.

Figure 3: Representative sample of sapric material from 30 to 50 cm layer in a Typic Sulfosaprist at Meranking ADA, Belait (Profile 21 0007) mixed with sodium-pyrophosphate in a beaker after extraction on white filter paper. The dark brown colour on the white filter paper has a value and chroma combination that qualifies the material as sapric according to Soil Survey Staff (2003).

2.2.2. Sulfidic Materials and Sulfuric Horizons Sulfidic Materials

The Soil Taxonomy (Soil Survey Staff 2003) definition of sulfidic materials is used in this report. In summary, sulfidic materials contain oxidisable sulfur compounds. They may be mineral or organic soil materials, have a natural pH value >3.5, and when incubated as a layer 1 cm thick under moist conditions, while maintaining contact with the air at room temperature, they show a drop in pH of 0.5 units or more to a value of 4.0 or less within 8 weeks (Soil Survey Staff 2003). If disturbed, the time required for the transition from sulfidic materials to a sulfuric horizon ranges from weeks to years.

Sulfidic materials are mostly accumulations of iron sulfide minerals in soils and sediments. Iron sulfide minerals are one of the end products that form as part of the process of sulfate reduction (i.e. the use of SO4

2– instead of O2 during microbial respiration). Sulfate reduction is a natural process that occurs in virtually all lakes, rivers, wetlands and oceans. However, the quantities of sulfidic material that will accumulate in a given environment are a function of many factors. The key requirements for high rates of sulfate reduction and sulfide accumulation are:

i) high concentrations of sulfate in surface or groundwater,


ii) saturation of soils and sediments for periods long enough to favour anaerobic conditions,

iii) availability of labile carbon to fuel microbial activity and

iv) availability of iron minerals (Figure 4).

To form sulfidic materials, the bicarbonate produced by the reduction reactions must be flushed from the sediment, for example by tides.

Figure 4: Schematic diagram for the formation of pyrite in anoxic sediments (After Berner 1984)

Sulfuric Horizon

The Soil Taxonomy definition of a sulfuric horizon is used in this report. To qualify as a sulfuric horizon, the horizon must be >15 cm thick; be composed of either mineral or organic soil material; have a pH value <3.5 and show evidence of either jarosite, underlying sulfidic material, or >0.05% soluble sulfate.

When sulfidic materials are drained and exposed to air, they oxidise and produce sulfuric acid (e.g. Dent and Pons 1995). If the amount of acidity produced exceeds the buffering capacity of water and sediments, acidification occurs. Prior to draining, materials that can cause acidification are called sulfidic materials (i.e. potential acid sulfate soil materials or PASS). Once sulfidic materials are drained they may transform to sulfuric materials (i.e. actual acid sulfate soil materials or AASS).

2.2.3. Aquic Conditions Aquic is the term used by soil taxonomy to describe waterlogged conditions. According to Soil Taxonomy, “Soils with aquic (L. aqua, water) conditions are those that currently undergo continuous or periodic saturation and reduction. The presence of these conditions is indicated by redoximorphic features, except in Histosols and Histels, and can be verified by measuring saturation and reduction, except in artificially drained soils. Artificial drainage is defined here as the removal of free water from soils having aquic conditions by surface mounding, ditches, or subsurface tiles to the extent that water table levels are changed significantly in connection with specific types of land use. In the keys, artificially drained soils are included with soils that have aquic conditions. … The duration of saturation required for creating aquic conditions varies, depending on the soil environment, and is not specified.”


2.2.4. Soil Cracks, Slickensides and Cracking Clay Soils Soil cracks are features that are difficult to observe because they occur at the soil surface only when the soil is dry and often only in subsurface layers. Knowledge about soil behaviour during the year is required to determine if these features exist.

Slickensides: are polished and grooved surfaces that are produced when one soil mass slides past another. Slickensides result directly from the swelling of clay minerals and shear failure. They are common in swelling clays that undergo marked changes in moisture content.

All cracking clay soils contain slickensides and crack when dry. In Brunei, this group of soils contains both acid sulfate and non–acid sulfate members. Only the acid sulfate members are discussed in this report. Cracking clay soils are characterised by swelling on wetting and shrinking on drying with consequent crack formation. This behaviour is caused by the presence of interlayered clay minerals such as smectite.

2.2.5. n Value n Value: characterizes the relation between the percentage of water in a soil under field conditions and its percentages of inorganic clay and humus. It is used to predict whether a soil can support loads and what degree of subsidence would occur after drainage. It is defined as (A – 0.2R)/(L + 3H), where A is the percentage soil water content in the field condition (calculated on a dry soil basis), R the percentage of silt plus sand, L the percentage clay and H the percentage of organic matter (or organic carbon × 1.724) (Soil Survey Staff 2003).

An n value of 0.7 or greater indicates that the soil is soft and would subside under a load. The n value can be estimated in the field by squeezing a sample of soil in the hand. If the soil flows easily between the fingers the n value is greater than 1.0. If it can be squeezed between the fingers with difficulty the n value is between 0.7 and 1.0.

2.2.6. Monosulfidic Black Ooze Material in Drain Sediments Monosulfidic black ooze (MBO) materials are subaqueous or waterlogged mineral or organic materials that contain mainly oxidisable monosulfides that have a field pH of 4 or more but which will not become extremely acid (pH <4) when drained.

The recognition of the occurrence and importance of monosulfides in soil materials led in 2005 to the inclusion of monosulfidic materials as a distinguishing property within mapping units of the Australian National Atlas of Acid Sulfate Soils (Fitzpatrick et al. 2006). High nutrient environments together with the activity of algae and micro-organisms generate redoximorphic conditions, which result in the formation of black smelly, iron monosulfides. When subaqueous materials rich in monosulfides are resuspended, for example during the flushing of drains by high runoff events, they rapidly oxidise, potentially removing most of the oxygen from the water column (Sullivan et al. 2002). This can lead to fish kills, especially in enclosed areas such as aquaculture ponds or estuaries. Hence, MBO is reactive if exposed to oxygen but is harmless if left undisturbed.

Monosulfidic soil materials have the ability to favourably affect surrounding environments by immobilizing potential metal pollutants (e.g. Simpson et al. 1998). However, when a drain is cleaned, iron and alumino-sulfo salts (e.g. jarosite and alunite), iron oxyhydroxy-sulfate salts (e.g. schwertmannite) precipitate on the soil surface along the drain edges. These soluble salts dissolve during rain events and contribute to MBO formation, acidity and metal content in drainage waters.

2.2.7. Sulfate-Containing Salt Efflorescences While common in drier environments, in the wet tropics of Brunei we have only observed efflorescences in drain spoil (e.g. jarosite) and on the surface of exposed pyritic shale. The significance of the minerals found in these salt efflorescences is that they appear during drier periods and are environmental indicators. A change in the minerals found will indicate a change in the nature of the salts entering the system.


2.3. Laboratory Analyses The following analyses were performed using the standard methods of the Analytical Chemistry Unit, CSIRO Land and Water, for:

• 1:2.5 soil–water extracts: pH, EC: 30 samples

• Total carbon and sulfur: 30 samples.

• Total actual acidity: 30 samples.

• Calcium carbonate equivalent: 30 samples.

• Arsenic and cadmium: 12 samples.

The following analysis was performed by the Environmental Analysis Laboratory, Southern Cross University, Lismore NSW Australia:

• Chromium reducible sulfur (SCr): 30 samples.

2.3.1. Laboratory Soil Analysis Methods The methods used are summarised below and results of these analyses are presented in the Appendix Tables A3 to A7.

Sample preparation and moisture content: A sub-sample was frozen, transported to Australia and usually within 48 hours of dispatch oven dried at 80°C, then crushed and sieved through a 2 mm sieve to prepare a dry, <2 mm sample for further analysis. Material greater than 2 mm was inspected (mostly coarse organic matter), and proportions recorded. The moisture content was calculated from the measured weight loss on further drying a weighed, representative sub-sample of the material at 105°C. For chromium reducible sulfur, fresh material was sub-sampled, frozen and freeze dried. The freeze dried material was then sieved, sub-sampled and hand ground in a mortar and pestle prior to dispatch to the laboratory for analysis.

Electrical conductivity (EC1:2.5): A 10 g sub-sample was placed in a screw cap container, 25 mL water added and the suspension shaken for one hour (1:2.5 soil:water ratio). The electrical conductivity was measured after calibrating the conductivity meter using 0.1M KCl (12.9 dS m–1); (Method 2B1: Rayment and Higginson 1992, with a modified soil: solution ratio of 1:2.5 to match methods used by the Brunei Soil and Plant Nutrition Unit).

pH1:2.5: The pH meter was calibrated using pH 7.00 and pH 9.00 buffers. The pH was measured on the same suspension as used for EC (Method 4A1: Rayment and Higginson 1992, modified as for EC).

Calcium carbonate equivalent: Sub-samples (1 to 2 g) of soil and pure calcium carbonate were analysed by adding HCl and measuring CO2 gas pressure in a glass vessel using a pressure transducer following a slightly modified method after Sherrod et al. (2002). Results for inorganic carbon are expressed as calcium carbonate equivalent. Note this analysis was only carried out when the soil pH1:2.5 was > 5.0. Where the pH1:2.5 was <5.0 the carbonate content was assumed to be negligible and below the detection limit of the method (0.5% CaCO3).

Total carbon and sulfur: Total C and S were measured using a Leco CS analyser.

Organic carbon: The organic carbon content was calculated by subtracting the inorganic (carbonate) carbon from the total carbon (Method 6B3: Rayment and Higginson 1992).

Total actual acidity and oxidised sulfur: The method for determining total actual acidity and oxidised sulfur (Sox) (1:40 KCl extractable S) is given by Ahern et al. (2004, Method Codes 23F and 23C respectively). The latter indicates the sulfate concentration including gypsum, jarosite and other sulfate minerals.


Saturation extract oxidized sulphur and chloride: Oxidised sulfur (Sox) and chloride were measured in the saturation extract (Method 4F2: USDA-NCRS 2004). This measure of Sox only include part of the sulfate from gysum, jarosite and other poorly soluble sulfate minerals. The deviation in the ratio of Cl:S from that of seawater (21) indicates an input of sulfate from ASS oxidation.

Chromium reducible sulfur: Methods for analysing soil samples to assess acid generation potential (AGP) are given in Ahern et al. (2004), including the chromium reducible sulfur method (SCr) (Method Code 22B), which measures reduced inorganic sulfur (RIS), and its conversion to AGP.

Net acid generating potential (NAGP): Net acid generating potential was calculated by subtracting the acid neutralising capacity (ANC) from the AGP. The NAGP is conventionally expressed as the calcium carbonate equivalent to neutralise the potential acid generated (Ahern et al. 2004). A positive value for NAGP indicates acid generating potential and the potential for formation of an ASS, while a negative value indicates an excess of neutralising capacity over acidity, with little likelihood of ASS formation. When converted to a lime requirement a safety factor of 1.5 is employed to account for lime purity and reactivity (fineness or particle size).

Arsenic and cadmium: Arsenic and cadmium were determined by flameless AAS and ICP–OES respectively, following microwave assisted acid digestion (Method 3051A: USEPA 1998).

Bulk density: Bulk density, which is required for calculating the lime requirement of soil layers, was estimated from organic carbon content using the method of Avnimelech et al. (2001).


3. Soil Classification

3.1. Soil Classes Identified A list of the parts of the Soil Taxonomy Classifications identified as being relevant to the Agricultural Development Areas of Negara Brunei Darussalam is outlined below in Table 1. Seven soil Orders were identified leading to 24 Subgroups. Acid sulfate soils are represented in four of these Orders and 10 Subgroups.

Table 1: Soil Taxonomy classifications of surveyed Agricultural Development Areas in Negara Brunei Darussalam. Non acid sulfate soils are in grey font type. The soil marked *, while not acid sulfate, has pH <4.5 resulting from oxidation of sulfides.

Order Suborder Great Group Subgroup

Histosols Saprists Sulfosaprists Terric Sulfosaprists

Typic Sulfosaprists

Sulfisaprists Terric Sulfisaprists

Typic Sulfisaprists

Spodosols Aquods Epiaquods Ultic Epiaquods

Umbric Epiaquods

Vertisols Aquerts Sulfaquerts Sulfic Sulfaquerts

Dystraquerts Typic Dystraquerts*

Ultisols Humults Kandihumults Aquic Kandihumults

Typic Kandihumults

Palehumults Aquic Palehumults

Oxyaquic Palehumults

Typic Palehumults

Haplohumults Oxyaquic Haplohumults

Typic Haplohumults

Udults Paleudults Arenic Paleudults

Alfisols Aqualfs Epiaqualfs Aeric Epiaqualfs

Typic Epiaqualfs

Inceptisols Aquepts Sulfaquepts Hydraquentic Sulfaquepts

Typic Sulfaquepts

Entisols Aquents Sulfaquents Haplic Sulfaquents

Thapto-Histic Sulfaquents

Fluvaquents Sulfic Fluvaquents

Endoaquents Humaqueptic Endoaquents

3.2. Soil Identification Key To assist users identify these soil classes a user-friendly soil identification key was developed (Table 2 and Table 3) to more readily identify the various ASS and other soils of Brunei found in the surveyed ADAs (Grealish et al. 2007a). The key is designed for people who are not experts in soil classification systems such as Soil Taxonomy. Hence it has the


potential to deliver soil-specific land development and soil management packages to advisors, planners and engineers working in the ADAs.

The soil identification key uses non-technical terms to categorise ASS and other soils in terms of attributes that can mainly be assessed in the field by people with limited soil classification experience. Attributes include texture, colour, soil cracks, features indicating waterlogging and ‘acid’ status – already acidified, i.e. sulfuric, or with the potential to acidify, i.e. sulfidic) – and the depths at which they occur or change in the soil profile.

The key consists of a systematic arrangement of soils into 4 broad ASS types and 6 other soil types, each of which can be divided into up to 4 soil sub-types. The key layout is bifurcating, being based on the presence or absence of particular soil profile features (i.e. using a series of questions set out in a key). A soil is allocated to the first type whose diagnostic features it matches, even though it may also match diagnostic features further down the key. The soil types and subtypes in the Soil Identification Key are largely in the same order as occurs in the Keys to Soil Taxonomy (Soil Survey Staff 2003). A collection of plain language soil type and subtype names was developed to correspond to the major Soil Taxonomy Suborder and Subgroup classes found in the survey. These names are intended to provide some assistance in understanding the intent and general nature of the soils classified using the Soil Taxonomy classification. The 4 ASS types in the Key are: (i) Organic Soils, (ii) Cracking Clay Soils, (iii) Sulfuric Soils and (iv) Sulfidic Soils. These are further sub-divided into 11 subtypes based on depth to sulfuric/sulfidic horizon; firmness; and drainage (waterlogging).


Table 2: Summary soil identification key for major acid sulfate soil types in surveyed Agricultural Development Areas of Negara Brunei Darussalam. Bracketed words are the corresponding Soil Taxonomy classification. ‘No *’ indicates to restart the key or consider that a new soil has been identified that is not classified in this identification key. After finding the soil type use Table 3 to find the soil subtype.

Diagnostic features for Soil Type Soil Type

Does the upper 80 cm of soil consist of more than 40 cm of organic material (peat)? No Yes

Organic soil (Saprist)

Does the subsoil have a whitish to light grey coloured soil layer overlying a dark brown coloured (organic) layer that is within 2 m of the soil surface?

No Yes

White soil (Aquod) (not ASS)

Does the soil develop cracks at the surface OR in a clay layer within 100 cm of the soil surface OR have slickensides (polished and grooved surfaces between soil aggregates),

AND is the subsoil uniformly grey coloured (poorly drained or very poorly drained)? No Yes

Cracking clay soil (Aquert)

Does the subsoil have a dominantly yellowish colour AND a texture contrast (sandy surface layer above loamy or clayey subsoil)? No Yes

Texture contrast yellow soil (Udult) (not ASS)

Does the upper subsoil have a dominantly yellowish or brownish colour, AND is the soil depth greater than 150 cm? No Yes

Very deep yellow soil (Humult) (not ASS)

Does the subsoil have a dominantly yellowish or brownish colour, AND is the soil depth less than 150 cm? No Yes

Yellow soil (Haplohumult) (not ASS)

Does the subsoil have a yellowish brown coloured layer with red/orange mottles (spots) overlying a grey layer that has its upper boundary within 50 cm of the soil surface?

No Yes

Brown over grey soil (Aqualf) (not ASS)

Does a sulfuric layer (pH<3.5) occur within 150 cm of the soil surface, AND is the subsoil uniformly grey coloured (poorly drained)? No Yes

Sulfuric soil (Aquept)

Does sulfidic material (pH>3.5 which changes on ageing to pH<3.5) occur within 100 cm of the soil surface, AND is the subsoil uniformly grey coloured (poorly drained)? No Yes

Sulfidic soil (Aquent)

Does the subsoil have a greyish colour and no other diagnostic features within 150 cm of the soil surface? No * Yes

Grey soil (Aquent) (not ASS)


Table 3: Soil identification key for acid sulfate soil subtypes in surveyed Agricultural Development Areas of Negara Brunei Darussalam. Bracketed words are the corresponding Soil Taxonomy classification. ‘No *’ indicates to restart the key or consider that a new soil has been identified that is not classified in this identification key.

Soil Type Diagnostic features for Soil Subtype Soil Subtype Soil Taxonomy Subgroup

Representative Profiles – Agricultural Development Area

Organic soil (Saprist)

Does a sulfuric layer (pH<3.5) occur within 50 cm of the soil surface? No Yes

Sulfuric organic soil (Sulfosaprist) Does a mineral soil layer >30 cm thick occur within 100 cm of the soil surface? No Yes

Mineral sulfuric organic soil

Terric Sulfosaprist

230001 - Labi Lama (see page 65)

Sulfuric organic soil

Typic Sulfosaprist

210007 - Merangking, Bukit Sawat (see page 66)

Does sulfidic material (pH>3.5 which changes on ageing to pH<3.5) occur within 100 cm of the soil surface? No * Yes

Sulfidic organic soil (Sulfisaprist) Does a mineral soil layer >30 cm thick occur within 100 cm of the soil surface? No Yes

Mineral sulfidic organic soil

Terric Sulfisaprist

030002 - Si Tukak, Limau Manis (see page 67)

230004 - Labi Lama

Sulfidic organic soil

Typic Sulfisaprist

010015 - Betumpu (see page 68) 050004 - Lumapas 210010 - Merangking, Bukit Sawat

Cracking clay soil (Aquert)

Does a sulfuric layer (pH<3.5) or do sulfidic materials (pH>3.5 which changes on ageing to pH<3.5) occur within 100 cm of the soil surface? No Yes

Poorly drained cracking clay soil (Aquert) Does sulfidic material occur within 100 cm of the soil surface? No * Yes

Sulfidic poorly drained cracking clay soil

Sulfic Sulfaquert

080003 - Wasan 080004 - Wasan (see page 70) 080015 - Wasan (see page 72)

Poorly drained cracking clay soil (Aquert) Does a soil layer with pH<4.5 occur within 50 cm of the soil surface? No * Yes

Acid poorly drained cracking clay soil

Typic Dystraquert

080012 - Wasan (see page 73)


Soil Type Diagnostic features for Soil Subtype

Soil Subtype Soil Taxonomy Class

Representative Profiles – Agricultural Development Area

Sulfuric soil (Aquept)

Does the sulfuric layer occur within 50 cm of the soil surface? No * Yes

Poorly drained sulfuric soil (Sulfaquept) Does a soft layer occur within 100 cm of the soil surface? No Yes

Soft poorly drained sulfuric soil

Hydraquentic Sulfaquept

090015 - Tungku (see page 74)

Poorly drained sulfuric soil

Typic Sulfaquept

010011 - Betumpu (see page 76) 010012 - Betumpu 060002 - Limpaki (see page 78)

Sulfidic soil (Aquent)

Does the sulfidic material occur within 50 cm of the soil surface? No Yes

Poorly drained sulfidic soil (Sulfaquent) Does a soft layer occur between 20 and 50 cm of the soil surface? No Yes

Soft poorly drained sulfidic soil

Haplic Sulfaquent

010013 - Betumpu (see page 80) 010016 - Betumpu (see page 82) 290004 - Pengkalan Batu

Does a buried organic layer (organic material covered by mineral soil) occur within 100 cm of the soil surface? No * Yes

Organic poorly drained sulfidic soil

Thapto-Histic Sulfaquent

050005 - Lumapas (see page 84)

Poorly drained moderately deep sulfidic soil (Aquent) Does a buried organic layer (organic material covered by mineral soil) occur within 125 cm of the soil surface? No * Yes

Organic poorly drained moderately deep sulfidic soil

Sulfic Fluvaquent

220002 - Melayan A (see page 85)

Where: Organic material is confirmed by field observation and laboratory data (organic carbon, clay); Cracking clay is confirmed by field observation, cracks, texture. Sulfuric horizon is confirmed by field observation (pH measurement using pH strips or meter). Sulfidic material is initially inferred from field observations and confirmed by sampling and incubation for 8 weeks (Soil Survey Staff 2003). Poorly drained = Aquic conditions, confirmed by field observation.


4. Major Characteristics of ASS ASS were identified at 80 sites in 13 ADAs. Site descriptions are provided for these sites (Appendix A Table A1) and detailed field soil morphology / profile descriptions for soil pits and cores (Appendix A Table A2). Photographs of type sites including chip trays, soil pits (where available) and landscape setting are provided in Appendix B.

The morphological and chemical characteristics are outlined below. Appendix Tables A2 to A7 contain the complete data set for the site and soil profile descriptions and the analyses used in the assessment.

The following information is stored in the GIS database:

• Regional locality map and site summary,

• Site locality map.

4.1. Morphology 4.1.1. Field Description and Morphology In all soil profiles, distinct layers or master soil horizons with suffix symbols were demarcated, described and summarised in Table 1. Soil colour, structure, texture and consistency along with field pH are the most useful properties for soil identification and appraisal. Soil colour, structure and consistency provide practical indicators of soil redox status and existing acidity. This relates directly to soil aeration and organic matter content in the soils of Brunei. Consequently, these field indicators were used to help develop a user-friendly soil identification key to categorise the various ASS and other soils in section 3 (see Table 2).

4.1.2. Sulfidic Material Sulfidic materials (potential acid sulfate soil materials) are common on the floodplain areas of Brunei. In many instances these materials underlie sulfuric horizons. In most cases there has been some oxidation as these materials contain moderate to high amounts of actual acidity, although the pH has not dropped sufficiently for them to form sulfuric horizons (<pH 3.5).

All soils analysed except Tungku (Site 09 0015) contain high enough concentrations of chromium reducible sulfur to require an ASS management plan (Table 5).

4.1.3. Sulfuric Horizons Many of the soils described have sulfidic material that has already oxidised and formed a sulfuric horizon.

4.1.4. Tests to Identify Sulfidic Material and Predict the Consequences of Disturbance

Field Test – Field pH after oxidation with 30% Hydrogen Peroxide (pHFOX)

The peroxide field test is based on artificially accelerating oxidation of sulfidic material to release potential acidity. The pH of a sample after reaction with hydrogen peroxide (with pH adjusted to pH4.5-5.5 before going into the field) is a qualitative indication of the likelihood that a soil material or sediment has the potential to form sulfuric material or an acid sulfate soil when exposed to the atmosphere (e.g. when excavated). The hydrogen peroxide reacts with sulfides to produce sulfuric acid. Sulfuric acid in turn reacts with neutralising agents in the sample, such as carbonates and clay minerals. The final pH and reaction vigour can then be interpreted to qualitatively assess soil or sediment materials (Table 4, Figure 5).

Sulfidic material + hydrogen peroxide sulfuric acid + iron sulfate minerals + heat

Method details, precautions for the use of hydrogen peroxide and interpretation of results are detailed in Ahern et al. (1998, 2004). These are dangerous chemicals and protective gloves and glasses are other safety measures should be closely followed when doing these tests.


Table 4: Soil rating scale for the pHFOX test. If the field pH in hydrogen peroxide (pHFOX) is at least one unit below field pH, it may indicate potential ASS. The greater the difference between the two measurements, the more indicative the value is of sulfidic material. The lower the final pHFOX value is, the better the indication of a positive result.

pHFOX Indication of ASS

<3 High probability.

3–4 Probable; confirm with laboratory tests.

4–5 Sulfides may be present in small quantities or may be unreactive, or neutralising material is present. Confirm with laboratory tests.

>5 Combined with little drop from field pH, little net acid generation potential is indicated. Confirm with laboratory tests.

Figure 5: Photographs of the peroxide field test for the presence of ASS (sulfidic material). Note the change in colour of the pH test strips indicating the drop in pH.

Incubation of Soil Material

The formal Soil Taxonomy test (Soil Survey Staff 2003) for identification of sulfidic material is to:

• Incubate mineral or organic soil materials, which have a natural pH value >3.5, for 8 weeks (as a layer 1 cm thick under moist conditions, while maintaining contact with the air at room temperature);

• Measure the pH and determine the pH has fallen by 0.5 units or more to a value of 3.5 or less within 8 weeks;

• Observe formation of jarosite mottles, which implies that the pH has dropped below 3.5.


Collection and storage of moist samples in chip trays (Figure 6) produces identical conditions to those required for the test and can be used as a diagnostic test for the presence of sulfidic material. Incubation tests have the advantage of not requiring 30% hydrogen peroxide, which should only be handled by a trained operator.

Soil samples collected in Brunei were placed in compartments of the chip tray as a 1 cm thick layer and kept moist (Figure 6). After 8 weeks (or longer) of aging, the soils were visually checked for the formation of minerals that indicate significant acidification, for example jarosite (Figure 6). Since the solution in contact with the soil in the chip tray compartments is in equilibrium with the soil, pH indicator strips (Merck item numbers 1.09541.0001 [pH 2.5-4.5]; 1.09541.0002 [pH 4.0-7.0]; 1.09543.0001 [pH 6.5-10.0]) were used to indicate the pH of the samples (Figure 6). A value of 3.5 or less confirms that the field soil is likely to develop sulfuric material on drying. pH values greater than this indicate that the soil materials should not acidify significantly.

Figure 6: Left hand side: chip tray samples from profiles 23 0001 and 23 0004 after ageing and testing with pH indicator strips, which indicate strongly acidic samples with pH below 3.5 (red colour indicates pH 2.5 to 3.5). Right hand side: Chip tray samples for profile 09 0011 after aging for several months showing bright yellow jarosite mottles and coatings, which is especially evident in the sample at depth 5-20 cm. pH indicator strips confirmed pH values had fallen below 3.5.

4.2. Chemistry 4.2.1. Soil pH and Electrical Conductivity (EC) The floodplain soils and sediments generally have low pH values (Appendix A Table A3) ranging from 2.5 for the sub-surface (80–180 cm) of the Soft poorly drained sulfuric soil at Limpaki (06 0002) to 6.2 in the surface (0–5 cm) of the Mineral sulfuric organic soil from Labi Lama (23 0001), indicating that acid neutralising capacity is already exhausted. EC values ranged from 0.02 dS m-1 at 20–70 cm in the Organic poorly drained moderately deep sulfidic soil at site 2 Melayan A (22 0002) to 8.6 dS m-1 for the sub-surface (80–180 cm) of the Soft poorly drained sulfuric soil at Limpaki (06 0002). (Appendix A Table A3).

4.2.2. Sulfur In sediments, total sulfur is an inexpensive convenient measure to screen samples for acid sulfate soil potential. However, this analysis estimates the maximum potential environmental risk, so that when a trigger value is exceeded, more detailed analysis is required. Directly measuring the amount of reduced sulfur in a sample using the chromium reduction method has become the accepted standard for further investigation. Chromium reducible sulfur (SCr) is a direct measure of reduced inorganic sulphur (RIS). It can be directly equated with the acid generating potential (AGP) of a soil or sediment, and is one component of the net


acidity, the other being the existing or actual acidity. The difference between reduced sulfur and total sulfur is the quantity of sulfate plus organic sulfur in the sample. Further analysis is required to separate the individual contribution of these components. For coastal acid sulfate soils in Australia the following action criteria for the preparation of an ASS management plan have been set (Table 5 below).

Total sulfur values in samples, range from 0.04% below 30 cm at Tungku (09 0015) to 4.4% in the sub-soil (80–180 cm) at Limpaki (06 0002). Chromium reducible sulfur values range from below the detection limit (0.005%) throughout the soil profile at Tungku (09 0015) to 3.4% in the sub-soil (150–200 cm) at Betumpu (01 0015). Generally, chromium reducible sulfur concentrations are lower to around 50 cm depth (<0.05%) and higher below 100 cm (>1%). In the limited number of analysed profiles the exception is Limpaki (ADA 06) where the top 40 cm contains chromium reducible sulfur concentrations >0.2%. The soft poorly drained sulfuric soil at Tungku is also an exception, but here the acid originates in adjacent outcrops of weathering pyritic shale and not in the soil profile.

Table 5: Thresholds indicating the need for an ASS management plan based on texture range and chromium reducible sulfur concentration (SCr) and amount of soil material disturbed (Dear et al., 2002).

SCr (%S) Texture range

<1000 t disturbed soil >1000 t disturbed soil

Coarse: Sands to loamy sands 0.03 0.03

Medium: Sandy loams to light clays 0.06 0.03

Fine: Medium to heavy clays 0.10 0.03

The results and the pH values indicate that all of the soils investigated exceed the thresholds in Table 5 and therefore warrant further investigation based on criteria used for tropical and temperate coastal ASS. However the applicability of these criteria in Brunei where the environment is dominated by highly leached, low pH soils and naturally occurring actual acid sulfate soils is untested particularly in relation to the off-site effects (Appendix A Table A3).

4.2.3. Carbon Carbonate minerals in a soil are a component of its acid neutralising capacity (ANC). However, in the low pH, highly leached Brunei environment carbonate levels are expected to be low. The exceptions would be soils in proximity to carbonate rich sedimentary rocks or in soil profiles containing shell. In Brunei ASS pH values were too low for measurable carbonate, shells were absent from the profiles and none of the ASS profiles occurred near carbonate rich sedimentary rocks. While shell may be present in soils closer to the coast, it should be noted that carbonate from shell material is usually not a good source of neutralising capacity as it can become unreactive, when acidic waters result in the shell fragments becoming coated with iron and/or gypsum. Repeated wetting and drying cycles in wetlands may similarly armour carbonates with unreactive coatings. Detailed discussion of precautions and factors to be used when using carbonate values as a measure of ANC can be found in manuals and technical documents published for the assessment of coastal acid sulfate soils (e.g. Dear et al. 2002). None of the soils examined had measurable acid neutralising capacity (i.e. carbonate minerals in the soil).

In the Organic soils, organic carbon concentrations are (by definition) at least 12% in at least half of the top 80 cm. In the organic soil class, the maximum concentration was 59% organic carbon at 60–80 cm in a Sulfuric organic soil at Meranking (21 0007) and 0.35% at 70–150 cm in a Mineral sulfidic organic soil at Labi Lama (23 0004). Sulfuric soils have a range in carbon concentrations from 0.18% in the Soft poorly drained sulfuric soil from site 15 at Tungku (09 0015) to 17% in a Poorly drained sulfuric soil at site 11 in Betumpu (01 0011). The range in organic carbon found in Sulfidic soils was from 0.14% at 20–70 cm to 24% at


130–200 cm, both in the Organic poorly drained moderately deep sulfidic soil at Melayan A (22 0002). Cracking clay soils contain between 0.94% organic carbon between 20–70 cm at Si Tukak, Limau Manis B (03 0001) and 6.5% between 0–10 cm of the same soil. (See Appendix A Table A3.1 for the complete set of results).

4.2.4. Acid–Base Budget Total Actual Acidity

Actual acidity is a measure of the existing acidity in acid sulfate soils that have already oxidised. The method measures acidity stored in a number of forms in the soil such as iron and aluminium oxyhydroxides and oxyhydroxysulfate precipitates (e.g. jarosite, schwertmannite and alunite) which dissolve to produce acidity. Because some samples thawed in transit and potentially oxidised before analysis for total actual acidity, this measure as a stand alone variable to assess the current level of acidity in Brunei acid sulfate soils is not reliable. However, it can be applied to the acid–base budget, which uses the total of actual and potential acidity to assess the acid generation potential of a soil. All sites had existing acidity, which ranged from 49 moles H+ t-1 in the sub-surface (30–50 cm) of the Soft poorly drained sulfuric soil at Tungku (09 0015) to 760 moles H+ t-1 in the sub-surface (80–150 cm) of the Sulfidic organic soil at Betumpu (01 0015). (Appendix A Table A3).

Acid Neutralising Capacity (ANC)

By definition any soil with a pH<6.5 has a zero ANC. All acid sulfate soils examined had pH values of <6.5 throughout the profile.

Acid Generation Potential (AGP)

This parameter is calculated from the concentration of reduced sulfur in the sample. Methods for analysing soil samples to assess AGP are given in Ahern et al. (2004), which includes the chromium reducible sulfur (SCr) (Method Code 22B) and its conversion to AGP.

Net Acid Generation Potential (NAGP)

NAGP is calculated by subtracting the ANC from the AGP and is a measure of the overall acidification risk of a soil. A positive value indicates an excess of acid and the likelihood of sulfuric materials (or an actual acid sulfate soil material) forming in the soil when it is disturbed and oxidised:

NAGP = AGP – ANC.

Net Acidity

The net acidity of a soil where there is existing acidity includes both NAGP and the existing or titratable actual acidity (TAA) so that:

Net Acidity = TAA + AGP – ANC

or

Net Acidity = TAA +NAGP.

All soils sampled had positive net acidities. Net acidities ranged from 49 moles H+ t-1 in the sub-surface (30–50 cm) of the Soft poorly drained sulfuric soil at Tungku (09 0015) to 2,900 moles H+ t-1 in the sub-surface (150–200 cm) of the Organic sulfidic soil at Betumpu (01 0015). (Appendix A Table A5). The soil at Limpaki (ADA 06) had a high acid generating potential, being >500 moles H+ t-1 throughout the profile and >2000 moles H+ t-1 below 80 cm.

4.2.5. Arsenic and Cadmium Arsenic concentrations in the acid sulfate soils analysed ranged from 0.1 to 20 mg kg-1. Cadmium concentrations in these soils ranged from less than the detection limit of 0.2 mg kg–1 to 1.8 mg kg-1. Both arsenic and cadmium were below the serious risk concentrations in soil for human and ecotoxicological protection set in soil standards for the Netherlands (576 and 85 mg kg–1 respectively for As and 28 and 13 mg kg-1 respectively for Cd; Lijzen et al. 2001 ) and below the soil investigation levels set in Australia (100 mg kg-1 for As and 20 mg kg-1 for Cd; Imray and Langley 1999). The highest levels of cadmium were


found at Labi Lama (23 0001) and may reflect fertilisation of the orchard. There is evidence of over-fertilisation in some intensively used areas, which carries with it the risk of elevated concentrations of cadmium in soil and produce. Such areas may need further investigation. Another difficulty in assessing levels of arsenic and cadmium in the soil of Brunei is the low pH, compared with the soil pH values assumed in developing the standards (pH 7.0 and 6.0 respectively for the Netherlands and Australia). The low pH values (3.9–4.2) of the Brunei soils may increase metal availability and uptake by crops.


5. Management of ASS for Soil Fertility, Agricultural Production and Environmental Protection

5.1. Management Options We propose three options for the management of ASS in Brunei. These are to (i) avoid disturbance where tests show high levels of sulfidic material, (ii) minimise disturbance where tests show low levels of sulfidic material and (iii) treat disturbed areas where tests show a sulfuric horizon or acid water.

5.1.1. Avoiding Disturbance The preferred management strategy for ASS is to avoid disturbance i.e. do not develop. Any decision to develop ASS should be made in the knowledge of the severe economic and environmental risks posed by them. In the case of organic soils there is a substantial risk of subsidence and eventually complete loss of the resource. The subsidence is accompanied by greenhouse gas emissions from the oxidation of fossil carbon accumulated during the Holocene period. It is important to note that most ASS management strategies are focused on minimising acidic discharges and may be ineffective in controlling either subsidence or greenhouse gas emissions. In the absence of avoidance choices fall to either minimising disturbance or total reclamation. Total reclamation is expensive and development is only likely to be successful if a number of factors are present:

• Strong demand for land;

• No alternative land available;

• Favourable climate;

• Favourable hydrology;

• Availability of lime and fertilizers; and

• Demand for the agricultural products at a price that reflects the true cost of production.

5.1.2. Minimising Disturbance Management of ASS relies on managing the acid and iron released into the drainage system; leaching and neutralising acidity in both the soil and drainage water; and preventing further oxidation and acid generation. Water and the water table are the key elements. In Brunei, both the climate and hydrology are favourable for managing water to improve production and protect the environment.

Water table: To minimise the disturbance of ASS the water table must be maintained above the level of sulfidic material to prevent further oxidation. In organic soils this strategy also assists in preventing subsidence through the loss of organic matter from microbiological oxidation and fire. Water tables can be managed by drainage design, weirs, sluices and floodgates and by the use of irrigation water.

Drains: Drain design is a key tool in managing ASS. The main function of drains in controlling water tables is to rapidly remove surface water to prevent infiltration rather than dewatering the soil profile through lateral drainage. Laser levelling combined with reduced drain depth and increased drain width and spacing will result in less aeration (i.e. oxidation) of pyrite and smaller exports of acid oxidation products.

Irrigation water: Root development is always restricted in ASS environments so that access to irrigation water for use during dry spells can both alleviate plant stress and maintain the water level above the sulfidic layer.

Raised beds: The current practice of constructing raised beds can be assisted by identifying the depth to sulfidic material to maximise the available non-ASS material. Where insufficient depth of material is available, treating soil from sulfuric horizons with lime and/or accelerated oxidation of sulfidic material and soil ripening can provide additional soil for raised beds


provided the acidic leachate can be managed. For high value crops it may be economic to import non-ASS mineral soils from outside the district to supplement the construction of raised beds. Constructing raised beds from organic soils is only a short term solution because the soil material will rapidly oxidise and subside. Crop choice is also important, with shallow rooted annual crops preferable to perennial tree crops. Sequence farming on new areas starting with acid tolerant crops such as pineapples is another alternative.

Managing ripening ASS: Mineral ASS often has good physical properties, and accelerated oxidation may be viable provided leachate can be controlled. Options for leachate management include collecting and liming leachate, and flushing leachate into drains and neutralising with seawater. The latter option requires well managed drains and control structures plus proximity to seawater to neutralise acidic leachate.

5.1.3. Rehabilitation Basic Principles

The basic principles of rehabilitation are to curtail pyrite oxidation and to neutralise or leach existing acidity.

Pyrite oxidation can only be stopped by removing the oxygen supply. This can be done by re-flooding or capping. After the removal of the oxygen supply, oxidation of pyrite by FeIII may continue for some time. Pyrite oxidation can be slowed by decreasing the rate of FeIII production. Bactericides that inhibit Acidithiobacillus sp. or amendments that complex or precipitate the iron are ways to do this. However, this is only a temporary solution more suited to short term requirements such as stockpiling during engineering works.

Neutralisation can be achieved by the addition of lime (or other alkaline substances) and by the reduction of FeIII oxides which consumes protons.

Leaching is only possible using a water management system that discharges acidic surface water. This is usually done at times of high flow to reduce the environmental impact. Most successful ASS rehabilitation schemes in south east Asia rely on a combination of leaching through sophisticated water management and amendments to the leached soil. Management that relies on the discharge of acidic surface water containing toxic elements may not be an acceptable option for Brunei.

Liming

Soil: In the surface soil (0–50 cm depth interval), the existing acidity ranges from 40 to 100 t CaCO3 ha-1 equivalent and potential acidity from 0 to 42 t CaCO3 ha-1 equivalent. While requiring substantial lime input, in most instances there is little remaining potential acidity, so that once treated, retreatment should only be required if ASS material or acid water is imported. This is in contrast to the sub-soil where substantial reserves of pyrite remain, with in some instances an acid generation potential equivalent to >500 t CaCO3 ha-1 for a 50 cm interval.

Drains: Acidic drain water can be neutralised by the addition of lime. The neutralisation of leachate with lime drains requires costly maintenance as iron precipitates clog drains and coat the surface of the lime making it inactive.

Re-flooding

Re-flooding with tidal water has been successful in reducing the production of acid or halting the continued oxidation of pyrite in Australian ASS. Re-flooding of rice paddies with fresh water is also a successful management tool, although there are problems with nutrition and with the toxicity of hydrogen sulfide and dissolved iron. Re-flooding as a management tool relies on establishing conditions where the reduction of the Fe, Mn, S and N can take place. The reduction of these elements consumes protons and is responsible for the increase in pH commonly observed in acid soils after waterlogging. It should be noted that the subsidence


and the loss of soil material through accelerated oxidation and burning will complicate water management.

5.2. Acid Sulfate Soil Classification and Management Options Table 6 and Table 7 list options for the management of ASS in Brunei ADAs.

Table 6: Potential management options based on the soil characteristics of acid sulfate soil types.

Soil Type Soil Subtype Management options

Organic soils Mineral sulfuric organic soil Sulfuric organic soil Mineral sulfidic organic soil Sulfidic organic soil

3 Treat disturbed areas 3 Treat disturbed areas 1&2 Avoid/minimize disturbance 1&2 Avoid/minimize disturbance

Cracking clay soils

Sulfidic poorly drained cracking clay soil Acid poorly drained cracking clay soil

2 Minimize disturbance 2 Minimize disturbance

Sulfuric soils Soft poorly drained sulfuric soil

Poorly drained sulfuric soil

3&2 Treat disturbed areas Minimize further disturbance

3&2 Treat disturbed areas Minimize further disturbance

Sulfidic soils Soft poorly drained sulfidic soil Organic poorly drained sulfidic soil Poorly drained moderately deep sulfidic soil

1&2 Avoid/minimize disturbance 1&2 Avoid/minimize disturbance 1&2 Avoid/minimize disturbance

1. Avoid disturbance where tests show high levels of sulfidic material. 2. Minimize disturbance where tests show low levels of sulfidic material

(Broad, shallow drains; Minimize drying by controlling water table – e.g. flood gate control). 3. Treat disturbed area where tests show sulfuric material or acid water

(Neutralize current/historical disturbance; contain acid; reverse disturbance).


Table 7: Management and treatment class of acid sulfate soil types in surveyed ADAs.

Impacted element Soil Type Soil subtype ADA Site nos

Aquatic Infrastructure Land Treatment

class Management

Betumpu 010018, 010019, 010020 Lumapas 050002 Mineral sulfuric

organic soils Labi Lama 230001, 230005

Betumpu 010007, 010010, 010014 Limpaki 060001, 060004, 060005 Sulfuric

organic soils Meranking Bukit Sawat 210007

Si Tukak, Limau Manis 030002 Lumapas 050001, 050004 Meranking Bukit Sawat 210017, 210018

Mineral sulfidic organic soils

Labi Lama 230002, 230003, 230004

Betumpu 010001, 010008, 010009, 010015

Lumapas 050003 Meranking Bukit Sawat 210010

Organic soils

Sulfidic organic soils

Melayan A 220001

i) Acid discharges to waterways.

ii) Reduced biodiversity.

iii) Reduced value of fisheries.

Damage to bridges and concrete-lined drains.

i) Crop toxicity & nutrition.

ii) Greenhouse gas emissions.

iii) Subsidence, loss of soil resource.

VH

i) Avoid if undeveloped, otherwise minimise further disturbance.

ii) Maintain water table above sulfidic material.

iii) Treat soil and drainage water with lime.

iv) Use mineral soil for raised beds.

v) Otherwise import mineral soil for raised beds.



class Management

Sulfidic poorly drained cracking clay soils

Wasan 080001, 080003, 080004, 080005, 080006, 080011, 080015, 080016, 080019

Cracking clay soils Acid poorly

drained cracking clay soils

Wasan 080007, 080008, 080009, 080010, 080012, 080013, 080014, 080017, 080018





Crop toxicity & nutrition. L-M Treat soil and drainage water with lime

Treatment classes: L low level treatment; M medium level treatment; H high level treatment; VH very high level treatment; XH extra High level treatment (based on the treatment categories of Dear et al. 2002).




class Management

Tungku 090003, 090004, 090010, 090011, 090015

Soft poorly drained sulfuric soils

Batang Mitus (Halaman)

150017

i) Crop toxicity & nutrition.

ii) Upslope erosion

M

i) Treat toxicity and nutritional deficiencies in crop.

ii) Avoid upslope erosion (further exposure of pyritic rock).

iii) Treat soil and drainage water with lime.

Betumpu 010003, 010005, 010006, 010011, 010012, 010017, H

Limpaki 060002, 060003,

Crop toxicity & nutrition.

VH

Tungku 090016, 090017 i) Crop toxicity & nutrition.

ii) Upslope erosion

M

Sulfuric soils

Poorly drained sulfuric soils

Pengkalan Batu 290001, 290002, 290003





Crop toxicity & nutrition. M-H

i) Avoid further disturbance of sulfidic material at depth.

ii) Treat soil and drainage water with lime.



class Management

Betumpu 010002, 010004, 010013, 010016, 010021, 010022 H Soft poorly

drained sulfidic soils Pengkalan Batu 290004 M-H

Si Bongkok Parit Masin 040003 H Organic poorly drained sulfidic soils Lumapas 050005 H

Melayan A 220002

Crop toxicity & nutrition

H

i) Shallow sulfidic material: avoid if undeveloped.

ii) Otherwise minimise further disturbance.

iii) Treat with soil and drainage water with lime.

Sulfidic soils

Organic poorly drained moderately deep sulfidic soils

KM 26, Jalan Bukit Puan Labi

240007, 240008, 240009





Severe crop toxicity and nutrition

H i) Shallow sulfidic material ii) Do not develop

Treatment classes: L low level treatment; M medium level treatment; H high level treatment; VH very high level treatment; XH extra High level treatment (based on the treatment categories of Dear et al. 2002).


5.2.1. ASS Hazard Maps Maps of the ASS hazard are presented for each ADA in the accompanying Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-1.2 – Soil Maps (Grealish et al. 2007b). These maps are derived from the soil maps shown in the same report. The ASS hazard class of each soil map unit is based on the estimated proportion of the map unit area occupied by soil types with sulfidic material or a sulfuric layer. These soil types are those with the ‘c’ attribute in the Fertility Capability Classification (Sanchez et al. 2003) that indicates the presence of sulfidic/sulfuric material as discussed in Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-3/4 – Fertility and Limitations to Cultivation of Major Soil Type (Wong et al. 2007) and Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P2-1 – Suitability of Major Soil Types for Cropping (Ringrose-Voase et al. 2008). The ASS hazard classes are defined in Table 8.

Table 8: Acid Sulfate Soil Hazard Classes

Class Proportion of area with sulfidic material or a sulfuric layer

1 Negligible ≤5%

2 Low >5% and ≤25%

3 Moderate >25% and ≤50%

4 High >50% and ≤75%

5 Very high >75%

These ASS hazard classes indicate the likelihood of a site being an actual or potential ASS. They do not indicate the severity of problem when encountered, which is given by the ‘Treatment class’ in Table 7.

Hazard subclasses are defined by the most common depth to the sulfidic material or sulfuric layer sometimes with the minimum depth in brackets. For example, “3 / 40cm [15cm]” means there is a moderate likelihood of sulfidic material or a sulfuric layer (hazard class 3), which is most commonly at 40 cm depth but can be as shallow as 15 cm.

The maps show that the greatest problem with actual or potential ASS is in ADAs in the low-lying areas of Brunei-Muara and, to a lesser extent, Belait. Their occurrence in Tutong and Temburong is negligible. Table 9 shows the ASS hazard associated with the maps units of ADAs where ASS occur. Several patterns of ASS occurrence can be identified. In Brunei-Muara, six ADAs (Betumpu, Si Tukak Limau Manis, Si Bongkok Parit Masin, Lumapas, Limpaki and Pengkalan Batu) are almost entirely covered by actual or potential ASS (very high hazard). Only in the elevated part of Si Tukak Limau Manis A is the ASS hazard negligible. In addition, the areas are dominated by Organic soils that mostly require very high levels of treatment with smaller areas of Sulfuric soils requiring high levels of treatment, and Sulfidic soils requiring moderate levels. Since these ADAs are already developed for agriculture, it is important that the treatment recommendations in Table 7 are followed to prevent oxidation of sulfidic material, which would acidify the soil and could lead to acid being leached into nearby waterways.

Wasan also has extensive areas of ASS (if the Acid poorly drained cracking clay soils are included), but because they are Cracking clay soils they require only low to moderate treatment. Indeed, if used for rice, for which this area is suitable (see Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Report P1-1.2 – Soil Maps,


Grealish et al. 2007b) they can be cultivated with almost no special treatment, since it is kept waterlogged for most of the year.

The pattern of ASS in Tungku is rather different, with ASS being only moderately extensive in most of the ADA. Soft poorly drained sulfuric soils occur in the lower parts of the landscape and require moderate levels of treatment.

In Belait, four ADAs (Tungulian, Melayan A, Labi Lama and Km26 Jalan Bukit Puan Labi) have very high ASS hazard in the lowland areas associated with the AN (be) map unit. This map unit is dominated by Organic soils requiring very high levels of treatment. In Km26 Jalan Bukit Puan Labi there are also pockets of Organic poorly drained moderately deep sulfidic soils that require a high treatment level. Within these four ADAs, much of the area with very high ASS hazard is currently undeveloped for agriculture. Given that very high levels of treatment are necessary to successfully develop these areas, consideration should be given to leaving them undeveloped (see Table 7).

Merangking Bukit Sawat has isolated pockets of ASS, accounting for only a small part of its total area. If this ADA is developed for agriculture, these areas of organic soil would best be left undeveloped, since they require a very high treatment level (see Table 7).


Table 9: Acid Sulfate Soil (ASS) Hazard of the map units of Agricultural Development Areas (ADAs) where ASS occur. Also shown are the component soil subtypes of each map unit and their treatment classes (after Dear et al. 2002) derived from Table 7.

ADA Map unit symbol

Area (ha)

ASS hazard class Subclass

% of map unit1

Soil Taxonomy class Soil subtype description Treatment class

40% Typic Sulfaquepts Poorly drained sulfuric soil H

25% Haplic Sulfaquents Soft poorly drained sulfidic soil H

15% Typic Sulfisaprists Sulfidic organic soil VH

10% Terric Sulfosaprists Mineral sulfuric organic soil VH

Betumpu (Brunei-Muara)

BJ (bm) 474 Very high 5 / 30cm [15 cm]

10% Typic Sulfosaprists Sulfuric organic soil VH

50% Terric Sulfisaprists Mineral sulfidic organic soil VH AN (bm) 2 Very high 5 / 30 cm


MA (bm) 57 Very high 5 / 40cm

100% Sulfic Sulfaquerts Sulfidic poorly drained cracking clay soil L-M

BK.3 (bm) 41 Negligible 100% Oxyaquic Haplohumults Moderately well drained yellow soil -





Si Tukak, Limau Manis (Brunei-Muara)







Si Bongkok Parit Masin (Brunei-Muara)




ADA Map unit symbol

Area (ha)


% of map unit1








Lumapas (Brunei-Muara)

BJ (bm) 24 Very high 5 / 30cm [15cm]






BK.2 (bm) <1 Negligible 100% Oxyaquic Haplohumults Moderately well drained yellow soil -





Limpaki (Brunei-Muara)



50% Sulfic Sulfaquerts Sulfidic poorly drained cracking clay soil L-M BJ (wa) 329 Moderate 3 / 40 cm

50% Typic Dystraquerts Acid poorly drained cracking clay soil L-M



Wasan (Brunei-Muara)

BK.3 (bm) 1 Negligible 100% Oxyaquic Haplohumults Moderately well drained yellow soil -


ADA Map unit symbol

Area (ha)


% of map unit1


60% Ultic Epiaquods Loamy poorly drained podsol soil MR 5 Moderate 3 / 0 cm

40% Hydraquentic Sulfaquepts Soft poorly drained sulfuric soil M

40% Ultic Epiaquods Loamy poorly drained podsol soil -

40% Hydraquentic Sulfaquepts Soft poorly drained sulfuric soil M

LU/BJ 191 Moderate 3 / 0cm

20% Oxyaquic Haplohumults Moderately well drained yellow soil -

70% Oxyaquic Haplohumults Moderately well drained yellow soil - BK/NY.2 60 Negligible

30% Typic Kandihumults Sandy very deep yellow soil -

40% Typic Haplohumults Well drained yellow soil -


NY.3 4 Negligible






Tungku (Brunei-Muara)







Pengkalan Batu (Brunei-Muara)




ADA Map unit symbol

Area (ha)


% of map unit1


40% Terric Sulfisaprists Mineral sulfidic organic soil VH


AN (be) 13 High 4 / 30 cm

25% Arenic Paleudults Sandy over loamy yellow soil -

40% Typic Haplohumults Well drained yellow soil -


Tungulian (Belait)

NY.3 79 Negligible


50% Oxyaquic Palehumults Moderately well drained clayey very deep yellow soil - BDG-TTN-1-2 <1 Negligible

50% Typic Epiaqualfs Very deep brown over grey soil -

BKT-BTN-3 BKT-BTN-4

33 Negligible 100% Typic Palehumults Clayey very deep yellow soil -

50% Typic Palehumults Clayey very deep yellow soil - SKN-4 19 Negligible

50% Oxyaquic Palehumults Moderately well drained clayey very deep yellow soil -

35% Typic Palehumults Clayey very deep yellow soil -


BTN-SKN-4 8 Negligible





BTN-3 BTN-4

270 Low 2 / 30 cm




Merangking, Bukit Sawat (Belait)

TTN-KDN-1-2 156 Negligible






Melayan A (Belait)

BK.2/AN 3 Negligible 100% Arenic Paleudults Sandy over loamy yellow soil -


ADA Map unit symbol

Area (ha)


% of map unit1






Labi Lama (Belait)

BJ (be) MA (be)

10 Negligible 100% Aquic Kandihumults Somewhat poorly drained very deep sandy yellow soil

-





40% Umbric Epiaquods Sandy poorly drained white soil -


KM26 Jalan Bukit Puan Labi (Belait)

BU/MR.1 35 Moderate 3 / 70 cm

30% Sulfic Fluvaquents Organic poorly drained moderately deep sulfidic soil H


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Appendices


Appendix A Data Tables Table A1: ASS site descriptions. * Infrequent occurrence of this soil did not justify the creation of a soil subtype and will result in reaching a “No*” point when using the Brunei key.

ADA Site ID Soil classification Lab-oratory analysis

data

Map unit Land-scape

Land-form

Slope gradient

(%)

Slope position

Drainage Depth to water table (cm)

Earth cover

Eastings Northings

01 0001 Typic Sulfisaprist no BJ (bm) AP AP 0 FL PD 85 RBV 261644 53557001 0002 Haplic Sulfaquent no BJ (bm) AP AP 0 FL PD 50 RBV 261732 53557401 0003 Typic Sulfaquept no BJ (bm) AP AP 0 FL VP 35 RBV 261792 53558001 0004 Haplic Sulfaquent no BJ (bm) AP AP 0 FL PD 80 RBV 261792 53558101 0005 Typic Sulfaquept no BJ (bm) AP AP 0 FL VP 40 RBV 261756 53544601 0006 Typic Sulfaquept no BJ (bm) AP AP 0 FL VP 20 RBV 261651 53542601 0007 Typic Sulfosaprist no BJ (bm) AP AP 0 FL PD NR CL 261728 53482001 0008 Typic Sulfisaprist no BJ (bm) AP AP 0 FL PD 50 RBV 261849 53483101 0009 Typic Sulfisaprist no BJ (bm) AP AP 0 FL PD 40 RBV 261890 53467701 0010 Typic Sulfosaprist no BJ (bm) AP AP 0 FL PD 60 RBV 261762 53466301 0011 Typic Sulfaquept yes BJ (bm) AP AP 0 FL PD 80 RBV 262695 53607901 0012 Typic Sulfaquept yes BJ (bm) AP AP 0 FL VP 60 IBT 262698 53608101 0013 Haplic Sulfaquent yes BJ (bm) AP AP 0 FL PD 30 RT 262681 53541801 0014 Typic Sulfosaprist no BJ (bm) AP AP 0 FL PD 60 RT 262606 53544501 0015 Typic Sulfisaprist yes BJ (bm) AP AP 0 FL VP 25 RBV 262578 53527101 0016 Haplic Sulfaquent yes BJ (bm) AP AP 0 FL VP 30 RT 262665 53527701 0017 Typic Sulfaquept no BJ (bm) AP AP 0 FL VP 60 RTG 262225 53481301 0018 Terric Sulfosaprist no BJ (bm) AP AP 0 FL VP 10 RT 262372 53472001 0019 Terric Sulfosaprist no BJ (bm) AP AP 0 FL VP 20 CL 262485 53473801 0020 Terric Sulfosaprist no BJ (bm) AP AP 0 FL VP 10 RBV 262571 53472701 0021 Haplic Sulfaquent no BJ (bm) AP AP 0 FL VP 20 RBV 261745 53515201 0022 Haplic Sulfaquent no BJ (bm) AP AP 0 FL VP 20 RBV 261807 535171

Si Tukak, Limau Manis

03 0002 Terric Sulfisaprist yes BJ (bm) AP AP 0 FL PD 20 BP 259490 527277

Si Bongkok Parit Masin

04 0003 Thapto-Histic Sulfaquent no BJ (bm) AP AP 0 FL VP 0 SW 259418 533705

Betumpu



data

Map unit Land-scape

Land-form

Slope gradient

(%)

Slope position


Earth cover

Eastings Northings

05 0001 Terric Sulfisaprist no AN (bm) VA VF 2 TS SP 50 RTG 268500 53218005 0002 Terric Sulfosaprist no AN (bm) VA VF 1 TS SP 80 RTG 268406 53239705 0003 Typic Sulfisaprist no BJ (bm) VA VF 0 TS PD 50 RBV 268520 53257305 0004 Typic Sulfisaprist yes BJ (bm) VA VF 1 TS PD 25 RBV 268546 53280505 0005 Thapto-Histic Sulfaquent yes BJ (bm) VA VF 1 TS PD 50 RBV 268610 53279206 0001 Typic Sulfosaprist no BJ (bm) VA VF 0 TS VP 40 RT 260206 53805406 0002 Typic Sulfaquept yes BJ (bm) VA VF 0 TS VP 30 RT 260129 53806706 0003 Typic Sulfaquept no BJ (bm) VA VF 0 TS VP 110 RT 260266 53758906 0004 Typic Sulfosaprist no BJ (bm) VA VF 0 TS PD 0 RT 260251 53767306 0005 Typic Sulfosaprist no BJ (bm) VA VF 0 TS PD 0 RT 260265 53790008 0001 Sulfic Sulfaquert no BJ (wa) AP AP 0 FL PD NR RTG 257838 52969508 0003 Sulfic Sulfaquert yes BJ (wa) AP AP 0 FL VP 0 PR 256970 52995808 0004 Sulfic Sulfaquert yes BJ (wa) AP AP 0 FL VP 0 PR 257351 52983508 0005 Sulfic Sulfaquert no BJ (wa) VA VF 1 TS SP 10 PR 258193 52916408 0006 Sulfic Sulfaquert no MA (bm) VA VF 1 TS SP 0 PR 258063 52959508 0007 Typic Dystraquert no BJ (wa) VA VF 1 TS SP 5 PR 257578 52977208 0008 Typic Dystraquert no BJ (wa) VA VF 1 TS SP 0 PR 257958 52926308 0009 Typic Dystraquert no BJ (wa) VA VF 1 TS SP 0 PR 257827 52888508 0010 Typic Dystraquert no BJ (wa) VA VF 1 TS SP 0 PR 257902 52908708 0011 Sulfic Sulfaquert no BJ (wa) AP AP 0 FL VP 0 PR 257250 52962108 0012 Typic Dystraquert yes BJ (wa) AP AP 0 FL VP 5 PR 257208 52949908 0013 Typic Dystraquert no BJ (wa) AP AP 0 FL VP 5 PR 257127 52922508 0014 Typic Dystraquert no BJ (wa) AP AP 0 FL VP 5 PR 257057 52898108 0015 Sulfic Sulfaquert yes BJ (wa) AP AP 0 FL VP 0 PR 256988 52873608 0016 Sulfic Sulfaquert no BJ (wa) AP AP 0 FL VP 0 PR 256555 52841008 0017 Typic Dystraquert no BJ (wa) AP AP 0 FL VP 0 PR 256728 52870808 0018 Typic Dystraquert no BJ (wa) AP AP 0 FL VP 0 PR 256904 52934808 0019 Sulfic Sulfaquert no BJ (wa) AP AP 0 FL VP 0 PR 257039 529807

Lumapas

Limpaki

Wasan



data

Map unit Land-scape

Land-form

Slope gradient

(%)

Slope position


Earth cover

Eastings Northings

09 0003 Hydraquentic Sulfaquept no LU/BJ HI HS 0 TS PD 35 RTG 265534 54662109 0004 Hydraquentic Sulfaquept no LU/BJ HI HS 0 TS PD 35 RTG 265547 54661109 0009 Typic Sulfudept* no LU/BJ HI HS 10 BS MW NR CL 265835 54675509 0010 Hydraquentic Sulfaquept no LU/BJ HI HS 3 TS SP 20 CL 265842 54675709 0011 Hydraquentic Sulfaquept no LU/BJ HI HS 3 TS SP 20 CL 265806 54681309 0015 Hydraquentic Sulfaquept yes LU/BJ HI VF 2 TS PD 60 CL 265812 54680909 0016 Typic Sulfaquept no LU/BJ HI VF 3 FS PD 50 RF 265809 54688409 0017 Typic Sulfaquept no LU/BJ AP AP 1 FL VP 0 RF 265822 546885

Batang Mitus (Halaman)

15 0017 Hydraquentic Sulfaquept no BK/NY.2 VA VF 0 TS VP 0 RF 251390 527384

21 0007 Typic Sulfosaprist yes BTN-3 VA VF 1 TS PD 30 RF 232094 50251021 0010 Typic Sulfisaprist yes BTN-3 VA VF 1 TS PD 35 RF 231711 50176821 0017 Terric Sulfisaprist no BTN-3 HI HS 2 TS PD 60 RF 232284 50192721 0018 Terric Sulfisaprist no BTN-3 HI HS 2 TS PD 60 RF 232269 50196322 0001 Typic Sulfisaprist no AN (be) VA VF 2 FS VP 0 RF 218227 49641722 0002 Sulfic Fluvaquent yes AN (be) VA VS 2 FS PD 70 RF 218279 49640223 0001 Terric Sulfosaprist yes AN (be) VA VF 1 TS PD 60 CT 217900 48823723 0002 Terric Sulfisaprist no AN (be) VA VF 1 TS PD 60 CT 217820 48827023 0003 Terric Sulfisaprist no AN (be) VA VF 1 TS PD 50 CT 217876 48838023 0004 Terric Sulfisaprist yes AN (be) VA VF 1 TS PD 40 CL 217754 48835223 0005 Terric Sulfosaprist no AN (be) VA VF 2 TS PD 40 BP 217869 48811424 0002 Histic Sulfaquent* no BU/MR.1 VA VF 2 TS PD 0 RF 217998 49731724 0007 Sulfic Fluvaquent no BU/MR.1 VA VF 1 TS VP 0 RF 217954 49734424 0008 Sulfic Fluvaquent no BU/MR.1 VA VF 2 FS PD 30 RF 217948 49735524 0009 Sulfic Fluvaquent no BU/MR.1 VA VF 2 FS PD 20 RF 217927 49737929 0001 Typic Sulfaquept no BJ (bm) VA TE 1 TS PD 50 RBV 258487 53369129 0002 Typic Sulfaquept no BJ (bm) VA TE 0 TS VP 15 RBV 258500 53313129 0003 Typic Sulfaquept no BJ (bm) VA TE 0 TS PD 50 RBV 258494 53297629 0004 Haplic Sulfaquent yes BJ (bm) VA TE 0 TS PD NR RBV 258435 532954

KM 26, Jalan B

Pengkalan Batu

Tungku

Merangking, Bukit Sawat

Melayan A

Labi Lama


Site description codes for Table A1

Landscape AP Alluvial flat HI Hills VA Valley

Landform AP Alluvial flat HS Hill slope TE Terrace VF Valley floor VS Valley side

Geomorphic component BS Backslope FL Flat FS Footslope TS Topeslope

Depth to watertable NR Not recorded

Drainage MW Moderately well drained PD Poorly drained SP Somewhat poorly drained VP Very poorly drained

Earth cover BP Banana palms CL Cleared CT Citrus trees IBT Interbed trough PR Paddy rice RBV Raised bed vegetables RF Regrowth forest RT Regrowth trees RTG Regrowth tall grass SW Swamp


Table A2: Description of soil profiles

Upper Lower01 0001 1 sml pit no Ap 0 12 10YR 2/2 sandy clay loam 5% f Fe concentrations 5YR 5/8 mod f subang blocky friable 4.7

2 sml pit no Bg 12 75 10YR 2/2 clay loam 30% m Fe concentrations 10YR 6/8 weak f subang blocky firm 4.13 auger no BCg 75 100 5Y 2/2 clay 10% f Fe concentrations 7.5YR 5/8 massive x firm 4.5

01 0002 1 sml pit no Ap 0 10 10YR 2/2 clay loam strong f subang blocky friable2 sml pit no Bg1 10 55 2.5Y 5/2 clay 20% m Fe concentrations 10YR 6/8 mod f subang blocky firm3 auger no Bg2 55 75 2.5Y 5/2 clay 3% f Fe concentrations 5YR 5/8 massive firm4 auger no BCg 75 100 2.5Y 5/1 clay 3% f Fe concentrations 5YR 5/8 massive firm

01 0003 1 sml pit no Ap 0 5 10YR 3/2 clay loam mod f subang blocky friable2 sml pit no Bg 5 55 10YR 4/2 clay loam 30% c Fe concentrations 10YR 6/8 massive firm 3.83 auger no BCg 55 100 10YR 5/1 clay loam 3% m Fe concentrations 5YR 6/8 massive x firm

01 0004 1 sml pit no Ap 0 25 10YR 3/2 clay loam mod f subang blocky friable 4.72 auger no Bg 25 80 10YR 4/2 clay 30% c Fe concentrations 10YR 6/8 massive firm 3.83 auger no BCg 80 100 10YR 5/1 clay massive firm

01 0005 1 sml pit no Ap 0 12 10YR 6/2 clay loam mod f subang blocky friable2 sml pit no Bg 12 70 10YR 5/2 clay 30% c Fe concentrations 10YR 6/8 weak f subang blocky firm3 auger no BCg 70 100 10YR 5/1 clay massive x firm

01 0006 1 sml pit no Ap 0 5 10YR 6/2 clay loam mod m subang blocky friable2 sml pit no Bg 5 60 10YR 5/2 clay 30% c Fe concentrations 10YR 6/8 weak c subang blocky firm3 auger no BCg 60 100 10YR 5/1 clay massive x firm

01 0007 1 sml pit no Ap 0 5 7.5YR 6/2 clay loam mod f granular friable 3.32 sml pit no Bg1 5 75 7.5YR 5/2 clay loam 30% c Fe concentrations 10YR 6/8 weak f subang blocky firm3 auger no Bg2 75 100 7.5YR 5/1 clay loam massive firm 4.0

01 0008 1 sml pit no Ap 0 15 10YR 6/2 clay mod c subang blocky friable 4.72 sml pit no Bg 15 85 10YR 5/2 clay loam 40% m Fe concentrations 10YR 6/8 weak m subang blocky firm 4.03 auger no BCg 85 100 10YR 5/1 sandy clay loam 3% f Fe concentrations 5YR 6/8 massive firm 4.2

01 0009 1 sml pit no Ap 0 35 7.5YR 3/2 clay loam 3% f Fe concentrations 5YR 6/8 mod m subang blocky friable 4.02 auger no Bg 35 100 7.5YR 5/1 clay loam 3% f Fe concentrations 5YR 6/8 massive firm 4.3

01 0010 1 sml pit no Ap 0 40 7.5YR 3/2 clay loam weak f subang blocky friable 3.62 auger no Bg 40 85 5YR 2.5/2 clay loam weak f subang blocky firm 4.43 auger no BCg 85 100 7.5YR 5/1 clay loam massive x firm

Layerno.

Redoximorphic features(abundance, size, type, colour)

Structure(development, size,

type)

Consist-enceHorizonSite no. Texture Field

pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower01 0017 1 sml pit no Ap1 0 5 sandy clay loam mod f subang blocky friable

2 sml pit no Ap2 5 10 sandy clay loam mod f subang blocky friable 3.53 sml pit no ABg 10 40 sandy clay loam massive firm4 auger no Bg1 40 60 clay loam 3% f Fe concentrations 10YR 6/6 massive firm5 auger no Bg2 60 80 clay loam 3% f Fe concentrations 5YR 6/8 massive firm6 auger no BCg 80 100 clay massive x firm 3.0

01 0018 1 sml pit no O -2 0 litter 2 sml pit no A1 0 5 sandy clay loam mod f subang blocky friable3 sml pit no A2 5 10 sandy clay loam mod f subang blocky friable4 sml pit no ABg 10 50 clay loam massive firm 3.35 auger no Bg1 50 80 clay 3% f Fe concentrations 7.5YR 6/8 massive x firm6 auger no Bg2 80 90 clay 3% f Fe concentrations 7.5YR 6/8 massive x firm7 auger no BCg 90 100 clay massive x firm 2.8

01 0019 1 sml pit no Ap 0 10 clay 2 sml pit no Bg 40 50 clay

01 0020 1 sml pit no Ap1 0 5 sandy clay loam mod f cloddy friable2 sml pit no Ap2 5 10 sandy clay loam mod f subang blocky friable3 sml pit no AB 10 20 clay massive firm4 sml pit no Bg 20 60 clay massive firm5 auger no B 60 80 peaty clay 6 auger no Oi 80 100 hd plant material 3.3

01 0021 1 sml pit no Ap1 0 5 10YR 2/2 sandy loam mod f cloddy friable2 sml pit no Ap2 5 20 10YR 2/2 sandy loam mod f cloddy friable3 sml pit no B1 20 40 10YR 2/1 peaty clay massive friable4 auger no B2 40 90 10YR 4/1 peaty clay massive friable5 auger no Oi 90 100 peat soft

01 0022 1 sml pit no Ap1 0 5 sandy clay loam mod f cloddy friable2 sml pit no Ap2 5 20 sandy clay loam mod f cloddy friable3 sml pit no B 20 60 peaty clay loam massive friable4 auger no Oi 60 80 peat massive soft5 auger no BCg 80 100 clay massive friable

03 0002 1 sml pit yes Oe 0 30 5YR 3/2 peat soft2 auger yes B 30 60 10YR 2/2 mucky clay loam soft3 auger yes B 60 100 10YR 2/1 peaty clay loam soft

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower04 0003 1 auger no Ap 0 20 10YR 4/2 clay loam strong m granular soft

2 auger no Bg1 20 90 10YR 3/2 clay loam massive soft 3.93 auger no Bg2 90 150 10YR 3/2 sandy loam massive firm 4.24 auger no Oe1 150 170 10YR 2/1 md plant material massive firm 3.95 auger no Oe2 170 180 10YR 2/1 md plant material massive firm6 auger no Oe3 180 200 7.5YR 2/0 md plant material massive soft 3.9

05 0001 1 sml pit no Oe1 0 5 5YR 2.5/2 peat massive soft2 sml pit no Oe2 5 50 5YR 2.5/2 peat massive soft3 auger no 2Bg 50 90 10YR 3/1 mucky clay massive v firm4 auger no 2Bgj1 90 150 10YR 3/1 mucky clay massive v firm5 auger no 2Bgj2 150 200 10YR 5/1 clay massive v firm

05 0002 1 sml pit no Oe1 0 10 5YR 2.5/2 peat massive friable 2.82 sml pit no Oe2 10 60 5YR 2.5/2 peat massive friable 3.33 auger no Oa 60 80 5YR 2.5/2 peat massive friable4 auger no 2Bg1 80 150 7.5YR 3/0 clay loam massive v firm 4.75 auger no 2Bg2 150 190 7.5YR 3/0 clay loam massive v firm6 auger no 2Bg3 190 200 7.5YR 3/0 clay loam massive v firm 5.3

05 0003 1 sml pit no Oi1 0 20 5YR 2.5/2 peat massive firm 3.52 sml pit no Oi2 20 90 5YR 2.5/2 peat massive soft 5.03 auger no Bg1 90 120 7.5YR 3/0 clay loam massive soft 5.24 auger no Bg2 120 180 7.5YR 3/0 clay loam massive soft 5.25 auger no Bg3 180 200 7.5YR 3/0 clay loam massive soft 5.3

05 0004 1 sml pit yes Ap 0 10 10YR 2/2 sandy clay loam strong f granular firm2 sml pit yes Oa1 10 30 5YR 2.5/1 peat weak f subang blocky firm3 sml pit yes Oa2 30 110 7.5YR 5/0 peat massive soft4 auger no Bg 110 170 7.5YR 4/0 clay massive soft5 auger no Cg 170 200 7.5YR 4/0 clay massive soft

05 0005 1 sml pit yes Ap 0 10 10YR 2/1 sandy clay loam strong f granular firm 4.52 sml pit yes Oa1 10 30 10YR 2/2 peat massive firm 4.73 sml pit yes Oa2 30 110 10YR 6/2 peat massive soft 4.64 auger no Bg 110 180 10YR 6/2 clay massive soft 5.05 auger no Cg 180 200 7.5YR 4/0 clay massive soft 5.0

06 0001 1 sml pit no Apj 0 5 10YR 6/4 clay mod f cloddy firm2 sml pit no Oi1 5 20 5YR 2.5/2 peat massive firm3 sml pit no Oi2 20 40 5YR 3/2 peat massive friable 3.04 auger no Oe 40 140 7.5YR 3/0 md plant material massive firm 3.35 auger no Cg1 140 180 7.5YR 4/0 mucky clay massive soft 3.86 auger no Cg2 180 200 7.5YR 4/0 mucky clay massive soft

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower06 0002 1 sml pit no Oi1 0 5 5YR 3/2 peat massive firm

2 sml pit yes Oi2 5 10 5YR 3/2 peat massive firm 2.83 sml pit yes Oi3 10 40 7.5YR 3/2 peat massive friable 3.24 sml pit no Oi4 40 80 5YR 4/2 peat massive friable5 auger yes Oe 80 180 7.5YR 3/0 mucky peat massive soft 3.76 auger yes Cg 180 200 7.5YR 4/0 clay massive soft

06 0003 1 sml pit no Ap 0 20 7.5YR 4/1 clay mod f cloddy firm2 sml pit no Apj 20 80 7.5YR 4/0 clay massive firm3 auger no Oi 80 100 5YR 3/2 peat massive soft4 auger no Oe 100 120 7.5YR 4/1 mucky peat massive v fiable5 auger no Cg1 120 150 7.5YR 4/0 clay massive friable6 auger no Cg2 150 180 7.5YR 4/0 clay massive soft7 auger no Cg3 180 200 7.5YR 4/0 clay massive friable

06 0004 1 sml pit no A1 0 5 10YR 5/2 clay massive firm2 sml pit no A2 5 40 10YR 5/2 clay massive firm3 auger no Oi1 40 90 5YR 2.5/2 mucky peat massive friable4 auger no Oi2 90 110 5YR 3/2 peat massive soft5 auger no Bg1 110 160 7.5YR 4/0 clay massive friable6 auger no Bg2 160 200 7.5YR 4/0 clay massive soft

06 0005 1 sml pit no A 0 10 10YR 5/2 clay massive firm2 sml pit no Oi 10 50 5YR 2.5/2 peat massive soft3 auger no Oe 50 80 5YR 3/2 mucky peat massive friable4 auger no Bg1 80 140 7.5YR 4/1 clay massive firm5 auger no Bg2 140 200 7.5YR 4/0 clay massive soft

08 0001 P auger no 08 0003 1 auger no A 0 5 10YR 2/1 clay loam massive soft

2 auger no Oe 5 10 10YR 2/1 mucky peat friable3 auger yes Oi 10 20 5YR 3/1 peat friable4 auger no Oi 20 30 5YR 3/1 peat friable5 auger no Oe 30 50 5YR 3/1 mucky peat firm6 auger no Cg 50 80 10YR 4/1 clay massive firm7 auger no Cg 80 90 10YR 4/1 clay massive firm

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower08 0004 1 auger no A 0 5 10YR 4/2 clay loam massive soft

2 auger no Oa 5 20 5YR 3/1 mucky peat soft3 auger no Bg 20 50 10YR 4/2 clay massive firm4 auger yes Bg 50 80 10YR 4/1 clay massive firm5 auger yes Bg 80 90 10YR 4/1 clay massive v firm6 auger yes Bg 90 110 10YR 4/1 clay massive v firm7 auger no BCg 110 120 10YR 4/1 clay massive v firm8 auger no BCg 120 140 10YR 4/1 clay massive v firm

08 0005 1 sml pit no A1 0 5 10YR 4/2 clay loam massive friable 5.02 sml pit no A2 5 30 10YR 4/2 clay loam massive soft3 sml pit no Bg1 30 40 10YR 4/3 clay massive firm 5.14 auger no Bg2 40 60 10YR 4/2 clay 20% m Fe concentrations 10YR 5/8 massive firm5 auger no Bgj 60 90 10YR 4/2 clay massive firm 4.46 auger no BC 90 100 10YR 4/1 clay massive v firm

08 0006 1 auger no L 0 60 10YR 3/2 litter massive soft2 auger no Bg1 60 80 10YR 6/1 clay massive soft3 auger no Bg2 80 100 10YR 6/2 clay massive v firm

08 0007 1 sml pit no L1 0 5 10YR 3/2 litter massive soft 5.32 sml pit no L2 5 30 10YR 3/2 litter massive soft 5.23 auger no A 30 50 10YR 4/2 clay massive firm4 auger no Bg1 50 70 10YR 4/1 clay 20% c Fe concentrations 10YR 6/8 massive firm 5.05 auger no Bg2 70 90 10YR 4/1 clay 20% f Fe concentrations 5YR 5/8 massive v firm

08 0008 1 sml pit no L 0 5 10YR 3/2 litter massive soft 5.12 sml pit no A 5 30 10YR 4/3 clay loam massive soft3 sml pit no Bg1 30 50 10YR 4/2 clay 20% c Fe concentrations 10YR 6/8 massive firm 5.04 auger no Bg2 50 80 10YR 4/1 clay 20% c Fe concentrations 10YR 6/8 massive firm5 auger no Bg3 80 100 10YR 4/1 clay 10% f Fe concentrations 5YR 5/8 massive v firm 4.6

08 0009 P cut no 08 0010 P no 08 0011 1 auger no A 0 5 10YR 2/1 mucky clay loam massive soft

2 auger no Bg 5 40 10YR 3/2 clay 3% f Fe concentrations 7.5YR 5/6 massive v firm3 auger no BCg 40 100 7.5YR 4/0 clay massive v firm

08 0012 1 auger no Oi -10 0 10YR 3/2 sd plant material massive v firm2 auger yes Ap1 0 5 10YR 3/1 mucky clay massive soft3 auger yes Ap2 5 20 10YR 3/1 mucky clay massive soft4 auger no Bg 20 60 7.5YR 5/0 clay massive firm5 auger no BCg 60 100 7.5YR 7/0 clay massive firm

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower08 0013 1 auger no Oi -10 0 10YR 3/2 sd plant material massive v firm

2 auger yes Ap1 0 5 10YR 3/1 mucky clay massive soft3 auger yes Ap2 5 20 10YR 3/1 mucky clay massive soft4 auger no Bg 20 60 7.5YR 5/0 clay massive firm5 auger no BCg 60 100 7.5YR 7/0 clay massive firm

08 0014 1 auger no Oi -10 0 10YR 3/2 sd plant material massive v firm2 auger yes Ap1 0 5 10YR 3/1 mucky clay massive soft3 auger yes Ap2 5 20 10YR 3/1 mucky clay massive soft4 auger no Bg 20 60 7.5YR 5/0 clay massive firm5 auger no BCg 60 100 7.5YR 7/0 clay massive firm

08 0015 1 auger no Oi -10 0 10YR 5/1 sd plant material massive soft2 auger yes Ap 0 5 10YR 5/1 mucky clay massive soft3 auger yes Bg1 5 40 10YR 5/1 mucky clay 20% c Fe concentrations 7.5YR 5/6 massive firm4 auger yes Bg2 40 90 10YR 5/1 clay 40% f Fe concentrations 7.5YR 5/6 massive v firm5 auger no BCg 90 160 7.5YR 5/0 clay massive v firm

08 0016 1 auger no Oi 0 5 5YR 2.5/1 sd plant material massive soft2 auger no Bg 5 50 10YR 5/1 clay 40% f Fe concentrations 7.5YR 5/6 massive v firm3 auger no BCg 50 100 7.5YR 5/0 clay massive v firm

08 0017 1 auger no A 0 5 10YR 4/3 clay loam massive soft2 auger no Bg 5 40 10YR 5/1 clay 40% m Fe concentrations 10YR 5/8 massive firm 3.93 auger no BCg 40 100 10YR 5/1 clay 60% c Fe concentrations 10YR 5/8 massive v firm 4.4

08 0018 1 auger no A 0 5 10YR 4/3 clay loam massive soft2 auger no Bg 5 40 10YR 5/1 clay 40% m Fe concentrations 10YR 5/8 massive firm 3.93 auger no BCg 40 100 10YR 5/1 clay 60% c Fe concentrations 10YR 5/8 massive v firm 4.4

08 0019 1 auger no A 0 2 5YR 3/2 mucky clay loam massive soft2 auger no Oi1 2 40 5YR 3/2 peat 3% f Fe concentrations 7.5YR 5/6 massive soft3 auger no Oi2 40 60 5YR 3/2 peat massive firm4 auger no Bg1 60 80 7.5YR 4/0 clay massive v firm5 auger no Bg2 80 100 7.5YR 4/0 clay massive v firm

09 0003 1 sml pit no L 0 5 10YR 3/2 litter massive loose2 auger no A 5 10 10YR 4/2 loamy sand massive firm 3.93 auger no Bg 10 70 10YR 7/2 loamy sand 5% m Fe-Mn concretions 5YR 5/8 massive v firm 4.24 auger no BCg 70 100 10YR 7/2 loamy sand massive v firm 3.9

09 0004 1 sml pit no L 0 5 10YR 2/2 litter massive loose2 auger no A 5 15 7.5YR 3/2 loamy sand massive friable 4.43 auger no Bw 15 45 10YR 6/4 loamy sand massive v firm 4.74 auger no Bg 45 100 10YR 6/2 loamy sand massive v firm 5.3

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower09 0009 1 sml pit no A 0 10 10YR 4/1 sandy clay massive s rigid

2 sml pit no B 10 20 10YR 4/1 sandy clay massive s rigid3 sml pit no C 20 50 10YR 3/1 sandy clay massive s rigid4 auger no 2B 50 55 10YR 3/1 sandy clay massive s rigid5 auger no 2C 55 90 10YR 6/1 clay 30% f Fe concentrations 10YR 6/8 massive s rigid

09 0010 1 sml pit no A 0 20 10YR 6/6 sand massive v firm2 sml pit no B 20 50 10YR 3/2 clay massive v firm3 auger no C 50 70 10YR 4/2 sand 30% f Fe concentrations 10YR 6/6 massive v firm

09 0011 1 sml pit no A 0 5 7.5YR 5/3 sand massive v firm 3.52 sml pit no Bj 5 20 7.5YR 5/3 sand massive v firm 2.53 sml pit no C1 20 30 10YR 6/6 sand massive v firm 3.54 sml pit no C2 30 40 10YR 6/6 sand massive v firm 2.55 sml pit no C3 40 70 10YR 6/6 sand 20% f Fe concentrations 10YR 4/2 massive v firm 2.56 auger no C4 70 90 10YR 7/1 sand massive v firm 3.07 auger no C5 90 100 5Y 4/2 sand 60% m Fe concentrations 5YR 6/8 massive v firm 3.0

09 0015 1 sml pit yes C1 0 10 10YR 5/3 sand massive soft 2.62 sml pit no C2 10 30 10YR 5/2 loamy sand massive firm 3.23 sml pit yes C3 30 50 7.5YR 5/4 loamy sand massive soft 3.34 auger yes 2Bj 50 60 10YR 4/1 sandy loam 30% f Fe concentrations 7.5YR 5/4 massive x firm 3.35 auger no 3BC 60 100 2.5YR 4/8 sandy clay massive s rigid 3.6

09 0016 1 sml pit no A 0 25 10YR 3/3 loamy sand mod f subang blocky friable 3.52 sml pit no Bw 25 80 10YR 6/8 sand massive firm 3.63 sml pit no BCg 80 100 10YR 6/1 sand 30% m Fe concentrations 10YR 5/8 massive firm 3.5

09 0017 1 sml pit no A 0 30 10YR 4/2 sandy clay loam mod f subang blocky soft2 sml pit no Bg 30 80 10YR 6/1 sandy clay 50% c Fe concentrations 7.5YR 5/8 massive firm3 auger no BCg 80 100 10YR 6/1 loamy sand 5% f Fe concentrations 7.5YR 5/8 massive firm

15 0017 1 sml pit no A 0 5 10YR 2/2 sandy clay loam mod f granular soft2 sml pit no ABg 5 20 10YR 4/2 mucky sandy clay loam 10% f Fe concentrations massive soft3 sml pit no Bg1 20 60 10YR 5/2 mucky clay loam 20% f Fe concentrations massive soft4 auger no Bg2 60 90 10YR 5/2 clay loam 30% f Fe concentrations massive soft5 auger no C 90 100 10YR 7/2 clay loam massive soft

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

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Soil colour- moist


Upper Lower21 0007 1 sml pit no L -2 0 10YR 3/2 litter soft

2 sml pit yes Oe1 0 5 5YR 2.5/1 mucky peat soft3 sml pit yes Oe2 5 15 10YR 3/2 mucky peat soft4 sml pit yes Oe3 15 30 5YR 2.5/2 mucky peat soft 3.45 sml pit yes Oe4 30 50 5YR 2.5/1 mucky peat soft 4.26 sml pit yes Oe5 50 60 5YR 2.5/1 mucky peat soft7 sml pit yes Oe6 60 80 5YR 2.5/1 mucky peat soft 4.58 sml pit yes Oe7 80 120 5YR 2.5/1 mucky peat soft9 auger yes Oe8 120 170 5YR 2.5/1 mucky peat soft10 auger yes Cg 170 190 10YR 3/2 mucky clay firm 4.711 auger yes 2Oe 190 250 5YR 2.5/1 mucky peat soft 4.7

21 0010 1 sml pit yes Oe 0 30 7.5YR 3/2 mucky peat soft2 auger no Aj 30 35 10YR 2/1 clay firm3 auger no Oi1 35 90 5YR 3/2 peat soft 3.34 auger no Oi2 90 200 5YR 3/2 peat soft 3.5

21 0017 1 sml pit no Oe 0 20 10YR 2/1 hd plant material massive soft2 sml pit no C 20 70 10YR 6/1 clay massive v firm3 auger no 2Oe 70 100 10YR 2/1 hd plant material massive soft

21 0018 P cut no / 22 0001 1 sml pit no Oe 0 10 10YR 2/1 hd plant material massive loose

2 sml pit no Oi1 10 20 10YR 2/1 sd plant material massive loose3 auger no Oi2 20 70 10YR 2/1 sd plant material massive loose 3.94 auger no Oi3 70 100 10YR 2/1 sd plant material massive loose 4.2

22 0002 1 sml pit no L 0 10 10YR 5/4 litter massive loose2 sml pit yes A 10 20 10YR 3/3 sand single grain friable 5.83 sml pit yes B 20 70 10YR 7/1 sand single grain friable 5.74 auger no B 70 110 10YR 7/1 sand single grain friable5 auger no Bhs 110 130 7.5YR 2/1 peaty sand massive soft 6.06 auger yes Bh 130 200 7.5YR 2/1 peaty sand massive soft 5.9

23 0001 1 sml pit yes Ap 0 5 7.5YR 3/2 sandy clay loam weak f subang blocky firm2 sml pit yes Oe 5 30 10YR 2/2 mucky peat massive friable3 sml pit yes 2Bg 30 60 10YR 5/1 clay massive v firm4 auger no 3Oe1 60 70 5YR 2.5/2 peat massive soft5 auger yes 3Oe2 70 110 5YR 2.5/2 peat massive soft6 auger yes 3Oe3 110 200 5YR 2.5/2 peat massive soft

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower23 0002 1 sml pit no Oe 0 5 10YR 2/2 md plant material massive firm

2 sml pit no Bg 5 20 10YR 6/2 sandy loam massive firm3 sml pit no Bg 20 60 10YR 6/2 clay massive soft4 auger no Oi 60 80 10YR 2/1 peat massive soft5 auger no C 80 100 10YR 3/2 sand massive soft

23 0003 1 sml pit no A 0 20 10YR 4/2 sandy loam massive firm2 sml pit no Oa 20 50 2.5YR 3/2 hd plant material massive soft3 auger no Bg 50 80 10YR 4/2 clay massive soft4 auger no Oi 80 100 2.5YR 3/2 peat massive soft

23 0004 1 sml pit yes A 0 10 7.5YR 3/2 peaty sandy loam mod f cloddy soft2 sml pit yes A 10 20 5YR 2.5/1 peaty sandy loam mod f cloddy soft3 sml pit no B 20 30 10YR 2/1 clay massive firm4 auger yes Oi1 30 40 5YR 2.5/1 peat massive soft5 auger no Oi2 40 70 5YR 2.5/1 peat massive soft6 auger yes C 70 150 10YR 7/1 sand massive v firm

23 0005 1 sml pit no Oa 0 30 10YR 2/2 peat massive firm2 sml pit no Bg 30 60 10YR 5/2 clay massive soft3 auger no Oi 60 100 5YR 2.5/1 peat massive soft

24 0002 1 sml pit no L -1 0 7.5YR 3/2 litter 2 sml pit no Oe 0 5 7.5YR 3/2 peat massive soft 4.23 sml pit no Oi 5 10 5YR 2.5/2 peat massive soft4 sml pit no Bh1 10 25 10YR 4/2 sand single grain loose5 auger no Bh2 25 50 10YR 4/2 sand single grain loose6 auger no Bh3 50 70 10YR 4/2 sand single grain loose7 auger no B 70 90 10YR 4/2 sand single grain loose8 auger no C 90 100 10YR 6/2 sand single grain loose

24 0007 1 auger no Oi 0 50 5YR 2.5/2 sd plant material massive soft24 0008 1 sml pit no L -3 0 10YR 2/2 litter massive loose

2 sml pit no C 0 80 10YR 8/1 sand single grain loose 5.03 auger no Oi 80 100 10YR 2/1 peat massive soft

24 0009 1 sml pit no L 0 3 10YR 2/2 litter massive loose2 sml pit no C 3 60 10YR 8/1 sand single grain v fiable 3.03 auger no Oi 60 100 5YR 2.5/2 peat massive soft 3.6

29 0001 1 sml pit no A 0 10 10YR 2/1 clay loam mod f subang blocky loose2 sml pit no A 10 20 10YR 2/1 clay loam mod f subang blocky friable3 sml pit no Bg1 20 50 10YR 5/2 clay massive firm4 auger no Bg2 50 80 10YR 5/1 clay 30% f Fe concentrations massive firm5 auger no Bg3 80 150 10YR 4/1 peaty clay massive firm6 auger no Cg 150 200 10YR 5/1 peaty clay massive soft

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist


Upper Lower29 0002 1 sml pit no A 0 15 10YR 2/1 clay loam weak m cloddy friable

2 sml pit no Bg 15 80 10YR 3/2 clay 10% f Fe concentrations massive firm3 auger no Bg 80 120 10YR 4/1 peaty clay massive firm4 auger no Cg 120 200 10YR 5/1 clay massive soft

29 0003 1 sml pit no A 0 10 10YR 2/1 clay loam weak m cloddy friable 4.62 sml pit no Bg1 10 50 10YR 3/1 clay massive firm 4.63 auger no Bg2 50 90 10YR 3/1 clay 20% f Fe concentrations massive firm4 auger no Bg3 90 150 10YR 4/1 clay massive soft 4.75 auger no Cg 150 200 10YR 4/1 clay massive soft 4.6

29 0004 1 sml pit yes A 0 5 10YR 2/2 clay loam mod f subang blocky friable 4.22 sml pit yes ABg 5 20 10YR 2/2 clay loam 20% c Fe concentrations 7.5YR 5/6 mod f subang blocky firm3 sml pit yes Btg 20 70 10YR 3/2 clay 40% m Fe concentrations 7.5YR 5/6 massive firm 3.94 auger no Bt 70 160 10YR 3/2 clay massive firm 3.75 auger no BC 160 200 10YR 3/2 clay massive v firm 4.2

Layerno.



type)


pH

Observ-ation

method

Horizon depth (cm)

Lab-oratory

data

Soil colour- moist

Layer Description abbreviations for Table A2

Layer no. P Whole profile observation – layers not recorded

Observation Method sml pit small pit

Texture vf very fine f fine c coarse sd slighty decomposed md moderately decomposed hd highly decomposed

Redoximorphic features (size) f fine m medium c coarse vc very coarse xc extremely coarse

Structure (development) mod moderate

Structure (size) vf very fine f fine m medium c coarse vc very coarse xc extremely coarse

Structure (type) ang angular subang subangular

Consistence s slightly v very x extremely


Table A3.1: Results of laboratory analyses for soil samples – EC, pH, organic C, N, S, reduced inorganic S (RIS) and titratable actual acidity (TAA). EC and pH of samples with high organic matter contents (marked *) were measured on a 1:5 extract.

ADA Site Layer Upper Lower E.C. pH pH Δ pH Total Total Total RIS TAAno. no. depth depth (1:2.5 soil:water) (1M KCl) pHH2O - Org.C N S (SCr)

cm cm dS/m pHKCl % % % % mol H+ t-1

Betumpu 01 0011 1 0 5 0.94 4.8 4.2 0.6 14.7 0.7001 0011 2 5 20 0.56 4.0 3.4 0.6 16.6 0.65 0.30 0.05 24001 0011 4 30 60 0.69 3.3 3.1 0.2 7.1 0.27 0.31 0.04 26301 0011 5 60 100 0.79 3.3 3.2 0.1 3.3 0.12 0.35 0.15 15301 0011 7 150 180 1.56 3.3 3.2 0.0 2.3 0.08 1.65 1.61 9901 0011 8 180 200 1.51 3.3 3.3 0.0 1.8 0.06 0.96 0.98 98

Betumpu 01 0012 1 0 5 0.37 3.8 3.3 0.4 16.4 0.6001 0012 2 5 20 0.53 3.5 3.1 0.4 10.5 0.38

Betumpu 01 0013 2 1 5 1.13 3.0 2.8 0.3 14.0 0.43 0.32 0.03 14601 0013 3 5 20 0.41 3.2 2.9 0.4 14.8 0.41 0.26 0.03 18301 0013 5 30 45 0.98 3.3 3.0 0.2 7.5 0.24 0.49 0.07 31001 0013 7 50 150 2.64 3.0 2.9 0.1 2.8 0.09 1.51 1.34 19001 0013 8 150 200 1.69 3.7 3.4 0.3 1.5 0.06 1.50 1.40 64

Betumpu 01 0015 1 0 5 0.81 0.12 29401 0015 2 5 20 0.40 3.2 2.6 0.6 0.92 0.31 29801 0015 5 50 80 1.70 0.01 34801 0015 6 80 150 4.12 1.65 75801 0015 7 150 200 4.15 3.44 738

Betumpu 01 0016 1 0 5 0.84 3.3 3.0 0.3 16.3 0.80 0.31 0.04 37401 0016 3 10 30 0.59 3.4 3.2 0.2 6.4 0.26 0.21 0.03 26401 0016 4 30 50 0.71 3.3 3.0 0.3 5.2 0.22 0.27 0.04 27701 0016 5 50 70 0.42 3.5 3.3 0.2 2.6 0.11 0.16 0.03 13001 0016 6 70 100 1.89 3.1 3.0 0.1 1.8 0.08 1.55 1.50 16401 0016 8 130 175 2.05 3.0 2.9 0.1 1.0 0.04 1.33 1.24 87

Si Tukak, Limau Manis A&B 03 0002 1 0 30 0.54 3.6 3.4 0.2 19.2 0.8303 0002 2 30 60 1.03 3.7 3.6 0.2 6.3 0.2203 0002 3 60 100 5.66 3.1 3.0 0.0 12.1 0.33

Lumapas 05 0004 1 0 10 1.67 5.3 5.0 0.3 17.9 1.4605 0004 2 10 30 0.30 3.9 3.3 0.6 21.2 1.3805 0004 3 30 110 1.35 3.7 3.3 0.4 18.8 0.93

Lumapas 05 0005 1 0 10 0.24 4.6 3.6 1.0 12.8 1.0505 0005 2 10 30 0.21 4.5 3.5 1.0 13.1 1.0805 0005 3 30 110 0.84 3.7 3.1 0.6 10.5 0.49

Limpaki 06 0002 2 5 10 0.93 3.1 2.9 0.2 14.1 0.32 1.15 0.27 41806 0002 3 10 40 1.03 3.1 2.9 0.3 13.9 0.30 1.12 0.23 38406 0002 5 80 180 8.61 2.5 2.4 0.2 10.8 0.21 4.44 3.34 60806 0002 6 180 200 6.89 2.8 2.6 0.2 6.9 0.19


ADA Site Layer Upper Lower E.C. pH pH Δ pH Total Total Total RIS TAAno. no. depth depth (1:2.5 soil:water) (1M KCl) pHH2O - Org.C N S (SCr)

cm cm dS/m pHKCl % % % % mol H+ t-1

Wasan 08 0003 3 10 20 1.62 3.6 3.3 0.4 5.1 0.30Wasan 08 0004 4 50 80 0.58 4.6 3.8 0.8 0.15 0.06 116

08 0004 5 80 90 0.20 0.03 17808 0004 6 90 110 0.27 0.05 240

Wasan 08 0012 2 0 5 0.43 4.2 3.4 0.7 4.5 0.3608 0012 3 5 20 0.21 4.4 3.4 1.0 3.4 0.29

Wasan 08 0015 2 0 5 0.30 4.4 3.6 0.8 3.2 0.3208 0015 3 5 40 0.15 4.8 3.5 1.3 1.4 0.1608 0015 4 40 90 0.29 4.4 3.3 1.1 1.0 0.15

Tungku 09 0015 1 0 10 1.51 2.8 2.7 0.2 0.3 <0.02 0.13 <0.005 20409 0015 3 30 50 0.49 3.5 3.3 0.2 0.2 <0.02 0.04 <0.005 4909 0015 4 50 60 0.54 3.6 3.4 0.2 0.3 0.03 0.04 <0.005 72

Merangking, Bukit Sawat 21 0007 2 0 5 * 0.37 * 3.9 * 3.2 * 0.6 25.4 1.2421 0007 3 5 15 0.18 4.0 3.2 0.7 11.8 0.5321 0007 4 15 30 0.27 3.5 3.0 0.6 24.1 0.8621 0007 5 30 50 48.1 1.4621 0007 6 50 60 * 0.80 * 3.5 54.5 1.3021 0007 7 60 80 * 1.22 * 3.6 * 3.0 * 0.6 59.3 1.0421 0007 8 80 120 * 1.23 * 3.7 * 3.1 * 0.6 55.7 1.6921 0007 9 120 170 46.5 1.4721 0007 10 170 190 24.1 0.6721 0007 11 190 250 47.7 0.74

Merangking, Bukit Sawat 21 0010 1 0 30 0.17 3.8 3.3 0.5 18.5 0.93Melayan A 22 0002 2 10 20 0.07 4.1 3.5 0.6 1.0 0.05

22 0002 3 20 70 0.02 4.8 4.3 0.5 0.1 <0.0222 0002 6 130 200 0.33 3.7 3.3 0.4 24.5 0.59

Labi Lama 23 0001 1 0 5 1.43 6.2 5.9 0.3 14.6 1.0623 0001 2 5 30 * 0.31 * 4.8 * 4.0 * 0.8 23.7 1.1323 0001 3 30 60 0.30 3.7 3.1 0.6 4.8 0.2423 0001 5 70 110 * 1.00 * 3.5 * 3.3 * 0.3 43.9 1.0123 0001 6 110 200 * 2.20 * 3.2 * 3.0 * 0.2 46.6 0.98

Labi Lama 23 0004 1 0 10 0.26 3.7 3.2 0.5 24.2 1.1223 0004 2 10 20 * 0.45 * 3.7 * 3.3 * 0.4 40.4 1.6623 0004 4 30 40 * 0.30 * 3.7 * 3.3 * 0.4 28.2 0.6623 0004 6 70 150 0.13 3.9 3.7 0.1 0.4 <0.02

Pengkalan Batu 29 0004 1 0 5 0.43 5.0 4.1 0.8 6.4 0.4929 0004 2 5 20 0.44 4.7 3.8 0.9 5.8 0.4429 0004 3 20 70 0.19 4.1 3.4 0.8 2.8 0.17


Table A3.2: Results of laboratory analyses for soil samples (exchangeable cations, Al and Mn). ADA Site Layer Upper Lower E.C.E.C. Exch. Al

no. no. depth depth Ca Mg Na K Total Al Mn percentcm cm

Betumpu 01 0011 1 0 5 2.9 2.1 0.16 0.89 6.1 7.2 1.00 0.06 1401 0011 2 5 20 1.4 1.0 0.21 1.14 3.8 10.0 6.20 0.03 6201 0011 4 30 60 1.0 0.7 0.13 0.20 2.0 14.3 12.23 <0.01 8601 0011 5 60 100 0.8 0.5 0.06 0.12 1.5 7.8 6.35 <0.01 8101 0011 7 150 180 0.9 0.6 0.09 0.09 1.7 6.5 4.78 <0.01 7401 0011 8 180 200 0.9 0.6 0.13 0.08 1.7 5.7 3.91 <0.01 69

Betumpu 01 0012 1 0 5 2.3 1.0 0.26 0.47 4.0 14.9 10.87 0.03 7301 0012 2 5 20 0.2 0.7 0.27 0.27 1.5 16.5 15.04 0.01 91

Betumpu 01 0013 2 1 5 0.5 0.7 0.11 0.23 1.5 5.2 3.64 <0.01 7001 0013 3 5 20 0.3 0.3 0.08 0.10 0.8 5.3 4.50 <0.01 8401 0013 5 30 45 0.9 1.4 0.13 0.21 2.6 14.7 12.07 0.02 8201 0013 7 50 150 1.2 1.1 <0.05 0.12 2.4 11.2 8.76 0.05 7801 0013 8 150 200 1.5 2.5 0.20 0.11 4.2 5.4 1.15 0.03 21

Betumpu 01 0015 1 0 5 2.7 1.5 0.38 0.54 5.1 9.4 4.27 0.03 4601 0015 2 5 20 0.6 0.8 0.25 0.37 2.0 6.7 4.77 0.01 7101 0015 5 50 80 0.9 1.2 0.32 0.34 2.7 15.0 12.23 0.01 8201 0015 6 80 150 1.0 0.6 0.28 0.23 2.1 41.1 38.91 0.03 9501 0015 7 150 200 6.9 5.6 0.55 0.21 13.3 55.8 42.43 0.09 76

Betumpu 01 0016 1 0 5 0.8 0.6 0.20 0.28 1.8 12.3 10.48 0.01 8501 0016 3 10 30 0.4 0.2 0.09 0.17 0.9 14.4 13.52 <0.01 9401 0016 4 30 50 0.3 0.5 0.15 0.17 1.1 11.1 10.00 <0.01 9001 0016 5 50 70 0.6 0.3 0.05 0.13 1.1 6.7 5.65 <0.01 8401 0016 6 70 100 0.6 0.5 <0.05 0.12 1.2 8.8 7.58 0.02 8601 0016 8 130 175 0.7 0.8 0.07 0.06 1.6 4.2 2.63 0.03 62

Si Tukak, Limau Manis A&B 03 0002 1 0 30 0.7 0.8 0.20 0.16 1.9 11.7 9.73 0.04 8303 0002 2 30 60 0.8 1.5 0.18 0.14 2.6 6.6 3.97 0.06 6003 0002 3 60 100 1.2 1.7 0.21 0.13 3.3 24.0 20.60 0.10 86

Lumapas 05 0004 1 0 10 28.2 5.3 0.69 4.92 39.1 39.4 0.09 0.15 005 0004 2 10 30 2.8 1.2 0.14 0.60 4.8 20.0 15.21 0.07 7605 0004 3 30 110 3.9 4.7 0.42 0.56 9.6 19.6 9.78 0.15 50

Lumapas 05 0005 1 0 10 15.9 2.0 0.06 0.99 19.0 23.1 3.91 0.15 1705 0005 2 10 30 11.9 1.9 0.11 0.85 14.8 21.7 6.84 0.09 3205 0005 3 30 110 4.8 4.7 0.34 0.73 10.5 16.8 6.19 0.11 37

Limpaki 06 0002 2 5 10 0.3 1.1 0.45 0.15 2.1 17.9 15.81 0.02 8806 0002 3 10 40 0.3 1.2 0.39 0.15 2.0 18.9 16.81 0.02 8906 0002 5 80 180 3.0 5.5 0.42 <0.05 8.9 36.2 26.94 0.29 7406 0002 6 180 200 5.8 10.4 0.67 0.18 17.0 25.0 7.78 0.19 31

I---------------- Exch.Cations NH4OAc pH 7.0 ----------------I 1M KCl ext

I--------------------------------------- cmol(+)/kg ---------------------------------------I cmol(+)/kg


ADA Site Layer Upper Lower E.C.E.C. Exch. Alno. no. depth depth Ca Mg Na K Total Al Mn percent

cm cmWasan 08 0003 3 10 20 4.0 5.5 0.43 0.35 10.3 15.4 5.03 0.12 33Wasan 08 0004 4 50 80 8.3 4.5 0.46 0.23 13.5 15.1 1.48 0.12 10

08 0004 5 80 90 2.4 3.1 0.45 0.25 6.2 10.8 4.57 0.06 4208 0004 6 90 110 1.9 3.1 0.50 0.19 5.7 14.5 8.70 0.06 60

Wasan 08 0012 2 0 5 2.2 2.9 0.52 0.27 5.9 10.5 4.59 0.06 4408 0012 3 5 20 1.8 2.6 0.59 0.25 5.2 9.9 4.60 0.07 47

Wasan 08 0015 2 0 5 1.4 2.9 0.50 0.43 5.2 9.2 3.79 0.12 4108 0015 3 5 40 1.1 2.8 0.70 0.24 4.9 9.1 4.11 0.10 4508 0015 4 40 90 0.9 4.9 1.16 0.30 7.3 12.1 4.72 0.08 39

Tungku 09 0015 1 0 10 0.1 0.4 0.15 <0.05 0.6 0.609 0015 3 30 50 0.2 0.3 0.31 <0.05 0.9 3.3 2.44 0.01 7409 0015 4 50 60 0.3 0.6 0.17 0.09 1.1 6.0 4.89 0.02 81

Merangking, Bukit Sawat 21 0007 2 0 5 1.3 1.9 0.09 0.83 4.1 14.4 10.17 0.13 7121 0007 3 5 15 0.5 0.7 <0.05 0.21 1.4 10.3 8.86 0.02 8621 0007 4 15 30 0.8 1.3 0.05 0.25 2.3 25.7 23.28 0.06 9121 0007 5 30 50 3.7 2.3 0.05 0.26 6.3 20.2 13.74 0.14 6821 0007 6 50 60 4.8 4.3 0.11 0.10 9.3 22.6 12.92 0.33 5721 0007 7 60 80 3.5 6.3 <0.05 0.11 10.0 10.021 0007 8 80 120 2.6 7.8 0.52 0.14 11.1 11.121 0007 9 120 170 2.2 7.6 0.16 0.32 10.2 20.0 9.54 0.30 4821 0007 10 170 190 2.4 6.6 0.18 0.36 9.5 9.521 0007 11 190 250 2.8 4.4 0.06 0.17 7.5 18.2 10.52 0.19 58

Merangking, Bukit Sawat 21 0010 1 0 30 <0.1 0.9 0.11 0.33 1.4 24.1 22.66 0.03 94Melayan A 22 0002 2 10 20 0.1 0.1 0.31 0.08 0.6 1.7 1.07 <0.01 63

22 0002 3 20 70 <0.1 <0.1 0.35 <0.05 0.5 1.0 0.52 <0.01 5122 0002 6 130 200 0.1 0.3 0.28 0.07 0.8 8.4 7.56 0.01 90

Labi Lama 23 0001 1 0 5 29.1 10.3 0.40 4.65 44.5 44.6 0.02 0.06 023 0001 2 5 30 16.4 3.7 0.23 2.40 22.7 24.8 1.89 0.13 823 0001 3 30 60 1.4 1.2 0.28 1.09 4.0 13.5 9.43 0.06 7023 0001 5 70 110 5.4 4.7 0.60 1.34 12.1 22.3 9.70 0.50 4423 0001 6 110 200 3.4 4.0 0.64 0.53 8.5 8.5

Labi Lama 23 0004 1 0 10 1.0 0.6 <0.05 0.57 2.2 18.9 16.63 0.06 8823 0004 2 10 20 0.6 0.6 <0.05 0.63 1.9 19.9 18.03 0.05 9023 0004 4 30 40 0.6 0.5 0.22 0.88 2.2 18.2 15.96 0.04 8723 0004 6 70 150 0.1 <0.1 0.14 0.05 0.4 0.7 0.34 <0.01 49

Pengkalan Batu 29 0004 1 0 5 10.9 2.3 0.27 1.13 14.6 15.2 0.44 0.17 329 0004 2 5 20 10.8 2.0 0.23 0.88 13.9 15.5 1.48 0.14 1029 0004 3 20 70 2.3 0.6 0.06 0.32 3.2 15.0 11.76 0.02 78

I---------------- Exch.Cations NH4OAc pH 7.0 ----------------I 1M KCl ext

I--------------------------------------- cmol(+)/kg ---------------------------------------I cmol(+)/kg


Table A4: Results for laboratory analyses of selected soluble salts in soil samples. Sox: Oxidised S (see Section 2.3.1)

ADA Site Layer Upper Lower 1:40 KCl ext Cl:Sno. no. depth depth Sox Cl

cm cm % % mg kg-1 mg kg-1

Betumpu 01 0011 1 0 501 0011 2 5 20 0.043 0.016 162 70.5 0.4301 0011 4 30 60 0.046 0.024 241 48.9 0.2001 0011 5 60 100 0.060 0.030 297 26.9 0.0901 0011 7 150 180 0.170 0.075 750 23.5 0.0301 0011 8 180 200 0.170 0.070 703 180.4 0.26

Betumpu 01 0012 1 0 5 0.016 155 62.2 0.4001 0012 2 5 20 0.015 152 31.8 0.21

Betumpu 01 0013 2 1 5 0.070 0.048 485 40.2 0.0801 0013 3 5 20 0.032 0.021 214 24.0 0.1101 0013 5 30 45 0.059 0.038 382 35.0 0.0901 0013 7 50 150 0.31001 0013 8 150 200 0.150

Betumpu 01 0015 1 0 5 0.05401 0015 2 5 20 0.04001 0015 5 50 80 0.07401 0015 6 80 150 0.55001 0015 7 150 200 0.740

Betumpu 01 0016 1 0 5 0.088 0.028 277 34.8 0.1301 0016 3 10 30 0.028 0.015 149 46.5 0.3101 0016 4 30 50 0.044 0.022 225 45.5 0.2001 0016 5 50 70 0.019 0.011 107 22.2 0.2101 0016 6 70 100 0.220 0.127 1268 20.7 0.0201 0016 8 130 175 0.180 1.124 11238 42.4 0.00

Si Tukak, Limau Manis A&B 03 0002 1 0 30 0.023 231 13.3 0.0603 0002 2 30 60 0.040 399 6.4 0.0203 0002 3 60 100 0.419 4191 14.7 0.00

Lumapas 05 0004 1 0 1005 0004 2 10 3005 0004 3 30 110

Lumapas 05 0005 1 0 10 0.008 81 47.4 0.5905 0005 2 10 30 0.006 62 27.7 0.4505 0005 3 30 110 0.026 264 32.5 0.12

Limpaki 06 0002 2 5 10 0.120 0.062 620 56.0 0.0906 0002 3 10 40 0.084 0.052 524 30.1 0.0606 0002 5 80 180 0.910 0.858 8578 89.4 0.0106 0002 6 180 200 0.361 3611 109.1 0.03

Saturation extractSox (seawater=21)


ADA Site Layer Upper Lower 1:40 KCl ext Cl:Sno. no. depth depth Sox Cl

cm cm % % mg kg-1 mg kg-1

Wasan 08 0003 3 10 20 0.069 687 57.2 0.08Wasan 08 0004 4 50 80 0.035

08 0004 5 80 90 0.02408 0004 6 90 110 0.035

Wasan 08 0012 2 0 5 0.012 117 4.4 0.0408 0012 3 5 20 0.005 46 37.9 0.83

Wasan 08 0015 2 0 5 0.008 75 21.3 0.2808 0015 3 5 40 0.003 27 21.1 0.7808 0015 4 40 90 0.010 103 10.0 0.10

Tungku 09 0015 1 0 10 0.01009 0015 3 30 50 0.03209 0015 4 50 60 0.036

Merangking, Bukit Sawat 21 0007 2 0 521 0007 3 5 1521 0007 4 15 3021 0007 5 30 5021 0007 6 50 6021 0007 7 60 8021 0007 8 80 12021 0007 9 120 17021 0007 10 170 19021 0007 11 190 250

Merangking, Bukit Sawat 21 0010 1 0 30Melayan A 22 0002 2 10 20

22 0002 3 20 7022 0002 6 130 200

Labi Lama 23 0001 1 0 523 0001 2 5 3023 0001 3 30 6023 0001 5 70 11023 0001 6 110 200

Labi Lama 23 0004 1 0 1023 0004 2 10 2023 0004 4 30 4023 0004 6 70 150

Pengkalan Batu 29 0004 1 0 529 0004 2 5 2029 0004 3 20 70

Saturation extractSox (seawater=21)


Table A5: Acid base accounting. (* When pH1:2.5 <5.0 then ANC=0). ADA Site Layer Upper Lower Est. bulk TAA AGP ANC*

no. no. depth depth density (RIS)cm cm t m-3 mol H+ t-1 kg t-1 t ha-1 kg t-1 t ha-1 kg t-1 t ha-1

Betumpu 01 0011 1 0 501 0011 2 5 20 0.8 240 29 0 18 20 2 2 20 2301 0011 4 30 60 1.1 263 25 0 20 63 2 6 22 6901 0011 5 60 100 1.3 153 95 0 11 61 7 38 19 10001 0011 7 150 180 1.5 99 1004 0 7 33 75 333 83 36601 0011 8 180 200 1.6 98 612 0 7 23 46 144 53 167

Betumpu 01 0012 1 0 501 0012 2 5 20

Betumpu 01 0013 2 1 5 0.8 146 19 0 11 3.6 1 1 12 401 0013 3 5 20 0.8 183 21 0 14 16 2 2 15 1801 0013 5 30 45 1 310 46 0 23 36 3 5 27 4201 0013 7 50 150 1.4 190 836 0 14 199 63 874 77 107301 0013 8 150 200 1.6 64 873 0 5 39 65 535 70 574

Betumpu 01 0015 1 0 5 0.4 294 72 0 22 4 5 1 27 4.901 0015 2 5 20 0.4 298 192 0 22 14 14 9 37 2201 0015 5 50 80 0.5 348 6 0 26 40 0 1 27 4101 0015 6 80 150 0.6 758 1029 0 57 249 77 339 134 58901 0015 7 150 200 0.6 738 2146 0 55 166 161 484 216 650

Betumpu 01 0016 1 0 5 0.8 374 23 0 28 11 2 1 30 1101 0016 3 10 30 1.1 264 19 0 20 44 2 3 21 4701 0016 4 30 50 1.2 277 22 0 21 49 2 4 22 5301 0016 5 50 70 1.4 130 19 0 10 28 1 4 11 3201 0016 6 70 100 1.6 164 936 0 12 58 70 328 82 38601 0016 8 130 175 1.8 87 773 0 7 51 58 458 64 509

Si Tukak, Limau Manis A&B 03 0002 1 0 3003 0002 2 30 6003 0002 3 60 100

Lumapas 05 0004 1 0 1005 0004 2 10 3005 0004 3 30 110

Lumapas 05 0005 1 0 1005 0005 2 10 3005 0005 3 30 110

Limpaki 06 0002 2 5 10 0.8 418 168 0 31 13 13 5 44 1806 0002 3 10 40 0.8 384 143 0 29 71 11 27 40 9706 0002 5 80 180 0.9 608 2083 0 46 416 156 1423 202 183906 0002 6 180 200

Lime (CaCO3) equivalents (including 1.5 factor)TAA AGP Net acidity


ADA Site Layer Upper Lower Est. bulk TAA AGP ANC*no. no. depth depth density (RIS)

cm cm t m-3 mol H+ t-1 kg t-1 t ha-1 kg t-1 t ha-1 kg t-1 t ha-1

Wasan 08 0003 3 10 20Wasan 08 0004 4 50 80 2 116 39 0 9 53 3 18 12 71

08 0004 5 80 90 2 178 18 0 13 27 1 3 15 3008 0004 6 90 110 2 240 30 0 18 73 2 9 20 82

Wasan 08 0012 2 0 508 0012 3 5 20

Wasan 08 0015 2 0 508 0015 3 5 4008 0015 4 40 90

Tungku 09 0015 1 0 10 2.2 204 0 0 15 34 0 0 15 3409 0015 3 30 50 2.4 49 0 0 4 18 0 0 3.7 1809 0015 4 50 60 2.3 72 0 0 5 12 0 0 5.4 12

Merangking, Bukit Sawat 21 0007 2 0 521 0007 3 5 1521 0007 4 15 3021 0007 5 30 5021 0007 6 50 6021 0007 7 60 8021 0007 8 80 12021 0007 9 120 17021 0007 10 170 19021 0007 11 190 250

Merangking, Bukit Sawat 21 0010 1 0 30Melayan A 22 0002 2 10 20

22 0002 3 20 7022 0002 6 130 200

Labi Lama 23 0001 1 0 523 0001 2 5 3023 0001 3 30 6023 0001 5 70 11023 0001 6 110 200

Labi Lama 23 0004 1 0 1023 0004 2 10 2023 0004 4 30 4023 0004 6 70 150

Pengkalan Batu 29 0004 1 0 529 0004 2 5 2029 0004 3 20 70

Lime (CaCO3) equivalents (including 1.5 factor)TAA AGP Net acidity


Table A6: Trace metal analyses ADA Site Layer Upper Lower

no. no. depth depth Cu Zn As Cdcm cm mg kg-1 mg kg-1 mg kg-1 mg kg-1

Betumpu 01 0011 1 0 5 <0.1 1.4 11.3 0.301 0011 2 5 20 <0.1 0.9 13.5 <0.201 0011 4 30 60 <0.1 0.8 3.9 0.501 0011 5 60 100 0.9 2.0 8.8 <0.201 0011 7 150 180 1.1 27.101 0011 8 180 200 2.5 87.7

Betumpu 01 0012 1 0 5 <0.1 0.801 0012 2 5 20 <0.1 0.5

Betumpu 01 0013 2 1 5 <0.1 1.001 0013 3 5 20 <0.1 1.801 0013 5 30 45 <0.1 2.101 0013 7 50 150 <0.1 11.301 0013 8 150 200 0.1 8.5

Betumpu 01 0015 1 0 501 0015 2 5 20 <0.1 1.601 0015 5 50 8001 0015 6 80 150 <0.1 16.501 0015 7 150 200 <0.1 21.1

Betumpu 01 0016 1 0 5 <0.1 1.101 0016 3 10 30 <0.1 0.801 0016 4 30 50 <0.1 1.101 0016 5 50 70 <0.1 1.701 0016 6 70 100 <0.1 9.101 0016 8 130 175 <0.1 7.5

Si Tukak, Limau Manis A&B 03 0002 1 0 30 0.1 0.903 0002 2 30 60 <0.1 0.203 0002 3 60 100 <0.1 5.5

Lumapas 05 0004 1 0 10 0.2 24.3 12.4 0.205 0004 2 10 30 <0.1 1.8 19.3 <0.205 0004 3 30 110

Lumapas 05 0005 1 0 10 <0.1 6.905 0005 2 10 30 1.2 1.105 0005 3 30 110 <0.1 7.2

Limpaki 06 0002 2 5 10 <0.1 1.306 0002 3 10 40 <0.1 1.4 10.3 0.206 0002 5 80 180 <0.1 28.6 20.4 0.406 0002 6 180 200

DTPA ext


ADA Site Layer Upper Lowerno. no. depth depth Cu Zn As Cd

cm cm mg kg-1 mg kg-1 mg kg-1 mg kg-1

Wasan 08 0003 3 10 20 <0.1 1.6Wasan 08 0004 4 50 80 <0.1 0.3

08 0004 5 80 9008 0004 6 90 110

Wasan 08 0012 2 0 5 <0.1 0.808 0012 3 5 20 <0.1 0.3

Wasan 08 0015 2 0 5 <0.1 0.408 0015 3 5 40 0.8 0.808 0015 4 40 90 0.8 0.6

Tungku 09 0015 1 0 10 0.1 2.409 0015 3 30 50 0.6 1.209 0015 4 50 60 0.7 2.0

Merangking, Bukit Sawat 21 0007 2 0 5 0.1 2.221 0007 3 5 15 <0.1 0.621 0007 4 15 30 <0.1 3.121 0007 5 30 5021 0007 6 50 6021 0007 7 60 8021 0007 8 80 12021 0007 9 120 17021 0007 10 170 19021 0007 11 190 250

Merangking, Bukit Sawat 21 0010 1 0 30 <0.1 0.8Melayan A 22 0002 2 10 20 <0.1 0.2 1.1 <0.2

22 0002 3 20 70 0.1 <0.1 0.7 <0.222 0002 6 130 200 <0.1 0.6

Labi Lama 23 0001 1 0 5 11.0 32.1 20.0 1.823 0001 2 5 30 1.6 7.1 17.3 0.423 0001 3 30 60 0.2 3.3 4.8 <0.223 0001 5 70 11023 0001 6 110 200

Labi Lama 23 0004 1 0 10 <0.1 0.623 0004 2 10 20 <0.1 0.923 0004 4 30 40 0.6 2.623 0004 6 70 150 <0.1 0.4

Pengkalan Batu 29 0004 1 0 5 4.5 19.4 8.2 0.529 0004 2 5 20 2.6 15.6 10.1 <0.229 0004 3 20 70 0.1 1.4

DTPA ext


Table A7: Mineralogical composition of bulk samples, <2 µm (clay) and 63-200 µm fractions.

ADA Site Layer Upper Lowerno. no. depth depth

cm cmBetumpu 01 0011 4 30 60 CD T T - T T CD T - M D - T

01 0011 5 60 100 D T T - T T SD ?T - M D T -Betumpu 01 0016 5 50 70 D T T - T T SD M - M D T -Lumapas 05 0005 3 30 110 M T ?T - ?T M D M - SD D M -Limpaki 06 0002 3 10 40 CD T T - T T CD - - M D - -

06 0002 5 80 180 CD T ?T M ?T M CD M - M D M -Wasan 08 0003 3 10 20 CD T - T T M CD M - M D T -Tungku 09 0015 3 30 50 D - - - - T T T - CD CD CD -

09 0015 4 50 60 D - T - T T T T - CD CD CD -Labi Lama 23 0001 3 30 60 M T T - T SD D SD - D SD M -

ADA Site Layer Upper Lowerno. no. depth depth

cm cmWasan 08 0003 3 10 20 CD T - T ?T T CD M - -Labi Lama 23 0001 3 30 60 D T T - - - - M ?T -

Composition of 63-200 µm fraction

Qua

rtz

Alb

ite

Ort

ho-

clas

e

Pyrit

e

Ana

tase

Kao

lin

Mic

a/Ill

ite

Chl

orite

/Ve

rmi-

culit

e

Smec

tite

Composition of bulk sample Composition of <2µm fraction

Goe

thite

Smec

tite

Goe

thite

Kao

lin

Mic

a/Ill

ite

Chl

orite

/Ve

rmi-

culit

e

Ana

tase

Kao

lin

Mic

a/Ill

ite

Chl

orite

/Ve

rmi-

culit

e

Qua

rtz

Alb

ite

Ort

ho-

clas

e

Pyrit

e

D: dominant (>60%); CD: co-dominant (sum of phases >60%); SD: sub-dominant (20-60%); M: minor (5 20%); T: trace (<5%); ?: possible.


Appendix B: Photographic Reference for Brunei Acid Sulfate Soils


Mineral sulfuric organic soils (Terric Sulfosaprists) (Representative profile) Typical pedon number: 23 0001 Location: UTM grid reference 217900 mE 488237 mN Zone 50 Agricultural Development Area: Labi Lama District: Belait Physiography Slope: <1 degree Slope position: flat of alluvial terrace Water table depth: 60 cm Drainage class: poorly

Morphological Description: Horizon depth

cm Horizon designation

Upper Lower

Soil colour - Moist

Texture class Redoximorphic features Structure - Type Consistence - Rupture

resistance

Reaction (field pH)

Comments

Ap 0 5 7.5YR 3/2 sandy clay loam 0% concentrations firm Oe 5 30 10YR 2/2 mucky peat 0% concentrations friable 2Bg 30 60 10YR 5/1 clay 0% concentrations very firm sulfuric layer 3Oe1 60 70 5YR 2.5/2 peat 0% concentrations soft sulfuric layer 3Oe2 70 110 5YR 2.5/2 peat 0% concentrations soft sulfuric layer 3Oe3 110 200 5YR 2.5/2 peat 0% concentrations soft sulfuric layer

Depth, cm Depth, cm

0 - 5 70 - 110

5 - 30 110 - 200

30 - 60

60 - 70


Sulfuric organic soils (Typic Sulfosaprists) (Representative profile) Typical pedon number: 21 0007 Location: UTM grid reference 232094 mE 502510 mN Zone 50 Agricultural Development Area: Merangking, Bukit Sawat District: Belait Physiography Slope: <1 degree Slope position: flat of alluvial terrace Water table depth: 30 cm Drainage class: poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

L -2 0 10YR 3/2 leaf litter 0% concentrations soft Oe1 0 5 5YR 2.5/1 mucky peat 0% concentrations soft Oe2 5 15 10YR 3/2 mucky peat 0% concentrations soft Oe3 15 30 5YR 2.5/2 mucky peat 0% concentrations soft 3.4 Sulfuric layer Oe4 30 50 5YR 2.5/1 mucky peat 0% concentrations soft 4.2 Sulfidic material? Oe5 50 60 5YR 2.5/1 mucky peat 0% concentrations soft Sulfidic material? Oe6 60 80 5YR 2.5/1 mucky peat 0% concentrations soft 4.5 Sulfidic material? Oe7 80 170 5YR 2.5/1 mucky peat 0% concentrations soft Cg 170 190 10YR 3/2 clay 0% concentrations firm 4.7 2Oe 190 250 5YR 2.5/1 mucky peat 0% concentrations soft 4.7

Depth, cm Depth, cm Depth, cm

-2 - 0 30 - 50 120 - 170

0 - 5 50 - 60 170 - 190

5 - 15 60 - 80 190 - 200

15 - 30 80 - 120 200 - 250


Mineral sulfidic organic soils (Terric Sulfisaprists) (Representative profile) Typical pedon number: 03 0002 Location: UTM grid reference 259490 mE 527277 mN Zone 50 Agricultural Development Area: Si Tukak, Limau Manis A & B District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of alluvial terrace Water table depth: 20 cm Drainage class: poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Oe 0 30 5YR 3/2 peat 0% concentrations soft Be 30 60 10YR 2/2 Clay loam with

moderately decomposed plant material

0% concentrations soft 4.2 Sulfidic material

Bi 60 100 10YR 2/1 slightly decomposed plant material

0% concentrations soft

Depth, cm

0 - 30

30 - 60

60 - 100


Sulfidic organic soils (Typic Sulfisaprists) (Representative profile and acid-base accounting) Typical pedon number: 01 0015 Location: UTM grid reference 262578 mE 535271 mN Zone 50 Agricultural Development Area: Betumpu District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of alluvial terrace Water table depth: 25 cm Drainage class: very poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Ap 0 5 10YR 3/2 sandy clay loam 0% concentrations subangular blocky friable Oi1 5 20 5YR 3/2 peat 0% concentrations subangular blocky friable Oi2 20 30 5YR 3/1 peat 0% concentrations massive very friable Oe1 30 50 5YR 3/1 moderately

decomposed plant material

0% concentrations massive very friable Sulfidic material

Oe2 50 80 5YR 2.5/1 moderately decomposed plant material

0% concentrations massive very friable

Oa 80 150 5YR 2.5/1 highly decomposed plant material

0% concentrations massive firm

Bh 150 200 7.5YR 2/0 sandy clay 0% concentrations massive firm


0 - 5 50 - 80 175 - 200

5 - 10 80 - 100

10 - 30 100 - 150

30 - 50 150 - 175


Site Layer Upper Lower E.C. pH Total Total RIS TAA AGP ANC* Net acidityno. no. depth depth (1:2.5 soil:water) Org.C S (SCr)

cm cm dS/m % % %01 0015 1 0 5 0.81 0.12 294 72 0 36601 0015 2 5 20 0.40 3.2 0.92 0.31 298 192 0 49001 0015 3 20 3001 0015 4 30 5001 0015 5 50 80 1.70 0.01 348 6 0 35401 0015 6 80 150 4.12 1.65 758 1029 0 178701 0015 7 150 200 4.15 3.44 738 2146 0 2884

mol H+ t-1

RIS: Reduced inorganic sulphur TAA: Titratable actual acidity AGP: Acid generating potential (calculated from RIS) ANC: Acid neutralising capacity (* When pH1:2.5 <5.0 then ANC=0) Net acidity: TAA + AGP – ANC.


Sulfidic poorly drained cracking clay soils (Sulfic Sulfaquert) (Acid-base accounting) Typical pedon number: 08 0004 Location: UTM grid reference 257351 mE 529835 mN Zone 50 Agricultural Development Area: Wasan District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of alluvial valley Water table depth: 0 cm Drainage class: very poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

A 0 5 10YR 4/2 clay loam massive soft Oa 5 20 5YR 3/1 mucky peat soft Bg 20 50 10YR 4/2 clay massive firm Bg 50 80 10YR 4/1 clay massive firm Bg 80 90 10YR 4/1 clay massive very firm Bg 90 110 10YR 4/1 clay massive very firm BCg 110 120 10YR 4/1 clay massive very firm BCg 120 140 10YR 4/1 clay massive very firm

Depth, cm Depth, cm

0 - 5 80 - 90

5 - 20 90 - 110

20 - 50 110 - 120

50 - 80 120 - 140



cm cm dS/m % % %08 0004 1 0 508 0004 2 5 2008 0004 3 20 5008 0004 4 50 80 0.58 4.6 0.15 0.06 116 39 0 15508 0004 5 80 90 0.20 0.03 178 18 0 19608 0004 6 90 110 0.27 0.05 240 30 0 27008 0004 7 110 12008 0004 8 120 140

mol H+ t-1



Sulfidic poorly drained cracking clay soils (Sulfic Sulfaquerts) (Representative profile) Typical pedon number: 08 0015 Location: UTM grid reference 256988 mE 528736 mN Zone 50 Agricultural Development Area: Wasan District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of alluvial valley Water table depth: 0 cm Drainage class: very poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Oi -10 0 10YR 5/1 slightly decomposed plant material

0% concentrations massive soft

Ap 0 5 10YR 5/1 mucky clay 0% concentrations massive soft Bg1 5 40 10YR 5/1 clay 20% iron concentrations

7.5YR 5/6 massive firm cracks

Bg2 40 90 10YR 5/1 clay 40% iron concentrations 7.5YR 5/6

massive very firm cracks, sulfidic material

BCg 90 160 7.5YR 5/0 clay 0% concentrations massive very firm

Depth, cm Depth, cm

-10 - 0 90 - 160

0 - 5

5 - 40

40 - 90


Acid poorly drained cracking clay soils (Typic Dystraquerts) (Representative profile) Typical pedon number: 08 0012 Location: UTM grid reference 257208 mE 529499 mN Zone 50 Agricultural Development Area: Wasan District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of alluvial valley Water table depth: 5 cm Drainage class: very poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Oi -10 0 10YR 3/2 Slightly decomposed plant material

0% concentrations massive very firm

Ap1 0 5 10YR 3/1 mucky clay 0% concentrations massive soft Ap2 5 20 10YR 3/1 mucky clay 0% concentrations massive soft Bg 20 60 7.5YR 5/0 clay 0% concentrations massive firm BCg 60 100 7.5YR 7/0 clay 0% concentrations massive firm

Depth, cm

-10 - 0

0 - 5

5 - 60

60 - 100


Soft poorly drained sulfuric soils (Hydraquentic Sulfaquepts) (Representative profile and acid-base accounting) Typical pedon number: 09 0015 Location: UTM grid reference 265812 mE 546809 mN Zone 50 Agricultural Development Area: Tungku District: Brunei Muara Physiography Slope: 2 degrees Slope position: flat of alluvial plain Water table depth: 60 cm Drainage class: poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

C1 0 10 10YR 5/3 sand 0% concentrations massive soft 2.6 sulfuric layer C2 10 30 10YR 5/2 loamy sand 0% concentrations massive firm 3.2 sulfuric layer C3 30 50 7.5YR 5/4 loamy sand 0% concentrations massive soft 3.3 sulfuric layer 2Bj 50 60 10YR 4/1 sandy loam 30% iron concentrations

7.5YR 5/6 massive extremely firm 3.3 jarosite?

3BC 60 100 2.5YR 4/8 sandy clay 0% concentrations massive slightly rigid 3.6

Depth, cm Depth, cm

0 - 10 60 - 100

10 - 30

30 - 50

50 - 60



cm cm dS/m % % %09 0015 1 0 10 1.51 2.8 0.3 0.13 <0.005 204 0 0 20409 0015 2 10 3009 0015 3 30 50 0.49 3.5 0.2 0.04 <0.005 49 0 0 4909 0015 4 50 60 0.54 3.6 0.3 0.04 <0.005 72 0 0 7209 0015 5 60 100

mol H+ t-1



Poorly drained sulfuric soils (Typic Sulfaquepts) (Representative profile and acid-base accounting) Typical pedon number: 01 0011 Location: UTM grid reference 262695 mE 536079 mN Zone 50 Agricultural Development Area: Betumpu District: Brunei Muara Selapon Selapon Physiography Slope: <1 degree Slope position: flat of alluvial plain Water table depth: 80 cm Drainage class: poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Ap1 0 5 10YR 5/2 clay loam 0% concentrations subangular blocky friable 5.2 Ap2 5 20 10YR 5/2 clay loam 5% iron concentrations

7.5YR 5/8 subangular blocky firm

B 20 30 10YR 5/2 clay loam 5% iron concentrations 7.5YR 5/8

subangular blocky firm

2Oab 30 60 10YR 2/2 highly decomposed plant material, clay

0% concentrations subangular blocky very friable sulfuric layer

2Oeb 60 100 10YR 3/2 moderately decomposed plant material, clay

0% concentrations massive firm 3.5 sulfuric layer

2Bg1 & 2 100 180 10YR 3/1 sandy clay loam 0% concentrations massive firm 2Bg3 180 200 10YR 5/1 sandy clay loam 0% concentrations massive very firm

Depth, cm Depth, cm Depth, cm0 - 5 85 - 100

Very top layer

30 - 45

100 - 110

5 - 10 110 - 150

10 - 20

45 - 60

150 - 180

20 - 30 60 - 85 180 - 200



cm cm dS/m % % %01 0011 1 0 5 0.94 4.8 14.701 0011 2 5 20 0.56 4.0 16.6 0.30 0.05 240 29 0 26901 0011 3 20 3001 0011 4 30 60 0.69 3.3 7.1 0.31 0.04 263 25 0 28801 0011 5 60 100 0.79 3.3 3.3 0.35 0.15 153 95 0 24801 0011 6 100 15001 0011 7 150 180 1.56 3.3 2.3 1.65 1.61 99 1004 0 110301 0011 8 180 200 1.51 3.3 1.8 0.96 0.98 98 612 0 710

mol H+ t-1



Poorly drained sulfuric soils (Typic Sulfaquepts) (Acid-base accounting) Typical pedon number: 06 0002 Location: UTM grid reference 260129 mE 538067 mN Zone 50 Agricultural Development Area: Limpaki District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of valley Water table depth: 30 cm Drainage class: very poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Oi1 0 5 5YR 3/2 peat massive firm Oi2 5 10 5YR 3/2 peat massive firm 2.8 Oi3 10 40 7.5YR 3/2 peat massive friable 3.2 Oi4 40 80 5YR 4/2 peat massive friable Oe 80 180 7.5YR 3/0 mucky peat massive soft 3.7 Cg 180 200 7.5YR 4/0 clay massive soft

Depth, cm Depth, cm

0 - 5 80 - 180

5 - 10

10 - 40

40 - 80



cm cm dS/m % % %06 0002 1 0 506 0002 2 5 10 0.93 3.1 14.1 1.15 0.27 418 168 0 58606 0002 3 10 40 1.03 3.1 13.9 1.12 0.23 384 143 0 52706 0002 4 40 8006 0002 5 80 180 8.61 2.5 10.8 4.44 3.34 608 2083 0 269106 0002 6 180 200 6.89 2.8 6.9

mol H+ t-1



Soft poorly drained sulfidic soils (Haplic Sulfaquents) (Acid-base accounting) Typical pedon number: 01 0013 Location: UTM grid reference 262681 mE 535418 mN Zone 50 Agricultural Development Area: Betumpu District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of alluvial plain Water table depth: 30 cm Drainage class: poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

L 0 1 litter loose A 1 5 10YR 3/2 sandy loam granular very fiable AB1 5 20 5YR 2.5/1 sandy clay loam subangular blocky friable AB2 20 30 5YR 2.5/1 sandy clay loam subangular blocky friable Oi 30 45 10YR 3/1 peat massive soft Oe 45 50 10YR 3/1 moderately


massive soft sulfidic

Bj 50 150 7.5YR 4/0 sandy clay 2% Fe concentrations 2.5Y 6/6

massive firm

BCgj 150 200 10YR 6/1 sandy clay 5% Fe concentrations 2.5Y 6/6

massive firm 5.8


0 - 1 20 - 30 70 - 95

1 - 5 30 - 45 95 - 130

5 - 10 45 - 50 130 - 150

10 - 20 50 - 70 150 - 170



cm cm dS/m % % %01 0013 1 0 101 0013 2 1 5 1.13 3.0 14.0 0.32 0.03 146 19 0 16501 0013 3 5 20 0.41 3.2 14.8 0.26 0.03 183 21 0 20401 0013 4 20 3001 0013 5 30 45 0.98 3.3 7.5 0.49 0.07 310 46 0 35601 0013 6 45 5001 0013 7 50 150 2.64 3.0 2.8 1.51 1.34 190 836 0 102601 0013 8 150 200 1.69 3.7 1.5 1.50 1.40 64 873 0 937

mol H+ t-1



Soft poorly drained sulfidic soils (Haplic Sulfaquents) (Representative profile and acid-base accounting) Typical pedon number: 01 0016 Location: UTM grid reference 262665 mE 535277 mN Zone 50 Agricultural Development Area: Betumpu District: Brunei Muara Physiography Slope: <1 degree Slope position: flat of alluvial plain Water table depth: 30 cm Drainage class: very poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

A 0 5 10YR 2/1 clay loam 0% concentrations granular loose Oi1 5 10 10YR 2/1 peat 0% concentrations subangular blocky friable Oi2 10 30 10YR 2/1 peat 0% concentrations massive friable Oa 30 50 10YR 3/1 highly


0% concentrations massive firm sulfidic material

Bg1 50 70 10YR 3/1 sandy clay 0% concentrations massive very firm Bg2 70 100 7.5YR 4/0 sandy clay 0% concentrations massive very firm 2Bgj1 100 130 7.5YR 5/0 sandy clay 5% iron concentrations

2.5Y6/6 massive very firm

2Bgj2 130 175 7.5YR 5/0 sandy clay 15% iron concentrations 2.5Y6/6

massive very firm

3C 175 200 10YR 7/1 sandy clay 0% concentrations massive extremely firm


0 - 5 50 - 70 150 - 175

5 - 10 70 - 100 175 - 200

10 - 30 100 - 130

30 - 50 130 - 150



cm cm dS/m % % %01 0016 1 0 5 0.84 3.3 16.3 0.31 0.04 374 23 0 39701 0016 2 5 1001 0016 3 10 30 0.59 3.4 6.4 0.21 0.03 264 19 0 28301 0016 4 30 50 0.71 3.3 5.2 0.27 0.04 277 22 0 29901 0016 5 50 70 0.42 3.5 2.6 0.16 0.03 130 19 0 14901 0016 6 70 100 1.89 3.1 1.8 1.55 1.50 164 936 0 110001 0016 7 100 13001 0016 8 130 175 2.05 3.0 1.0 1.33 1.24 87 773 0 86001 0016 9 175 200

mol H+ t-1



Organic poorly drained sulfidic soils (Thapto-Histic Sulfaquents) (Representative profile) Typical pedon number: 05 0005 Location: UTM grid reference 268610 mE 532792 mN Zone 50 Agricultural Development Area: Lumapas District: Brunei Muara Physiography Slope: 1 degree Slope position: flat of valley Water table depth: 50 cm Drainage class: poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Ap 0 10 10YR 2/1 sandy clay loam 0% concentrations granular firm 4.5 Oa1 10 30 10YR 2/2 peat 0% concentrations massive firm 4.7 Oa2 30 110 10YR 6/2 peat 0% concentrations massive soft 4.6 sulfidic layer Bg 110 180 10YR 6/2 clay 0% concentrations massive soft 5.0 Cg 180 200 7.5YR 4/0 clay 0% concentrations massive soft 5.0

Depth, cm Depth, cm

0 - 10 180 - 200

10 - 30

30 - 110

110 - 180


Organic poorly drained moderately deep sulfidic soils (Sulfic Fluvaquents) (Representative profile) Typical pedon number: 22 0002 Location: UTM grid reference 218722 mE 496418 mN Zone 50 Agricultural Development Area: Melayan A District: Belait Physiography Slope: 2 degrees Slope position: foot slope of valley side Water table depth: 70 cm Drainage class: poorly



Upper Lower

Soil colour - Moist


resistance

Reaction (field pH)

Comments

Oi 0 10 10YR 5/4 leaf litter 0% concentrations loose A 10 20 10YR 3/3 sand 0% concentrations single grain friable 5.8 C 20 70 10YR 7/1 sand 0% concentrations single grain friable 5.7 C 70 110 10YR 7/1 sand 0% concentrations single grain friable sulfidic 2Oab1 110 130 7.5YR 2/1 peat 0% concentrations massive soft 6.0 sulfidic 2Oab2 130 200 7.5YR 2/1 peat 0% concentrations massive soft 5.9 sulfidic

Depth, cm Depth, cm

0 - 10 110 - 130

10 - 20 130 - 200

20 - 70

70 - 110

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