Pertanika 12(1), 59-63 (1989)

Chemical Characterisation of Podzols in Sabah, East Malaysia

MARCUS JOPONY and TAN YI G CHIUFaculty of Science and Natural Resources

Universiti Kebangsaan Malaysia, Sabah Campus88996 Kota Kinabalu, Sabah, Malaysia.

Key words: Podzol; horizon; horizon Rh.

ABSTRAKAnalisis kimia telah dilakukan terhadap tiga sampel podzol dari daerah Tarnbunan dan Keningau, Sabah.pH, kandungan karbon organik, muatan pertukaran kation, amaun kation bolehtukar serta arnaun logamyang terekstrak dengan HC] 1.0 M adalah berbeza antara horizon. Perbezaan tersebut adalah paling ketaraantara horizon E dengan horizon Bh. Kecuali pH, nilai bagi setiap parameter di atas adalah terendah danterting",oi rnasing-rnasing pada horizon E dan Bh.

ABSTRACTChemical analyses were carried out on three podzol samples from the Tambunan and Keningau districts inSabah. The values ofpH, O1ganic carbon content, cation exchange capacity and HCI extractable metals varydistinctly between horizons. Such variation was most significant between horizons E and Bh and except forpH, the values f01- the above parameters were lowest and highest in horizons E and Bh respectively.

INTRODUCTIONPodzols can be found mainly in humid temper-ate and humid tropical areas, particularly inareas where the parent materials are predomi-nantly of quartz or silicious minerals. In Malay-sia, podzols are found in Peninsular Malaysia,Sarawak and Sabah. In Sabah, significant areasoccur in the Tambunan, Keningau and Sipi-tang districts (Acres et al. 1975) The generalcharacteristics of podzols have been well des-cribed (McKeague et al. 1985; Fitzpat-rick 1983; Burnham 1984; Duchau-four 1982; Russell 1973; Muir 1961). Theprofile of a podzol is generally characterised byits clearly defined horizons. An intensively wea-thered bleached (eluvial) horizon, E, is locatedimmediately below the upper horizon A. BelowE is a dark coloured illuvial horizon, Bh, alsoknown as the spodic horizon. A reddish browncoloured hon-zon, Bh/s, is sometimes found inbetween Bh and the parent material (horizonC) .. Podzols are basically differentiated fromother soils by the presence of a spodic horizon.Often the spodic (Bh) horizon is overlain by analbic (E) horizon.

The chemical characteristics of podzolsare widely reported in several works (McKeagueet al. 1985; Torrent and Gomez-Martin 1985;Evans 1982; Forth 1978; Townsend 1977;Mohr et al. 1972; Andriesse 1969;Burnham 1968; Klinge 1965). However, pub-lished chemical data of Malaysian pod~zols isvery limited and confined mainly to podzols inWest Malaysia.

Therefore the following study was carriedout to assess the chemical characteristics ofpodzols in Sabah, East Malaysia. The resultingdata would be a valuable addition to the exist-ing data on podzols in Malaysia and elsewhere.

MATERIALS AND METHODSThe podzol samples were obtained from Ken-ingau (PI and P2) and Tambunan (P3) dis-tricts in Sabah, Malaysia. The soils are of theKapayan Association and Brantian Associationrespectively, both having terrace landform andalluvium paren t material (Acres et al. 1975) .Road construction works currently' going onalong the Kota Kinabalu - Tambunan - Kening-au highway exposed some areas where the soil

MARCUS JOPONY AND TAN VI IG CHIU

was found to be podzols. The podzols at allsampling sites have distinct A, E, Bh, Bh/s andC horizons of varying thickness. Soil sampleswere taken from the respective horizons with-out much difficulty since the sites are locatedalong the highway.

All soil samples were air dried and onlythe < 2mm fractions were used in the chemicalanalyses. All analyses were carried out in dupli-cates. Soil pH was measured in a 1:2 suspensionin distilled water using a pH meter. Organiccarbon was determined according to the Walkley- Black method as described by Nelson andSommers (1982). Cation exchange capacitywas determined by 1.0 M ammonium acetate,and the exchangeable basic cations in theleachate was measured by atomic absorptionspectrophotometry. Exchangeable AI and Hwere extracted with 1.0M KCI (Thomas 1982).The metals Na, K, Mg, Ca, Fe, Mn, Cu and Znwere extracted for two hours using 2.0M HCl(1:20 wIv), and its concentration in the ex-tracts were measured by atomic absorption spec-trophotometry. The extractant was randornlychosen but was expected to remove the relative-ly more soluble fractions of each metal, inclu-ding the exchangeable and a large proportionof the oxide and organic bound fractions. Theamount obtained is presented as HC] - ex-tractable metal.

RESULTS AND DISCUSSIONThe chemical characteristics of the soil samplesare shown in Table 1. Each soil profile consists

of five distinct horizons, namely A, E, Bh, Bhlsand C horizons. All samples show distinctdifferences in chemical characteristics betweeneach horizons, particularly between thebleached (E) and the spodic (Bh) horizons.

The pH distribution of each profile fol-lows a similar general trend. It increases to amaximum at horizon E, deCl'eases to a mini-mum at horizon Bh and then gradually increasesagain at the lower horizons. Unlike ph, per-cent organic carbon decreases significallllv fi'om0.51 - 0.97% in horizon A to 0.05 - O.Ol:i% inhorizon E. It, however, increases significantlyto 1.18 -1.79% in horizon Bh before decreasinggradually in the lower horizons. The lowest andhighest values obtained for horizon E and 8hare in agreement with the observed bleachedand dark colour of the respective horizons. Thiscontrasting levels of organic carbon bet\\'eenthe two horizons has been reported to he dueta mobilization of organic matter from the up-per A horizons during intensive weathering ,1I1dleaching and later deposition in horilOn Bh(McKeague et at. 1985; Fitzpatrick IllW2;Bridge 1982; Russell 1973).

Changes of cation exchange Clp,ICil\(CEC) down the soil profile at all sites alsofallow a similar trend as that of organic carbon.The high and low CEC of horizons Bh ane! Erespectively is likely to be related to the signifi-cant difference in organic carbon content ofthe horizons since the organic componcIlt of asoil is a well known contributor to soil's CEC.The relationship between the CEC of soils ane!

TABLE ISome chemica! characteristics of the respective horizons of the podzol samples PI, P2 and P'I

PI P2 P3Parameter A E Bh Bhs C A E Bh Bhs C A E Eh Blls c:

pH (H2O) 4.8 5.8 3.9 4.3 4.0 4.6 5.J 4.2 4.3 4.3 4.2 4.7 4.0 4.1 4.4

% Organic-C 0.51 0.06 1.79 0.20 0.15 095 0.06 1.18 0.61 0.15 0.97 0.05 1.26 1.05 0.33

Exch. Cations(me/lOOg)

Na 0.46 0.16 0.51 0.36 0.17 0.39 0.14 0.46 0.33 0.15 0.30 0.16 0.4! 0.22 0.18

K 0.04 0.02 0.05 0.04 0.03 0.05 0.01 0.03 0.03 0.05 0.03 0.02 0.07 0.04 0.03

Ca 0.08 0.02 0.06 0.04 0.04 0.08 0.02 0.06 0.06 0.02 0.08 0.02 0.06 0.06 0.04

Mg 0.06 O.OJ 0.06 0.04 0.04 0.06 0.01 0.06 0.04 0.02 0.06 O.OJ 0.06 0.06 0.04

H 0.06 0.03 0.53 0.43 0.40 O.ll 0.03 0.39 0.29 0.39 0.11 0.02 0.52 1.04 0.71Al 0.03 0.03 0.39 0.27 0.24 0.03 0.01 0.27 0.27 0.33 003 0.03 0.42 n.5! n.48

60 PERT.-\l'\lIKA VOL. 121'\0. I, 191;9

CHE\1ICAL CHARACTERISATIO"J OF rODZOLS IN SABAH, EAST tvlAI.AYSIA

Amount ex t r ac ted100 ZOO 300

I i

4:

(a )

wc0N

.s::H CO0::r: H

.s::CO

U

NTh)unt extracted100 200 300 400 500

----y

<(b)

w

c0 ,-N asH H0 ......::r:

iiiu

ATIOunt extracted1 2 3 4

Amount extracted0.2 0.4 0.6 0.8 1.0

[..l..1

~'(C)C ')vo0N .s::H CO0::r: H......

---.s:: 10/ NhlCOU

Amount extracted1.0 2.0

caN

Ha

:r:

(d)

wc0N .s::...... COHa H::r: ......

---.s::o:J

euu

Fig. I: HCi·extractable basic cations, Fe, Mn, C1I and Zn (in ug/g)for podzol sam/lies Pi (0 - 0), P2 (0 - 0) and P3 (!J -0)

PERTANIKA VOL. 12 NO.1, 1989

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MARCUS JOPONY AND TAN VING CHIU

its organic carbon content is well described else-where (Brady 1984; Stevenson 1982; Sch-nitzer and Khan 1972). Differences in mine-ralogical characteristics could also be a possiblefactor. The amount of each individual ex-changeable basic cation is less than 0.5 mellOOg and is generally of the order Na » Ca MgK. Exchangeable acidic cations meanwhile is ofthe order H > AL. The distribution of theseexchangeable cations within the profile followa similar general pattern as that of the organiccarbon, and CEC significant differences in levelsof exchangeable Hand AL are observed forhorizons E and Bh. This could be a possible ex-planation for the higher acidity of horizon Bhcompared to horizon E. Apart from direct con-tribution from the exchangeable H, the ex-changeable AL is capable of undergoing hy-drolysis in soil solution to produce hydrogenions (Brady 1984; Russell 1973; Sanchez1972). The net result could therefore be a highconcentration of hydrogen ions in the soilsolution and thus higher acidity.

The amount of HCI-extractable Na, K, Mgand Ca is relatively higher than the amountexchangeable but follow a similar distributionpattern within the soil profile. A plot of the sumof HCI-extractable Na, K, Ca and Mg againstsoil horizon is shown in Figure 1, clearly indicat-ing a significant difference between horizon Eand Bh with respect to HCI- extractable basiccations. A similar distribution pattern for HCI-extractable Fe, Mn, Zn and Cu was also observ-ed for all podzol samples (Figure 1). These re-sults generally indicate that cations or metalshave been depleted from horizon E and accu-mulated in horizon Bh.

Various hypothesis have been proposedfor the distinct differences in chemical charac-teristics, particularly in metal and organiccarbon contents between horizon E and hori-zon Bh. One such hypothesis was related toorganic matter (McKeague et al. 1985). Sol-uble humic substances, particularly fulvic acid,produced by microbial attack on plant litter areleached down the soil profile as rain percolate.Due to its acidic nature, these organic substancesare thought to be capable of causing the break-down of soil minerals (including clay minerals)by disrupting the mineral structure and releas-

ing the component elements. The released ele-lllents then form soluble complexes (chelates)with the humic subtance and are removed fromthe surface horizons as the solutions percolatedownwards. The humic substance could com-plex with additional metal cations as it perco-late downwards and becomes increasingly satu-rated with metal cations. Its solubility decreaseswi th increasing metal saturation and finally be-comes insoluble and is precipitated as it reacheshorizon Bh. As a result, deposition of organiclllatter as well as metal cations take place inhorizon Bh after being leached down from theupper horizons.

CONCLUSIONThis study showes that the podzol samples haveprofile chemical characteristics similar to mostof the podzols described in the literature.Marked maxima of organic carbon, cation ex-change capacity, exchangeable cations andextractable Na, K, Ca, Mg, Fe, Mn, Cu and Zn(in this case, extracted with 2.0m HCI) occurin the Bh horizon relative to the other hori-zons.

ACKNOWLEDGEMENTThe authors wish to extend their thanks to Mrs.Elizabeth Ginsos for typing this manuscript, andto UKMS and the Lab technicians of JabatanKimia FSSA for their technical support.

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ANDRIESSE,j.P. 1969. A Study of the Environmentand Characteristics of Tropical Podzols in Sara-wak (East Malaysia). Geoderma 2: 210-227.

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CHEMICAL CHARACTERlSATION OF PODZOLS It SABAH, EAST MALAYSIA

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KUNCE, H. 1965. Podzo! Soils in the AmazonBasin. j. Soil Sci. 16: 95-103.

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(Received 10 Novembn; 1988)

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