morphology, mineralogy and chemistry of an ex-mining land ... papers/pert vol... · mineral dominan...

Pertanika 9(1), 89-97 (1986)

Morphology, Mineralogy and Chemistry of an Ex-Mining Landin Ipoh, Perak

J. SHAMSHUDDIN, NIK MOKHTAR and S. PARAMANANTHANDepartment of Soil Science,

Faculty of Agriculture,Universiti Pertanian Malaysia,

43400 Serdang, Selangor, Malaysia.

Key words: Sandy deposits; slime; organic matter; morphology; mineralogy.

ABSTRAK

Satu kajian telah dijalankan untuk mencirikan 20.3 ha tanah bekas lombong di Kg. KepayangBaru, Ipoh. Keputusan kajian menunjukkan tanah bekas lombong itu boleh dikelaskan kepada tigakumpulan iaitu endapan berpasir, endapan berlempung dan campuran berpasir dan berlempung.Kandungan bes, karbon organik, fosforus and nitrogen didapati sangat rendah. KPKjuga rendah,tetapipH tanah sangat tinggi. Mineral dominan di dalam bahagian lempung ialah kaolinit, mika danklorit.

ABSTRACT

A study was carried out to characterize the 20.3 ha of ex-mining land at Kg. Kepayang Baru,Ipoh. The study shows that the ex-mining land can be classified into three groups i.e., sandy, clayeyand a mixture of sandy and clayey deposits. The bases, organic carbon, phosphorus and nitrogen con-tents are very low. The cation exchange capacity is low, but pH is very high. The dominant mineralsin the clay fraction are kaolinite, mica and chlorite.

INTRODUCTION

Active tin mining in Malaysia took place inthe late nineteenth century, immediately afterthe British colonization of the Malay Peninsulahad begun. As a result of about 100 years ofmining, the country is now left with over 200,000ha of ex-mining land. The largest concentrationof these abandoned mines occur in the vicinity ofIpoh and Kuala Lumpur. The lands often havesandy deposits, clayey deposits and areas withmixtures of the two often with mining poolsinterpersed throughout the area.

Mining activities have been cited to causedestruction of plants and animals, shallowing ofriver bed, siltation of drainage system and de-struction of agricultural land. The ex-miningland, usually referred to as tin-tailing areas, are

known to have low water holding capacity, highhydraulic conductivity, low nutrient status andpoor structural stability (Lim et ai, 1981). Insome areas, in particular in the vicinity ofDengkil, Selangor, the pH is very low with valuesof 2.8 - 3.0 (Maesschalck and Lim, 1978). If themining areas are underlain by limestone, the pHcould rise to 7 or more. The soils are also limitedby high soil surface temperatures, which can goup to as high as 45°C on a hot sunny day (Maeneetai, 1978).

A typical ex-mining land consists of pond(sometime very deep) surrounded by sand and amixture of silt and clay deposits usually referredto as slime (Fig. I). There can also be areaswhere slime and sand occur together. It is thisseparation of sand and slime that limits the soilsfor crop production because they are either too

J. SHAMSHUDDIN, NIK MOKHTAR AND S. PARAMANANTHAN

LEGEND

Sand tailings

Mixture of sand and slime

Slime

Lake

Ipoh(8km)

Fig. 1: A soil map of ex-mining land at Kg. Kepayang Baru, Ipoh

sandy or too clayey. In either case, soil structuraldevelopment is very slow or none.

Research into the application of varioustypes of organic materials to ameliorate tin-tail-ings and trials on the suitability of various typesof legumes have been carried out (Lim et ai,1981). It is reported that these soils have poten-tial for crop production if properly managed. Assuch some of the tin tailings in the vicinity ofKuala Lumpur and Ipoh are intensively culti-vated for vegetable and fruit production (Tanand Khoo, 1981). The farmers in the areas useorganic manures and sprinkler irrigation to growtheir crops.

The objective of this paper is to characterizethe ex-mining land at Kg. Kepayang Baru, Ipohmorphologically, mineralogically and chemical-ly and to relate these properties to managementpractices for crop production. Some of the dataavailable in this paper might be useful to soilscientist, agronomists, agricultural planners andgeologists, as very little work to characterizethese deposits have been reported.

MATERIALS AND METHODS

The area under consideration is situatedabout 8 km south of Ipoh, roughly at longitude101° 10' E and latitude 4° 32' N, in an areaknown as Kinta Valley. Kinta Valley is wellknown throughout the world for her rich placertin deposits. The valley is surrounded by acidpluton of Carboniferrous age (Gobbett, 1972) tothe east and west. The alluvial deposits, whichare mainly derived from the granitic mountains,are underlain by limestone of Upper Paleozoicage. Tin deposits are found in the alluvialmaterials overlying the limestone.

About 20.3 ha (50 acres) of ex-mining landat Kg. Kepayang Baru, 8 km from Ipoh havebeen set aside by the Department of Agriculture,Perak for agricultural research by the staff ofSoil Science Department, Universiti PertanianMalaysia. The area was identified and subse-quently surveyed in detail, and a soil map wasprepared (Fig. 1). The four mapping unitsshown in Fig. 1 describe the textural propertiesof the tin-tailings and their geographical distri-

90 PERTANIKA VOL. 9 NO. 1, 1986

MORPHOLOGY, MINERALOGY AND CHEMISTRY OF AN EX-MINING LAND IN IPOH, PERAK

bution. The Arabic numerals (1, 2, 3 .... 8)inthe map indicate the observation points wheresamples were examined and collected.

At the observation points of interest, a set ofdata were compiled and these are given in Table1. The data in Table 1 are presented in the formof a formula: —

1.2-3.45.6

where,

1 = texture at 25 — 50 cm depth2 = profile development3 = colour at 25 - 50 cm depth4 * drainage5 = surface texture6 = soil depth

This is actually a modified version of theField Legend (Paramananthan, 1978) in which

parent material and terrain class are not takeninto account.

Samples were collected by an auger at threedepths, namely 0 - 1 5 , 15 -30 and 3 0 - 4 5 cm.These samples were air-dried, ground and sievedto pass through a 2 mm sieve. Analysis for tex-ture, pH (H2O), bases, CEC (NH4 OAc), P, C,N, Fe2O3and micronutrients (Zn, Mn, Cu) byaqua regia were subsequently carried out. pH ,which is an important soil chemical parameter,was determined by the method of Gillman andUehara (1980). Total Na, K, Mgf Al, Mn, Feand heavy metals (As, Dy, V, Co, Sb, Cr, U)were determined by nuclear activation analysis(NAA) using facilities available at Unit TenagaNuklear (Puspati), Bangi. The pH of water inthe ponds was also determined.

The type of minerals present in the clayfraction was identified by X-ray diffraction(XRD) analysis. A complementary study bytransmission electron microscopy (TEM) to iden-tify clay minerals was also carried out.

TABLE 1Morphological properties of ex-mining land at Kg. Kepayang Baru, Ipoh

SITE(Sample No.)

1

2

3

4

5

6

7

8

SOIL PROPERTIES (January 1985)

Sandy loam • Entisol — 10 YR 5/6 • Poorly drainedSand • Deep

Clay loam • Entisol — 5 YR 5/6 • Well drainedLoan • Deep

5*7ty loam • Entisol — 10YR3/6 • Watertable 50 cmClay loam • Deep

Sand • Entisol — 10YR4/4 • Watertable 60 cmFlat Silty Clay • Deep

Sand • Entisol — 10 YR 5/6 • Well drained% Sand • Deep

Sand • Entisol — 5 YR 5/6 (Mottle 2. 5 YR 5/8) • Well drainedSand • Deep

Silty clay • Entisol — 5 YR 5/6 (Mottle 10 YR 6/6) • Watertable 50 cmSilty Clay • Deep

Clay • Entisol — 10 YR 4/6 • Well drainedClay • Deep

PERTANIKA VOL. 9 NO. 1, 1985 91


RESULTS AND DISCUSSION

Morphology

Morphologically, there is no profile deve-lopment in the tin-tailings as a whole, as suchhorizon differentiation is non-existent. This isbecause the deposits are young and therefore notmuch affected by soil forming processes, as themine ceased operation only about 10 years ago.These soils could thus be classified as Entisols.

Generally, the sandy deposits occur in thewell drained areas, while the slimes occur in thedepressions, where the watertable varies from50-60 cm depth. During the rainy season thewatertable in the depressions could rise to thesurface and cause flooding.

The clayey materials appear to be reddish,with colour notation of SYR 5/6 or redder, couldbe due to leaching of some iron-rich materials.In some areas, the textural composition changeswith depth, especially at sites 3 and 4. At site 4(see map), the top 30 cm of the deposits areclayey, but at 30 — 45 cm they are sandy with asand content of more than 95%. At best, we candescribe the texture of tin-tailings as variableboth vertically and horizontally.

Physical Properties

The textural distribution with depth of thestudied samples is given in Table 2. Taking thecase of the sandy deposits (sites 1, 5 and 6), it isnoted that the sand content is very high withvalues exceeding 90%. This condition results in

TABLE2Textural and Selected Elemental Composition

SITE(SAMPLE)

NO.

1

2

3

4

5

6

7

DEPTH(cm)

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

TEXTURE(

Sand

94.290.357.5

58.872.531.2

27.15.0

60.8

13.516.695.6

97.997.395.5

97.796.595.4

3.52.7

12.8

Silt

1.54.2

27.7

17.414.130.4

35.082.526.2

35.132.1

1.9

0.9

1.23.7

1.01.52.3

43.421.541.2

%)

Clay

1.93.1

13.3

16.87.8

31.5

27.610.87.7

43.443.3

1.1

0.70.61.0

0.30.61.1

44.671.440.8

Na

0.09—

0.08

0.06—

0.07

0.07—

0.09

TOTAL ANALYSIS ('

K

1.12—1.10

0.49—

0.51

0.80—1.12

Mg

2.23—

0.87

—

—

0.22

1.38—

2.23

Al

14.20—

8.78

2.25—

2.25

16.50—

14.20

%)

Mn

0.26—

0.10

0.14—

0.17

0.12—

0.26

Fe

1.65—

3.11

1.63—

1.90

5.25—

6.03



excessive draining and intensive leaching ofbases in the soil, and these will be reflected in thelow CEC and bases, given in Table 3. Thepresence of too much sand in particular soil willslow down the process of soil structure develop-ment and as such the soil will retain a single-grain structure unless remedial steps are under-taken quickly.

The slimes, however, are subjected to adifferent set of conditions. The clay content isquite high, with values exceeding 40% in somecases (sites 4 and 7). Currently, the structure israther massive, but in time to come the structuremay develop, especially if organic matter is pre-sent. The development of structure is possible inthe presence of clay, silt and sand in a favourableratio.

Chemical Properties

Table 3 summarizes the chemical propertiesof the studied soils. Regardless of the texturalcomposition, the bases are very low, except forCa + + in some parts of the soil profile at sites 2and 4. In terms of total elemental composition,there appears to be a high amount of K, Mg andAl (Table 2). The high amounts of K and Mgcan be accounted by the presence of mica andchlorite respectively (Fig. 2). Likewise, total Al ispresent in high amounts because it is one of thebasic chemical constituents of mica, kaoliniteand chlorite.

Organic carbon and nitrogen are far toolow compared to normal soils under Malaysianconditions. This is somewhat related to the

TABLE 3Chemical properties of ex-mining land at Kg. Kepayang Baru, Ipoh

SAMPLE

1

2

3

4

5

6

7

DEPTH(cm)

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

BASES (meq/lOOg

Na +

0.130.140.10

0.120.100.11

0.110.150.18

0.990.170.17

0.110.190.17

0.160.090.11

0.090.120.11

K +

0.030.030.05

0.040.050.05

0.080.040.04

0.050.060.03

0.020.030.03

0.020.020.02

0.110.050.06

C a + +

0.710.891.38

6.091.834.26

5.632.782.41

0.285.041.07

0.660.880.45

0.470.470.50

3.994.563.67

soil)

Mg + +

0.190.370.59

1.200.541.34

1.780.830.77

0.911.600.38

0.270.370.41

0.270.320.31

1.151.251.23

P(ppm)

2.586.29L99

13.846.244.24

14.194.625.07

6.374.004.24

1.873.293.88

1.282.232.70

3.414.952.11

C(%)

0.340.150.30

1.860.240.39

0.380.090.30

0.21trtr

0.370.300.03

trtrtr

0.520.280.39

N

(%)

0.020.010.02

0.040.200.03

5.060.040.02

0.020.010.01

0.010.020.02

0.020.030.01

0.020.020.03

Fep,(%)

1.291.932.57

2.641.506.69

7.653.573.74

5.987.521.50

2.121.501.66

1.311.661.45

5427.066.90

P H(H2O)

7.307.196.40

7.206.957.05

5.707.657.74

7.557.698.22

6.538.087.98

7.898.018.01

6.326.636.53

p H ( )

5.755.903.50

5.804.254.65

4.105.805.30

4.^04.155.60

4.004.504.50

4.455.205.10

2.552.752.85

CECmeq/100 g

1.201.402.00

6.902.905.80

2.905.50

7.506.601.00

1.001.001.00

1.201.101.30

7.807.506.10



3.57

3.25

Glycol

Fig. 2: X-ray diffractograms of the clay fraction ofsoil sampled at site 7

recent nature of the deposits which have justbeen exposed by the mining operation. Incor-poration of organic manure (cow dung) and/oragricultural waste from the factory (POME) isconsidered essential to improve the organicmatter content of the soils. In so doing, soilstructure development is encouraged and morenutrients are added. Also noticeable in thechemical properties is the lack of phosphorus inthe soil. P fertilization is a necessity in theamelioration of these soils.

Generally, the pH of these soils is high withvalues of 6 or more. In some areas (sites 4, 5 and6) the pH is more than 8 (Table 3). The high pHvalues is possibly due to the influence of the lime-stone which underlies the deposits. The pH ofwater in the mining ponds is even higher; thevalue is 8.8. In contrast to the pH of tin-tailingsin Dengkil, Selangor, where the pH was reportedto be 2.8 - 3.0 (Maesschalck and Lim, 1978), thetin-tailings of Kg. Kepayang Baru, Ipoh arebetter because the problem of acidity does notarise. In fact the pH is a little bit too high, whichmay reduce the availability of the most micro-nutrients. This rather high pH can easily beovercome by using acid producing fertilizerssuch as (NH4) 2SO4 . Continuous application of(NH4) 2SO4can lower the pH to a more favour-

able level for crop growth. When pH is in theregion of 6.0, Al precipitate as Al(OH) 3 and istherefore rendered unavailable. Although totalAl appears to be a dominant element in the soils(Table 2), it does not cause problems as it existsas a mineral component and is therefore notavailable to plants.

pH9is much lower than the soil pH indicat-ing that the soils are net negatively charged(Uehara and Gillman, 1980). T h e p H o value islowest in the soils at site 7 (Table 3). This lowvalue (< 3) is consistent with the recent stage ofweathering of the soils where mica and chloritestill exist. The sandy deposits register highervalues probably because of the coating of thesand by gibbsite, similar to what has beenreported by Shamshuddin and Tessens (1985).However, gibbsite is poorly manifested on theXRD diffractogram because it was removedfrom clay sample during deferrification bydithionite.

The CEC is low in this soils even for soilswith more than 50% clay content. The value atsites 1, 5 and 6 is 2 meq/100 g soil or less. This isrelated to the mineralogy, in which kaolinite,mica and chlorite are found to be dominant inthe clay fraction. The CEC of these soils canprobably be improved somewhat by incorporat-ing organic matter into the soil.

The total micronutrients (Zn, Mn, Cu)determined by aqua regia in the soils studied aregiven in Table 4. Zinc and copper content aremoderately high. But this does not necessarilymean that they are available to the plants as thesoil pH is very high. Manganese content is excep-tionally high regardless of the textural composi-tion, comparable to soils derived from serpen-tinite reported by Paramananthan (1977). TheMn content in Table 4 obtained by aqua regiaare comparable to the values obtained by NAAin Table 2. Manganese exists as impurities inlimestone and on weathering it accumulates inthe soils. As the pH is high, Mn toxicity will notbe a problem. This manganese probably exists asMnO2.


MORPHOLOGY, MINERALOGY AND CHEMISTRY OF AN EX MINING LAND IN IPOH, PERAK

TABLE4Total micronutrient in the ex-mining land at Kg. Kepayang Baru, Ipoh

SAMPLE

1

2

3

4

5

6

7

DEPTH(cm)

0 - 1 515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

0-1515-3030-45

Zn

30.6061.1775.89

101.2762.00

135.73

129.0687.0186.18

169.07159.0753.97

44.2150.8856.72

42.8239.7740.32

115.11125.67177.90

MICRONUTRIENT (ppm)

Mn

505.341779.401637.00

1480.40797.15

1501.80

2597.012327.402455.40

2355.902135.201399.30

1227.801227.801575.90

925,301419,901149.50

953.701622.802227.00

Cu

9.5312.7824.12

22.8314.4043.58

37.0923.4814.40

46.8241.9613.60

9.8610.8310.18

10.519.219.53

34.8238.7247.79

Table 5 gives heavy metal content of soils at and V remain to be known. Cobalt content issite 1, 6 and 7 at 0 — 15 cm and 30 — 45 cm found to be lower than those found in the seden -depth. Heavy metals of interest which are known tary soils of Peninsular Malaysia as reported byto affect plants and/or humans are As, Co and Paramananthan (1977). Furthermore, Co isCr. The influence of others, such as Dy, V, Sb rendered less available by the high pH. Cr is high

TABLESHeavy metal in the ex-mining land at Kg. Kepayang Baru, Ipoh

SAMPLE(Site)

1

6

7

DEPTH(cm)

0-1530-45

0-1530-45

0-1530-45

As

67.2298.3

139.8256.9

337,2389.8

Dy

5.361.03

6.438.03

13.014.7

HEAVY

V

17.855.2

24.943.2

167.5152.0

METAL

Co

5.4710.32

7.115.85

14.9022.60

(ppm)

Sb

0.690.99

0.610.47

2.171.96

Cr

39.10-

10.369.45

134.70158.50

U

5.5717.40

5.378.41

20.1019.40



at site 7, but low in the sandy soils (sites 1, 6).Sedentary soils with similar amounts of Cr giverise to toxicity problems in rubber, as reportedby Law (1968).

Mineralogical Properties

The clay fraction at site 7 (slime) from thetextural analysis was deferrified and X-rayed.XRD diffractograms for Mg, glycol, K andheated samples are given in Fig. 2. A Mg saturat-ed sample gave reflections at 14A, 10A, 7.2A,5.0A, 4.85A, 4.75A, 4.25A, 3.57A, 3.35A and3.25A. The 14A, 7.2A and 4.75A indicate thepresence of chlorite. This is confirmed by thepresence of 14A reflection in the heated samples.The chlorite appears to be relatively unweather-ed as there is no 16 A reflection in the glycolatedsample. The 16A reflection would indicate thepresence of chlorite-mixed layers.

Otherminerals which are present in largeamounts are mica (10A, 5.0A, 3.35A) andkaolinite (7.2A, 3.57A), shown by their veryprominent peaks. The exact amounts of theminerals were not determined. Quartz (4.25A),gibbsite (4.85A) and feldspar (3.25A) arepresent in small amounts. Like chlorite micaappears to be relatively fresh as there is no in-dication of the presence of mica-mixed layers.Mica-mixed layers are shown by the presence ofXRD reflection between 10 - 14A in Mg saturat-ed sample. This peak either remains undisturbedor expands to 14.A on glycolation. Part of thispeak collapses to 10 A on K saturation.

There are also some halloysite in the soil asshown by TEM. Halloysite is tubular in shape,while kaolinite is hexagonal (Plate 1). Theamount of halloysite is less than kaolinite if onerefers to the TEM micrographs (Plate 1b).

General Discussion

It is clear that the soils of the ex-miningland of Kg. Kepayang Baru, Ipoh can be sub-divided into three types namely the sandytailings, the slime and the mixture of sandytailings and slime. The textural composition israther similar to those reported by Lim et ai,

Plate 1: TEM micrographs of the clay mineralsshowing kaolinite (hexagonal) andhalloysite tubular (a x 16,5000, b x27,500)

(1981) and Tan and Khoo (1981) in other placesin the country. From the point of view of soilformation, the sandy deposits do not retainwater, are poorly structured and lack horizona-tion. On the other hand, hydraulic conductivityis low in the slime.

Incorporation of organic materials into thetailings will increase the organic matter content,thereby increasing water holding capacity, en-couraging microbial activities, increasing theCEC and improving the rate of soil formation.Decomposition of the organic materials releasesa substantial amount of nutrients into the soil.



Application of organic manures or palm oil-milleffluents (POME) over a period of time leads toan accumulation of organic matter content inthe Ap horizon.

POME cake has been reported (Zulkifli andShamshuddin, 1985) to increase soil CEC anddecrease soil pH . Lowering of pH results in theincrease of the net negative charge of the soil(Uehara and Gillman, 1980). POME, with anannual production of around 8 million ton (Tan,1983) is a potential organic material foramelioration of tin-tailings.

Inorganic fertilizers should also be used tosupplement nutrients supplied by the organicmanures. In the case of tin-tailings of Kg.Kepayang Baru, the use of (NH4) 2SO4is recom-mended as a source of nitrogen. Continuousapplication of (NH4) £O 4 lower soil pH to amore favourable level. The present pH of morethan 7 in some areas can cause micronutrientdeficiency.

CONCLUSION

The ex-mining land of Kg. Kapayang Baru,Ipoh can be classified into sandy, clayey (slime)and a mixture of sandy and clayey deposits. Thesandy deposit occurs in the well drained areas,while the slime occurs in the poorly drainedareas. These soils contain low amounts of bases,phosphorus, nitrogen and organic carbon. ThepH is high and the CEC is low. High pH reducesthe availability of micronutrients to plants.Mineralogically, the clay fractions are dominat-ed by kaolinite, mica and chlorite. There are nomica or chlorite mixed-layers.

ACKNOWLEDGEMENTS

The authors wish to record their gratitudeto Universiti Pertanian Malaysia for financialsupport, Department of Agriculture Perak forgiving permission to use the ex-mining land atKg. Kepayang Baru, Ipoh for this study andUnit Tenaga Nuklear (Puspati) for allowing theuse of NAA facilities.

REFERENCES

GILLMAN, G.P. and UEHARA, G. (1980): Chargecharacteristics of soils with variable and perma-nent charge minerals: 11. Experimental. Soil Set.Soc. Am. J. 44: 2 5 2 - 255.

GOBBETT, D.J. (1972): Geological Map of the MalayPeninsula. GeoL Soc. Malays. Kuala Lumpur.

LAW, W.M. (1968): Reconnaissance Soil Survey of theRaub-Temerloh-Jerantut Area of NorthwestPahang. Malayan Soil Survey Report No. 1/1968.Ministry of Agriculture, Kuala Lumpur.

LIM, K.H., MAENE, L.M., MAESSCHALCK, G.G. andWAN SULAIMAN, W.H. (1981): Reclamation ofTin Tailings for Agriculture in Malaysia. Tech.Bull. Faculty of Agriculture, UPM.

MAESSCHALCK, G.G. and LIM, K.H. (1978): The effectof organic waste materials, fertilization andmulching on the physical properties and yield ofmungbean on tin-tailings. Paper presented atWorkshop on Research and Activities of SoilScience Department, UPM, Serdang.

MAENE, L.M., CONNOR, C L . and YAACOB, O. (1978):Food production on tin-tailings in the SeriKembangan — Balakong area, Malaysia. In:Food and Agriculture Malaysia 2000. Chin, H.F.,Enoch, I.C. and Wan Mohamed, W O . (Edi.).Faculty of Agriculture, UPM, Serdang.

PARAMANANTHAN, S. (1977): Soil Genesis on Igneousand Metamorphic Rocks in Malaysia. D.Sc.Thesis, RUG., Ghent, Belgium.

PARAMANANTHAN, S. (1978): Draft Field Legend inSoil Survey in Malaysia. Cawangan Tanah danAnalisa, Jabatan Pertanian Semenanjung Malay-sia, Kuala Lumpur.

SHAMSHUDDIN, J. and TESSENS, E. (1985): Some T^

terrace soils of Peninsular Malaysia: 111. Surfacecharge. Pertanika 8(2): 169 - 179.

TAN, W.H. and KHOO, S.H. (1981): The utilizationof ex-mining land in Peninsular Malaysia.Malays. Geo. 3: 36 - 46.

TAN, K.P. (1983): Land application of d igged palmoil mill effluents to mature oil palm on inlandsoils — some preliminary results. Proc. Sem. onland Appl. of Palm Oil and Rubb. Fac. Eff. Lim,K.H., Abu Talib, B. and Poon, Y.C. (Edi.).MSSS, UPM, Serdang.

ZULKIFLI, A. and SHAMSHUDDIN, J. (1985): The effectof palm oil mill effluents on charge characteristicsof two weathered soils in Peninsular Malaysia.PorimBull. 1 0 : 1 0 - 1 5 .

(Received 10 October, 1985)


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