PertanikaJ. Trop. Agric. Sci. 18(2): (1995) ISSN: Uni"ersiti Pertanian Malaysia Press

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1 PertanikaJ. Trp. gric. Sci. 18(2): (1995) ISSN: Uni"ersiti Pertanian Malaysia Press melirating Effects f Palm Oil Mill Effluent n the Chemical Prperties f Sils and Maize Grwth in Pts J. SHMSHUDDIN, G.G. NG and Z. HMD RUZINI Department f Sil Science, Faculty f g>iculture, Uniuersiti Perlanian Malaysia, Serdang. Selangr, Malaysia Keywrds: acid sils, aluminium, magnesiwn, maize BSTRK Tanah terluluhawa di Malaysia kebanyakkannya berasid, mengandungi tinggi ketepuan l dan nmdah kandungan Ca dan/atau Mg. Satu kajian la-rutiesap dengan menggunakan klum PVC dan kajian berpasu telah dy'ala,nkan untuk mengurangkan ketidaksuburan tanah asid ini dengan penggunaan ejluen kilang kelapa sawit (EKKSJ. Keputusan daripada kajian larutlesap menunjukkan ph, C rgan;k, dan "'lg bertukargant; t.anah atas bertambah dengan bertambahn}'a kadarpenggunaan EKKS. ]agung tumbuh secam terbantut di atas tanah asid tanpa sebarang pembaikan. Berat bandingan tumbuhan alas bertambah dengan berelti dengan bertambahnya ph (Hpj dan Mg bertukarganti. D; sebaliknya, berat bandingan tumhuhan atas berlwrangan secara linear apabilal bertukarganti dan ketepuan l bertambah. Dengan rawatan EKKSpH (H,OJ manakala Mg bertukarganti k,itikal pula ialah 0.5 cml/kg tanah. BSTRCI' Highly weathered Malaysian sils are mstly acidic having high l saturatin and lw Ca and/r l\1g cntents. leaching experiment in PVC clumns and a pt trial were carried ut t alleviate these acid sil infertilities by applicatin f palm il mill effluent (POlvlE). The results f the leaching study shwed that the tpsil ph, rganic C and exchangeable Mg increased with increasing rate fpome applicatin. Maiu grew prl}1 n acidic Malaysian sils withut any amendment. Relative plant tp weight increased significantly as the ph (HpJ and exchangeable Mg increased. On the ther hand, the relative plant tp weight decreased linearly as the exchangeable l and l saturatin increased. With POME treatment, the critical ph (H 2 0) fr maiu grwth was , whereas the critical exchangeable Mg was 0.5 C1IUJl/kg sii INTRODUCTION Highly weathered sils, classified as Ultisls and Oxisls. ccupy an area f abut 72% f Peninsular Malaysia. These acid sils, cntaining variable-eharge minerals, are mainly used fr rubber, cca and il palm cultivatin. In additin t high acidity, the sils have lw CanODexchange capacity (GEG) and high sil slutin I cncentratin. and are usually deficient in Ga and/r Mg (Tessens and Shamshuddin, 1983). These sils have ccasinally been used fr intercrpping with maize and grundnut during immature perid f lubber and il palm replanting. but yields were reprted t be lw due t pr sil fertility, including I txicity and subsil Ca and/r Mg deficiencies (Sharnshuddin et al., 1991) cid sil infertility usually requires limestne applicatin in the plugh layer, but Ca frm the limestne usually remains in the zne f incrpratin (Paven et al., 1984). Depending n the type f crps planted. the recmmended rate f grund magnesium limestne (GML) applicatin fr acid Malaysian sils is usually abut 2 t/ha (Shamshuddin et ai, 1991). Shamshuddin et ai (1992a; 1992b) using pt experiments shwed that I loxicity in these sils culd be vercme t a certain extent by palm il mill eflluent (POME) applicatin. This finding was supprted by a field trial experiment cnducted n a similar sil (Shamshuddin and Sharifuddin, 1993). Raw POME cntaining substantial amunts f N, p. K, Mg and Ca (Hishamuddin et al., 1985) has been fund t

2 J. SHMSHUDDIN, C.C. NG ND Z. HMD RUZlNI increase sil ph and reduce exchangeable I when incrprated int the sil (Shamshuddin et al., 1987), and furthennre it causes minimal pllutin t undergrund water (Zin et al, 1983). Malaysia prduces large quantities fpome annually (Chan et al, 1983); fr every tnne f crude palm il prduced, abut tnnes f POME are discharged by the palm il prcessing mills. The current rate f crude palm il prductin f ver 7 millin tnnes means that mre than 21 millin tnnes f POME are generated annually as prcessing waste water. The bjectives f this study were t determine the effects f land applicatin f POME n the chemical prperties f a Ultisl and an Oxisl in Malaysia, and t determine the respnse f grwth f maize t the changes in the sil prperties. MTERILS ND METHODS Palm Oil Mill Effluent Treated POME used in this study was btained frm an anaerbic panding treaunent system f a palm il mill in Selangr. The POME was mist (misture cntent abut 50%) and had an rganic C f 23%. The ph (H 2 0) was 6.6 and the N, P, SO.' Ca and Mg cntent was 1.9, 0.5, 0.6, 1.8 and 0.3%, respectively. Sils Tw sil series were selected fr the study. The first sil was the Kuala Brang series, belnging t the lamy, mixed family f Typic Hapludult. The ther sil was the Munchng series, belnging t the clayey, kalinitic family ftypic Hapludx. Bth sils are derived frm shale, and are cmmnly used fr cultivatin f rubber. il palm and annual crps. The Kuala Brang sil cntains kalinite and mica with sme smectite in the day fractin, while the ther sil cntains similar minerals but withut smectite. Experimental Design l...eaching experiment in PVC clumns The 1:\\'0 sils were sampled in the field at depth intervals f 15 cm t a depth f 90 cm. They were air-<1ried and grund t pass thrugh a 2 mm sieve. The sils were placed int PVC leaching clumns and carefully repacked accrding t their depths. The experiment cnsisted ffive treatments, ammged in a cmpletely randmized design, with three replicatins. The five treatments were 0, 10, 20 and 40 t POME/ha, and GML applied at 2 t GML/ha as a standard. The POME and GML were apprpriately incrprated int tpsil (0-15 em depth). The sils were watered twice weekly at a rate equivalent t 2100 mm/year. The sils were sampled at the end f 160 days. Pl Experiment ir dried surface sil (0-15 em, < 2 Inm) frm each f the Kuala Brang and Munehng series was mixed with POME. The applicatin rate was 0, 10, 20 and 40 t POME/ ha. n additinal treatment was 2t GML/ha. The respnse f maize (7..ea mays, vadety Thai Super Sweet) t the amelirants was assessed in a glasshuse trial, using a cmplete randmised experimental design, with three replicatins. Pts were filled with 5 kg air.ctried sil and allwed t equilibrate with the amelirants and basic fertilizers (180 kg N/ha as urea, 150 kg P,O,/ha as triple superphsphate and 75 kg K,0/ha as muriate f ptash) fr 30 days prir t the seeding f maize. The plants were "''atered daily with 500 ml HO and grwn fr 40 days, after which they we;e harvested. The water was nt allwed t drain ut f the pt. Plant tp weight and plant height were detennined at the time f hajvcsl. The plant tps were then dried in an ven at 65' '''C and the dry weight recrded. Sil nal)'sis Sil ph in water (w/v 1:1) and CaCl, (1:1) was detennined after 1 h fintermittent shaking and an vernight stand. Basic exchangeable catins were extracted by I M NH.c buffered at ph 7; Ca and Mg were determined by atmic absrptin spectrphtmetry, while K and Na were detelmined by flame phtmeuy. luminium wa~ extracted by I M KCl and determined clolimetrically (Bamhisel and Bertsch, 1982). Free irn xide was determined by the methd f Mehra and Jacksn (1960), while rganic C was estimated by the Walkeley-Black methd (Nelsn and Smmers, 1982). Sil texture was determined by the pipette methd f Day (1965) and the mineralgy f the clay fractin was determined by X-ray diffractin. RESULTS ND DISCUSSION Changes in the Sil Chemical Prperties with Depth The Kuala Brang sil was very acid, having ph (H,O) f<4.5 and exchangeable I f>13 cmij kg sil thrughut the prfile (Table I). Basic 126 PERTNlKJ. TROP. GRIC. SCt. VOL. 18 NO

3 EFFECTS OF PLM OIL MILL EFFLUENT ON CHEMICL PROPERTIES OF SOILS exchangeable bases in the sil were very lw. On the ther hand, Lhe ph (H 2 0) f the Munchng sil was slightly higher than that f the Kuala Brang sil (Table 2). The exchangeable I in the Munchng sil ranged frm 1.9 t 2.4 cmal/ kg sil. The results were cnsistent with the findings f Tessens and Shamshuddin (1983) wh reprted that the ph was lwer and the exchangeable I was higher in the Vltisl (Kuala Brang) cmpared t the Oxisl (Munchng). In the leaching experiment. it was bseived that the tpsil ph (HP) increased significantly TBLE 1 The chemical prperties f Kuala Brang sil series with depth Depth (COl) ph Exchangeable catins O.C Fe\! 0., (eml/kg) (%) (%) H, CaCl, K Na Ca Mg I D tl' tl' 0.1 IT IT 0.1 LI' tl' 0.1 IT IT LI' 0.1 tl' tl' IT 0.1 tl' TBLE 2 The chemical prperties f Munchng sil series with deplh Depth (cm) ph Exchangeable catins O.C Fe\! 03 (cml/kg) (%) (%) H, CaCl, K Na Ca Mg I D tr tl' IT tr tr 0.3 IT tr 0.3 IT wilh increasing rate f POME applicatin (Table 3), which is cnsistent \vith the high ph f the POME itself. Hwever, the tpsil ph (H,O) f bth sils was higher fr the GML than the POME treatments. The rganic C, exchangeable Ca and exchangeable Mg increased significantly with the POME treaunents, which is because the POME cntained significant amunts f rganic matter, Ca and Mg. The percenlage f reductin in the exchangeable l in the Kuala Brang sil arising frm POME applicatin was small. Hwever, treating the Munchng sil with 40 t POME/ha reduced Lhe tpsil exchangeable I frm 2.43 t 1.72 cml/kg sil. The increase in the ph (HP), rganic C and exchangeable Ca nly ccurred in the tpsil where the POME r GML was riginally incrpraled (Table 4). The sils belw the zne fincrpratin appeared t be unaffected by the treatment. This is evident in the ph (H,O) in the cm zne in the Munchng sil, which seems t be hardly changed. The phenmenn f Ca accumulatin in the zne f lime incrpratin was previusly reprted by PERTNIKJ. TROP.CRIC. SCI. VOL. 18NO. 2,

4 J SHMSHUDDIN. C.C. NG ND Z. HMD RUZINI TBLE 3 Changes in the sil ph, rganic C and exchangeable Ca, Mg and l in me tpsil (0-15 em) as affected by POME applicatin n tw sil series Sil Rale ph Organic C Exchangeable catins (1/ha) (H,O) (%) (emljkg) Ca Mg l Kuala Brang t POME 3.75e 1.52e 0.12e 0.02d 13.40a 10 t POME 4.08d 1.86e 0.28d O.lOe 11.80b 20 I POME 4.14c 1.96b 0.3ge 0.13b 1I.00e 40 t POME 4.4lb 2.12a 0.43b 0.16a 9.70d 2 I GML 4.68a 1.63d 1.49a O.lIe 9.40e Mllnchng t POME 4.33e 1.66d O.0ge 0.02d 2.43a 10 I POME 4.32e 2.03b 0.37d 0.0ge 2.19b 20 I POME 4.25e 2.07b 0.50e 0.14b 1.87e 40 I rome 4.46b 2.13a 0.56b 0.16a I.72d 2 I GML 5.12a 1.76e 1.21a O.lOe 0.93e TBLE 4 Changes in the sil ph, rganic C, exchangeable Ca and exchangeable I with depth in the Muchng sil series as affected by POME applicatin POME (t/ha) 40 Depth ph (H,O)' Organic C Exch. Ca* Exch. l* (ern) (%) (ernljkg) (ernljkg) e 1.66a 0.09r 2.43a lIe 1.55b 0.21e 2.18b d 1.0ge 0.31a 1.85e d 1.05d 0.17e 1.85e b 0.84e 0.26b 1.61d a 0.71f 0.19d 1.54e a 2.13a 0.56a 1.72b e 1.54b 0.35b 1.96a IOd 1.02e 0.28e 1.70b e 0.97d 0.24d 1.51e b 0.83e 0.18e 1.51e a 0.75f 0.17e 1.44d '" Fr each POME treattnem, means within a clumn with the same leuer are nt significantly different (P<0.05). Pavan el at. (1984) and Gillman el al (1989). Shamshuddin and Ismail (1995) explained that Ca stayed in lhe zne f lime incrpratin due t negative charge increase when ph increased. The mechanism f Ca retentin in the POME treaunent is similar t that f the lime treatment as explained by Shamshuddin and Ismail (1995). Effeel n Maize Grwth Maize grew prly in the unamended sils, as is shwn clearly by the lw plant tp dry weighl (Table 5). Overall, grwth was better n the Munchng than the Kuala Brang sil; the plant tp dry weight fr the Munchng sil was 1.7 times higher than that n the Kuala Brang sil. 128 PERTNlKJ. TROP. GRlC. SCI. VOL. 18 NO

5 EFFECTS OF PLM OIL MILL EFFLUEI\'T ON CHEMICL PROPERTIES OF SOILS The prer grwth in the Kuala Brang sil was presumably due t the presence f higher exchangeable l (Table 6). The exchangeable l in the Kuala Brang sil remained very high even after POME applicatin. There was little difference in the sil ph (H,O), exchangeable Ca and Mg in either sil type at the time f maize harvest. The difference in plant height with the rreatments fllwed the same trend as the difference f plant tp dry weight. The plant height and the plant tp dry weight in the 2 t GML/ha treatment were cmparable t the 20 t POME/ha treatment fr bth sil types. Shamshuddin and Sharifuddin (1993) fund in a field trial that 20 t POME/ha were needed t prduce a reasnable maize yield grwn n an Ultisl. The imprved plant grwth resulting frm POME treatment was als manifested by increased Mg in the tissue (Table 5). Relatinship between Maize Grwth and Sil ttributes Sil ph The relative plant tp dry weight (Fig. 1) was linearly cn'elated with sil ph (H,O). The regressin line fr the Kuala Brang sil was psitined t the left f the regressin line fr the Munchng sil, indicating that every unit increase in sil ph results in a greater increase in the grwth f maize n the Kuala Brang cmpared with the Munchng sil. This was cnsistent with the greater acidity in the Kuala Brang cmpared with Munchng sil. 10% drp in the relative plant tp dry weight crrespnded t sil ph (H,O) This value was lwer than the critical sil ph fr maize f 4.7 reprted frm a liming trial cnducted n an Ultisl (Shamshuddin et al., 1989). This shws that POME is a gd sil amendlnent which allws maize t grw satifactrily even at a lw sil ph. ~ -: Fig..0. Kul 8rn9 I K91 loo C MU"'/ln9 IMunl Y.. - ~44 0';' 147-0X 0 9~. P<O-Ot IKBJ Y. -!lob O';'13!1 OX r 0'96. P<O 01 IMunJ +----~~'--~---~--- j, 1: Rtlalinship between relative dry weight Q1ld ph (H,O) as affected by POME appticatian n tw sil series TBLE 5 The mean plant lop weight, plant height and tissue Mg as affected by POME treatment n tw sil series Sil series Kuala Brang Treatment Plant tp wt Plant height Tissue Mg (t/ha) (g/pt) (em) (%) t POME t POME t POME t GML LSD Munchng t POME t POME t POME t GML LSD PERTNlKJ. TROP. GRIC. SCI. VOL. 18 NO

6 1- SHMSHUDDIN, C.c. NG ND Z. HMD RUZINI The ph (H 2 0) in the zer treaunent n the Kuala Brang sil was 3.9, crrespnding t the relative plant tp dry weight f 5% (Table 7). In the Munchng sil, the ph (HP) fr the zer treatment was als 3.9, but the relative plant tp dry weight was 20%. The 2 t GML/ha treaunent gave nly 55% f the best grwth. The abslute grwth in this treaunellt was less cmpared with that f the 20 t POME/ha treatment (Table 5). This shws again that POME u eatment imprves the sil cnditin, thus prmting better grwth than the standard lime treatment. Exchangeable Mg Exchangeable Mg in the treated sils ranged frm O. II t 0.58 cml/kg sil, depending n the rate f POME applicatin (Table 6). The increase in the sil exchangeable Mg by POME applicatin resulted in the linear increase f tissue Mg (Fig. 2). The increase in the tissue Mg appeared t be higher in the Kuala Brang than in the Munchng sil Relative plant tp dl]' weight increased linearly as Mg in tissue increased (Fig. 3). The tissue Mg crrespnding t 90% relative plant tp dry weight was abut 0.3%. ~., ~-, (ucic 91C"9 I ' 0', ~ 0' Mu"cn"'l (Mu") r :>618X, r _ 0 64, P<OOl Oi , P <0 01 (Mu'" ><...- r X l--~"'-~-~--~-~-~-,-" 0 I 02 0.: ~ Exeh M9 (CmOlc/k91 '00 80 ~ 60 ;; '0.0. l(ulq B'0fI9 IKB I Mu,,~nO"9 (Mit" I 60.., ~ OX r. 86,P<001 I Mun I 6.., )( r _ 0 91, P<O OI r KB I f'-----c.:-,---c.,,",----;'0,,",---:1 06 nuul!! Mq{Ot.l Fi~. 2: Rl'latinship beltljfell rflative tvig and exchangeable Mf{ as affect.ed b)' POME treatment n tw sil se-d,s Fig. 3: Relatinship between relative dry weight and tissue Mg as affected by POME treatment n tw sil series TBLE 6 The mean sil ph, exchangeable I, Ca and Mg as affected by POME treatment n tw sil series Sil Treatment ph Exchangeable catins series (Vha) (H,O) (cml/kg) I Ca Mg Kuala Brang t POME t POME t POME I t GML LSD Munchng t POME t POME t POME t GML LSD PERTNIKJ. TRap. GRIe. SCI. VOL. 18 NO

7 EFFECTS OF PLM OIL MILL EFFLUENT ON CHEMICL PROPERTIES OF SOILS Relative plant tp dry weight increased when exchangeable Mg increased (Fig. 4). The imprtance f Mg maize nutritin planted n acid sil has been reprted by Shamshuddin el al (1991) and Ismail el at. (1993); where the exchangeable Mg crrespnding t 90% relative lop weight was reprted t be abut 0.9 cml/ kg sil. Hwever, in this study critical exchangeable Mg value was abut 0.5 cml/kg. Hence, POME applicatin tended t reduce the Mg in the sil available fr maize grwth. Exchangeabk t Fig 5. shw5 the relatinship between plant tp dry weight and the exchangeable l. The plant tp dry weight decreased linearly as the exchangeable I increased. The exchangeable l crrespnding t a 10% drp in Lhe relative plant tp weight fr the Kuala Brang and Munchng sils was 9.6 and 1.7 cml/kg 50il, respectively. lthugh the critical exchangeable I,,,-as higher fr the Kuala Brang cmpared with the Munchng sil (Table 5) _The effect f I txicity n maize grwth is clearly shwn in this study. fter amending the sils with POME, maize was able t grw satisfactrily even in the presence f very high cncentratins f exchangeable I (Kuala Brang sil). The reductin in l txicity by POME applicatin can be explained because as the POME cntained high amunts frganic matter (23% rganic C), it is able t bind l thrugh chelatin. Organically bund I bas been shwn t>. Mun,~cnQ (Mlln I 100 [l KlIOl Brent (I<BJ t>. 40. " m Y X-...,. r.. 0 8~,P<0 01 (KBl ""-v _ 205 Ox l 03 i'i'g. 4: Relatinship between relative Mg and exchangeable Mg as affected by POME treatmn!t n tw sil series '0 a EHh , P<O OI IM"nl,.j':_~~d',---~_~ ~_-,-_~ 0' MljIl cmol c I kljll Fig. 5: &latinship between relative dry weight and exchangeablp t as affected by POlHE treatment n tw SQit snil's t be nn-txic (Hue et al, 1986). The I M KCl slutin used in this study fr the extractin f exchangeable I was unable t remve rganically bund l (Oates and Kamprath, 1983). Hence, the exchangeable l repned in this study culd have affected maize grwth. t Saturatin The I saturatin in the zer treatment f the Kuala Brang and Munchng sils was 91 and 70%, respectively (Table 7). The respective relative plant tp weight was 5 and 20%. On a Nigerian Vitisl under 45% l saturatin, 30% relative grwth f maize \'I'aS repned by Friesen el at. (1980), and n a Brazilian Oxisl under 72% I saturatin 48% relative grwth f maize was reprted by Gnzalez-Enric el at. 1979). PERTNlKJ. TROP. CRIC. SCI. VOL. 18 NO.2,

8 J. SHMSHUDDIN, C.C. NG ND Z. HMD RUZINI TBLE 7 The sil ph (H 2 0), I saturatin and relative plant lop dry weight fr the cntrl and GML treatments n tw sil series TreaLment (t GML/ha) 100..: BO ~ 60 Kuala Brang Series '" Kuala 8rng > '" '" ~ Y, '2BX 0: 20 r = 0-84, P<O OI '!- Fig. 6: Relatinship between relative dry weight and exchangeable t saturatin as affected 11)' POME treatment n tw sil serres a ~ 0 75 BO B '" BO 2 2 '" '" "" '" ph (HP) l sat. ReI. dry wt. (%) (%) Munchng "'",'" ~ 60 > y X 0; r ". 0,86, P <0 01 0: Munchng Series '" '" BO I. St. (0/0 ) '" The abve data indicate that maize grwth is affected by l. When I saturatin decreased maize grew better. This is cnsistent with the data presented in Fig. 6, where relative plant tp weight clearly decreased linearly as the I saturatin increased. The critical I saturatin fr the Kuala Brang sil was 82%. and 47% fr Munchng sil. Hwever, the actual grwth was better fr the Munchng than the Kuala Brang sils (Table 5). The fact that maize was able t grw under 80% I saturatin (Kuala Brang) shws that POME is able t reduce I txicity. Evidently, POME has the capability t bind I, thus rendering it nn-txic t the maize. CONCLUSION Tpsil ph. rganic C and exchangeable Mg increased as the rate f POME applicatin increased. Relative plant tp weight increased as the sil ph (H,) and exchangeable Mg increased. On the ther hand, the relative plant tp weight decreased as the exchangeable I and I saturatin increased. With applicatin f POME, the critical ph (H,O) fr maize was whereas critical exchangeable Mg was 0.5 cml/kg sil. Withut amendment maize grws prly n acid Malaysian sils. Palm il mill effluent, available in large quantities in Malaysia, can be used t alleviate the acid sil infertilities. CKNOWLEDGEMENTS The authrs wish t recrd their appreciatin t Universiti Pertanian Malaysia, and Sutheast sia Reginal Center fr Graduate Study and Research in griculture fr the technical and financial supprt. REFERENCES BRNHISEL., R. and P.M.BE.RTSCH lurninwn. In L. Page. RH. Miller and D.R. Keeney (Eds.) Metlwds f Sil nalysis. PI. 2. pp nd Ed. grnmy Mngr.9. S and SSS, Madisn. US CHN, K.W., T.c. P'NG, and R. MOHD. MINUDDIN Palm il mill effluent utilizatin and its future research directins in the il palm indusuy. In: K.H. Lim. T. Bachik and Y.C. Pn (Eds). PP pp. Prc. Seminar n Land pplicatin f Palm Oil Mill and Rubber Factry' Effluents. Malaysia Sciety f Sil Science, Kuala Lumpur. 132 PERTNIKJ. TROP. GRIC. SCI. VOL. 18 NO

9 EFFECTS OF PLM OIL MILL EFFLUENT ON CHEMICL PROPERTIES OF SOILS DY, P.R Particle fractinatin and particle analysis. In C.. Black (Ed). Me/hds j Sil nalysis. Part 2. pp st ed. grnmy Mngr. 9 S, Madisn, US. FRJE.":N, DK, M.H. MUll. and.s.r. Ju Liming and limephsphrus zinc interactins in tw Nigerian Ultisls: II. Effects n maize rt and sht grwth. Sil Sci. Sc. m. j. 44: I GILLMN, G.P" K.L. BRISTOW and MJ. Hu.~L~~. 1989, Leaching f applied calcium and ptassium frm an Oxisl in humid trpical Queensland. nsi. j. Sil Res. 27: GNZLEZ-ENRICO, E. EJ. KMIPRTH. G.G. NDERM.'l and W.V. SRES Effect f depth f lime incrpratin n the grwlh f cm n an Oxisl f central Brazil. Sil Sci. Sc. m.j 43: 1I55-lI58. HISH.\nJDDIN, Mj., H. BDUL HLL", S. BDUL SHR and M. mtd Hf1zI Pem.sahaan Kelapa Sruit di iwalaysia Satu Pallduan. Palm Oil Research Instinue Malaysia, Ministry f Primary Industries Malaysia, Kuala Lumpur. 102 p. HUE, N.V., C.R. CRnOCK and F. DMS EffeclS f rganic acids n aluminum txicity in subsil. Sil Sci. Sc. m. j. 50: 21>-34. Is\lU., H., J. SHMISHUDDIN and S.R. S\'ED OMR lleviatin f sil acidity in Ultisl and Oxisl fr cm grwth. Plant and Sil 151: MEHR, O.P. and M.L. JCKSO~ Irn Oxide remval frm sils and clays by dithinitecitrate-system with bicarbnate buffer. Clays and Clay Minerals 7: NEl~ON; D. W. and L.E. SmL\fERS Ttal carbn, rganic carbn and rganic matter. In:.L. Page, R.H. Miller and D.R. Keeney (eds). Methds f Sil nalysis. Part 2. pp nd ed. grnmy Mngr. 9. S and SSS, Madisn, US OTES, K.M. and EJ. KM!PRTH Sil acidity and liming: II. Evaluatin f aluminum extracted by varius chlride salls fr determining lime requirements. Sil Sci. m. j. 47: PV~, M.., F.T. BINGH.\l and P.F. PRT Redistributin f exchangeable calcium, magnesium, and aluminum fllwing lime r gypsum applicatins t a Brazilian Oxisl. Sil Sci. Sc. m. j. 48: SHMSHUDDIK,j., Lj."m.Ji and.m. MOKHTRUDDIN Chemical changes in sils affected f palm il mill effluent. Pertanika 10: SHMSHUDDlN, j., H..H. SHRIFUDDIN and Z. SH~\ISUDDL'I Reductin faluminium txicity thrugh liming. UPlvl Research News 3 (2): 2-3. SJlMSHUDDIN, ]., I. CHE FUZIH and H..H SHRmJDD1N Effects f limestne and gypsum applicatins t a Malaysian Ultisl n sil slutin cmpsitin and yields f maize and grundnut. Plant and Sil 134: SHMSHUDDIN, j.. 1. jmij..h, R.R SHRIFUDDlN and L.G. BEL.L 1992a. Changes in slid phase prperties f acid as affected by limestne, gypsum, palm il mill effiuent and rck phsphate applicatins. Pertanik 15: SHMSHUDDrN, J., 1. j.\iilh, H.H SHRm..lDDIN and L.C.. BELL 1992b. Limestne, gypsum, palm il mill emuem and rck phsphate effects n sil slutin prperties f sme Malaysian Ultisls and Oxisls. Perlmlika 15: SH."fSHUDDL'I, J. and H.H SIIR.IFUDDII': lleviatin f sil acidity fr crn and grundnut prductin thrugh use f palm il mill emuent. Paper presented at 3rd Int. S)'mp. n Pln-nt-sil Intcractwns at LQw ph, Brisbane. SH.\ISHUDDrN, J and H. IS~flL Reactins f grund magnesium limestne and gypsum in sils with variable-eharge mineral. Sil Sci. Sc m]. 59: TENSSE?>;S, E. and J. SHMSHUDDIN Quantitative Relnf.inship Between Mineralg)' and Prperties f Trapical Sils. Universiti Pertanian Malaysia Press, Serdang, Se1angr, Malaysia. 190 p. ZI:\', Z.Z., MOHO T\'EB DOL\fT, N. i\'l, KH. YEOH and K.H. LI},! Mnitring and envirnment assessment - water quality. In: K.H. Lim,.T. Bachik and Y.C. Pn (Ed). Prc. Seminar n Land pplu:alin jpalm Oil Mill and Rubber Fac/r)' Effluents. pp Malaysian Sciety f Sil Science, Kuala Lumpur (!I r.eiued 30 Nvember 1994; aaep/ed 12 september 1995) PERTNlKj. TROP. GRIC. SCI. VOL. 18 NO.2,