CLRA 2006 Réclamation and Remediation: Policy toPractice

31st Annual Meeting and ConférenceCanadian Land Réclamation Association (CLRA) Association

Canadienne de Rehabilitation des Sites Dégrades (CRSD)and thé

9th Meeting of thé International Affiliation of Land Reclamationists (IALR)

August 20 - 23, 2006Crowne Plaza Hôtel

Downtown Ottawa, Canada

-\JACRSV

CLRA/ACRSD (www.clra.ca)

The Canadian Land Réclamation Association/Association canadienne de réhabilitation des sitesdégradés (CLRA/ACRSD) is a non-profit organization that was incorporated in 1975. TheAssociation encourages personal and corporate involvement where réclamation or rehabilitationof disturbed lands is planned or implemented. Members meet annually for technical discussion,information exchange and personal interaction. Local activities occur in Alberta, BritishColumbia, Ontario and thé Maritimes where there are active provincial chapters.

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GREENHOUSE EVALUATION OF PHOSPHORUS AVAILABILITY TOCORN GROWN ON LIMED SULPHIDE TAILINGS1

Ahmed Aajjane , Antoine Karam and Léon-Etienne Parent

Abstract. Liming can modulate phosphorus (P) availability to plants growing inacid- forming média. The objectives of mis study were to détermine thé effects oflime and phosphorus rates on corn (Zea mays L.) grown under greenhouseconditions on an acid-producing mine tailing, and to evaluate P desorption fromthé mine tailing after harvest. The acid sulphide tailing (pH 2.65) collected fromthé Solbec-Cupra mine in Québec was limed using CaCOs to theoretical pHvalues of 5 (llg/kg), 6 (17 g/kg) and 7 (30 g/kg) prior to corn production.Phosphorus was thoroughly mixed with thé tailing at rates of 0, 22.4, 44.8 and89.6 mg P/kg. A commercial peat moss-shrimp wastes compost, commercial boneflour fertilizer and reagent-grade KH2PÛ4 were used as P sources. Ail potsreceived basai N-K fertilization. The treatments were arranged in a randomizedcomplète block design with three replications. Corn was grown for 50 days fromémergence. After harvest, thé mean tailing pH values varied from 4.20 to 7.20.Dry matter yield of plant tops was significantly affected by lime and phosphorustreatments. Corn yields were significantly correlated with pH, salinity index andammonium acetate-extractable Ça. In ail P treatments, thé highest yield wasobtained with plot receiving 44.8 mg P/kg and lime rate to achieve pH 6 (17 gCaCOs/kg). In général, métal concentration in thé shoot did not show toxicaccumulation. The amounts of DTPA-TEA-CaC^ (pH 7.3)-extractable substrate Pincreased with extraction température. The DTPA-extractable P data from thé 30tailing samples over a period of 1 to 48 hours were best described by an empiricalfirst-order-rate équation using t°5 instead of t as thé time variable. Liming and Pfertilization were déterminant factors for thé growth of corn in acid sulphidetailings.

Key Words: P desorption, liming, compost, bone flour, amendment.

1 Paper presented at thé CLRA 2006 Conférence, Ottawa, Ontario, August 20-23,2006.2Department of geology. Université Chouaïb Doukkali, Faculté des Sciences, ElJadida, Morocco. E-mail address: aajjaneahmed@yahoo.fr.3Équipe de Recherche en Sols Agricoles et Miniers, Département des sols et degénie agroalimentaire, FSAA, Université Laval, Québec, Canada G1K 7P4. E-mail adresses : antoine.karam@sga.ulaval.ca; leon-etienne.parent@sga.ulaval.ca

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Résumé. Le chaulage peut influencer la disponibilité du phosphore (P) pour lesplantes cultivées dans des résidus miniers acides. Les objectifs de cette étudeétaient de déterminer la disponibilité du P pour le maïs (Zea mays L.) cultivé enserre dans un résidu minier acide (RM) recevant différentes doses de chaux etd'évaluer les caractéristiques de désorption de P dans les échantillons de RMaprès la récolte. Des échantillons de RM ont été amendés avec quatre doses deSM (0, 11, 17 et 30 g kg"1) et quatre doses de P (0, 22.4, 44.8 et 89.6 mg P/kg).Les sources de P provenaient des produits suivants : compost de mousse de tourbeet de résidus de crevettes, farine d'os et KL^PO/t. La durée de croissance du maïsétait de 50 jours. Les traitements ont été répétés trois fois et disposés selon undispositif complètement aléatoire. Après la récolte, les valeurs moyennes de pHvariaient de 4.20 à 7.20. Le chaulage et la fertilisation phosphatée ontsignificativement influencé le rendement en matière sèche (RMS) du maïs. Deplus, le RMS était significativement corrélé avec le pH, l'indice de salinité et lesquantités de Ça extraites à l'acétate d'ammonium. Le meilleur rendement a étéobtenu aux doses de 44.8 mg P kg"1 et 17 g kg"'de chaux. En général, il n'y a paseu d'accumulation toxique de métaux lourds. Les quantités de P extraites auDTPA-TEA-CaCb (pH 7.3) augmentaient avec la température de la solutionextractive. Une équation cinétique de premier ordre (In C = In C0 + kt°5) décrivaitle mieux les données de désorption du P (DTPA-TEA-CaCb) en fonction dutemps d'extraction dans tous les échantillons de RM. Le chaulage des RM et lafertilisation phosphatée sont des facteurs déterminants pour la croissance du maïsdans les RM.

Mots clés: Désorption de P, chaulage, compost, farine d'os, amendement.

Introduction

Phosphorus (P) is an essential nutrient for plant growth. The low P concentration and availabilityin minesoils and strip-mined sites, however, make it a critical nutrient limiting plant growth(Dant, 1984).

Liming can improve tailing base cation status and modulate P availability to plants growing inacid sulphide mine tailings (Karam and Azzaria, 1989). However, liming has been reported toincrease, decrease or not affect thé availability of P (Hayes, 1982). It is known that P availabilityin limed acid soils dépends on pH, P fixing capacity and P source (Mullins et al. 1996; Bohn etal., 2001). Lowell and Weil (1995) reported that pH is an important factor in P release from rockphosphate-pyrite mixtures. Sencindiver and Bhumbla (1989) showed that corn yields were higheron phosphatic clay-treated minesoils than one minesoil treated with monocalcium phosphate.

Although P fertilization has been found essential for revegetating of coal mine spoils, théfertilizer requirement should be enhanced in limed acid tailing compared to agricultural soils. Itis possible, however, that at high pH, P forms insoluble compounds which can reduce théavailable P in tailings to lower levels. Lime-induced dépressions in plant P content due to heavyliming hâve been reported (Jones and Fox, 1978). A liming program should be planned so thatthé pH can be kept between 5.5 and 7.0 (Tisdale et al., 1993).

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The primary objectives of thé current study were to détermine thé effects of lime and phosphoruson corn grown on a highly acid-producing mine tailing and to examine thé P desorptioncharacteristics of thé tailing after harvest.

Materials and Mcthods

Composite (oxidized + unoxidized) acidic tailing samples were collected in 1993 in thé 0-25 cmupper layer of thé Solbec tailings site. The Solbec-Cupra Mine, operated from 1962 till 1970, is apolymetallic ore mine located 80 km North East of thé city of Sherbrooke, Québec, Canada. Thechemical characteristics of thèse tailings were described by Karam and Guay (1994).

Tailings were air-dried in thé laboratory and crushed to <2 mm, well mixed, and stored in plasticcontainers. Pots containing one kg of air-dried tailings were limed with three levels of reagent-grade CaCOs (11, 17 and 30 g/kg) at field moisture capacity for two weeks before sowing toattain thé theoretical desired pH values of 5, 6 and 7. Phosphorus was thoroughly mixed with thétailing samples at rates of 0, 22.4, 44.8 and 89.6 mg P kg"1. Commercial peat-shrimp wastecompost, commercial bone flour and reagent-grade KlHbPCu were used as P sources. Thetreatments were arranged in a randomized complète block design with three replications. Ailtreatments received a basic N, K, Zn, Cu, Mn, B and Mo fertilization. After fertilization, thésubstrates were watered to field moisture capacity using distilled water and allowed to equilibratefor 4 days before sowing. Five seeds of corn (Zea mays L. cv. 'Pride 1122') were planted andsubsequently thinned to two seedlings per pot 5 days after émergence. Distilled water was addeddaily. After 50 days of growth, plant tops and roots were harvested, separated, washed withdistilled water, and then dried at 70° C for 48 h in a forced-air oven. Plants were weighed and drymatter yields recorded. Tissue samples were ground to pass a 250 um (60-mesh) sieve andoxidized in HNOs cône. Plant nutrients and heavy metals in acid extracts were analyzed byplasma émission spectroscopy. After harvest, tailing samples were air-dried and crushed to <2mm for analysis. Tailing pH was measured in 1:1 tailing-distilled water suspensions. Electricalconductivity (EC) of thé tailing solutions was measured after mixing 30 g of tailing with 30 mLof distilled water equilibrated for 1 h. The chemical properties of tailing samples (total P,Mehlich-3 extractable P and Ça, ammonium acetate-extractable Ça, oxalate-extractable Fe) and Pdesorption (Mehlich-3, acid ammonium oxalate and DTPA-TEA-CaCli extracting solutions)were determined following standard methods as described in Carter (1993).

The reaction rate of P desorption was evaluated for each cultivated tailing sample using DTPA-TEA-CaCb (pH 7.3) as extracting solution and 1, 12, 24 and 48 h as extraction time. The DTPAmethod was used to minimize thé dissolution of CaCOs (Liang and Karamanos, 1993) during théextraction in ail limed tailing samples. The effect of température on P release from cultivatedtailings was determined using DTPA-TEA-CaCb (pH 7.3) as extracting solution and threetempératures (4°, 10°, 20° and 30° ± 0.5°C).

Phosphorus was determined colorimetrically and métal cations were determined by atomicabsorption spectrophotometry.

Analysis of variance was conducted using thé General Linear Model (GLM) statisticalprogramme of thé SAS package (SAS Institute Inc., 1999). Linear corrélation and régression

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analyses were used to détermine thé effect of some chemical properties of cultivated tailing oncorn dry matter yield (DM).

Results and Discussion

Yield response

The pH of thé cultivated tailings reflected thé liming treatments (Table 1). The mean pH increasefor tailing samples was about 2.21 units with 11 g/kg lime, 3.59 units with 17 g/kg lime and 4.52units with 30 g/kg lime. Analysis of variance (data not shown) revealed highly significant (P <0.001) simple effects of lime rate, P source and P rate on tailing pH and ammonium acetate-extractable Ça (Cacx). Tailing pH was closely related to Ca^ (r = 0.937, PO.001) and Mehlich-3extractable Ça (CaM3) (r = 0.861, P < 0.001). The amount of Mehlcih-3 extractable P (PMs) variedfrom 32.7 to 49.5% of total P with an average of 42%.

Table 1. Chemical properties of tailing samples as affected by CaCOa and added phosphorus.

P source''

MKP

PSC

BF

CaCO3 PM3C/ total

rateb (%)

Ça,Ca2

Ca3

Ça,Ca2

Ca3

Ça,Ca2

Ca-j

41.949.537.5

42.048.742.0

37.942.632.7

P CaM3

(tng/kg) ;>

1826.34076.75766.7

2962.33510.75600.0

2138.73043.04966.7

Cacxc

6.617.036.3

15.223.838.4

7.921.437.7

ECd

(dS/cm)

2.262.302.21

2.322.292.54

2.012.282.34

Tailing

pH

4.206.357.20

5.556.507.16

4.835.887.14

Dry matter yields (g/pot)

Tops

5.0618.8013.25

15.7817.0415.31

9.3215.5314.03

Roots

3.128.316.57

8.7810.929.42

5.908.928.44

a MKP: KH2PO4; PSC: peat moss-shrimp waste compost; BF: bone flour.Rate of P application: 22, 44.8 and 89.6 mg P/pot (same for ail sources).

b Cab Ca2 and Ca3: 11, 17 and 30 g CaCO3/pot, respectively.

c PM3 and CaM3: Mehlich(lII)- extractable P and Ça; Caex: ammonium acetate-extractable Ça.

d Electrical conductivity of thé tailing aqueous extract.

The ANOVA of treatment effects on DM indicated significant main effects of CaCC-3, P sourceand P rate, and a significant lime x P source interaction (Table 2). The lime effect was quadraticand thé P rate effect was linear. The highly significant quadratic effect of lime indicated thatyield was maximum at thé intermediate lime rate. The smallest dry matter yield was obtained atthé lowest lime application rate (tailing pH near 4.2) and thé highest yield was obtained at thé

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intermediate rate (tailing pH near 6.5). Liming tailings to pH 7.14 to 7.20 resulted in a yield 10 to22% below maximum. In général, thé effect of liming was more pronounced than P source oncorn yield, as indicated by a higher F value (Table 2). Thèse results are in agreement with thosereported by many workers who showed thé benefit of liming acid minéral soils (Jones and Fox,1978; Fernandez and Coutinho, 1999) or acid mine tailings (Karam and Azzaria, 1989).

Table 2. Analysis of variance on thé influence of CaCOj, P source and P rate on dry matter yieldof thé above ground portion of corn grown on a sulphide tailing.

Source of variation

Main effectsCaCO3 rate (Ça)

LinearQuadratic

Source ofP(P)P rate (R)

LinearQuadratic

InteractionsC a x PC a x RP x RÇa x P x R

Degree offreedom

2

22

4448

F values

37.42***38.81***33.29***33 33***

6.85***

9.36**NS

9.90**NSNSNS

** #** Significantat,P<0.01 and PO.001, respectively.

Top corn yield was positively correlated with Pvi3 (r = 0.468**), CaeX (r = 0.410*), Ca\i3 (r =0.426*) and salinity index (EC) (r=0.398*). This data indicate that corn growth was not affectedby thé tailing salinity. Several workers (Cramer et al., 1988; Cramer, 1992) showed a significantimprovement of corn growth following thé addition of calcium ions to thé substrate in order tomitigate thé négative effect of sodium salts on root and leaf elongations of corn. Tailing pHaccounted for thé greatest proportion of thé variability in dry matter yield (R2 = 43.6%).However, inclusion of PMS, PM3/total P ratio, and C&MI into thé multiple linear régression modelincreased thé R2 value to 66.1%.

The négative corrélation between thé concentration of P in top plant tissues and tailing pH (r = -0.758***), Cacx (r = -0.762***) and CaM3 (r=-0.757***) indicated that thé interaction between Psource and lime rate is related to thé influence of pH or exchangeable Ça level on P availability.Concentrations of P in roots were also negatively correlated with tailing pH (r = -0.692***), Ca^(r = -0.757***) and CaM3 (r = -0.723***). At high tailing pH (heavy liming), soluble phosphatescould become less available to plants due to chemical précipitation as calcium phosphates oncarbonate surfaces (Bohn et al., 2001). This, however, does not necessarily imply that liming did

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not affect possible biochemical transformations in thé tailing which may govern P availability tocorn roots.

The lack of significant corrélation between corn yield and oxalate-extractable Fe indicated thatonly a small proportion of thé P fixed on metal-oxide surfaces accounted for thé variation in cornyield. At ail level of CaCOs, DM was significantly higher in PSC-treated tailing samples than inMKP- or BF-treated tailing samples (Table 3). Hountin et al. (1995) also found that applicationof thé same commercial PSC with lime to an acid loamy sand soil maintained high yield ofbarley and soil fertility. Corn response to compost could be attributable to supplemental nutrientssupplied by thé compost (Sauvesty and Karam, 1998). The bone flour amendment was leastsuccessful due to its inability to provide available nutrient levels sufficient for thé maintenance ofgood végétative growth. Bone flour contained higher amounts of water-insoluble P than PSC andMKP. Thèse results are similar to those of Mullins et al. (1990), who evaluated phosphatefertilizers having a wide range of water-soluble P contents under greenhouse conditions. Mullinset al. (1990; 1996) reported that water-insoluble P compounds isolated from commercialphosphate fertilizers are less available than water-soluble forms. It was shown by Owens et al.(1955) that thé P content of sugar beet plants fertilized with a high water soluble phosphatefertilizer was significantly higher than for plants fertilized with a low water soluble phosphate.The advantage of BF fertilizer would resuit from its effect as calcareous amendment and Psource in thé long run. Indeed, among P sources, thé flour of bone (pH 7.45) provided thé highesttotal Ça (21.8%) and total P (5%) contents.

Table 3. Effect of P source at three rates of CaCOs on top dry matter yield of corn.

P source3 CaCO3 rateb

Ça, Ça, Ça,

Peat moss-shrimp waste compost 15.78a 17.04a 15.31a

Bone flour 9.32ab 14.79b 14.03b

Monopotassium phosphate 5.06b 15.53b 13.25b

a Rate of P application: 22, 44.8 and 89.6 mg P/pot (same accross sources).

Cab Ca2 and Ca3: 11,17 and 30 g CaCO3/pot, respectively.

The values followed with a same letter are not significantly différent at P< 0.05.

As for thé major éléments P, Ça and Mg, P tissue decreased while thé Ça and Mg tissuesincreased with increasing tailing pH. In général, thé content of some heavy metals (Zn, Cu, Feand Mn) in top plant tissue decreased with increasing tailing pH (data not shown) as a resuit ofadding increasing rates of lime. The mean concentrations (mg/kg) of heavy metals in top corn

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tissues (Cd: <0.2; Co: <0.3; Cu: 4.5; Fe: 100; Mn: 36; Ni: 2; Pb: <2.0; Zn: 15) were comparablewith those normally met at thé majority of thé plants cultivated on non polluted agricultural soils(Pais and Jones, 1997; Kabata-Pendias, 2001). It is advisable to mention that corn rootsaccumulated much more Fe, Mn, Zn and Cu than shoots. This support thé idea according towhich thé roots of terrestrial plants constitute not only one intermediate médium between thé soiland thé aerial part of thé plant but also a protective shield for this one.

P desorption characteristics

The amount of P released increased nonlinearly with extracting solution température (Fig. 1),indicating that P desorption by DTPA was temperature-dependent. For minéral soils, Beaton etal. (1965) found that thé rate of dissolution of pellets containing 15 mg of P prepared from water-soluble P fertilizers increased markedly as extraction température was increased from 5° to 35°C.Numerous reports indicated that thé optimum growth conditions for common microbial speciesin sulphide tailings such as Thiobacillus ferrooxidans was 30°C (Guay et al., 1975). In addition,température may influence thé amount of desorbable P présent in thé tailing by changing théstability of amorphous Fe and Al complexes and Ça précipitâtes (Sharpley and Ahuja, 1982).

DPSC D BF MKP

600 i

4°C 10°C 20°C 30°C

Température, °C

Figure 1. Phosphate desorbed by DTPA as a fonction of extraction température in limed tailingsamples receiving commercial peat-shrimp waste compost (PSC), commercial bone flour (BF)and reagent-grade KH2PO4 (MPK).

In général, thé release of DTPA-extractable P in relation to température from tailing samplesincreased in thé following order: MKP < BF < PSC (Fig. 1). The higher amount of readily-extractable P was observed with PSC, due possibly to mineralization of organic P compounds.The activity of microorganisms involved in thé décomposition of organic P into inorganic P or inthé oxidation of iron sulphide into P-fixing iron hydroxide could be stimulated as températurerosé from 4° to 30°C. Despite those opposite reactions, thé amount of DTPA-extracted P washighest in thé température range of 20° to 30°C across treatments.

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In another séries of experiments, thé kinetics of P desorption in cultivated tailings wasinvestigated during a shorter period of time, so that P release from tailings could be interpretedfor rainfall and runoff water events. In order to be useful, a desorption kinetic model must fit thédata and yield parameters related to plant response (Onken and Matheson, 1982). The kinetics ofP desorption from 12 limed tailing samples was described by six kinetic models (Sparks, 1999)such as:First-order reaction: In C = In Co + kt (1 )Second-order: 1/C = 1/Q, - kt (2)Elovich-type équation: In C =a + b In t (3)Two-constant rate équation: In C = In k + b In t (4)Parabolic diffusion law: C = C0 + kt°5 (5)Modified first-order desorption model: In C = In Co + kt0'5 (6)

where C is desorbed P concentration in mg/L (same for ail models); t is extraction time in hours(same for ail models); CQ, a, b and k are empirical constants estimated by thé least squaresmethod. The modified first-order équation (6) provided thé best fit (R2 = 0.857*** to 0.998***;SE - 0.028 to 0.135), followed by thé two-constant rate model (4). The slope varied amongtreatments due to variations in surface reactivity for various P compounds in cultivated tailingsamples. The k values of thé modified first-order model (6) was correlated to Mehlich-3extractable-P (r = 0.394*), indicating that k values could dépend on labile P levels. The k valueswere negatively correlated to top yield (r = -0.336*) and root yield (r = -0.326*). On thé otherhand, Co values were positively correlated with dry matter of corn tops (r = 0.385*) and rootyield (r = 0.460*). Onken and Matheson (1982) also found significant corrélations betweenkinetic P parameters and crop yield response to applied P. However, corn yield could be hardlypredicted accurately from P desorption measurements in acidic mine tailings.

Conclusions

Calcium and phosphorus deficiency in acid mine tailing are limiting plant growth. Lime and Papplications stimulated thé growth of corn. Among thé three P amendments, compost resulted inhighest yield values and bone floor thé lowest. Results from thé P sorption study supported théhypothesis that, in this sulphide tailing, P sorption decreases with increasing pH. Corn yield wasloosely related to P desorption measurements in limed mine tailings. Application of CaCOs at arate of 17g/kg in order to attain a pH-range between 6 and 6.5 during cultivation would berequired for optimal plant growth.

Acknowledgement

The financial assistance provided by thé National Sciences and Engineering Research Council ofCanada is gratefully acknowledged.

Literature Cited

Anjos, J.T. and D.L. Rowell. 1987. The effect of lime on phosphorus adsorption and barleygrowth in three acid soils. Plant Soil 103: 75-82.

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Beaton, J.D., R.C. Speer and G. Brown. 1965. Effect of soil température and length of reactionperiod on water solubility of phosphorus in soil fertilizer reaction zones. Soil Sci. Soc. Amer.Proc. 29: 194-198.

Bohn, H.L, McNeal, B.L. and G.A. O'Connor. 2001. Soil Chemistry (3rd Ed.). A Wiley-Interscience Publication, New York, USA, 307 pp.

Carter, M.R. 1993. Soil Sampling and Methods of Analysis. Canadian Society of Soil Science.Lewis Publishers, Boca Raton, USA, 823 pp.

Cramer, G.R. 1992. Kinetics of maize leaf elongation: II. Response of a Na-excluding cultivarand a Na-excluding cultivar to varying Na/Ca salinities. J. Exp. Bot. 43: 857-864.

Cramer, R., Epstein, E. and A. Lauchli. 1988. Kinetics of root elongation of maize in response toshort-term exposure to NaCl and elevated calcium concentrations. J. Exp. Bot. 43: 1513-1522.

Dant, J.M., 1984. Greenhouse évaluation of phosphorus availability on selected West Virginiamine soils. M.S. Thesis. West Virginia University, USA, 163 pp.

Fernandes, M.L.V. and J.F. Coutinho. 1999. Effect of liming and phosphate application onsudangrass growth and phosphorus availability in two temperate acid soils. Commun. SoilSci. Plant Anal. 30:855-871.

Guay, R., A.E. Torma and M. Silver. 1975. Oxydation de l'ion ferreux et mise en solution del'uranium d'un minerai. Ann. Microbiol. 126B: 209-219.

Hayes, R.J. 1982. Effects of liming on phosphate availability in acid soils. Plant Soil 68: 289-308.

Hountin, A.J., A. Karam, L.E. Parent and D. Isfan. 1995. Effect of peat-shrimp wastes composton thé growth of barley (Hordeum vulgare L.) on a loamy sand soil. Commun. Soil Sci. PlantAnal. 26: 3275-3289.

Jones, J.P. and R.L. Fox, 1978. Phosphorus nutrition of plants influenced by manganèse andaluminium uptake from an oxisol. Soil Sci. 126: 230-236.

Kabata-Pendias, A. 2001. Trace Eléments in Soils and Plants (3nd Ed.), CRC Press, Boca Raton,USA, 413pp.

Karam, A. and L.M. Azzaria, 1989. Utilisation de substances organiques à des fins de mise envégétation végétation de rejets miniers acides, pp. 645-650. In D.G Walker, C.B. Powter andM.W. Pôle (Eds). Proceedings of thé Conférence: Réclamation, A Global Perspective.Alberta Land Conservation Réclamation Council.

Karam, A. and R. Guay. 1994. Inondation artificielle du parc à résidus miniers Solbec-Cupra:études microbiologique et chimique. Rapport final. CANMET/DSS/MER 94, Canada, 70 pp.

637

Liang, J. and R.E. Karamanos. 1993. DTPA-extractable Fe, Mn, Cu, and Zn. pp. 87-99. In M.R.Carter (Ed.). Soil Sampling and Methods of Analysis. Canadian Society of Soil Science.Lewis Publishers, Boca Raton, USA.

Lowell, K. and R.R. Weil. 1995. Pyrite enhancement of phosphorus availability from Africanphosphate rocks: A laboratory study. Soil Sci. Soc. Am. J. 59: 1645-1654.

Onken, A.B. and R.L. Matherson. 1982. Dissolution rate of EDTA-extractable phosphate fromsoils. Soil Sci. Soc. Am. J. 46: 276-279.

Owens, L., Lawton, K., Robertson, L.S. and C. Apostolakis. 1955. Laboratory, greenhouse andfield studies with mixed fertilizers varying in water-soluble phosphorus content and particlesize. Soil Sci. Soc. Amer. Proc. 19: 315-319.

Pais, I. and J.B.Jr. Jones. 1993. The Handbook of Trace Eléments. St. Lucie Press, Boca Raton,USA, 223 pp.

Parfïtt, R.L. 1977. Phosphate adsorption on an Oxisols. Soil Sci. Soc. Am. J. 41: 1064-1067.

Mullins, G.L., Sikora, F.J., Bartos, J.M. and H.H. Bryant. 1990. Plant availability of phosphorusin thé water-insoluble fraction of commercial triple superphosphate fertilizers. Soil Sci. Soc.Am. J. 54: 1469-1472.

Mullins, G.L., Sikora, F.J. and J.C. Williams. 1996. Effect of water-soluble phosphorus on théeffectiveness of triple superphosphate fertilizers. Soil Sci. Soc. Am. J. 59: 256-260.

SAS Institute, Inc. 1999. SAS Statistical Analysis System, SAS/STAT user's guide. Version 6(4th Ed.). SAS Inst., Cary, NC.

Sauvesty, A. and A. Karam. 1998. Utilisation de composts à des fins de mise en végétation desites miniers. Agrosol 10: 60-65.

Sencindiver, J.C. and O.K. Bhumbla. 1989. Effects of phosphatic amendments on yield andelemental composition of corn grown on acid minesoils. pp. 635-644. In D.G Walker, C.B.Powter and M.W. Pôle (Eds.). Proceedings of thé Conférence: Réclamation, A GlobalPerspective. Alberta Land Conservation Réclamation Council.

Sharpley, A.N. and L.R. Ahuja. 1982. Effects of température and soil-water content duringincubation on thé desorption of phosphorus from soil. Soil Sci. 133: 350-355.

Sparks, D.L. 1995. Environmental Soil Chemistry. Académie Press, New York, USA, 267 pp.

Sparks, D.L. 1999. Soil Physical Chemistry (2nd Ed.). CRC Press Inc., Boca Raton, USA, 409 pp.

Tisdale, S.L. Nelson, W.L. Beaton, J.D. and J.L. Havlin. 1993. Soil Fertility and Fertilizer (5Ul

Ed.). Macmillan, New York, USA, 634 pp.