WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero The sludge nd mnure effects on the growth of citrus trees MANUEL COSTA Ru Pdre António Vieir, 24 Unidde de I&D Centro de Geo-Sistems CVRM Instituto Superior Técnico - Lison 81-611 Loulé PORTUGAL mscost2@hotmil.com JOSE BELTRAO, JOAO CARRASCO DE BRITO AND MARIA ALCINDA NEVES, Fculty of Sciences nd Technology (FCT) University of Algrve Cmpus de Gmels, 85-139 Fro PORTUGAL jeltro@ulg.pt, jrito@ulg.pt, mneves@ulg.pt; CARLOS GUERRERO ICAAM-Polo Algrve Fculty of Sciences nd Technology (FCT) University of Algrve Cmpus de Gmels, 85-139 Fro PORTUGAL fpestn@ulg.pt; cguerre@ulg.pt Astrct: The ojective of this study ws to evlute the griculturl use of orgnic solid wstes. Hence two types of wstes were selected to e pplied in citrus orchrd: the sewge sludge (the most common on the urn world) nd the mnure (the most common on the griculturl fields). The sewge sludge is residue originted from the wstewter tretment the solid phse. Its ppliction s n orgnic fertilizer my represent n lterntive to the pollution consequences in nture. The effect of sludge nd mnure ppliction on the growth of ornge trees (Citrus sinensis [L.] Os.), estlished on Fluvisol, ws evluted in reltion to the iometric prmeters numer of leves per tree, dimeter of the trunk, lef re, specific lef re nd lef chlorophyll (estimted y using SPAD vlues). In generl, the citrus plnts response to the ppliction of sewge sludge nd of mnure ws positive, compred to the control trees. The ppliction of the mnure nd especilly the sewge sludge (once this fertilizer/soil mendment is ville in lrger mounts) my e profitle lterntive ppliction to the use of minerl fertilizers nd to other orgnic soil mendments. Moreover, s the other possile destintions of sewge sludge (lndfill or incinertion) re ssocited to potentil environmentl prolems, its griculturl use when correctly pplied, represents etter lterntive. The ppliction of this solid wstes, s clen nd sfe technique to preserve the environment contmintion, cn lso e successfully used s n orgnic mendment of citrus orchrds. Key-Words: citrus leves, mnure, plnt development, sewge sludge, soil orgnic mendments ISSN: 179-579 721 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero 1 Introduction In the lst five decdes nd especilly in the lst yers, the improving of fertilizers use in crops hs een trend on griculturl studies especilly the orgnic mendment mngement [1, 2]. The economic spects relted to the ppliction of treted sewge sludge to the soil, re principlly originted y etter crop productions nd y the decresing of chemicl fertilizers nd mendments tht it represents [3, 4]. Socil nd environmentl requirements to give n dequte destintion to sewge sludge hve stimulted the use of this mteril s soil fertilizer or mendment. This lterntive llows the utiliztion of minerls nd orgnic mtter present in sewge sludge, which cn e eneficil for the soil structure nd fertility, nd, consequently, for the growth of plnt species. In the Algrve, sewge sludge, due to their reduced toxicity (trce elements), represents n dvntge for griculture use [5] nd hs een occsionlly used s fertilizer, in citrus nd in cro trees (Certoni silíqu). The ppliction of sludge in griculture hs some potentilities in the se shore nd mountin res, where the soils re chrcterized y low ph nd low orgnic mtter content. Thus, the ppliction of these residues, s soil mendment, my represent n dvntge for the crop productions [6]. With the World popultion s growth, the demnd of fertilizers ws expected to rise. World fertilizer production ws expected to outstrip demnd over the 28-213 period nd should support higher levels of food nd iofuel production. The FAO report estimted tht world fertilizer supply (nitrogen, phosphte nd potsh nutrient) should increse y some 34 million tonnes representing n nnul growth rte of 3 percent etween 27/8 nd 211/12, comfortly sufficient to cover demnd growth of 1.9 percent nnully [7]. Totl production is expected to grow from 26.5 million tonnes in 27/8 to 241 million tonnes in 211/12. Fertilizer demnd will increse from 197 million tonnes tody to 216 million tonnes in 211/12. According to the sme uthors, world nitrogen supply is forecst to rise y 23.1 million tonnes y 211/12; world phosphte fertilizer supply will increse y 6.3 million tonnes nd potsh supply y 4.9 million tonnes. The popultion increse nd the industril development produce enormous mount of orgnic residues which, nowdys, generte gret environmentl prolems. On the other hnd, inorgnic fertilizers production consumes energy nd its resources re limited. A potentil lterntive for reduce the inorgnic fertilizers use consists in etter use of the orgnic residues. By using sewge sludge, improving crop yield my e chieved with less chemicl hzrdous pollution s it ws demonstrted, when compred to ppliction of inorgnic fertilizers [8]. Currently, new orgnic wstes pper t significntly extent. Their deposition in lndfills nd incinertion must e voided. A rief clssifiction of orgnic residues which my e used in griculturl soils is shown in Tle 1 [9]. Tle 1. Brief clssifiction of treted residues used in the griculturl soils Orgnic References wstes/residues Urn nd Urn sludge [1, 11, 12] Industril Industril sludge Mills Mill mnure [13, 14] Livestock Mnure [15, 16, 17] Agro-industry Cro pulp Sugr cne pulp Wine pulp Beer pulp Olive pulp [9, 18] The effects of mnure nd treted sewge sludge ppliction were studied in citrus orchrd. The im of this work ws to show the effects of these wstes on the plnt growth. ISSN: 179-579 722 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero 2 Mteril nd methods 2.1 Experimentl procedure An experimentl plot ws estlished in n ornge (Citrus sinensis [L.] Os.) orchrd, in the Algrve, southern Portugl, on the sme conditions, s relted in [19]. A 2 h plnttion (6 m x 2 m tree compss) took plce in My nd twelve trees were chosen to conduct the experiments. A drip irrigtion system ws used Rm Netfim selfcompensting drippers, incorported in the pipes, t distnce of.75 cm with constnt 2.3 L h -1 dischrge. The irrigtion periods occurred six months per yer, etween My nd Octoer. The mount of wter ws 4.6 L per tree per dy (7 m 3 h -1 yer -1 ). Two different types of orgnic soil mendments were tested: sewge sludge (S) nd ovine mnure (M), which were compred to the control tretment (C), where ny fertilizer ppliction ws done. The experimentl procedure ws rndomized lock design with 3 tretments x 4 replictions, in totl of 12 young ornge trees. 2.2 Soil The soil of the experimentl site ws clssified s Fluvisol [2], defined s n lluvil soil, till 1 m depth, chrcterized y Terric superficil lyer (FLtr), originted from clcreous mterils. The soil ws chrcterised for texture, ph(h 2 O), orgnic mtter (OM), electric conductivity (EC, dsm -1 ), N, P 2 O 5, K 2 O, Fe, Mn, Zn, totl nd ctive lime (CCo 3 ), C, ction exchngele cpcity (CEC) nd the rtio of C to N (C/N) ws lso clculted. These results re presented in Tle 2. Tle 2 Soil physicl nd chemicl prmeters efore the plnttion of the ornge trees. Soil Prmeters Vlues Texture clss Silt lom Snd (%) 28.1 Silt (%) 45.5 Cly (%) 26.3 ph (H 2 O) 8. OM (%) 1.8 EC (ds m -1 ).9 N (%).1 P 2 O 5 (g kg -1 ) 29.1 K 2 O (g kg -1 ) 617 Fe (g kg -1 ) 25 Mn (g kg -1 ) 128 Zn (g kg -1 ) 4. Totl lime (%) 21.1 Active lime (%) 1.2 Orgnic Cron (%) 1. C/N 12.3 C (cmol c kg -1 ) 7.5 Mg (cmol c kg -1 ) 4.4 N (cmol c kg -1 ) 1.7 K (cmol c kg -1 ).7 Exchngele H (cmol c kg -1 ), CEC (cmol c kg -1 ) 14.7 2.3 Climte The climte of the Algrve cn e considered s Mediterrnen nd in prticulr the south shore, ccording to Köppen, is clssified s Cs, with semi-rid chrcteristics, identified y mild riny winters nd wrm-dry summers. Snow nd frost re not expected. The nnul verge temperture, in Fro, rnges etween 12ºC in Jnury nd 23ºC in August, difference of only 11ºC [21]. The nnul verge vlue for potentil evpotrnspirtion (ETp; Penmn ISSN: 179-579 723 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero Monteith) ws 128 mm, nd for precipittion round 45 mm. ETp nd precipittion hve n opposite pttern, during the yer. So, during the hottest semester, when the photosynthesis is more efficient nd the wter is more essentil for plnt growth, this resource is less ville; irrigtion is the only solution to lnce this sitution. The verge of the shortge of wter, defined y the difference etween the vlues of evpotrnspirtion nd precipittion rtes, verified long the driest months, reches 94 mm per yer. 2.3 Amendments The treted sewge sludge ws collected from the urn wstewter tretment of Vilmour (Algrve). The mnure cme from eef cttle stle ner the experimentl site. These mendments were pplied to the soil t depth etween.5 nd 1. m, during the plnttion of the trees. The physicl nd chemicl prmeters of the soil mendments re shown in Tle 3. Tle 3 Physicl nd chemicl prmeters of the soil mendments. Prmeters Sludge (S) Mnure (M) ph (H 2 O) 6.6 7.4 OM (%) 55.7 72.4 EC (dsm -1 ) 14.5 21.2 Wter content (%) 12.3 7.5 N (g kg -1 ) 31.7 23.8 P (g kg -1 ) 14.5 9.7 K (g kg -1 ) 1.9 31. C (g kg -1 ) 52.5 28.1 Mg (g kg -1 ) 1.6 3.2 C/N 17.6 3.4 The mounts of sludge nd mnure pplied per tree (g) nd respective nutrient contents (N, P 2 O 5, K 2 O nd MgO) re presented in Tle 4. The sludge nd mnure quntities pplied under ech tree were 9.5 kg nd 12.6 kg. These mounts represent the needs of the plnt, in reltion to N, during the first 3 yers of growth. Sewge sludge nd mnure were pplied nd incorported to the soil t one meter depth efore the citrus tree plnttion. 2.4 Plnt nlysis Severl plnt iometric determintions were done on the end of the 1 st nd 2 nd experimentl yer, in Novemer, s follows: numer of leves per tree (NLT); trunk perimeter (TP); lef re (LA); specific lef re (SLA), specific lef disk re (SLDA) nd degree of lef chlorosis (SPAD). Tle 4 Amounts nd nutrient contents of sludge (S) nd mnure (M) pplied per tree (g). Sludge (S) Mnure (M) Amount 95 126 N 3 3 P 2 O 5 314 28 K 2 O 124 47 Mg 15 4 The numer of leves per tree (NLT) is iologic prmeter used to define the vegettive development of the trees. The trunk perimeter (TP, cm) ws mesured t 2 cm height. This is no destructive iologic prmeter nd is used to define the trees vigour nd it is esy to determine nd very explicit in terms of results [22]. Lef re (LA, cm 2 ) is considered s iometric prmeter which defines the vegettive development, in function of time nd of the experimentl tretments. The LA ws mesured using lef re mesurer AT Delt-T (Devises Ld., Burwell, Cmridge, UK). The specific lef re (SLA, cm 2 g -1 ) is expressed s the rtio of lef re (LA) to lef dry weight [23]; this prmeter is useful to evlute the vegettive development, s function of time nd of the experimentl ISSN: 179-579 724 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero tretments; in ech tretment, 5 leves per tree were collected, oven dried t 6ºC, until constnt weight nd the respective dry weight ws determined. The specific lef disk re (SLDA, cm 2 ) ws determined in lef discs of 5.3 mm 2, in different leves, then oven dried t 6ºC nd weighted, in precision scle. This prmeter is lso useful to evlute the vegettive development. The degree of lef chlorosis [24] ws evluted using portle SPAD-52 meter (Minolt Co., Osk, Jpn). This pprtus mesures the sornces of the lef t two wvelengths in the red rnge (~ 65 nm), which corresponds to the pick of sorption y chlorophyll nd in the infrred rnge (~ 94 nm), used s reference. Using these two trnsmittnces, the SPAD-meter clcultes numericl vlue (SPAD units), which is proportionl to the mount of chlorophyll in the citrus. The numer of smples ws 59 for ech tretment nd prmeter, except to the numer of leves per tree (NLT), which ws reduced to 8. 2.5 Sttisticl nlysis The effects of tretments were evluted using nlysis of vrince (ANOVA) nd the mens compred using the Duncn Multiple Rnge Test (DMRT) t the 95% significnce level, using the SPSS 11. [25]. 3. Results 3.1 Sludge nd mnure effects on the 1st yer The ANOVA ws done etween the mens of the prmetric vlues of the plnt development to the tretments. After the first experimentl yer, significnt differences were oserved mong the men vlues of trunk perimeter (TP); lef re (LA); specific lef re (SLA), specific lef disk re (SLDA) nd degree of lef chlorosis (SPAD). The differences oserved mong the men vlues of NLT (numer of leves per tree) were not significnt. The sttisticl Duncn test ws used to the TP vlues nd the men vlues were ssocited into 2 homogeneous groups () nd (). It ws oserved higher vlues in the S nd M tretments thn in control (C). Fig. 1 shows the men vlues, stndrd devition nd the Duncn test of the perimeter of the trunk vlues (TP, cm) mong tretments. A positive reltion ws oserved etween the use of the S nd M mendments nd the perimeter of the trunks vlues (TP). Trunk perimeter (TP; cm) 9 8 7 6 5 4 3 2 1 Fig. 1 1 st yer - Trunk Perimeter (TP, cm) vlues for the tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). Fig. 2 shows the men vlues, stndrd devition nd the Duncn test of the lef re (AF cm 2 ) mong tretments. It ws shown tht the vlues of mnure (M) tretment were significntly higher thn those of control (C). Thus, it ws oserved positive reltion etween the mnure ppliction nd the plnt development. ISSN: 179-579 725 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero Lef Are (LA; cm 2 ) Fig. 2 1 st yer - Lef re (LA, cm 2 ) vlues for the different tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). Fig. 3 shows the men vlues, stndrd devition nd the Duncn test of the specific lef re (SLDA, cm 2 g -1 ), mong tretments. The SLDA ws significntly lower in plnts treted with sludge (S) nd mnure (M), compred to control (C). This shows tht the leves of plnts of control were thinner thn those where mnure nd treted sewge sludge were pplied. SLDA (cm 2 g -1 ) 1 9 8 7 6 5 4 3 2 1 9 8 7 6 5 4 3 2 1 Fig. 3 1 st yer Specific lef disk re (SLDA, cm 2 g -1 ) vlues for the different tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). Fig. 4 shows the men vlues, stndrd devition nd the Duncn test of the specific lef re (SLA, cm 2 g -1 ), mong tretments. Specific lef re ws significntly ffected y the tretments. This mens tht the leves of plnts of mnure (M) were thicker thn those where orgnic mendments were not pplied. Specific lef re (SLA;cm 2 g -1 ) 9 8 7 6 5 4 3 2 1 Fig. 4 1 st yer Specific lef re (SLA, cm 2 g -1 ) vlues for the different tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). Fig. 5 shows the men vlues, stndrd devition nd the Duncn test of the SPAD vlues mong tretments. SPAD vlues were within the rnge otined y [33] for green leves in citrus trees, indicting n dequte nutritionl level of the plnts in this experiment. The SPAD ws significntly higher in plnts treted with S nd with M, compred to C. This shows tht, in control plnts, the chlorophyll level ws ffected proly due to nutritionl imlnces, s iron chlorosis, which ws frequently oserved in citrus estlished in clcreous soils. ISSN: 179-579 726 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero SPAD vlues 8 7 6 5 4 3 2 1 Fig. 5 1 st yer SPAD vlues for the different tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). 3.2 Sludge nd mnure effects on the 2nd yer After the second experimentl yer, significnt differences were oserved mong the men vlues of trunk perimeter (TP), lef re (LA), nd specific lef disk re (SLDA). The numer of leves per tree (NLT), specific lef re (SLA), nd SPAD vlues were not significntly ffected y the tretments, nd re shown in Tle 5. Tle 5 - Numer of leves per tree (NLT); specific lef re (SLA, cm 2 g -1 ) nd totl lef chlorophyll (SPAD) for ech tretment: sewge sludge (S), mnure (M) nd control (C). NLT SLA SPAD C 396 54. 76.4 S 51 52.1 75.6 M 447 53.1 74.9 the trunks vlues (TP), it ws oserved tht sludge (S) nd mnure (M) were oth significntly higher thn the control tretment (C). The young citrus plnts mendment with tested wstes presented higher vlues of trunk perimeter (out 69%) compred to the control plnts. Trunk perimeter (TP; cm) 14 12 1 8 6 4 2 Fig. 6 2 nd yer Trunk perimeter (TP, cm) vlues for the tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). Fig. 7 shows the vlues of lef re (LA, cm 2 ) for ech tretment. The lef re incresed with sludge (S) ppliction. It ws shown tht the sewge sludge ppliction improved the lrger leves, compred to the mnure (M) nd to the control (C). Fig. 8 shows the specific lef disk re vlues (SLDA, cm 2 g -1 ). The SLDA ws significntly lower in plnts treted with sludge, compred to control (C). This mens tht the leves of plnts treted with sludge were thicker thn those of the control (C). Fig. 6 shows the vrition of the perimeter of the trunk vlues (TP, cm) mong tretments. A positive response ws oserved y the orgnic wstes ppliction. In reltion to the perimeter of ISSN: 179-579 727 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero Lef Are (LA; cm 2 ) Fig. 7 2 nd yer Lef re (LA, cm 2 ) vlues for the different tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). SLDA (cm 2 g -1 ) 14 12 1 8 7 6 5 4 3 2 1 8 6 4 2 Fig. 8 2 nd yer Specific lef disk re (SLDA, cm 2 g -1 ) vlues for the different tretments: C control, S sewge sludge, M mnure. Columns with the sme letter were not significntly different t P<.5 (Duncn Test). 4. Conclusions This work shows tht the treted sewge sludge nd the mnure re good soil orgnic mendments, once it increses the response of plnts - perimeter of the trunk, leve re, thickness of the leves nd lef chlorophyll level (the numer of leves per tree ws not significntly different). These orgnic wstes ppliction represents profitle lterntive to the use of minerl fertilisers, especilly the sewge sludge, since it is ville in lrger mounts. Moreover, s the possile destintions of urn sludge (lndfill or incinertion) provoke environmentl prolems, its griculturl use, when correctly pplied, is essentil to void these prolems. Considering the specific cse of the ppliction of sewge sludge our results were similr to those otined y [26], where the ppliction of sewge sludge incresed the vlues of lef re, totl dry mtter, lef re rtio nd rtes of solute nd reltive growth of the plnts of euclyptus (Euclyptus grndis), nd [27] there ws n increse in lef re of mint (Menth piperit L.) treted with sewge sludge. References: [1] Chtzikosm, D.; Tsgs, F.; Chspopoulou, A.; Protopps, A. L.; Zgorinkos, E. 26 Assessment of options for sustinle mngement of Psittli s wstewter sludge. WSEAS Trnsctions on Environment nd Development 2(5):667-676. [2] Billis, V. nd Stmtin, E. 26. Wste mngement plnning nd new priorities nd ojectives. Greek Omudsmn s interventions nd proposls. WSEAS Trnsctions on Environment nd Development 2(6): 88-815. [3] Brito, J.M.C.; Sntos, N.; Guerrero, C.; Fleiro, L.; Veliç A. e Beltrão, J. (1996). Reuse of municipl sludge nd industril wstes s orgnic fertilizers in pepper. Mediterrnen nd Europen Experience. Proceedings. R. Chourkr- Allh (ed.), Agdir, Morocco, pp. 455-463. [4] Domingues, H.; Monteiro, O.R.; Pedr, F.; Amro, J.T. e Gusmão, M.R. (21). Aplicção de lms residuis urns em solos grícols. Síntese dos estudos desenvolvidos no deprtmento de ciênci de solo, d Estção Agronómic Ncionl - INIA. Revist ds ISSN: 179-579 728 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero Ciêncis Agráris, edição especil XXV(3-4):341-352.). [5] Cost, M.; Beltrão, J.; Brito, J.; Dionísio, L. 28. Effects of mnure nd sludge ppliction on citrus orchrd. WSEAS Trnsctions on Environment nd Development 4(7):567-576. [6] Oliveir, A.L.F. (1967). Estudo d mtéri orgânic ns uniddes de solos crtogrfdos em Portugl ( sul do rio Tejo). Secretri de Estdo d Agricultur. Direcção dos Serviços Florestis e Aquícols (ed.). Liso, 198 p.. [7] FAO, 28. Current world fertilizer trends nd outlook to 211/12. http://www.fo.org/gl/gll/docs/cwfto11.pdf. [8] Brito, J.M.C.; Coelho, D.; Guerrero, C.A.; Mchdo, A.V.; Beltrão, J. 1999. Soil pollution y nitrtes using sewge sludges nd minerl fertilizers. In: D. Anç & P. Mrtin-Prével (Eds.).Improved Crop qulity y Nutrient mngement, Chpter 51: 223-227. Kluwer Acdemic Pulishers. [9] Cecinh, A.; Guerrero, C.; Beltrão, J.; Brito, J. 29. Cro seed residues soil orgnic mendment. 7 th WSEAS Interntionl Conference on Environment, Ecossystems nd Development. Puerto de l Cruz, Cnry Islnds, Spin, Decemer, 14 16, 29 (pp. 56-6). [1] Nscimento, D. M. C.; Brito, J. M. C.; Guerrero, C. A. C.; Dionísio, L.P. C. 22. Sewge Sludge use s Horticulturl sustrtum in Tgete ptul seed germintion. Act Horticulture, 573: 71-76. [11] Alvres, F; Dionisio, L.P.C.; Guerrero, C.A.C.; Brito, J.M.C. 22.The use of eroic nd neroic sewge sludges s n orgnic fertilizers in lettuce. Act Horticulture, 573: 55-62. [12] Chtzikom, D.;Tsgs, F.; Chspopoulou, A. 26. Assessment of options for sustinle mngement of Psitlli s wstewter sludge. WSEAS Trnsctions on Environment nd Development 2(5):567-576. [13] Guerrero, C.; Fleiro, M. L.; Pit, P.; Beltro, J.; Brito, J. 25. Inorgnic nd orgnic Fertiliztion of Leeks cultivted in pots: Yield, Plnt minerl Content nd Microil Qulity. Europen Wter 11/12:16 [14] Guerrero, C.A.C; Pit, P.; Brito, J.M.C 22. Inorgnic nd orgnic fertiliztion of Leeks cultivted in pots: Soil nd leching Chemicl properties. Act Horticulture, 573: 83-9. [15] Cost, M., Beltrão, J., Brito, J., Guerrero, C., Dionísio L. 28. Comprison etween the effects of sludge ppliction on citrus orchrd. Procedings of the 4 Th ISME/WSEAS Interntionl Conference on Energy, Environment, Ecosistems nd Sustinle Development (EESD 8):52-57. Fro]. [16] Anc, D; Hkerlerler, H.; nd Irget, M. 1993. The use of Industril wstes s mnures: A cse study with effluent from n olive oil processing plnt. Frgoso, M.A.C.; Beusichem, M.L. (eds.). Optimiztion of Plnt Nutrition. Development s in Plnt nd Soil Sciences 53:589-592. [17] Esiyok, D.; Okur, B; Delick, S.; Dumn, I. 1999. Effect of mnure doses nd Growth medi on the productivity nd minerl composition of rocket leves (eruc stiv). In: D. Anç & P. Mrtin-Prével (Eds.). Improved Crop qulity y Nutrient mngement, Chpter 54:237-24. Kluwer Acdemic Pulishers. [18] Brito, J.; Chd, I.; Pinto, P.; Guerrero, C.; Beltrão, J. 27. Sugrcne pulp residue s Horticulturl sustrtum nd s orgnic corrective. NAUN Interntionl Journl of Energy nd Environment, 2, vol. 1: 75-78. [19] Cost, M.; Guerrero, C.; Dionisio, L.; Beltrão, J.; Brito, J. 25. Pollution spects of hevy metls in citrus irrigted with wstewter. 6th Conference of EWRA Europen Wter Resources Assocition. Shring common vision of wter resources. Plis de l Europe, Menton, Frnce, Septemer, 7-1, 25 (CD-R). [2] FAO-ISSS-ISRIC. 1998. World reference se for soil resources, Ed. Food nd Agriculture Orgniztion, Interntionl Society of Soil Science nd Interntionl Soil Reference nd Informtion Centers. 87p. ISSN: 179-579 729 Issue 11, Volume 6, Novemer 21
WSEAS TRANSACTIONS on ENVIRONMENT nd DEVELOPMENT Mnuel Cost, Jose Beltro, Joo Crrsco De Brito, Mri Alcind Neves, Crlos Guerrero [21] Cunh, F. R. 1957. The climte of Algrve. Finl scientific report on the Agriculturl Engineer degree. ISA, Technicl University of Lison, 589 p. [22] Neves, M.A.R. (1997). Estudo comprtivo dos mecnismos de resistênci à secur de lguns port-enxertos do género Prunus e su plicção o melhormento. Tese de Doutormento. Universidde do Algrve. UCTA. Fro, 222 p.. [23] Jrvis, P.G. 1985. Specific lef weight equls 1. lwys. HortScience 2:1-812. [24] Pestn, M.; Bej, P.; Correi, P.J.; de Vrennes, A. nd Fri, E.A. 25. Reltionships etween nutrient composition of flowers nd fruit qulity in ornge trees grown in clcreous soil. Tree Physiology, 24: 761-767. [25] SPSS 11.. 22. SPSS Inc., Chicgo, Illinois, U.S.A. [26] Grci, G.O., Gonclves, I.Z., Mdlo, J.C., Nzrio, A.A. nd Reis, E.F. 21. Revist Ciênci Agronómic, 41 (1): 87-94. [27] Scvroni1, J., Ferreir, L.C., Vlmorid, J. nd Boro, C.S.F. 29. Development of Mint (Menth piperit L.) Grown on Biosolids. Evlution of Productivity nd Essentil Oil Content. Brzilin Archives nd Biology Technology. Vol. 52 (2): 365-377. ISSN: 179-579 73 Issue 11, Volume 6, Novemer 21