Olive Mill By-products Application: Organic Olive Orchard Yield Performance and Soil Fertility

Transcription

1 J. Agr. Sci. Tech. (216) Vol. 18: Olive Mill By-products Appliction: Orgnic Olive Orchrd Yield Performnce nd Soil Fertility Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 F. Montemurro 1, A. Fiore 1 L. D Andre 2, nd M. Dicono 2 ABSTRACT Sesonl ccumultion nd incorrect disposl of olive mill y-products my e detrimentl to the environment. Conversely, their proper recycling s soil mendments my e sustinle solution. Therefore, the ojectives of this three-yer field tril were: (i) Investigting the effects of Olive Mill Wstewter (OMW) nd Pomce Compost (PC) on plnt nutritionl sttus nd yield in n orgnic olive grove; (ii) The impct on min soil properties, nd (iii) Verifying if these experimentl fertilizers cn replce the widespred fertiliztion prctices. The OMW nd PC tretments were compred to commercil Orgnic-minerl Fertilizer (OF) nd green mnure of horse en (MV). Plnt nutritionl sttus, soil properties nd gronomicl performnce of tretments were ssessed. The OMW nd OF determined yield tht ws on verge significntly higher thn MV nd PC y 191 nd 55%, respectively. The est leves P contents in PC indicted more effective relese of this nutrient s compred to the other tretments, which cn e mtched with more fvorle soil conditions. The comprle yield nd leves composition for OMW nd OF suggested the possiility to replce the OF with the OMW. The effects on olive oil production nd soil fertility highlighted tht OMW (nd PC s second choice) could e pplied to sustin olive tree production, sustituting trditionl fertilizers. Keywords: Composting, Olive grove soils, Olive mill wstewter, Olive pomce, Orgnic frming. INTRODUCTION In the Mediterrnen countries, the olive (Ole europe L.) oil gro-industry genertes lrge mounts of different wstes. Olive pomce nd Olive Mill Wstewter (OMW) re the y-products of the threephse continuous centrifugtion (Sdi et l., 27). By contrst, the modern twophse system produces lignocellulosic olive pomce, which is humid, solid yproduct with high contents of wter ( %), phenols nd lipids (Chowdhury et l., 213). The sesonl ccumultion of these mill y-products, s well s their incorrect disposl, my represent potentil threts to the environment (Niounkis nd Hlvdkis, 26; Kpellkis et l., 28). In fct, the two-phse olive pomce is often rich in potentilly phytotoxic nd cteriosttic sustnces (e.g. polyphenols nd orgnic cids) nd elevted slt concentrtions tht my cuse negtive impcts on crops nd environment, when the pomce is pplied to the soil (Gigliotti et l., 212). However, pomce lso contins lrge mount of orgnic mtter nd nutrients tht could e recycled in griculture, y mixing nd composting this y-product with ulking mterils (e.g., cerel strw or 1 Council for Agriculturl Reserch nd Economics CREA-SCA, Reserch Unit for Cropping Systems in Dry Environments (Experimentl Frm of Metponto), SS 16 Jonic, km , Metponto (MT), Itly. 2 Council for Agriculturl Reserch nd Economics CREA-SCA, Reserch Unit for Cropping Systems in Dry Environments, Bri - Itly. Vi Celso Ulpini 5, 7125 Bri, Itly. Corresponding uthor; e-mil: mringel.dicono@cre.gov.it 1883

2 Montemurro et l. Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 pruning wstes) (Montemurro et l., 29). This lst eroic degrdtion process could drsticlly reduce the potentil phytotoxic compounds of the olive mill y-products (Dicono et l., 212). The proper direct ppliction of OMW to the soil, s n orgnic fertilizer, hs een proposed s low cost method to recycle it (Montemurro et l., 24). The Itlin Lw (n. 574, 1996) llows soil spreding of OMW for gronomicl use with mximum dosge of 8 m 3 h 1 yr 1 (for continuous centrifuge system). The eneficil effects of OMW on the yield of some crops indicted tht it my ecome very importnt source of nutrients nd orgnic mtter in griculture (Brer et l., 213). In prticulr, ccording to Cyuel et l. (21), in the southern regions of the Mediterrnen re the soil orgnic mtter content is extremely low. This condition is highly correlted with soil fertility reduction, due to negtive effects on physicl, chemicl nd iologicl properties of soil. Therefore, properly recycling the orgnic gro-industril wstes s soil mendments my represent solution for their disposl, to replce the losses of orgnic mtter (López-Piñeiro et l., 211). However, to this dte the effects of olive mill y-products on olive orchrds hve not een exhustively studied, prticulrly in orgnic olive-growing systems. Using olive mill y-products in these systems would crete virtuous cycle of iomsses return to the soil within the sme production chin. Moreover, severl olive grove soils hve low orgnic mtter content, thus it could e interesting to define the replcement of the most commonly used methods of fertiliztion y the orgnic fertilizers from the gro-food wstes. Bsed on these considertions, the ojectives of this threeyer field tril in n orgnic Mediterrnen olive grove were: (i) to investigte the effects of lterntive soil orgnic mendments/fertilizers, prticulrly OMW nd olive Pomce Compost (PC), on plnt nutritionl sttus nd yield; (ii) To ssess the impct of the tested experimentl tretments on min soil properties fter repeted pplictions, nd (iii) To verify if the use of olive mill wstes cn e sustinle within ctul cultivtion systems, sustituting the prctice of soil fertility mngement commonly used in locl olive orchrds of the study re. MATERIALS AND METHODS Site of Field Tril The reserch ws crried out from 26 to 28 in n orgnic olive-growing frm t Mter (Bsilict Region, southern Itly), 25 m sl (4 36' '' N, 16 37' '' E) on soil with 1.23 g kg -1 of N, 9.87 nd 834 mg kg -1 of ville P nd K, respectively, nd with 19.6 g kg -1 of orgnic mtter. The investigted cultivrs were Dipopp nd Ghinnr, with plnting spce of 1 1 m, which is typicl of the seculr olive-groves of the site. The olive grove ws plnted in the erly '9, re-grfted t the end of 196 seconds nd it hs never een irrigted. Before strting the tril, the field hs een uniformly mnged with orgnic frming prctices. In prticulr, s for fertilizer strtegy, in the previous 4 yers green mnure of horse en ws used. The climte is ccentuted thermomediterrnen (UNESCO-FAO clssifiction), with winter tempertures tht cn fll elow C, summer tempertures tht cn rise ove 4 C, nd rinfll unevenly distriuted during the yer, eing concentrted minly in the winter months. According to the dt recorded in the nery wether sttion, the totl rinfll vlues cn e rnked s follows: 28< 27< 26 (i.e., 423< 552< 587 mm). The highest verge mximum temperture during the criticl June-Septemer period ws recorded in 28 (31.4 C) nd the lowest in 26 (3.4 C), wheres the 26 hd the highest rinfll (279 mm) nd the 27 the lowest one (212 mm). Finlly, the men temperture vlues during Mrch-Novemer period cn e rnked s follows: 27< 26< 28 (i.e., 24.2< 24.6< 25. C). 1884

3 Olive Mill By-products nd Orgnic Olive Orchrd Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 Experimentl Tretments nd Mesurements In rndomized lock experimentl design with three replictions nd elementry plots of 4 m 2, the following experimentl tretments were compred: (i) OMW, distriuted t 8 m 3 h -1 ; (ii) Onfrm PC distriuted t 6 kg plnt -1, which were compred to: () A commercil NPK orgnic-minerl fertilizer (OF; Progress micro ILSA SpA), llowed in orgnic griculture, distriuted t 15 kg plnt -1, nd () Green mnure of horse en, Vici f L. minor Beck (MV), sown t rte of 15 kg seeds h -1. The pplied OMW rte ws the mximum mount llowed y the Itlin lw for it. The MV is one of the most used sustinle methods to supply N to olive groves in orgnic frming, thus it would e considered s control, nd it ws pplied t rte commonly used in the investigted re. Both the PC nd the OF rtes were sed on the N removl y the verge olive tree productions over the yers (Therios, 29). All mendments (except MV) were pplied nnully in mid-novemer on the soil fter the hrvest, followed y surfce tillge. The horse en ws sown in the first decde of Novemer, s it is usully done in our Mediterrnen conditions. It ws then chopped nd incorported into the soil (out 2 cm depth) y plowing, when plnts produced the first pods t the end of flowering (i.e., t the eginning of My). In regrds to the PC tretment, three onfrm composts were produced from 26 to 28, y mixing olive pomce (t 9.6% rte) from two phses continuous extrction system with whet strw, chicken mnure nd ure, in the following rtes (on fresh weight sis): 3.6, 5.3 nd.5%, respectively. In this reserch, the disposl of high doses of pomce ws preferred, lthough ll the composting mtrices were used in proportions so to otin n optiml C/N rtio (out 3). In ech yer, the mixtures were sumitted to composting in trpezoidl piles (1.5 m high with se of 2 3 m), for out 9 dys. The io-oxidtive phse ws considered finished when the temperture ws stle, close to the externl vlue, nd reheting did not occur. During composting, oth moisture content nd internl temperture of windrows were constntly monitored. To ensure iomss oxygention, the windrows were mechniclly stirred y using trctor with front loder when the internl temperture, mesured y thermocouple proe (CHEMIE, Bri, Itly) with digitl thermometer (Delt Ohm HD 9215), reched or exceeded 6 C. The moisture content in the windrow ws determined y grvimetricl method, nd it ws mintined over 4%. To evlute the chemicl nd physicl chrcteristics of the mteril, four smples of out.5 kg ech were rndomly collected from different horizons of the hep. Min chrcteristics of the composts produced were evluted on smples y using the officil nlyticl methodologies reported y Pglii nd Sequi (1997) nd Violnte nd Sequi (2). Since we did not find differences mong composts throughout the yers, the men of the compost properties (men ± stndrd devition) re reported in Tle 1. Plnt nutritionl sttus ws ssessed y nlyzing composite smple of the youngest mture leves of four (one-yerold) shoots per plnt, one for ech crdinl point. Plnt smplings were crried out ech yer during the following phenologicl stges: (i) Onset of vegettive growth; (ii) Flowering nd fruit setting; (iii) Drupe formtion, nd (iv) Pit-hrdening. On smples of ten fresh leves, nitrte (NO 3 - ) concentrtion of stem juice ws estimted y using the rpid pper test strips of the Nitrchek reflectometer (Merck Chemicls, Germny). Moreover, SPAD redings ( rpid nd non-destructive estimte of lef greenness) were determined y hnd-held chlorophyll meter (SPAD 52; MINOLTA), y performing three determintions in the middle of ech lef. On the ten leves, oven dried nd reduced to fine powder, the Phosphorus (P), potssium (K), Clcium (C) nd Mgnesium (Mg) contents were 1885

4 Montemurro et l. Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 lso determined, y Inductively Coupled Plsm-Opticl Emission spectrometry (ICP- OES), ccording to the method of Pge et l. (1982). Since we did not find significnt differences mong smpling times, the verge for NO 3 - nd SPAD re reported in Tle 2. Moreover, the gronomicl performnce of tretments ws evluted t hrvest (in erly Novemer of 26 nd in Octoer for the other yers) y compring the differences in yield (kg tree -1 ) nd olive oil production on 1 m -2. Drupe, pulp nd pit weights (g), pulp: pit rtio, drupe length (mm) nd drupe width (mm) were further determined on drupes smple of 2 g. In the common griculturl prctice, the two olive cultivrs tested re mixed to give typicl oil tht is loclly highly vlued. As consequence, here yield is given s men vlues per tree, s well s for oth lef nutrients nlysis nd soil smplings composite smple of the two cultivrs (in the sme rte for ech tretment) ws done. Soil smplings were crried out t -3 cm depth efore the ppliction of fertilizers Tle 2. Effects of yers nd experimentl tretments (OMW= Olive Mill Wstewter; OF= Orgnic-minerl Fertilizer; PC= Olive Pomce Compost, MV= Green mnure of horse en) on nitrte content (on dry weight sis) nd SPAD. - NO 3 SPAD mg kg -1 Yer (Y) *** ns Tretments (T) OMW OF PC MV ns ns Y T ns ns The vlues in the sme column followed y different letters re significntly different t P.5 (SNK). *, **, ***: Significnt t P<.5,.1 nd.1, respectively, ns= Not significnt. 1886

5 Olive Mill By-products nd Orgnic Olive Orchrd Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 (25; t) nd t the end (28, tf) of the field tril in erly Decemer (t the end of the hrvest). The smples were collected t the end of the projection of the tree cnopy nd etween two trees. In prticulr, five smples were tken nd then pooled in one smple t t, eing the previous fertiliztion mngement uniformly performed with green mnure. Susequently, the field ws divided mong fertilizer tretments, thus t tf stge smpling with 3 repetitions for elementry plot ws done. The smples were oven dried, ground to pss 2-mm sieve nd then nlyzed for determining the following prmeters: totl N content (g kg 1 ), y the Kjeldhl method; ville Phosphorus (P v ; mg kg 1 ), y using the mmonium molydtescoric cid method, ccording to the Olsen nd Sommers method (Pge et l., 1982); exchngele ses (K, C, N nd Mg; mg kg 1 ) with the Pge et l. (1982) methodologies nd ssyed y ICP-OES; Totl Orgnic Cron (TOC; g kg 1 ), ccording to the Springer nd Klee (1954) method; Totl Extrctle Cron (TEC; g kg 1 ) nd humified orgnic cron ((HA+FA)- C; g kg 1 ) y the Sequi et l. (1986) procedure; soil minerl N [N-nitrte (NO 3 )+Nmmonium (NH 4 + ) exchngele] extrcted y 2M KCl (1:1, w/v), mesured y continul flow colorimetry ccording to Krom (198) nd Henriksen nd Selmer-Olsen (197) for NH 4 + -N nd NO 3 -N, respectively; Zinc (Zn), Copper (Cu), led (P), nd Nickel (Ni) (mg kg 1 ), y ICP-OES fter digestion in HNO 3 65% in pressurized microwve. Sttisticl Anlysis The sttisticl nlysis ws crried out using the Generl Liner Model Procedure (PROC GLM) of the SAS pckge (Ss Institute, 212). The yers were considered s rndom effect, wheres fertilizer tretments were known s fixed one. The differences mong the experimentl tretments were nlyzed t the P.5 proility level, y pplying the Student- Newmn-Keuls (SNK) test. The differences found with the test for different min effect nd interction comprisons were clculted using the pproprite stndrd error term. Only the min effects of experimentl tretments re presented in this pper, ecuse the lrge prt of the interctions were not significnt. PROC BOXPLOT procedure ws used to generte ox plot for yield nd pulp:pit rtio prmeters in ech tretment, thus providing quntittive informtion out these vriles. RESULTS Chrcteristics of the Experimentl Compost nd Olive Mill Wstewter Tle 1 shows some importnt chrcteristics oth of PC nd OMW tht were pplied on the olive orchrd in the three-yer field tril. The ph vlue of PC ws within the rnge of 6 to 8.5 llowed for mixed wste compost y Itlin fertilizers legisltion (Decree n. 75, 21). As consequence of good level of totl N, the C/N rtio ws fr elow the threshold (< 25), wheres C content in line with the threshold ( 2% on dry mtter sis) ws found. The contents of hevy metls in PC were ll lower thn the mximum vlues (i.e. Zn 5 mg kg -1 ; Ni 1 mg kg -1 ; Cu 23 mg kg -1 ; P 14 mg kg -1 ) estlished y the legisltion in force. The OMW showed cidic ph, high C/N rtio (due to the low N content) nd very low levels of hevy metls. Nitrte nd SPAD Mesurements nd Chemicl Composition of Leves No significnt min effect of yer ws oserved on SPAD redings (Tle 2). Conversely, NO - 3, P, nd C contents showed significnt differences. In prticulr, the lowest - NO 3 ws oserved in the first yer s compred to the others. The P ws lower in 28 thn in 26 nd 27, wheres the highest C ws found in 26 nd the other 1887

6 Montemurro et l. Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 two yers hd lower nd comprle vlues etween them (dt not shown). No significnt yer tretment interctions were found. As regrds to tretment effects, no significnt - differences were found for NO 3 vlues nd SPAD redings. By contrst, the nlysis of chemicl composition of leves in ech phenologicl stge (i.e., 1. Onset of vegettive C K C K C K growth; 2. Flowering nd fruit setting; 3. Drupe formtion, nd 4. Pit-hrdening) reveled some differences, s shown in Figure 1. In stge 1, the OF tretment determined the highest K content, wheres t stge 4, on the verge of OF nd PC, this nutrient ws higher y 11 nd 8.6% thn OMW nd MV, respectively. At stge 3 the MV determined c c P Mg P Mg P Mg C K P Mg Figure 1. Effect of fertilizer tretments (OMW= Olive Mill Wstewter; OF= Orgnic-minerl Fertilizer; PC= Olive Pomce Compost, MV= Green mnure of horse en) on C nd K leves content, nd P nd Mg contents t ech phenologicl stge (1. Onset of vegettive growth, 2. Flowering nd fruit setting, 3. Drupe formtion, nd 4. Pit-hrdening) in three yers verge. Within prmeters, different letters indicte significntly different men vlues ccording to SNK t P.5 proility level. 1888

7 Olive Mill By-products nd Orgnic Olive Orchrd Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 C content significntly higher y 26% thn PC ut comprle to the other two tretments. The highest P vlue ws oserved for PC, s compred to the other tretments, oth t stges 1 nd 3. At stge 2, OMW determined vlue comprle to OF for this prmeter, ut higher y 17 nd 31% thn PC nd MV, respectively. At stge 4, no significnt differences were found for PC with OMW nd OF tretments. Finlly, significnt differences were found for Mg vlues etween OMW nd OF t stge 2, eing the experimentl tretment higher y 25% thn the commercil one. Effects of Fertilizer Tretments on Olive Tree Performnce Significnt min effect of yer ws oserved for olive yield, which ws higher in 27 s compred to the other yers (Figure 2). In ddition, oth 26 nd 28 presented production elow the minimum men vlue recorded for the tested olive grove. The ox plot for the yield in ech tretment over the three-yer tril, representing n overview of dt distriution nd vritions, showed significnt differences etween MV nd the other tretments (Figure 3). In prticulr, OMW nd OF oth presented lrger withintretment vrince nd they showed the highest yield, which ws on verge significntly higher thn MV nd PC y 191 nd 55%, respectively. No significnt yer effect ws oserved on ll the tested yield component prmeters, unlike drupes oil production tht showed the highest vlue in 27 (Tle 3). As for the tretment effect, most prmeters, except pit weight nd drupe length, showed significnt differences. Due to the low yield under PC tretment, the fruit weight incresed. In prticulr, the PC tretment hd drupe nd pulp weights higher thn those for OF nd MV, ut comprle to OMW. Drupe weight ws higher y 43% for PC thn for the verge of OF nd MV, wheres PC showed pulp weight higher y 54% thn the verge of OF nd MV tretments. Moreover, drupe width nd pulp:pit rtio vlues were oth the highest in PC, wheres no sustntil differences were oserved for these two prmeters mong the other tretments. Despite the oserved positive results for olive yield components in PC, it showed lower drupes oil production thn OMW nd OF (y 33 nd 36%, respectively) ut higher thn MV y 93%. No significnt yer tretment interction ws found for yield nd ll the yield components. Among them it could e crucil to focus on pulp pit -1, therefore, the ox plot displyed in Figure 4 represents summry sttistics. The interqurtile rnge for MV, indicting how spred out the middle vlues re, etter shows the significnt difference with PC. The long Figure 3. Box plot for yield (kg tree -1 ) in ech tretment, over the three-yer period. Results were significnt t P.1 proility level. 1889

8 Montemurro et l. Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 Tle 3. Effects of yers nd experimentl tretments (OMW= Olive Mill Wstewter; OF= Orgnicminerl Fertilizer; PC= Olive Pomce Compost, MV= Green mnure of horse en) on olive yield components nd drupes oil production. Drupe Drupe Pulp Olive oil Pulp weight Pit weight Drupe width weight length pit -1 (g) (g) (g) (mm) (mm) (kg tree -1 ) Yer (Y) ns ns ns ns ns ns * Tretments (T) OMW OF PC MV c * * ns ns * ** *** Y T ns ns ns ns ns ns ns The vlues in the sme column followed y different letters re significntly different t P.5 (SNK). *, **, ***: Significnt t P<.5,.1 nd.1, respectively, ns= Not significnt. upper whisker mens tht vlues re vried mongst the most positive qurtile group. Finlly, rod overlp etween the OMW, OF nd PC distriutions cn lso e oserved. Effects of Fertiliztion Strtegies on Soil Prmeters Despite the different nutrient supplied y tretments (i.e., 64 g N 1 m -2 nd 24 g P 1 m -2 y OMW; 9 g N 1 m -2 nd 371 g P 1 m -2 y PC; 9 g N plnt -1 nd 314 g P plnt -1 y OF nd 645 g N 1 m -2 nd 113 g P 1 m -2 y MV), the nlysis of their effects on the soil chemicl chrcteristics t the end (tf) of the three-yer tril showed significnt differences only for C content mong mcronutrients (Tle 4). Anywy, the P v vlue notly incresed fter repeted orgnic fertilizers ppliction compred to t. The PC nd MV tretments determined the highest C content, while intermedite vlue ws found for OF nd the lowest one ws in OMW. Tretments showed sustntilly decresing nd incresing C nd Mg vlues, respectively, compred to t. No significnt differences mong tretments were oserved for TOC nd TEC prmeters. Moreover, the TEC ws sustntilly higher fter fertilizers ppliction thn t the eginning of the experimentl tril. The (HA+FA)-C lso incresed t tf in ll the tretment plots (on verge y 82%), nd PC hd the highest vlue (higher y 24% thn MV), ut comprle to tht of OMW nd OF tretment plots. No significnt differences mong tretments were found for NH 4 + -N nd NO 3 - -N, the ltter eing notly higher t tf thn t t. As for the hevy metls content, the PC tretment hd higher vlue of Zn thn MV nd OMW, ut comprle to OF tretment. No significnt differences mong tretments were found for Cu, wheres the Ni content ws higher (ut comprle to MV) oth in PC nd OMW thn in OF plot. Finlly, the P content ws prticulrly higher in PC thn in OMW (y 33%) nd MV (y 18%). DISCUSSION Effects of Fertilizer Tretments on Trees nutritionl Sttus nd Yield Performnce The lef content of K, which is one of the most importnt minerls in olive nutrition (Erel et l., 213), fell elow the sufficiency threshold of 189

9 Olive Mill By-products nd Orgnic Olive Orchrd Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 Figure 4. Box plot for pulp pit -1 in ech tretment, over the three-yer period. Results were significnt t P.1 proility level. Tle 4. Min soil prmeters t the eginning (25, t) nd t the end (28, tf) of the field tril, divided y experimentl tretments (OMW= Olive Mill Wstewter; OF= Orgnic-minerl Fertilizer; PC= Olive Pomce Compost, MV= Green mnure of horse en). Prmeters t tf F N tot (g kg -1 ) 1.23± ns P v (mg kg -1 ) 9.87± ns c K ex (mg kg -1 ) 834± ns C ex (mg kg -1 ) 4737± c ** N ex (mg kg -1 ) 231± ns Mg ex (mg kg -1 ) 128± ns TOC d (g kg -1 ) 11.3± ns TEC e (g kg -1 ) 5.89± ns (HA+FA)-C f (g kg -1 ) 3.29± * NH + 4 -N (mg kg -1 ) 1.85± ns NO 3 -N (mg kg -1 ) 4.87± ns Zn (mg kg -1 ) 33.98± c c ** Cu (mg kg -1 ) 13.38± ns Ni (mg kg -1 ) 2.99± * P (mg kg -1 ) 7.91± d c *** ph 8.1± ns The vlues in the sme column followed y different letters re significntly different t P.5 (SNK). Aville; c exchngele; d Totl Orgnic Cron; e Totl Extrcted Cron, f Humified orgnic Cron. *, **, ***: Significnt t P<.5,.1 nd.1, respectively, ns= Not significnt..8% presented y Fernández-Escor (21) only t the first phenologicl stge (Figure 1). At this stge, the OF tretment determined the highest K content. However, lthough the OF performnce ws consistent in the susequent stges, the experimentl tretments (prticulrly PC) showed similr effective outcomes. The P ws the most vrile nutrient, suggesting etter response to fertiliztion thn the others. In prticulr, the est lef P results in PC, t ll phenologicl stges except the second one, could indicte more effective relese of this nutrient from composted mterils during the cropping cycle, which cn e mtched with more fvourle soil conditions. Conversely, the MV tretment determined significntly lower lef P 1891

10 Montemurro et l. Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 concentrtion in comprison with the other tretments in stge 2, which is one of the most importnt stges for olive production. This is proly s consequence of the smller P rte supplied with MV thn with the other tretments (on verge y 63%). It ppered to e temporry result, eing lef P content from MV in the other stges comprle to OMW nd OF, showing no evidence of P deficiency. Indeed, the comprle yield, drupes oil production nd leves composition results for OMW nd OF tretments suggest their similr nd suitle P supply. This indictes the possiility to replce OF with the wstewter. Although the cidic ph of OMW, likely due to the presence of orgnic cids nd the degree of fruit ripening (Brer et l., 213), did not negtively ffect plnt performnce, minly due to the ph uffering cpcity of soil. Furthermore, this ws proly consequence of the ppliction of reltively low doses, during the period when the trees were not ctively growing, which could reduce the possiility for toxic effects. These findings were in ccordnce with those of Chrtzoulkis et l. (21) on Cretn olive orchrd. The OMW ppered to e n lterntive to the MV, likely ecuse, despite n equl N supply, OMW provided more P to trees thn MV. Under rinfed conditions s in the study re, the climte vritions likely modified soil nutrients vilility t the crucil growing stges. Indeed, the olive tree is widely known for its tendency for lternte ering, which ffects fruit yield in different yers (Mert et l., 213). This ehvior is strtegic mechnism, sving nutrient reserves for vegettive growth, to survive iotic nd iotic stresses. In spite of such evidence, s explined y Connell et l. (22) fertiliztion regimes tht improve the plnt nutritionl sttus my mitigte the lternte ering cycle. It is necessry to note tht the distriution of lterntive orgnic mterils to the soil, s in our reserch, generlly shows positive effect fter repeted pplictions. Then, testing the olive mill y-products in longer-term field experiments could reduce the iennil ering cycle of the olive trees. No differences were found mong tretments for oil yield percent, ut only mong tril yers. The oil yield ws more influenced y the hrvesting period, thn y the tretments. Thus, the olive oil production ccurtely reflected the production of drupes. Although the lower yield nd oil production results otined for PC s compred to OMW nd OF trtments, the vlues of olive yield components fter compost ppliction were ll greter then those fter green mnure. Therefore, the MV might hve determined the verge yield reduction (Figure 2), wheres OMW nd PC hd n overll similr ehvior thn the OF. These results suggest tht composts otined y olive mill y-products, replcing the widespred fertilizing methods in orgnic frms, such s MV, re suitle to sustin olive orchrd production (Toscno et l., 213). In ddition, OMW nd PC fertilizers hd the highest comprle drupe nd pulp weights, showing their nlogous positive influence on olive yield components. The lst results for PC were contrdicted y olive oil production, unlike Toscno et l. (213) findings. However, the rod overlp of the OMW, OF nd PC distriutions in the ox plot of pulp:pit rtio suggests tht differences mong tretments could e interpreted only s tendency, due to the lrge within-tretment vrince (Figure 4). Therefore, despite the fct tht the PC tretment hd the highest men vlue, the OMW, OF nd PC seem to e ll eqully sustitutle etween them. In ny cse, from the point of view of drupes oil content, the PC ppered to e s second choice etween experimentl fertilizers, ecuse OMW (s OF) determined higher vlue. Effects of Fertilizer Tretments on Soil Fertility nd Environment No increse of totl soil N from t to tf fter OMW nd PC pplictions ws found, contrry to López-Piñeiro et l. (26). In our investigted orgnic olive-grove, the lterntive fertilizers from gro-food wstes determined totl N vlues comprle to those of OF nd MV plots. Furthermore, results regrding the effects on soil fertility highlighted tht oth the OMW nd PC could e pplied s fertilizers to sustin olive tree production, due to the possiility of supplying sufficient nutrients to plnts. These results confirm the Grcí-Ruiz et l. (212) findings in similr Mediterrnen conditions. On the other hnd, the increse of P v nd exchngele K contents of the soil t tf, s 1892

11 Olive Mill By-products nd Orgnic Olive Orchrd Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 compred to t, greed with the results otined y Montemurro et l. (211) fter repeted pplictions of OMW on other crops nd confirms the findings of Fernández-Hernández et l. (214) in olive grove. Similrly, Piotrowsk et l. (26) found n increse y 65% of ville P content, in comprison with control t zero incution time, due to the ppliction of 8 m 3 h -1 OMW. The low P content t t might e ttriuted to n effect of the previous fertiliztion strtegy (i.e, repeted green mnure) likely influenced y unknown iotic nd iotic fctors. The P increse t tf ws proly otined for positive cumultive effect in the MV plots, nd for different resons in the PC plots. In prticulr, ccording to Adler nd Sikor (23), dding compost to soil cn increse wter-extrctle soil P y direct ddition, dissolution or displcement of sored P, nd reduction of sorption cpcity for P. The oserved increse in P vlues ttriutle to the orgnic fertilizers ppliction, regrdless of the P mount supplied, is lso consistent with the results of other studies with different orgnic wstes (Predes et l., 25). As highlighted y Ordoñez-Fernández et l. (27), this increse cn improve crop growth, ut cn lso rise the concentrtion of dissolved P in surfce runoff, leding to contmintion of drinking wter especilly on olive groves more susceptile to soil loss. Therefore, it is importnt to define correct doses nd time of ppliction. On the other hnd, t high ph like tht in our study site (ph 8.1), soil P could ecome immoilized y lrge concentrtions of clcium (s in the MV plots) nd therefore, portion of the dded P ecomes unville for plnt uptke (Mengel nd Kirky, 1982), especilly under prevlent dry conditions. In MV plots this outcome is supported y the lower lef P contents during the cropping cycle (Figure 1) nd it could e further explntion for yield results. The low level of (HA+FA)-C fter the MV ppliction, likely reduced the possiility of forming solule complexes with P y inding the C. Conversely, in PC plots the P immoiliztion could not occur, s demonstrted y oth the firly good nutritionl sttus nd yield outcomes mye due to the higher (HA+FA)-C content in PC thn in MV plots. The C/N vlue of the on-frm PC produced in this reserch could e considered suitle for redy-to-use products, wheres the high C/N rtio of OMW is vlue commonly found for this kind of y-product (Niounkis nd Hlvdkis, 26). The incresing vlues of TEC fter PC (nd lso OMW) pplictions suggest tht it is possile to sustitute trditionl methods for soil fertility improvement in orgnic olive groves. As discussed ove, repeted pplictions of PC lso significntly incresed the (HA+FA)-C in comprison with MV nd t, wheres comprle vlues were found with OMW nd OF plots. Anywy, Vn-Cmp et l., (24) suggested tht PC could hve longer lsting eneficil effects on soil physicl nd iologicl properties s compred to OF. It could e inferred tht using PC is prticulrly importnt in semi-rid conditions, where the griculturl soils re sujected to degrdtion due to the high minerliztion rte of orgnic mtter (Dicono nd Montemurro, 21). Similr results were found y Grcí-Ruiz et l. (212) investigting the cumultive effects of composted olive pomce. Inorgnic soil N contents lso incresed with orgnic fertilizers ppliction s compred to the t, suggesting tht minerl N hd not een immoilized during the degrdtion of lile C constituents of orgnic mterils. This is in greement to tht reported y López-Piñeiro et l. (26). It cn lso e rgued tht it is possile to sustitute MV with the experimentl fertilizers, considering the comprle minerl N results of MV with PC nd OMW ones t the end of the three-yer experiment. The incresed NO 3 - -N fter three yers of orgnic fertilizers ppliction indicted tht portion of the N, derived from the fertilizers could remin in the soil, lthough suject to losses in the rinfll occurrence, insted of eing tken up y trees. In prticulr, the NO 3 - -N, eing minimlly dsored y the soil prticles, is highly susceptile to losses into ground nd surfce wters y infiltrting wter, thus ffecting the environment (Mengel nd Kirky, 1982). These residul N concentrtions represent n importnt potentil nutrient source nd should pilot the fertiliztion progrm for the succeeding cropping cycles. Finlly, despite the low Zn, Cu nd P contents in the experimentl compost, n increse ws found in soil concentrtion of these hevy metls fter PC ppliction t tf, proly due to ccumultion effects. According to 1893

12 Montemurro et l. Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 Lkhdr et l. (29) the presence of hevy metls in composts should not ffect soil ppliction in the short-term, ecuse ccumultion in soil occurs only fter repeted pplictions on the sme site. Moderte PC doses will not cuse ny risk of toxicity, nd therefore ppliction rtes lwys hve to e chosen on the sis of limited hevy metl lodings. CONCLUSIONS Rw (OMW) nd treted (PC) olive mill wstes could ply fundmentl role in orgnic olive tree ecosystems. Our findings suggested tht, in orgnic frming, these lterntive orgnic fertilizers/mendments could sustitute trditionl methods of soil fertility improvement for olive groves, without determining detrimentl effects on soil prmeters nd olive yields. Also, the use of these y-products might represent fesile solution for their recycling, thus solving the disposl prolem, nd closing the nturl cycle of residues-resources prticulrly in orgnic horticulturl production. The reserch outcomes further suggest tht orgnic producers should tke into ccount system pproch for olive grove fertilizing, to void the ccumultion of soil minerl N, thus reducing the risk of leching in the susequent growing sesons. Our study represents contriution to step up the knowledge on the olive mill wste recycling in orgnic olive orchrds, ut further studies should e encourged in other sites under Mediterrnen conditions, lso to ssess the possile long-term effects. REFERENCES 1. Adler, P. R. nd Sikor, L. J. 23. Chnges in Soil Phosphorus Avilility with Poultry Compost Age. Commun. Soil Sci. Pln., 34(1 2): Brer, A.C., Mucieri, C., Cvllro, V., Ioppolo, A. nd Spgn, G Effects of Spreding Olive Mill Wstewter on Soil Properties nd Crops: A Review. Agr. Wter Mnge., 119: Chrtzoulkis, K., Psrrs, G., Moutsopoulou, M. nd Stefnoudki, E. 21. Appliction of Olive Mill Wstewter to Cretn Olive Orchrd: Effects on Soil Properties, Plnt Performnce nd the Environment. Agric. Ecosyst. Environ., 138: Cyuel, M. L., Sánchez-Monedero, M. A. nd Roig, A. 21. Two-phse Olive Mill Wste Composting: Enhncement of the Composting Rte nd Compost Qulity y Grpe Stlks Addition. Biodegrd., 21: Chowdhury, A. K. Md. M. B., Akrtos, C. S., Vyens, D. V. nd Pvlou, S Olive Mill Wste Composting: A Review. Int. Biodeter. Biodegr., 85: Connell, J. H., Ferguson, L., Metheney, P. D., Reyes, H., Krueger, W. H. nd Siett, G. S. 22. Effects of Folir Appliction of Ure on Olive Lef Nitrogen, Growth, nd Yield. Act Hortic., 586: Dicono, M. nd Montemurro, F. 21. Longterm Effects of Orgnic Amendments on Soil Fertility: A Review. Agron. Sustin. Dev., 3(2): Decree n.75, 29/4/21. Riordino e Revisione Dell Disciplin in Mteri di Fertilizznti, Norm Dell'rticolo. 13 Dell Legge 7 Luglio 29, n. 88". GU n /5/21. (in Itlin) 9. Dicono, M., Ferri, D., Cicci, C., Tittrelli, F., Ceglie, F., Verrstro, V., Ventrell, D., Vitti, C. nd Montemurro, F Biossys nd Appliction of Olive Pomce Compost on Emmer: Effects on Yield nd Soil Properties in Orgnic Frming. Act Agr. Scnd. B-S P, 62: Erel, R., Yermiyhu, U., Vn Opstl, J., Ben- Gl, A., Schwrtz, A. nd Dg, A The Importnce of Olive (Ole europe L.) Tree Nutritionl Sttus on Its Productivity. Sci. Hortic-Amsterdm, 159: Fernández-Escor, R. 21. Fertiliztion. In: Olive Growing, (Eds.): Brrnco, D., Fernández-Escor, R. nd Rllo, L. RIRDC, Austrli, PP Fernández-Hernández, A., Roig, A., Serrmiá, N., Grcí-Ortiz Civntos, C. nd Sánchez- Monedero, M. A Appliction of Compost of Two-phse Olive Mill Wste on Olive Grove: Effects on Soil, Olive Fruit nd Olive Oil Qulity. Wste Mnge., 34: Grcí-Ruiz, R., Ocho, M. V., Hinojos, M. B. nd Gómez-Muñoz, B Improved Soil Qulity fter 16 Yers of Olive Mill Pomce Appliction in Olive Oil Groves. Agron. Sustin. Dev., 32: Gigliotti, G., Proietti, P., Sid-Pullicino, D., Nsini, L., Pezzoll, D., Lur, R. nd 1894

13 Olive Mill By-products nd Orgnic Olive Orchrd Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 Porceddu, P. R Co-composting of Olive Husks with High Moisture Contents: Orgnic Mtter Dynmics nd Compost Qulity. Int. Biodeter. Biodegr., 67: Henriksen, A. nd Selmer-Olsen, A. R 197. Automtic Methods for Determining Nitrte nd Nitrite in Wter nd Soil Extrcts. Anlyst, 95: Kpellkis, I. E., Tsgrkis, K. P. nd Crowther, J. C. 28. Olive Oil History, Production, nd Byproduct Mngement. Rev. Environ. Sci. Biotech., 7: Krom, M. D Spectrophotometric Determintion of Ammoni: A Study of Modified Berthelot Rection Using Slicylte nd Dichloroisocynurte. Anlyst, 15: Lkhdr, A., Ben Achi, W., Montemurro, F., Jedidi, N. nd Adelly, C. 29. Effect of Municipl Solid Wste Compost nd Frmyrd Mnure Appliction on Hevy-metl Uptke in Whet. Commun. Soil Sci. Pln., 4(21): López-Piñeiro, A., Fernández, J., Rto Nunes, J.M., Grcí, A., 26. Response of Soil nd Whet Crop to the Appliction of Two-phse Olive Mill Wste to Mediterrnen Agriculturl Soils. Soil Sci., 171: López-Piñeiro, A., Alrrán, A., Nunes, J. M. Rto, Peñ, D. nd Crer, D., 211. Cumultive nd Residul Effects of Twophse Olive Mill Wste on Olive Grove Production nd Soil Properties. Soil Sci. Soc. Am. J., 75: Mengel, K. nd Kirky, E. A Principles of Plnt Nutrition. 3 Edition, Internt. Potsh Inst., Worlufen-Bern. 22. Mert, C., Brut, E., Ípek, A., 213. Quntittive Sesonl Chnges in the Lef Phenolic Content Relted to the Alternteering Ptterns of Olive (Ole europe L. cv. Gemlik). J. Agr. Sci. Tech., 15: Montemurro, F., Convertini, G. nd Ferri, D. 24. Mill Wstewter nd Olive Pomce Compost s Amendments for Rye Grss. Agronomie, 24: Montemurro, F., Dicono, M., Vitti, C., nd Deise, G. 29. Biodegrdtion of Olive Husk Mixed with Other Agriculturl Wstes. Biores. Technol., 1: Montemurro, F., Dicono, M., Vitti, C. nd Ferri, D Potentil Use of Olive Mill Wstewter s Amendment: Crops Yield nd Soil Properties Assessment. Commun. Soil Sci. Pln., 42(21): Niounkis, M. nd Hlvdkis, C. P. 26. Olive Processing Wste Mngement: Literture Review nd Ptent Survey. Wste Mngement Series 5, 2 nd Edition, Elsevier, Amsterdm, The Netherlnds. 27. Ordoñez-Fernández, R., Rodríguez-Lizn, A., Espejo-Pérez, R., González-Fernández, P. nd Svedr, M. M. 27. Soil nd Aville Phosphorus Losses in Ecologicl Olive Groves. Eur. J. Agron., 27: Pge, A. L., Miller, R. H. nd Keeny, D. R Methods of Soil Anlysis. Prt II. 2 nd Edition, Americn Society of Agronomy, Mdison, Wisconsin. 29. Pglii, M. nd Sequi, P Metodi di Anlisi Fisic del Suolo. (Ed.): Angeli, F. MIPA, Osservtorio Nzionle Pedologico e per l Qulità del Suolo, Milno. 3. Predes, C., Cegrr, J., Bernl, M. P. nd Roig, A. 25. Influence of Olive Mill Wstewter in Composting nd Impct of the Compost on Swiss Chrd Crop nd Soil Properties. Environ. Int., 31: Piotrowsk, A., Imrino, G., Ro, M. A. nd Ginfred, L. 26. Short-term Effects of Olive Mill Wste Wter (OMW) on Chemicl nd Biochemicl Properties of Semirid Mediterrnen Soil. Soil Biol. Biochem., 38: Sdi, I., Lor, Y., Rviv, M. nd Medin, S. 27. Lnd Spreding of Olive Mill Wstewter: Effects on Soil Microil Activity nd Potentil Phytotoxicity. Chemosphere, 66: SAS SAS/STAT Softwre Relese 9.3. SAS Institute Inc., Cry, NC, USA. 34. Sequi, P., De Noili, M., Leit, L., Cergignni, G., A New Index of Humifiction. Agrochimic, 3: Springer, U. nd Klee, J Prüfung der Leistungsfähigkeit von Einigen Wichtigeren Verfhren zur Bestimmung des Kohlemstoffs Mittels Chromschwefelsäure Sowie Vorschlg einer Neuen Schnellmethode. Z. Pflnzenernähr. Dng. Bodenk., 64: Therios, I. 29. Olives. In: Crop Production Science in Horticulture. CABI Pulishing, Wllingford, UK. 37. Toscno, P., Cscchi, T., Dicono, M. nd Montemurro, F Composted Olive Mill By-products: Compost Chrcteriztion nd Appliction on Olive Orchrds. J. Agric. Sci. Technol., 15: Vn-Cmp, L., Bujrrl, B., Gentile, A.-R., Jones, R.J.A., Montnrell, L., Olzl, C., 1895

14 Montemurro et l. Downloded from jst.modres.c.ir t 5:54 IRST on Fridy Octoer 12th 218 Selvrdjou, S. -K. 24. Reports of the Technicl Working Groups Estlished under the Themtic Strtegy for Soil Protection, EUR EN/3, Office for Officil Pulictions of the Europen Communities, Luxemourg, 872 PP. 39. Violnte, P. nd Sequi, P. 2. Metodi di Anlisi Chimic del Suolo. (Ed.): Angeli, F. MIPA, Osservtorio Nzionle Pedologico e per l Qulità del Suolo. : (PC) (OMW) (1 : (3 (2.. (MV) horse en (OF) - PC OMW OF OMW. PC.(%55 %191 ) PC MV.. OMV OF OF OMW PC ) OMW. ( 1896