Long term effect of wastewater irrigation of forage crops on soil and plant quality parameters

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1 Deslintion 215 (27) Long term effet of wstewter irrigtion of forge rops on soil n plnt qulity prmeters Munir J. Mohmm Rusn *, Smi Hinnwi, Lith Rousn Fulty of Agriulture, Jorn University of Siene n Tehnology (JUST), P.O. Box 33, Iri 2211, Jorn emil: mrusn@just.eu.jo Jorn University of Siene n Tehnology (JUST), P.O. Box 33, Iri 2211, Jorn Deprtment of Plnt Proution, Jorn University of Siene n Tehnology, P.O. Box 33, Iri 2211, Jorn Reeive 31 July 26; revise epte 24 Otoer 26 Astrt In this stuy, sites irrigte with wstewter for 1, 5, n 2 yers n site not irrigte were smple for soil n plnt hemil nlysis to evlute its long term effet. Long term wstewter irrigtion inrese slts, orgni mtter n plnt nutrients in the soil. Soil ph ws not onsistently ffete. Soil Cu ws not ffete y wstewter pplition while Zn, Fe n Mn ws not onsistently ffete. Wstewter irrigtion h no signifint effet on soil hevy metls (P n C) regrless of urtion of wstewter irrigtion. The rley iomss inrese with e wstewter n nutrients provie with the wstewter. However, longer perio of wstewter pplition (1 yers) resulte in lower iomss proution ut remine higher thn tht of the ontrol plnts. Plnt essentil nutrients (Totl-N, NO 3, P, n K) were higher in plnts grown in soils irrigte with wstewter. Plnt Cu, Zn, Fe, Mn inrese with 2 yers of wstewter irrigtion, then reue with longer perio. Plnt P n C inrese with wstewter irrigtion n their levels were higher the longer the perio of wstewter irrigtion. Bse on these results, it n e onlue tht proper mngement of wstewter irrigtion n perioi monitoring of soil n plnt qulity prmeters re require to ensure suessful, sfe, long-term wstewter irrigtion. Keywors: Trete wstewter; Long-term effet; Brley; Soil 1. Introution Wter is vitl resoure ut severely limite one in most ountries of the Meiterrnen region *Corresponing uthor. suh s Jorn. Therefore, there is n urgent nee to onserve n protet fresh wter n to use the wter of lower qulity for irrigtion [1]. The use of trete muniipl wstewter in ountries poor in wter resoures is less expensive n onsiere n ttrtive soure of irrigtion A speil issue evote to n inspire y WT3R, MEDA WATER Interntionl Conferene on Sustinle Wter Mngement, Rtionl Wter Use, Wstewter Tretment n Reuse, Mrrkeh, Moroo, 8 1 June /6/$ See front mtter 26 Elsevier B.V. All rights reserve. oi:1.116/j.esl...

2 144 M.J.M. Rusn et l. / Deslintion 215 (27) wter n the interest in reusing wstewter for irrigtion is rpily growing in these ountries [2]. Consequently the reuse of wstewter for griulture is highly enourge [3,4]. Irrigtion with trete muniipl wstewter is onsiere n environmentlly soun wstewter isposl prtie ompre to its iret isposl to the surfe or groun wter oies [3]. In ition, wstewter is vlule soure of plnt nutrients n orgni mtter neee for mintining fertility n proutivity levels of the soil [5]. On the other hn, wstewter my ontin unesirle hemil onstituents n pthogens tht pose negtive environmentl n helth impts [6]. Consequently, mismngement of wstewter irrigtion woul rete environmentl n helth prolems to the eosystem n humn eings [7]. When wstewter will e use ontinuously s the sole soure of irrigtion wter for fiel rops in ri regions, exessive mounts of nutrients n toxi hemil sustnes oul simultneously e pplie to the soil-plnt system. This woul use unfvorle effets on proutivity n qulity prmeters of the rops n the soil [8]. Therefore, mngement of wstewter irrigtion shoul onsier the wstewter nutrient ontent, speifi rop nutrient requirements, soil nutrient ontent n other soil fertility prmeters [3]. Wstewter is reognize to hve iret effet on soil hemil properties. It ffets supply of minerl mro n miro nutrients for plnt growth, soil ph, soil uffer pity, n soil CEC. Mohmm n Mzhreh [3] t the en of the growing seson foun tht soil ph ws signifintly lower when wstewter pplition, n they ttriute this erese to the high ontent of mmonium in wstewter, whih its nitrifition woul serve s soure of hyrogen ions thus using erese in soil ph. It hs lso een foun tht wstewter irrigtion inrese the level of soil slinity ue to the wstewter slt ontent. Other reserhers foun tht wstewter irrigtions inrese soil nitrogen N, phosphorus P n potssium K, while hevy metl levels tene to generlly inrese in soil with inresing numer of yers of irrigtion [9]. In ontrry, Mohmm n Mzhreh [3], foun tht soil Zn n Cu were not signifintly ffete y wstewter irrigtion. The mjority of the reserh onute on wstewter reuse in griulture fouses minly on its short-term effet on plnt growth n evelopment with little ttention to the hnges inue in the soil fertility n hemistry prmeters. The ojetive of this stuy ws to evlute the impt of long-term ln pplition of wstewter on soil fertility prmeters n possile umultion of hevy metls in the soil-plnt system. 2. Mterils n methos The stuy ws onute t Rmth Wstewter Tretment Plnt, Jorn. The Plnt ws estlishe in 1987 where muniipl wstewter is trete with iologil stiliztion ons. The trete wstewter hs een use to irrigte severl forge rops (Sun grss, rley, orn et.). There re sites tht hve een irrigte with wstewter for out 1, 5, or 2 yers. In this stuy, soil n plnt smples were tken from the following sites: Site 1: Soils not irrigte with wstewter (ontrol). Site 2: Soils irrigte with wstewter uring the lst 1 yers. Site 3: Soils irrigte with wstewter uring the lst 5 yers. Site 4: Soils irrigte with wstewter uring the lst 2 yers. Eh site ws ivie into three lotions or loks, n omposite soil smple from 2, 2 4, n 4 6 m soil epth ws tken from eh lok. Soil Smples were ir rie, groun, n then sieve to pss through 2-mm sieve

3 M.J.M. Rusn et l. / Deslintion 215 (27) sreen, then nlyze for hemil n physil properties. Soil smples were then nlyze for ph n for eletril onutivity (EC) in the 1:5 soil:wter extrt [1]; for totl Kjelhl nitrogen [11]; for phosphorus y extrtion with.5 M NHCO 3 [12]; for CCO 3 y i neutrliztion metho [13]; for exhngele K y extrtion with 1 M NH 4 OA [14]; for tion exhnge pity (CEC) y Polemio n Rhoes [15] n for soil texture y hyrometer metho [16]. Soil orgni mtter ws mesure y rpi oxition [17], n Fe, Zn, Cu, n Mn y extrtions with DTPA [18]. Some of the mjor soil hrteristis re presente in Tle 1. The verge vlues of Tle 1 Selete properties of the trete wstewter Prmeters Units 23 ph 7.3 Totl issolve mg L slts (TDS) NO 3 -N mg L PO 4 mg L K mg L SAR 4.6 Zn mg L 1.19 Cu mg L 1.1 Mn mg L 1.7 Fe mg L 1.87 P mg L 1.77 C mg L 1.2 physil n hemil hrteristis of the trete wstewter re reporte in Tle 2. Plnt (Horeum vuljre L.) smples were lso tken from eh lotion t the mturity stge efore nthesis. The fresh weight of vegettive prts (Biomss) ws reore, then oven-rie t 7 C, for ry-weight etermintion. Plnt smples then were groun to fine power using lortory mill with (.5 mm) sieve. Plnt smples were nlyze for totl nitrogen y Kjelhl pprtus; for NO 3 [19]; totl phosphorus, soium, potssium, zin, opper, iron, mngnese, mgnesium, mium, n le were mesure in the ry sh igestion y Atomi Asorption Spetrophotometer [2]. 3. Results n isussion 3.1. Trete wstewter hrteristis The hrteristis of wstewter use for irrigtion vrie within n mong the yers of pplition. In the verge, the wstewter is lkline with si ph vlue of 7.3 n h moerte level of totl issolve solis (TDS) of 952 mg L 1 (Tle 1). The wstewter ontins onsierle mount of nitrte, phosphte n potssium whih re onsiere essentil nutrients for improving plnt growth n soil fertility n proutivity levels. On the other hn, the onentrtions of mironutrients n hevy metls in the wstewter re reltively low n meet the stnrs for wstewter reuse in Tle 2 Brley iomss (fresh weight n ry weight) n plnt mronutrient ontent s ffete y urtion of wstewter pplition (yers) Yers Fresh weight (g m 2 ) Dry weight (g m 2 ) NO 3 -N (mg kg 1 ) N totl (%) P (%) K (%) (Control) LSD

4 146 M.J.M. Rusn et l. / Deslintion 215 (27) irrigtion. Given the ft tht these metls oul e umulte in soil n plnts with ontinuous use of wstewter in irrigtion, therefore, their perioi monitoring shoul e n importnt omponent of wstewter mngement Soil hrteristis The soil is hrterize y eing si n lreous with ph vlue of 7.8 n hs fine texture. The soil is moertely sline with high tion exhnge pity (CEC = 32.1 mol kg 1 ) n high potssium ontent, ut poor in nitrogen n phosphorus ontent Soil hemil properties Soil ph, eletril onutivity (EC) n orgni mter ontent s ffete y urtion of wstewter pplition (yers) n soil epth re shown in Fig. 1. The tretments effet on soil ph ws not onsistent. The lowest vlue of soil ph ws oserve in the 2 yers of wstewter irrigtion. The inonsisteny in wstewter irrigtion effet on soil ph ws reporte y other reserhers. Shipper et l. [21] foun tht soil ph inrese following long term wstewter irrigtion n they ttriute this inrese to the hemistry n high ontent of si tions suh s N, C n Mg in the wstewter pplie for long perio. Other reserhers foun tht soil ph erese with wstewter irrigtion ue to the oxition of orgni ompouns n nitrifition of mmonium [3,22,23]. Soil slinity, mesure s eletril onutivity (EC) of the 1:5 soil extrt in S m 1, ws signifintly higher with wstewter irrigtion (Fig. 1). Mohmm n Mzhreh [3] stte tht the inrese in EC for soil irrigte with wstewter ompre with soil irrigte with potle wter ttriute to the originl high level of (TDS) of the wstewter. The highest vlue ws oserve with 1 yers of wstewter irrigtion with teneny to e the higher with longer perio of wstewter irrigtion. In ition, slts were umulte more in the eeper soil lyers ue lehing the solule slts into eeper soil [24]. Sine these slts re wter solule, wstewter irrigtion mngement shoul onsier ensuring lehing them elow the root systems with lehing frtion of the irrigtion rte. Otherwise, ontinuous uil up of slts in the topsoil will versely ffet the tivity of the soil miroorgnisms [25], plnt growth n soil proutivity [6]. Soil orgni ontent (OM) signifintly inrese with wstewter irrigtion pplition n with inresing the perio of pplition (Fig. 1), whih is ttriute iretly to the ontents of the nutrients n orgni ompouns in the wstewter pplie. The soil OM ontents ph EC, S m 1 OM, % Durtion of wstewter pplition, yers e e Durtion of wstewter pplition, yers e Durtion of wstewter pplition, yers Fig. 1. Soil ph, eletril onutivity (EC) n orgni mter ontent s ffete y urtion of wstewter pplition (yers) n soil epth.

5 M.J.M. Rusn et l. / Deslintion 215 (27) umulte more in the topsoil in ll tretments. Vzquezmontiel et l. [22] foun no positive effet on soil orgni mtter ontent with wstewter irrigtion, while other reserhers reporte n inrese in the soil orgni mtter following wstewter irrigtion [26] where more ws umulte in the topsoil [3] Soil mronutrients Wstewter irrigtion inrese signifintly the soil N, P, n K (Fig. 2). This inrese ws the highest in the top soil ( 2 m) n for the longer perio of wstewter pplition. Severl reserhers reporte umultion of N, P, n K in the soil with wstewter pplition Soil totl N, mg L 1 Soil P, mg L 1 Soil exh. K, mg L Durtion of wstewter pplition, yers fg Durtion of wstewter pplition, yers e f gh f gh h Durtion of wstewter pplition, yers Fig. 2. Soil nitrogen (N), phosphorus (P) n exhngele (exh. K) ontents s ffete y urtion of wstewter pplition (yers) n soil epth. whih ws ttriute to the originl ontents of these nutrients in the wstewter pplie [27]. Wstewter n provie N, P, n K in mount equl to 4, 1 n 8 time of the fertilizers requirement of the forge rops [28]. These results gree with those reporte y [3,29] who foun tht extrtle phosphorus ws higher in soils irrigte with wstewter thn in soil irrigte with fresh wter or rinfll wter. Nymngr n Mzezew [3] foun in their experiment tht the onentrtion of K on the ontrol tretment ws erese within epth. An this inrese in the soil surfe ws ttriute to their high ontent in the wstewter use [3]. Consiering the vrition in the hemil omposition of the wstewter, mngement of wstewter reuse shoul ount for the N, P, n K ontent prior to etermintion of the rte of wstewter pplition Soil mironutrients n hevy metls Soil mironutrients (Cu, Zn, Fe n Mn) n hevy metls (P n C) s ffete y the urtion of wstewter irrigtion n soil epths re shown in Fig 3. There ws no signifint ifferenes in the tretment effets on soil Cu ontent. The response of other mironutrients, nmely Zn, Fe n Mn ws in generl not inonsistent. However, it n e oserve tht these mironutrients eing immoile in the soil tene to umulte in the topsoil. Other reserhers foun tht soil mironutrients were higher n minly in the top soil then erese within epth [31]. There is inonsisteny on reserh finings on the impt of wstewter irrigtion on soil mironutrients. Mohmm n Mzhreh [3] reporte n inrese in soil Fe n Mn with wstewter irrigtion n no response with regr to the soil Cu n Zn. On the other hn, Mnino n Pepper [32] foun no effet on soil mironutrients. Soil Cu n Zn h umulte signifintly in the upper (25 3 m) of soil with wstewter irrigtion [33]. In long term wstewter

6 148 M.J.M. Rusn et l. / Deslintion 215 (27) Soil Cu, mg L Durtion of wstewter pplition, yers Soil P, mg L Durtion of wstewter pplition, yers Soil Zn, mg L 1 Soil Fe, mg L Durtion of wstewter pplition, yers Durtion of wstewter pplition, yers Soil C, mg L Durtion of wstewter pplition, yers Fig. 4. Soil le (P) n mium (C) ontents s ffete y urtion of wstewter pplition (yers) n soil epth. Soil Mn, mg L irrigtion (8 yers), Christin Siee [34] foun tht the ontents of soil Cu, Zn, Mn, n Fe fter 8 were inrese ompre to the soil irrigte with potle wter. Wstewter irrigtion h no signifint effet on soil hevy metls (P n C) regrless of urtion of wstewter irrigtion nor on soil epth (Fig. 4). Christin Siee [34] reporte tht the onentrtion of (P, C) in soil horizon ( 3 m) tht hs een irrigte for more thn 8 yers were inrese thn tht irrigte uner well wter. Similr results were otine y Durtion of wstewter pplition, yers Fig. 3. Soil opper (Cu), zin (Zn), iron (Fe) n mngnese (Mn) ontents s ffete y urtion of wstewter pplition (yers) n soil epth. Brr et l. [31]. On the other hn, Mohmm n Mzhreh [3] mentione tht the onentrtions of the soil P n C were not ffete signifintly y the wstewter irrigtion. It shoul e mentione tht mismngement of wstewter irrigtion espeilly uner longterm pplition n le to toxiity prolems y hevy metls n high levels of nutrient umultion, n eteriortion of soil n rop qulity prmeters. Aumultion of mironutrients n hevy metls from wstewter pplition oul e use iretly from the wstewter omposition or iniretly through inresing soluility of the inigenous insolule soil hevy metls s result of the heltion or iifition tion of the pplie wstewter [6] Biomss n mronutrient ontents of rley plnt The effet of ifferent yers of wstewter irrigtion on fresh n ry weight (iomss) n mronutrient (N, P n K) ontents re shown in Tle 2.

7 M.J.M. Rusn et l. / Deslintion 215 (27) The iomss proution of rley s n niml fee mesure s fresh weight n ry weight in frm per one meter s shown in Tle 2, ompre to rops grown in the ontrol (where wstewter ws never pplie) iomss proution ws signifintly higher. Both e wstewter n nutrients provie with wstewter pplition n e ttriute to suh inrese in iomss proution [7]. Similr results were reporte y Dy et l. [35] who oserve tht whet irrigte with wstewter proue tller plnts, more hes per unit re, hevier sees, higher grin yiels thn i whet grown with pump wter lone. They ttriute this inrese to the nitrogen n phosphorus in the e wstewter. The highest iomss ws proue in soil uner 5 yers t nnul wstewter pplition. However, longer perio of wstewter pplition (1 yers) resulte in lower iomss proution ut remine higher thn tht of the ontrol plnts. Aumultion of slts n some nutrients n hevy metls, where their levels were the highest fter 1 yers of wstewter irrigtion, oul hve use suh reution in the plnt iomss. Hussin n Al-Sti [36] foun tht whet n rley yiel erese with irrigtion with sline wter. Plnt essentil nutrient (totl N, NO 3, P, n K) were higher in plnts grown in soils irrigte with wstewter for ifferent perios. Nitrogen ontent inrese from.66% in the ontrol to 1.1% in the 1 yers irrigtion. In ition, nitrte onentrtion inrese with longer perio of wstewter irrigtion where, it inrese from 8.7 mg kg 2 in the ontrol to the 92.7 mg kg 2 in the 1 yers irrigte with wstewter. Enhnement of plnt N ontent with wstewter pplition inites tht wstewter pplition provie the soil with these nutrients whih enhne require for plnt growth n soil fertility. However, nitrte ontent shoul e monitore perioilly to voi its umultion to ritil levels tht might ffet its qulity for niml fees. Nitrogen onentrtion in plnt shoots ws reporte to e higher when grown with wstewter [35], who foun tht N reovery in plnts with wstewter ws higher thn the N reovery in plnt mteril grown with well wter. These results were ttriute to signifint inrese in soil nitrogen with wstewter irrigtion ompre with the ontrol. On the other hn, Ppopoulos n Stylinou [37] reporte tht uring the thir irrigtion seson for trikle irrigtion otton (Gossypium hirsutum L. v.), the NO 3 -N in petioles ws greter with the trete effluent supplemente with no nitrogen, lso in lmin; NO 3 -N ws greter t smpling of the lower N level. Phosphorus onentrtion in rley shoot inrese signifintly s yers of wstewter irrigtion inrese. It inrese from (.18%) in the ontrol tretment to (.28%) in the 1 yers irrigte with wstewter. There ws no signifint ifferene in phosphorus onentrtion etween the ontrol n the 2 yers irrigte with wstewter. Preite tht the effiy of phosphorus uptke y plnts ws ontrolle preominntly y the onentrtion of HPO 4 2 n H 2 PO 4 in the soil solution, whih ws in turn ffete y the ition of wstewter to soil. Potssium onentrtion in rley shoot ws erese signifintly from (2%) in the ontrol tretment to (4%) in the 2 yers irrigte with wstewter. There ws no signifint ifferene etween 1 n 5 yers irrigte with wstewter. Other reserhers, hve reporte n inrese in P n K uptke y the plnts irrigte with trete wstewter [3,37] Mironutrients n hevy metls ontent in rley plnt Mironutrient ontents (Cu, Zn, Fe, Mn) of the plnts s ffete y urtion t wstewter pplition re shown in Tle 3. These mironutrients re essentil for plnt nutrition lthough they re require y the plnts in reltively muh smller mounts ompre to mronutrients.

8 15 M.J.M. Rusn et l. / Deslintion 215 (27) Tle 3 Plnt mironutrient n hevy metl ontents s ffete y urtion of wstewter pplition (yers) Yers Cu (mg kg 1 ) Zn (mg kg 1 ) Fe (mg kg 1 ) Mn (mg kg 1 ) P (mg kg 1 ) C (mg kg 1 ) (Control) LSD The results inite tht Cu, Zn, Fe, Mn ontents in the plnt were the highest in the plnt grown in the soil reeiving wstewter in the previous 2 yers. Other reserhers reporte n inrese in mironutrients uptke y the plnt inrese in leves of plnts irrigte with sewge wter thn tht irrigte with groun wter [3,31]. However the onentrtions of these mironutrient signifintly reue in the plnts grown in the soil reeive wstewter for longer perio nmely for 5 1 yers. It is not ler why suh rops in mironutrient onentrtion ws oserve with longer perio t wstewter pplition. One possile explntion is tht with longer perio t wstewter pplition, higher orgni ompetes oul hve een provie to the soil tht hs higher t stronger ffinity to these mironutrient thus revmp fomy insolte omplex tht re unville for plnt sorption [7]. The reltively higher mironutrient ontent in the ontrol plnt n e expline y the onentrtion/ilution effet inue with reltively lower iomss. Suh phenomenon ws oserve y other reserhers. On the other hn, the onentrtion of hevy metls (le n mium) ws higher with wstewter pplition initing onern out possile umultion in the plnt (Tle 3). Although, these onentrtion remin within the eptle level for niml fee [38], their monitory when wstewter is use for irrigtion shoul e onsiere. Le (P) inrese from 4.85 mg kg 2 for the ontrol tretment to 7.64 mg kg 2 for the 1 yers wstewter irrigtion. For C, it inrese from.24 mg kg 2 for the ontrol tretment to.33 mg kg 2 for the 1 yers irrigte with wstewter. 4. Conlusion Soil n rop qulity prmeters re signifintly ffete y long-term wstewter irrigtion. This is minly etermine y the mngement of wstewter irrigtion n its omposition. In ition, ontinuous irrigtion with wstewter my le to umultion of slts, plnt nutrients n hevy metls eyon rop tolerne levels. Therefore, these onerns shoul e essentil omponents of ny mngement of wstewter irrigtion. On the other hn, plnt growth, soil fertility n proutivity n e enhne with properly mnge wstewter irrigtion, through inresing levels of plnt nutrients n soil orgni mtter. It n e onlue, se on these results tht proper mngement of wstewter irrigtion n perioi monitoring of soil fertility n qulity prmeters re require to ensure suessful, sfe n long term reuse of wstewter for irrigtion. Referenes [1] M.F. Al-Rshe n M.M. Sherif, Wter resoures in the GCC ountries: n overview, Wter Res. Mng., 14 (1) (2) [2] A. Arr, Wter mngement n onservtion mesures uner semi-ri n ri onitions,

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