The imprint of desalinated seawater on recycled wastewater: Consequences for irrigation in Lanzarote Island, Spain

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Agricultural Water Management 116 (2013) 62– 72

Contents lists available at SciVerse ScienceDirect

Agricultural Water Management

j ourna l ho me p ag e: www.elsev ier .com/ locate /agwat

he imprint of desalinated seawater on recycled wastewater: Consequences forrrigation in Lanzarote Island, Spain

rancisco J. Díaza,∗, Marisa Tejedora, Concepción Jiméneza, Steve R. Grattanb, María Dortaa,osé M. Hernándeza

Department of Soil Science and Geology, Faculty of Biology, University of La Laguna, La Laguna 38206, Tenerife, Canary Islands, SpainDepartment of Land, Air and Water Resources, University of California, Davis, CA 95616, USA

r t i c l e i n f o

rticle history:eceived 30 June 2012ccepted 11 October 2012vailable online 8 November 2012

eywords:on-conventional water resourceseawater desalinationrid zones

a b s t r a c t

Seawater desalination and recycling of urban wastewater originating from desalinated seawater are theonly sources of irrigation water on the extremely arid (∼150 mm year−1) Spanish island of Lanzarote.Irrigation with these two types of water has been introduced over the past few decades in traditionalrainfed agriculture systems as a means to increase crop production. The present study was carried out toevaluate the long term impact (5–30 years) of irrigation with desalinated seawater (DSW) and recycledwastewater originating from desalinated water (RWW) on the island’s soils used for farming. The effectsof irrigation were studied by evaluating the chemical characteristics of the topsoil of DSW-irrigated plots,RWW-irrigated plots and adjacent rainfed plots used as controls. The data indicate that irrigation with

gricultural irrigationoil salinity

DSW and RWW has increased soil salinity by a factor of 1.9 and 3.4, respectively, and boron concentrationsby a factor of 1.8 and 1.9, respectively, in relation to the control soils. Irrigation with RWW has also led to arise in sodicity, where SAR values increased by a factor of 1.6 with respect to the control soils. Apart fromthese effects DSW irrigation was not found to cause further adverse effects in regards to soil fertility. Thelong-term sustainability of these farming systems requires substantial improvements in DSW quality,which in turn will improve the quality of the RWW.

. Introduction

In a global context of water scarcity, use of water in agriculturalystems account for approximately 87% of total water consump-ion, a figure that will likely increase to meet the growing demandor food in the future (Ben-Gal et al., 2009). As a result, alternativeources of water for irrigation will need to be developed, partic-larly in arid and semi-arid regions. Seawater desalination andecycling of domestic wastewater (originating from desalinatedater) have emerged as feasible options for irrigation (Yermiyahu

t al., 2007a; Lahav et al., 2010).New technological advances have lowered production costs

f desalinated seawater (DSW) considerably to approximately.5$/m3 of DSW (Service, 2006). Consequently, there has been anxponential increase in the world production of desalinised waterrom around 19 million m3 day−1 in 1995 to 63 million m3 day−1 in

009 (Lew et al., 2009). In many arid and semi-arid countries, suchs Israel, Spain, Australia, and the United Arab Emirates, this waters being considered as a supplemental source of irrigation water

∗ Corresponding author. Tel.: +34 696 733144.E-mail address: [email protected] (F.J. Díaz).

378-3774/$ – see front matter © 2012 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.agwat.2012.10.011

© 2012 Elsevier B.V. All rights reserved.

(Beltran and Koo-Oshima, 2006; Ghermandi and Messalem, 2009).However, the cost of desalinating seawater is still too prohibitivefor extensive use by irrigated agriculture and is economically fea-sible for only high-value cash crops (e.g. greenhouse vegetables,flowers, etc.) (Beltran and Koo-Oshima, 2006).

In arid island regions such as Lanzarote (Canary Islands, Spain),desalination has been one of the few viable options for supply-ing water for irrigation (von Medeazza, 2004). Here, irrigation withDSW was introduced in the 1980s as a supplemental source of waterto improve the production of traditional rainfed cropping systems.These systems use volcanic materials to cover the soil surface inorder to reduce surface evaporation, increase water infiltrationand optimise the salt and water balance of the rootzone (Tejedoret al., 2002, 2007). Later, in the 1990s, recycled urban waste-water originating from desalination (RWW) (99% of the island’surban water comes from seawater desalination (Hernández Suárez,2002)) began to be used for irrigation as well. Therefore, Lanzarote’sagriculture is an example of how new technologies and traditionaltechniques can be combined to increase agricultural production.

Since DSW usage in agriculture is still in the early stages, very lit-tle research has been conducted on the quality of the waters usedfor irrigation and their effects on soil properties (Ben-Gal et al.,2009). Due primarily to its low salt content, DSW is viewed by

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F.J. Díaz et al. / Agricultural W

armers as good quality water (Yermiyahu et al., 2007a), but initialxperiences have not been entirely positive (Ben-Gal et al., 2009).n Israel, one of the leading countries that have adopted specificriteria governing desalinated water for domestic and agriculturalse (Lahav and Birnhack, 2007; Yermiyahu et al., 2007a), numer-us problems associated with the use of such water for irrigationave been identified (Yermiyahu et al., 2007b). For example, very

ow Ca2+, Mg2+, SO42− and K+ concentrations have been found to

nduce deficiencies of these elements in crops such as tomatoes,asil and flowers (Ben-Gal et al., 2009). Moreover, the very lowuffering capacity of DSW can cause sudden changes in pH duringertiliser addition and can have a profound impact on nutrient avail-bility and ultimately agricultural productivity (Yermiyahu et al.,007a). In addition, very high levels of boron (B) in the water haveeen found to cause boron toxicity in a number of B-sensitive cropsYermiyahu et al., 2007a). Several problems have also been detectedfter short and mid-term irrigation with RWW (i.e. increased salin-ty, boron toxicity, and elevated SAR levels affecting soil physicalharacteristics) (Lahav et al., 2010).

Because of the concerns mentioned above, it was essential toonduct a study to evaluate the influence of water quality fromSW and RWW on the chemical and nutritional characteristics of

ocal soils. In particular, the study evaluates: (i) the chemical qual-ty of DSW and RWW used for irrigation on the island of Lanzarotend (ii) the changes in salinity, sodicity, B content and nutrients sta-us in soils caused by the introduction of DSW and RWW irrigationn relation to those that remained under rainfed systems. The mainbjective of the research was to assess the mid to long-term impactn the soils of irrigation with the aforementioned types of waternd to evaluate the sustainability of the systems’ productivity inoil quality terms. The results of the study will enable us to establishhe management measures (DSW production and agricultural tech-iques) that should be considered to correct the potential adverseffects of irrigation with these waters. The information obtainedill be directly applicable in DSW management strategies in theanaries, while also affording useful information for the desali-ation industry, farmers and water quality regulators as regardshe possible benefits of and constraints on agricultural use of DSW.iven that Lanzarote is a pioneer zone in the use of DSW irrigation,

he study will also serve as a good reference for the growing numberf water-scarce regions, which are obliged to resort to desalinations a source of water for irrigation.

. Material and methods

.1. Study zone

The study was carried out on Lanzarote, the northeastern mostsland of the Canary Island chain (Spain). It is 862 km2 in size andormed by basaltic rock of volcanic origin. This arid/semi-arid islands situated in the Atlantic Ocean, approximately 115 km off the westoast of Africa, between parallels 29◦17 and 28◦02 north latitudend meridians 13◦25 and 14◦30 west longitude. Annual precipita-ion on most of the island is below 150 mm, with no part receiving

ore than 300 mm year−1. Rainfall is seasonal (October to March)nd presents high inter-annual variability. The combination of solaradiation (annual average of 7.8 h sunshine per day), high tem-eratures (annual average of 18 ◦C) and moderate–strong windsroduce extremely high evaporation rates (≈1800 mm year−1 invaporation pan) (Tejedor et al., 2003).

Aridity, the lack of adequate surface water supplies and the

carcity of groundwater resources make desalination the most fea-ible option to meet the water needs of the population (∼141,000nhabitants). Spain’s first desalination plant was built in Lanzarotesing multistage flash technology in 1964 (Palomar and Losada,

anagement 116 (2013) 62– 72 63

2010) and the island’s production of DSW has gradually increasedto the current figure of 22.7 million m3 year−1, representing 99%of total water consumption (INALSA, personal communication).Of the total DSW, approximately 637,000 m3 year−1 are used forirrigation. Treatment of urban wastewater commenced in the1990s and the treated volume currently stands at 6.9 millionm3 year−1, of which 773,000 m3 year−1 are used in farming(INALSA, personal communication).

Traditionally, Lanzarote’s agriculture has been based on rainfedsystems known locally as “arenados” (approximately 13,669 ha)and consisting of the use of layers of basaltic pyroclasts as soilcoverings (Tejedor et al., 2002). These volcanic mulches serve asa means to increase rainwater infiltration, reduce evaporation andbuffer the soil temperature (Tejedor et al., 2003; Diaz et al., 2005).As DSW and RWW availability has increased, the systems havebeen partly converted to irrigation in an effort to raise productiv-ity. Approximately 372 and 129 ha of local farmland are currentlyirrigated with DSW and RWW, respectively, using drip and micro-sprinklers as preferred methods. The most common rainfed cropsgrown are sweet potato, onion, pumpkin and grapevine. In additionto these, tomato, watermelon, melon and assorted vegetables arealso cultivated under irrigation.

2.2. Water sampling and analysis

Three DSW and three RWW samples were taken every 15 daysover a 1-year period (June 2010–July 2011) from stop-valves onagricultural land in different parts of the island. The water was col-lected in 2 L polyethylene bottles and taken to the laboratory foranalysis.

The DSW was produced by the Punta de los Vientos desalinationplant on the outskirts of the island capital, Arrecife. The plant pre-treats the seawater by filtering with filter cartridges prior to dual-membrane reverse osmosis (RO). Sodium carbonate is added to thewater produced by the RO in order to increase the pH and the wateris then disinfected by chlorination.

The RWW came from two urban wastewater treatment plants(EDAR1 and EDAR2), which receive water from the towns ofArrecife (population ∼58,000) and Tías (population ∼20,000),respectively. The wastewater originated from DSW produced by thedesalination plant referred to above. The RWW from the two treat-ment plants will be denoted RWW1 and RWW2 here to distinguishbetween them. The treatment process consists of pre-treatment(removal of solids using filters), primary treatment (decantation),secondary treatment (biological digestion) and tertiary treatment(microfiltration and chlorination).

The following parameters were analysed in the water sam-ples: electrical conductivity (EC), pH, total suspended solids (TSS),cations (Ca2+, Mg2+, Na+, K+, NH4

+), anions (HCO3−, Cl−, SO4

2−,PO4

−, NO3−), boron (B) and chemical oxygen demand (COD). The

sodium adsorption ratio (SAR) was calculated using the equation(Ayers and Westcot, 1985):

SAR (mmol L−1)0.5 = [Na+]

{([Ca2+] + [Mg2+])/2}0.5(1)

All the analyses were performed in accordance with StandardMethods for the Examination of Water and Wastewater (APHA,1998). The differences in parameters between the DSW and RWWsamples provided information on the amounts of the various com-ponents added to the DSW during urban use.

2.3. Soil sampling and analysis

In order to evaluate the effects of irrigation with DSW andRWW on the island’s agricultural soils, samples were taken from 80

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4 F.J. Díaz et al. / Agricultural W

oil-sample pairs in October 2010; one collected from an irrigatedlot and the other from an adjacent rainfed plot. Plots, 0.2–0.4 ha

n size, were located in different areas of the island supplied withrrigation water. All the soils had 8–12 cm coverings of pyroclasts.he rainfed plots (controls) have been cultivated regularly andore or less intensively (depending on rainfall) for the last 40 years.

he irrigated plots were initially cultivated as rainfed plots but dripr micro-sprinkler irrigation was subsequently incorporated overhe past 5–30 years. The irrigation has enabled these plots to be cul-ivated more intensively, using higher planting densities. For eachample pair the soils of both plots were assumed to have simi-ar physical and chemical characteristics prior to the introductionf irrigation. Accordingly, given that fertilisation – consisting ofrganic matter and nitrogen fertilisers (sulphate and ammoniumitrate) – was similar in both, differences between the two typesf soils were considered to be due essentially to irrigation.

Three sub-samples were taken from the top layer of soil0–30 cm) and combined to form a single sample for each plot. Ofhe 80 sample pairs, 50 corresponded to soils from plots irrigatedith DSW and 30 to soils from plots irrigated with RWW.

At six sites (included in the general sample and denoted P1–P6ere), a more detailed analysis was conducted in October 2006 tovaluate the spatial variability of the chemical parameters withinhe same plot. For this purpose, 10 samples (each sample is a com-ination of three sub-samples) were taken randomly from each sitet two different soil depths (0–10 cm, 10–30 cm) in both the rainfednd irrigated plots. In P1-P3, the plots had been irrigated with DSWor 20 years, while in sites P4–P6 RWW had been used for a periodf 10 years.

The cultivated soils are most commonly classified as Haplo-ambids, Haplocalcids, Paleargids, Calciargids, Torrifluvents andetrocalcids (Soil Survey Staff, 2006) and have surface soil texturesanging from loam to clay loam.

All the soil samples were air-dried and passed through a 2 mmieve prior to analysis. The following parameters were analysed inhe samples: texture (sand, loam and clays); pH (pHe), electricalonductivity (ECe), soluble cations (Ca2+, Mg2+, Na+, and K+) andoron (Be) in saturated paste extract; exchangeable cations (Ca2+,g2+, Na+, and K+); calcium carbonate equivalent (CaCO3); organic

atter (OM); Olsen phosphorous (P-Olsen); total nitrogen (TN) and

ot water soluble boron (HWSB). The sodium adsorption ratio (SAR)as calculated from soluble cation concentrations (Ca2+, Mg2+, Na+)sing Eq. (1) and the exchangeable sodium percentage (ESPc) was

able 1eneral characterisation of the desalinated seawater (DSW) and recycled wastewater (Rean ± standard deviation; asterisks denote significant differences (p < 0.05) with respec

Parameter DSW RWW1 RWW2

pH 6.9 ± 0.6 7.2 ± 0.3* 7.1

EC (dS m−1) 0.58 ± 0.08 1.44 ± 0.22* 1.48

TSS (mg L−1) 0.75 ± 1.36 3.27 ± 9.79* 1.27

Ca2+ (mg L−1) 4.17 ± 1.33 17.3 ± 2.7* 17.7

Mg2+ (mg L−1) 5.55 ± 1.47 10.7 ± 4.3* 11.9

K+ (mg L−1) 3.98 ± 0.66 22.7 ± 2.4* 23.3

Na+ (mg L−1) 89.3 ± 10.9 197.2 ± 29.9* 213.4

SAR (mmol L−1)0.5 6.80 ± 0.56 9.25 ± 0.78* 9.63

Alkalinity (mg L−1) as CaCO3 12.7 ± 2.2 130.5 ± 58.8* 93.8

Cl− (mg L−1) 156.5 ± 20.7 295.7 ± 59.7* 324.5

S SO42− (mg L−1) 4.62 ± 1.11 20.0 ± 3.6* 17.4

P PO42− mg L−1 0.11 ± 0.17 3.04 ± 2.43* 5.54

N NO3− (mg L−1) 2.06 ± 1.46 7.86 ± 5.77* 11.0

N NH4+ (mg L−1) 0.02 ± 0.02 14.2 ± 11.9* 5.98

COD (mg L−1) 1.78 ± 2.27 28.0 ± 7.1* 26.3

B (mg L−1) 0.71 ± 0.11 0.83 ± 0.08 0.82

RWW-DSW = differences between RWW and DSW. Average values of RWW1 and RWW2 ua Values based on Yermiyahu et al. (2007a).b Values based on Pereira et al. (2011).

anagement 116 (2013) 62– 72

calculated indirectly from the SAR. All the soil analyses followedStandard Methods (Soil Survey Staff, 1996).

2.4. Leaching fraction requirements

Estimation of leaching fraction (LF) applied at sites P1–P6 wasmade using two models, the steady-state leaching model of USSL(Richards, 1954) and the WATSUIT model (Wu et al., 2012). Thesteady-state leaching model of USSL assumes complete mixingbetween irrigation water and soil water in a one-layered root zone.In this model chloride was used to express soil salinity based on thefact that this ion does not react with the adsorption complex anddoes not precipitate at the prevailing concentrations (Van Hoornet al., 1997). Therefore the leaching fraction that maintains long-term equilibrium can be calculated as follow:

LF = CliwCldw

(2)

where Cliw is the chloride concentration in the irrigation water andCldw the chloride concentration in the soil water (Clsw) as it passesjust below the rootzone. Cldw must be divided by two for the con-version into chloride concentration of the soil saturation extract(Cle).

WATSUIT is a steady-state computer model that assumes a par-ticular leaching fraction which remains constant over time. Thismodel predicts the concentrations at equilibrium of the majorcations and anions in the soil water within an irrigated rootzoneas a function of irrigation water composition, LF, soil CaCO3 pres-ence or absence, and several alternative amendment treatments.The relative water uptake is assumed to be 40, 30, 20 and 10% of thetotal for first (upper), second, third and fourth (bottom) quarters ofthe rootzone, respectively. The depth of the rootzone is assumed tobe constant and it is not defined (Wu et al., 2012). With this modelthe leaching requirements (LR) were determined by accounting forthe chemistry of the irrigation water and soil mineralogy to esti-mate the LF for which the levels of chloride in the rootzone equalsthe actual chloride values measured in the soil analysis.

For the application of the models, the average DSW and RWWvalues set out in Table 1 were used. For the WATSUIT model, thesystem was saturated with CaCO3 and different LFs were applied.The results assume equilibrium in the root zone.

WW) used for irrigation; n = 27 (biweekly sampling from June 2010 to July 2011);t to DW.

�RWW-DSW Recommendationfor DSWa

Reference limit forRWWb

± 0.3* 0.25 <8.5 8.1± 0.22* 0.88 <0.3 2.0± 1.72* 1.52 – 3.0± 3.5* 13.3 32–48 120± 3.9* 5.75 12–18 50± 5.2* 19.0 – 40± 36.8* 116.0 <20 200± 0.97* 2.64 – 6.0± 61.3* 99.5 >80 150± 64.6* 153.6 <20 360± 4.3* 14.1 >30 500± 3.69* 4.18 – 30± 4.9* 7.37 – 50± 8.56* 10.1 – 40± 6.6* 25.4 – –± 0.08 0.12 0.2–0.3 0.75

sed.

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EC

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2+ +

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-1

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SA

R (

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ol L

-1)0

.5

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ycled

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Fig. 1. Variation of chemical parameters in desalinated seawater (DSW) and rec

.5. Statistical analyses

The differences in the study parameters between DSW andWW and between the rainfed and irrigated soils in the generalample were determined using a paired-sample t-test. A Wilcoxonigned Rank Test was used for parameters not presenting a nor-al distribution (Kolmogorov–Smirnov test) and homogeneity of

ariance (Levene test). In the case of study sites P1–P6, the soilarameter differences between the rainfed and irrigated plots were

etermined for each site individually. For variables with a nor-al distribution (Kolmogorov–Smirnov test) and homogeneity of

ariance (Levene-test), an independent samples t-test was used.or those not presenting normal distribution and homogeneity of

wastewater (RWW) used for irrigation over time; mean ± standard error; n = 27.

variance, the non-parametric Mann–Whitney U test was used. Sta-tistical methods were implemented using SPSS (version 19.0). Thesignificance level for all tests was set at p < 0.05.

3. Results and discussion

3.1. Irrigation water quality. DSW vs. RWW

Table 1 shows the average values for the parameters studied in

the DSW and RWW used for irrigation, along with the variationsfrom urban usage of the DSW (RWW1 and RWW2). Also shown arethe Israeli recommendations for domestic and agricultural use ofDSW (Yermiyahu et al., 2007a), and the reference limits established

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Jun-

10

Jul-1

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Sep

-10

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-10

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-10

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-10

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ron m

g L

-1

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1.0

1.1

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RWW -1 RWW -2

cled w

be

3

wovi(awor

daftestLat(

fotiiEsfmdesrRiIRvDo

Fig. 2. Variation of boron concentration in desalinated seawater (DSW) and recy

y USEPA (USEPA, 2004) and other authors for RWW use (Pereirat al., 2011).

.1.1. Salinity and sodicityFig. 1 shows the variations of EC, cations and SAR in the irrigation

aters throughout the study period. The EC of the DSW increasedn average by 0.9 dS m−1 (≈570 mg L−1) following urban use. Thisalue is slightly higher than the range of the increase in dissolvednorganic solids (150–500 mg L−1) typically caused by domestic useCrook, 1998). Based on the average EC values noted (Table 1), therere no limitations on DSW use due to potential salinity problems,hereas slight to moderate limitations would apply in the case

f RWW (Pedrero et al., 2010). Both values are in line with thoseeported for DSW and RWW in the literature (Lahav et al., 2010).

Na+ was the cation that increased most in DSW followingomestic use (average increase of 116 mg L−1), followed by K+, Ca2+

nd Mg2+. The rise in Na+ is in line with the increases reportedor Israel (100–165 mg L−1) (Lahav et al., 2010) and is also withinhe range found by other authors (40–250 mg L−1) (Tchobanogloust al., 2003; Friedman et al., 2007). However, our data reveal a moreubstantial increase in Ca2+ (∼13.3 mg L−1) and Mg2+ (∼5.8 mg L−1)han is reported elsewhere (0–3.8 mg Ca2+ L−1 and 1.4–2.8 mg Mg2+

−1, respectively) (Lahav et al., 2010). The average values for Ca2+

nd Mg2+ in DSW are well below the ranges recommended inhe Israeli guidelines to avoid soil nutrient imbalances (Table 1)Yermiyahu et al., 2007a).

SAR values ranged from 4.8 to 8.5 (mmol L−1)0.5 in DSW androm 6.9 to 11.8 (mmol L−1)0.5 in RWW, with no clear trends evidentver time (Fig. 1). The increase is mainly due to the greater addi-ion of Na+ during urban use relative to added Ca2+ + Mg2+. SAR inrrigation water is a quantitative indicator of the risk due to sodic-ty of a soil (Lahav et al., 2010) and should be considered alongsideC in any evaluation of the potential effects of irrigation water onoil structure and water infiltration. The combination of these twoactors in the DSW and RWW studied here would result in light to

oderate restrictions on the use of the waters (Pedrero et al., 2010)ue to potential mid-long term deterioration of the physical prop-rties of the soils and the resulting impact on crop yield. Numeroustudies have reported clay dispersion problems, lower infiltrationates, lower hydraulic conductivity, etc., due to irrigation withWW (Leal et al., 2009; Muyen et al., 2011). However, no stud-

es have evaluated these processes in soils irrigated with DSW.sraeli legislation sets a maximum SAR value of 6 (mmol L−1)0.5 in

WW used for irrigation (Lahav et al., 2010). The average RWWalues found here greatly exceed this limit, as do the values forSW (Table 1). Based on the results obtained, the concentrationsf Na+, Ca2+ and Mg2+ in DSW need to be corrected and balanced

astewater (RWW) used for irrigation over time; mean ± standard error; n = 27.

to reduce considerably the current SAR values. Addition of gypsumto the water would simultaneously increase the EC and decreasethe SAR; both shifts would increase the suitability of DSW forirrigation.

Chloride was the dominant anion in both DSW and RWW,with average values of 156 and 310 mg L−1, respectively (Table 1).The Cl− levels in DSW are much higher than the maximum rec-ommended values (20 mg L−1), while in RWW they are closeto the upper limits (360 mg L−1) and restrictions on use mayapply to certain tree crops, vines and strawberries (Grieve et al.,2012). Sulphates are virtually eliminated during the desalina-tion processes and S SO4

2− levels in DSW averaged 4.6 mg L−1

but urban use increases these levels to ∼19 mg L−1 in the RWW(Table 1). The Israeli guidelines on domestic and agriculturaluse of DSW establish 30 mg L−1 as the recommended minimum,although in intensive horticulture the average S SO4

2− concentra-tion required for irrigation water is 58 mg L−1 (Yermiyahu et al.,2007a). Gypsum applications to improve the composition of waterfor soil physical conditions would also help raise the sulphateconcentrations.

3.1.2. BoronBoron levels in DSW and RWW ranged from 0.5 to 1.1 mg L−1

(Fig. 2), with slightly higher averages in the latter although the dif-ferences were not statistically significant (Table 1). These resultsindicate that practically all the B present in the water is derivedfrom the initial seawater content (∼4.5 mg L−1) and that very lit-tle (0.11 mg L−1 on average) addition takes place during domesticuse due to, for example, detergent use (Tarchitzky and Chen, 2004).The high DSW boron content is due largely to the fact that a largeportion of B in seawater takes the form of boric acid (H3BO3), withno ionic charge, which means it can pass through the RO mem-branes and a lower percentage of B is therefore eliminated (Hilalet al., 2011). Like other elements such as Na and Cl, B is unaffectedby the primary and secondary treatments in the treatment plantand the concentrations found in RWW are similar to that of thewastewater itself (Yermiyahu et al., 2011).

Although B is an essential micronutrient for plants, excessive Bis highly toxic for many crops and the difference between requiredlevels and toxic levels can be extremely small (Hilal et al., 2011;Grieve et al., 2012). Symptoms of B toxicity and reduced yield inmany crops have been reported following irrigation using DSWand RWW containing B concentrations of 0.6, 1.2 and 2.0 mg L−1

(Yermiyahu et al., 2007a, 2011). However the yield impact is largelyinfluenced by the sensitivity of the plant (Grieve et al., 2012). Inthe present study, the average B values are slightly higher than therecommended limits for irrigation with RWW (0.7 mg L−1) and well

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EC

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m-1

0

1

2

3

4

5

6

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8

rainfed s oil

soil irrigated with DSW

soil irrigated with RWW

Plot

EC

dS

m-1

0

1

2

3

4

5

6

7

8

soil dep th: 0-10 cm

soil dep th: 10-30 cm

P1 P2 P3 P4 P5 P6

* *

** *

*

*

*

*

*

F desas and

(

atp

3

iHrbaeetncDwsC

ig. 3. Electrical conductivity in rainfed soils used as controls, soils irrigated withtudy sites P1–P6 (October 2006); n = 10 per plot; boxes show 10th, 25th, 50th, 75thp < 0.05) with respect to control soils.

bove the upper limits for DSW set out in the Israeli recommenda-ions (0.2–0.3 mg L−1). However the Israeli recommendation wouldrotect even the most B-sensitive crop.

.1.3. Alkalinity and pHAlkalinity in DSW ranged from 5.5 to 24 mg L−1 CaCO3, whereas

n RWW it increased to an average of 112 mg L−1 CaCO3 (Table 1).igh DSW alkalinity values are recommended for a number of

easons: to increase buffering capacity, reduce corrosion in distri-ution systems, prevent discharge of metallic ions into the water,nd to stabilise pH where acidic or basic fertilisers are added (Lewt al., 2009; Birnhack et al., 2011). Likewise, high values are nec-ssary to stabilise the biological processes (e.g. nitrification) inreatment plants that treat wastewater originating from desali-ated water (Lew et al., 2009). For example, a low buffering capacityould seriously affect pH and, consequently, crop productivity if the

SW is mixed with other types of water, particularly groundwaterith low pH (Lahav and Birnhack, 2007). For all the above rea-

ons, the minimum recommended level of alkalinity is 80 mg L−1

aCO3 (Table 1). In any case, the DSW alkalinity found in the present

linated seawater (DSW), and soils irrigated with recycled wastewater (RWW) in90th percentiles; circles represent outliers; asterisks denote significant differences

study is below the minimum of 25 mg L−1 CaCO3 established in theEuropean Directive (Lew et al., 2009).

The pH of the DSW ranged from 5.2 to 8.6, compared to 6.3–7.6in RWW. Except for the lowest DSW values (pH < 6), which couldlead to metal corrosion problems and red water episodes due toiron addition from water pipes (Lahav and Birnhack, 2007), the pHvalues found are adequate for agriculture (Pedrero et al., 2010).The Israeli quality criteria for agricultural use of DSW recommendthat pH should be as high as possible (although always below 8.5),to favour the chemical and biological stability of the water (Lahavand Birnhack, 2007).

3.2. Effects of irrigation on soil chemical properties. Irrigationwith DSW vs. Irrigation with RWW

Table 2 presents the main physical and chemical characteris-

tics of the rainfed soils and the soils irrigated with DSW and RWWanalysed in the present study. In the DSW-irrigated soils, the soiltexture ranged from sandy-clay loam to clay, while in the soils irri-gated with RWW it varied from silty-clay loam to clay. In general,

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68 F.J. Díaz et al. / Agricultural Water Management 116 (2013) 62– 72

Table 2Chemical and physical characteristics of the surface layer (0–30 cm) of rainfed plots used as controls, plots irrigated with desalinated seawater (DSW), and plots irrigatedwith recycled wastewater (RWW), corresponding to the general sample (October 2010); mean ± standard deviation; asterisks denote significant differences (p < 0.05) withrespect to control soils.

Parameter Rainfed soils (control)n = 50

Soils irrigated with DSWn = 50

Rainfed soils (control)n = 30

Soils irrigated with RWWa

n = 30

ECe (dS m−1) 1.00 ± 0.56 1.93 ± 1.12* 0.88 ± 0.33 2.98 ± 1.66*pHe 8.2 ± 0.3 8.1 ± 0.2* 8.1 ± 0.4 7.9 ± 0.4*Exch. Ca (cmolc kg−1) 19.3 ± 4.5 20.1 ± 5.8 17.0 ± 5.3 17.0 ± 4.4Exch. Mg (cmolc kg−1) 6.23 ± 2.27 6.54 ± 2.25 5.55 ± 2.64 5.84 ± 1.76Exch. K (cmolc kg−1) 3.74 ± 1.78 4.21 ± 1.94 2.65 ± 1.14 2.55 ± 0.99Exch. Na (cmolc kg−1) 2.15 ± 1.47 2.37 ± 1.55 1.53 ± 0.88 2.31 ± 1.28*SAR (mmol L−1)0.5 4.33 ± 2.03 4.16 ± 2.08 4.18 ± 1.60 6.60 ± 2.79*ESPc (%) 4.80 ± 2.66 4.58 ± 2.72 4.62 ± 2.10 7.69 ± 3.40*CaCO3 (g kg−1) 171 ± 145 135 ± 142 61.8 ± 73.0 65.0 ± 76.0Organic C (g kg−1) 4.61 ± 2.15 4.74 ± 2.76 5.30 ± 2.56 5.94 ± 3.54TN (g kg−1) 0.56 ± 0.21 0.63 ± 0.29 0.47 ± 0.27 0.54 ± 0.36Olsen-P (mg kg−1) 6.45 ± 6.44 10.8 ± 11.3* 6.67 ± 12.1 21.9 ± 23.0*Be (mg L−1) 0.37 ± 0.23 0.68 ± 0.40* 0.29 ± 0.29 0.54 ± 0.24*HWSB (mg kg−1) 1.47 ± 0.82 2.58 ± 1.39* 1.65 ± 0.64 2.68 ± 0.97*Clay (g kg−1) 346 ± 154 375 ± 158 396 ± 109 366 ± 117Silt (g kg−1) 306 ± 102 269 ± 110 397 ± 92 392 ± 115

207 ± 108 241 ± 73

tc

3

sutofit1wvrtiubgaeRana

(di1(c1opeaDba

Fig. 4. Effect of leaching fraction on average soil water chloride (Cldw) concentra-tions in the bottom half rootzone of soils irrigated with desalinated seawater (DSW)

Sand (g kg−1) 348 ± 187 357 ± 151

a RWW1 or RWW2.

he soils had alkaline pH (average > 7.8), very low organic matterontent and considerable amounts of CaCO3.

.2.1. SalinityIn the general sample the EC of the soils (top 30 cm) increased

ignificantly as a result of irrigation, irrespective of the type of watersed (Table 2). The EC rose by an average of 0.9 and 2.1 dS m−1 inhe soils irrigated with DSW and RWW, respectively. The resultsbtained in the samples from sites P1–P6 reflected those obtainedor the general sample (Fig. 3). The EC in plots irrigated with DSWncreased 0.7 and 0.6 dS m−1 at 0–10 and 10–30 cm depth, respec-ively, while the EC of those irrigated with RWW increased by.3 dS m−1 at both depths. In general, the EC of the rainfed plotsas below 1 dS m−1, thus confirming the positive effect of the

olcanic mulch in reducing soil salinity, as reported in previousesearch (Tejedor et al., 2007). The maximum value reached inhe DSW-irrigated soils was 5.4 dS m−1, compared to 7.1 dS m−1

n those irrigated with RWW. Based on the average salinity val-es shown in Table 2, in the soils irrigated with DSW yield woulde affected in salt-sensitive crops only, whereas in those irri-ated with RWW a greater number of crops (moderately sensitivend moderately tolerant) might be affected (Landon, 1991; Grievet al., 2012). Although EC increases associated with irrigation usingWW have been reported by many researchers for various soilsnd crops (Morugán-Coronado et al., 2011; Tejedor et al., 2011),o information concerning the effect of DSW on soil salinity isvailable.

At sites P1–P6 the Cl− levels increased from 2.2 to 5.0 mmol L−1

at 0–10 cm depth), and from 3.1 to 6.7 mmol L−1 (at 10–30 cmepth) following irrigation with DSW. However, Cl− levels

ncreased from 1.8 to 6.7 (at 0–10 cm depth) and from 1.8 to1.5 mmol L−1 (at 10–30 cm depth) after irrigation with RWWdata not shown). Although the figures do not give cause for con-ern in the former case, in the soils irrigated with RWW levels of0 mmol L−1 in saturated paste extract constitute the threshold asf which crop yield may diminish due to Cl− toxicity (Kafkafi, 2011),articularly trees and vines grown on sensitive rootstocks (Grievet al., 2012). Meanwhile, SO4

2− levels at sites P1–P6 averaged 4.9

nd 6.3 meq L−1 in saturated paste extract in the soils irrigated withSW and RWW, respectively. Potential S deficiency problems notedy other authors following the use of DSW (Yermiyahu et al., 2007a)re therefore highly unlikely in the soils studied here.

and recycled wastewater (RWW), calculated using WATSUIT; leaching fractions cal-culated from actual Cldw concentration in the bottom half rootzone of study sitesP1–P6 using the steady-state leaching model of USSL.

Leaching requirements, calculated by the traditional steady-state leaching model of USSL, needed for maintaining salinity levels(expressed as Cldw concentrations) measured at the rootzone ofsites P1–P6, are shown at Fig. 4. The relationships between soilsalinity, and LF predicted using WATSUIT for DSW and RWW arealso shown in the same figure. The LR values determined by thetraditional method from Eq. (2) ranged from 0.25 to 0.40 at sitesirrigated with DSW and from 0.26 to 0.46 at sites irrigated withRWW. The LR values estimated by WATSUIT were slightly lower,ranging from 0.19 to 0.34 and from 0.19 to 0.36 for plots irrigatedwith DSW and RWW respectively. In order to keep salinity levelsunder toxicity threshold (∼10 meq Cle L−1) for sensitive crops, thetraditional model predicted LF of 0.22 and 0.42 for DSW and RWWirrigation respectively, while WATSUIT model predicted LF of 0.17and 0.34 respectively. Both model predictions fitted quite well andcould be used to estimate the long-term chloride concentration of

the rootzone at these agricultural systems.

High LF estimated here would require substantial amount ofirrigation water application. However, it should be noted thatthe mulch covering, which reduces evaporation by up to 92% in

Page 8

F.J. Díaz et al. / Agricultural Water Management 116 (2013) 62– 72 69

SA

R (

mm

ol L

-1)0

.5S

AR

(m

mo

l L-1

)0.5

0

1

2

3

4

5

6

7

8

9

10

11

12

soil dep th: 0-10 cm

Plot

0

1

2

3

4

5

6

7

8

9

10

11

12

rainfed soil

soil irrigated with DSW

soil irrigated with RWW

P1 P2 P3 P4 P5 P6

soil dep th: 10-30 cm

*

*

*

*

*

*

*

*

F th dess and

(

tesifp

wnvaaa

3

vo2Tt

ig. 5. Sodium adsorption ratio in rainfed soils used as controls, soils irrigated witudy sites P1–P6 (October 2006); n = 10 per plot; boxes show 10th, 25th, 50th, 75thp < 0.05) with respect to control soils.

hese systems (Diaz et al., 2005), can lower the ET value consid-rably, especially during the early stages of growth when mostoil water loss is due to evaporation, and thus allow the LF toncrease considerably. Moreover, seasonal leaching from rain-all would likely contribute to lowering the salinity of the soilrofile.

Our results indicate a substantial increase in salinity associatedith irrigation using DSW and RWW. The increase is more pro-ounced and is achieved in a shorter irrigation period (∼10 yearss. 20 years) in the case of RWW. Although the levels are toler-ted by the majority of the crops, adequate LF must be applied tovoid greater accumulations of salt in the root zone which coulddversely affect crop yield.

.2.2. SodicityThe results of the general sample show that the average SAR

alue of the irrigated soils increased with respect to the control soils

nly in the case of the RWW-irrigated plots, where the increase was.4 (mmol L−1)0.5 and values averaged 6.6 (mmol L−1)0.5 (Table 2).he SAR values of the DSW-irrigated plots were similar to those ofhe control plots (4.3 (mmol L−1)0.5 vs. 4.2 (mmol L−1)0.5). Likewise,

alinated seawater (DSW), and soils irrigated with recycled wastewater (RWW) in90th percentiles; circles represent outliers; asterisks denote significant differences

the values for exchangeable Na+ and ESPc increased significantlywith respect to the control plots only in the RWW-irrigated plots(Table 2). Fig. 5 gives the results for sites P1–P6. Here, two of theplots irrigated with DSW showed significant increases in SAR inthe top soil layer (0–10 cm), whereas all the RWW-irrigated soilsshowed significant increases in SAR at both depths. SAR increases insoils irrigated with RWW have been reported by numerous authors(Stevens et al., 2003; Leal et al., 2009; Muyen et al., 2011).

Sodium accumulation is one of the main problems associatedwith RWW use (Toze, 2006). Aside from direct toxicity effects, itsadverse impact on soil physical properties is well known. High SARand ESP values can cause deterioration of the physical properties inthe form of clay dispersion, resulting in structural collapse of aggre-gates, lower infiltration rates, water-logging, decreased leaching,higher soil salinity and low plant yield (Muyen et al., 2011). Lealet al. (2009), for example, found clay dispersion when the soil wasirrigated with RWW containing 120 mg Na+ L−1. Warrington et al.

(2007) reported a significant increase in clay dispersion in the uppersoil layers of loam and clay soils following intensive irrigation withRWW. Suarez et al. (2006) found adverse impacts of sodium oninfiltration in a loam soil and a clay soil when SAR values of

Page 9

70 F.J. Díaz et al. / Agricultural Water Management 116 (2013) 62– 72

Be m

g L

-1

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

Plot

Be m

g L

-1

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

rainfed s oil

soil irriga ted with DSW

soil irriga ted with RWW

P1 P2 P3 P4 P5 P6

soil dep th: 0-10 cm

soil dep th: 10-30 cm

*

*

*

*

*

*

*

*

*

*

**

F h dess h and

(

i4

isitwtLg

tbTttSacw

ig. 6. Soil solution boron (Be) in rainfed soils used as controls, soils irrigated wittudy sites P1–P6 (October 2006); n = 10 per plot; boxes show 10th, 25th, 50th, 75tp < 0.05) with respect to control soils.

rrigation water (EC = 1.0–2.0 dS m−1) were above 2 and (mmol L−1)0.5, respectively.

In the present study, the use of RWW has resulted in a signif-cant change in the soil SAR values, which can lead to more sodicoils if the average RWW SAR remains > 9 (mmol L−1)0.5 (Table 1),n which case remineralisation is advised during DSW productiono improve the proportion of Ca2+, Mg2+ and Na+ cations in theater produced. Also required are appropriate management prac-

ices, such as modifying irrigation applications to ensure higherFs to leach salts from the root zone and Ca2+ amendments such asypsum to mitigate the effects of the Na+ in soils and plants.

Although in the soils studied here there are no evident symp-oms of structural degradation and permeability problems have noteen detected, studies are required to evaluate these properties.he soil structure is unlikely to suffer degradation as long as con-inuous irrigation with RWW is maintained, due mainly to the facthat the relatively high salinity of the RWW counteracts the high

AR and resulting ESP (Muyen et al., 2011). Nonetheless, as otheruthors have noted, structural problems may set in when irrigationeases or the irrigation water is replaced with less saline/sodicater (Muyen et al., 2011).

alinated seawater (DSW), and soils irrigated with recycled wastewater (RWW) in90th percentiles; circles represent outliers; asterisks denote significant differences

3.2.3. BoronOur results show that the use of DSW and RWW has led to a

significant increase in Be and HWSB content in the irrigated plotswith respect to the rainfed plots (Table 2). In the case of the generalsample, the increase was found to be similar in both types of water(0.31 mg L−1 vs. 0.25 mg L−1 Be and 1.11 mg kg−1 vs. 1.03 mg kg−1

HWSB, in the plots irrigated with DSW and RWW, respectively). Insites P1–P6 the differences between the irrigated and non-irrigatedplots were significant in all cases at both soil depths (Fig. 6). TheRWW-irrigated soils of P4–P6 recorded the greatest increase in Be,with values averaging 1.2 and 1.0 mg L−1 for 0–10 cm and 10–30 cmdepths, respectively. For both types of water, the maximum valuesreached were 1.8–2.0 mg L−1. Other authors have reported signif-icant increases in B in soil surface layers as a result of long-termirrigation with RWW (Stevens et al., 2003; Tejedor et al., 2011).Similarly, irrigation with DSW has been found to increase soil Bcontent substantially, triggering B toxicity problems and leading to

diminished yields in sensitive crops (Yermiyahu et al., 2007a).

The soils of the present study appear to have relatively high Bretention, judging by the increases observed in HWSB, which repre-sents only a fraction of retained B. This retention capacity is affected

Page 10

ater M

bo(

i(bgsanicbigtbv

3

iDtipui(rbT

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F.J. Díaz et al. / Agricultural W

y various factors, including soil solution pH, texture, presence ofxides, carbonates, organic matter content and clay mineralogyGoldberg, 1993).

Although over 60% of the irrigated soil samples showed valuesn excess of the tolerance threshold established for sensitive plants0.7–1.0 mg L−1 Be) (Grieve et al., 2012), no toxicity symptoms haveeen observed in sensitive crops such as sweet potato and onionsrown on those soils. Boron toxicity mechanisms that operate inensitive plants are not fully understood nor how tolerant plantsvoid toxicity (Reid et al., 2004). Although some tolerance mecha-isms involve exclusion, the B concentration inside the plant tissue

s a poor indicator of B tolerance. Different varieties of the same cropan respond differently to excess B and toxicity may be influencedy the interactive effects of water stress, irrigation levels and salin-

ty (Yermiyahu et al., 2011). In this regard, it is worth noting thatrapevines – a traditional rainfed crop of major economic impor-ance to Lanzarote – are sensitive to boron and this element shoulde taken into consideration in any plans to convert the island’sineyards to irrigation with DSW and RWW.

.2.4. Organic matter and nutrientsOrganic carbon and total nitrogen levels did not increase signif-

cantly with respect to the rainfed soils following irrigation withSW or RWW (Table 2). The organic carbon results are similar

o those reported by other authors following variable periods ofrrigation with RWW (Morugán-Coronado et al., 2011). The incor-oration of easily degradable organic substances as a result of RWWse can increase both the microbial population and microbial activ-

ty and, consequently, can increase organic-matter mineralisationChen et al., 2011). In the case of total nitrogen, the addition rep-esented by RWW use (Table 1) can be offset by nitrogen leachingelow the root zone, losses to volatilisation and crop removal (Bar-al, 2011).

However, available phosphorous did increase significantly withoth types of water (Table 2). The increase noted in the DSW-

rrigated soils (∼4.4 mg kg−1) is particularly striking bearing inind that the amount of phosphorous added through the DSW is

ery low (Table 1). Palacios-Díaz et al. (2009) found similar resultshen comparing the effects of subsurface irrigation with DSW andWW in carbonated soils and attributed the increase to the mobil-

sation of residual phosphorous associated with soil carbonates as result of the combined action of microbial biomass and the dis-olving power of the DSW.

. Conclusions

The following conclusions may be drawn from the analysis ofoils irrigated with DSW and RWW and adjacent rainfed soils: (i)rrigation with DSW and RWW led to a significant increase in salin-ty and boron in the soils; in the case of the RWW-irrigated soils, thealinity levels reached could affect the yield of moderately tolerantrops; (ii) Irrigation with RWW led also to a significant increasen levels of exchangeable Na+ and SAR, whereas in most casesrrigation with DSW did not cause a significant rise in these twoarameters; iii) Contrary to the findings of other authors, irrigationith DSW did not cause nutrient imbalances (for example, Mg and

deficiency) in the study soils and even had a positive effect onssimilable phosphorous levels.

Long-term sustainability of the systems studied here requiresorrection of the aforementioned problems, essentially by improv-ng DSW quality through desalination techniques to reduce

levels and remineralisation processes to balance concentra-ions of Ca2+ and Mg2+ with respect to Na+. Also required areppropriate management practices, particularly the application ofdequate leaching fractions and calcium amendments to prevent

anagement 116 (2013) 62– 72 71

progressive increases in salinity and sodicity. Lastly, it is worthnoting the important role played in the systems by the continuedpresence and conservation of pyroclast mulches, whose positiveinfluence on evaporation processes allows irrigation water to beeconomised.

Acknowledgments

This work has been partially supported by a “Ramon y Cajal”contract from the Spanish Government (RYC-2011-07628).

References

APHA, 1998. Standard Methods for the Examination of Water and Wastewater, 20thed. APHA Publication Office, Washington, DC.

Ayers, R.S., Westcot, D.W., 1985. Water quality for agriculture. FAO Irrig. Drain. Paper29. FAO, Rome.

Bar-Tal, A., 2011. Major minerals, nitrogen in treated wastewater-irrigation. In:Levy, G., Fines, P., Bar-Tal, A. (Eds.), Treated Wastewater in Agriculture. Wiley-Blackwell Publishing Ltd., UK.

Beltran, J.M., Koo-Oshima, S., 2006. FAO expert consultation on water desalinationfor agricultural applications, Rome (Italy). FAO Land and Water Discussion Paper,No 5, 60 pp.

Ben-Gal, A., Yermiyahu, U., Cohen, S., 2009. Fertilization and blending alternativesfor irrigation with desalinated water. Journal of Environmental Quality 38,529–536.

Birnhack, L., Voutchkov, N., Lahav, O., 2011. Fundamental chemistry and engineeringaspects of post-treatment processes for desalinated water – a review. Desalina-tion 273, 6–22.

Chen, Y., Dosoretz, C.G., Katz, I., Jüeschke, E., Marschner, B., Tarchitzky, J., 2011.Organic matter in wastewater and treated wastewater-irrigated soils: proper-ties and effects. In: Levy, G., Fines, P., Bar-Tal, A. (Eds.), Treated Wastewater inAgriculture. Wiley-Blackwell Publishing Ltd., UK.

Crook, J., 1998. Water reclamation and reuse criteria. In: Asano, T. (Ed.), WastewaterReclamation and Reuse. Technomic Publisher, Lancaster, USA, pp. 627–703.

Diaz, F., Jimenez, C.C., Tejedor, M., 2005. Influence of the thickness and grain sizeof tephra mulch on soil water evaporation. Agricultural Water Management 74,47–55.

Friedman, H., Bernstein, N., Bruner, M., Rot, I., Ben-Noon, Z., Zuriel, A., Zuriel, R.,Finkelstein, S., Umiel, N., Hagiladi, A., 2007. Application of secondary-treatedeffluents for cultivation of sunflower (Helianthus annuus L.) and celosia (Celosiaargentea L.) as cut flowers. Scientia Horticulturae 115, 62–69.

Ghermandi, A., Messalem, R., 2009. Solar-driven desalination with reverse osmosis:the state of the art. Desalination Water Treatment 7, 285–296.

Goldberg, S., 1993. Chemistry and mineralogy of boron in soils. In: Gupta, U.C. (Ed.),Boron and its Role in Crop Production. CRC Press, Boca Raton, FL, pp. 3–44.

Grieve, C.M., Grattan, S.R., Maas, E.V., 2012. Plant salt tolerance. In: Wallender, W.W.,Tanji, K.K. (Eds.), ASCE Manual and Reports on Engineering Practice No. 71 Agri-cultural Salinity Assessment and Management, 2nd edition. ASCE, Reston, VA.

Hernández Suárez, M., 2002. Desalination in Canary Islands. Centro Canario del Agua,http://www.fcca.es/

Hilal, N., Kim, G.J., Somerfield, C., 2011. Boron removal from saline water: a compre-hensive review. Desalination 273, 23–35.

Kafkafi, U., 2011. Toxic elements, chlorides in treated wastewater and their effects onplants. In: Levy, G., Fines, P., Bar-Tal, A. (Eds.), Treated Wastewater in Agriculture.Wiley-Blackwell Publishing Ltd., UK.

Lahav, O., Birnhack, L., 2007. Quality criteria for desalinated water following posttreatment. Desalination 207, 286–303.

Lahav, O., Kochva, M., Tarchitzky, J., 2010. Potential drawbacks associated with agri-cultural irrigation with treated wastewaters from desalinated water origin andpossible remedies. Water Science and Technology 61, 2451–2460.

Landon, J.R., 1991. Booker Tropical Soil Manual. A Handbook for Soil Survey andAgricultural Land Evaluation in the Tropics and Subtropics. Longman Scientificand Technical, New York, 474 pp.

Leal, R.M.P., Herpin, U., da Fonseca, A.F., Firme, L.P., Montes, C.R., Melfi, A.J., 2009.Sodicity and salinity in a Brazilian Oxisol cultivated with sugarcane irrigatedwith wastewater. Agricultural Water Management 96, 307–316.

Lew, B., Cochva, M., Lahav, O., 2009. Potential effects of desalinated water qualityon the operation stability of wastewater treatment plants. Science of the TotalEnvironment 407, 2404–2410.

Morugán-Coronado, A., García-Orenes, F., Mataix-Solera, J., Arcenegui, V., Mataix-Beneyto, J., 2011. Short-term effects of treated wastewater irrigation onMediterranean calcareous soil. Soil and Tillage Research 112, 18–26.

Muyen, Z., Moore, G.A., Wrigley, R.J., 2011. Soil salinity and sodicity effects of waste-water irrigation in South East Australia. Agricultural Water Management 99,33–41.

Palacios-Díaz, M.P., Mendoza-Grimón, V., Fernández-Vera, J.R., Rodríguez-Rodríguez, F., Tejedor-Junco, M.T., Hernández-Moreno, J.M., 2009. Subsurfacedrip irrigation and reclaimed water quality effects on phosphorus and salinitydistribution and forage production. Agricultural Water Management 96,1659–1666.

Page 11

7 ater M

P

P

P

R

R

SS

S

S

S

T

T

T

2 F.J. Díaz et al. / Agricultural W

alomar, P., Losada, I.J., 2010. Desalination in Spain: recent developments and rec-ommendations. Desalination 255, 97–106.

edrero, F., Kalavrouziotis, I., Alarcón, J.J., Koukoulakis, P., Asano, T., 2010. Use oftreated municipal wastewater in irrigated agriculture – review of some practicesin Spain and Greece. Agricultural Water Management 97, 1233–1241.

ereira, B.F.F., He, Z.L., Silva, M.S., Herpin, U., Nogueira, S.F., Montes, C.R., Melfi,A.J., 2011. Reclaimed wastewater: impact on soil–plant system under tropicalconditions. Journal of Hazardous Materials 192, 54–61.

ichards, L.A., 1954. Diagnosis and improvement of saline and alkali soils. USDAAgric. Handbook, vol. 60. United State Department of Agriculture (USDA), Wash-ington, 160 pp.

eid, R.J., Hayes, J.E., Posti, A., Stangoulis, J.C.R., Graham, R.D., 2004. A critical anal-ysis of the causes of boron toxicity in plants. Plant, Cell and Environment 27,1405–1414.

ervice, R.F., 2006. Desalination freshens up. Science 313, 1088–1090.oil Survey Staff, 1996. Soil survey laboratory methods manual. Soil Survey Invest.

Rep. 42. USDA-NRCS, Natl. Soil Survey Center, Lincoln, NE.oil Survey Staff, 2006. Keys to Soil Taxonomy, 10th ed. USDA-NRCS. U.S. Gov. Print.

Office, Washington, DC.tevens, D.P., McLaughlin, M.J., Smart, M.K., 2003. Effects of long-term irrigation

with reclaimed water on soils of the Northen Adelaide Plains, South Australia.Australian Journal of Soil Research 41, 933–948.

uarez, D.L., Wood, J.D., Lesch, S.M., 2006. Effect of SAR on water infiltration undera sequential rain–irrigation management system. Agricultural Water Manage-ment 86, 150–164.

architzky, J., Chen, J., 2004. The environmentally problematic bleaching agents. In:Zoller, U. (Ed.), Handbook of Detergents. Marcel Dekker, NY, USA.

chobanoglous, G., Burton, F.L., Stensel, H.D., 2003. Wastewater Engineering: Treat-ment and Reuse, 4th ed. McGraw-Hill, New York.

ejedor, M., Jiménez, C., Díaz, F., 2002. Soil moisture regime changes in tephra-mulched soils: implications for Soil Taxonomy. Soil Science Society of AmericaJournal 66, 202–206.

anagement 116 (2013) 62– 72

Tejedor, M., Jiménez, C., Díaz, F., 2003. Volcanic materials as mulches for waterconservation. Geoderma 117, 283–295.

Tejedor, M., Jimenez, C., Díaz, F., 2007. Rehabilitation of saline soils by means ofvolcanic material coverings. European Journal of Soil Science 58, 490–495.

Tejedor, M., Jiménez, C., Hernández-Moreno, J.M., Díaz, F., 2011. Tephra-mulchedsoils irrigated with reclaimed urban wastewater in former dry-farming systemsof Lanzarote (Spain). Catena 84, 108–113.

Toze, S., 2006. Reuse of effluent water-benefits and risks. Agricultural Water Man-agement 80, 147–159.

USEPA, 2004. Guidelines for Water Reuse Office of Water. EPA/625/R-04/108. Wash-ington.

Van Hoorn, J.W., Katerji, N., Hamdy, A., 1997. Long-term salinity development in alysimeter experiment. Agricultural Water Management 34, 47–55.

von Medeazza, G.M., 2004. Water desalination as a long-term sustainable solutionto alleviate global freshwater scarcity? A North-South approach. Desalination169, 287–301.

Warrington, D.N., Goldstein, D., Levy, G.J., 2007. Clay translocation within the soilprofile as affected by intensive irrigation with treated wastewater. Soil Science172, 692–700.

Wu, L., Amrhein, C., Oster, J.D., 2012. Salinity assessment of irrigation water usingWATSUIT. In: Wallender, W.W., Tanji, K.K. (Eds.), ASCE Manual and Reports onEngineering Practice No. 71 Agricultural Salinity Assessment and Management., 2nd ed. ASCE, Reston, VA, pp. 787–800 (Chapter 25).

Yermiyahu, U., Ben-Gal, A., Keren, R., 2011. Toxic elements, boron. In: Levy, G.,Fines, P., Bar-Tal, A. (Eds.), Treated Wastewater in Agriculture. Wiley-BlackwellPublishing Ltd., UK.

Yermiyahu, U., Tal, A., Ben-Gal, A., Bar-Tal, A., Tarchitzky, J., Lahav, O., 2007a. Rethink-

ing desalinated water quality and agriculture. Science 318, 920–921.

Yermiyahu, U., Ben Gal, A., Cohen, S., Shemer, D., Golan, D.R., Bar Tal, A., 2007b.Irrigation of crops with desalinated water. Report Submitted to Chief Scientist,Israel Ministry of Agriculture and Rural Development. Project # 301-00527-05,15 pp.