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30 Pags., 3 Tabls., 9 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/01678809, Irrigation district salt balances identify the main sources and sinks of salts and quantify salt loads in irrigation return flows. Salt balances were performed in La Violada Irrigation District during the 80s (1982–1984), 90s (1995–1998) and 00s (2006–2008) decades. Total Dissolved Solids (TDS) and loads in irrigation return flows were related with changes in irrigation performance and infrastructures during these decades. TDS increased linearly to increases in Irrigation Consumptive Use Coefficient (ICUC) (P < 0.01), and decreased with increases in Drainage Fraction (DRF) (P < 0.001). The salt balances revealed that 82% of the exported salts originated from soil gypsum dissolution. Annual salt yields in return flows were high and similar in the 80s and 90s (about 19.3 Mg/ha year), and halved in the 00s (9.9 Mg/ha year) due to comparable reductions in irrigation and drainage volumes derived from a better irrigation performance. Irrigation season salt yields were high and steady around 14.1 Mg/ha for ICUC < 51% and DRF > 66%, and decreased exponentially for values above and below these thresholds, respectively. Therefore, the key management strategy to reduce salt discharge to downstream areas is to decrease drainage volumes by improving irrigation management., This work was sponsored by the Spanish Ministry of Science and Education project AGL2006-11860/AGR, the European Regional Development Fund (FEDER) and the European Union project INCO CT-2005-015031.

9 Pag., 5 Tabl., 6 Fig., Irrigated agriculture may impair negative “on-site” (i.e., soil salinization) and “off-site” (i.e., salts exported in irrigation return flows) effects. The aim of this study was to assess these effects, and the relationships between soil- and drainage-water salinity in a basin before and after the development of irrigation. Soil salinity (ECe) was estimated through electromagnetic induction (EMI) techniques (ECa) and the corresponding calibration equations, and drainage water salinity (ECdw) was measured in the outlets of 22 watersheds delineated within a 505-ha study area before (Year 2006) and after (Year 2008) irrigation development. Apparent soil EC was about 50% higher in 2008 than in 2006 due to increasing soil water contents, but estimated ECe was about 15% lower in 2008 than in 2006 due to salt leaching induced by irrigation. Drainage water EC increased by one order of magnitude from the upper (ECdw = 0.4 dS m−1) to the lower (ECdw = 4.5 dS m−1) reaches of the drainage network. The mean ECdw of the 22 watershed drainage outlets increased from pre-irrigation 2006 (2.4 dS m−1) to post-irrigation 2007 (3.1 dS m−1) and 2008 (2.7 dS m−1) years. Drainage water EC significantly depended (P < 0.001) on surface-weighted EC (ECe*) of each watershed, but the linear regressions were different in 2006 and 2008. The transformation from dryland to irrigation led to the leaching of salts and its export in the irrigation return flows. A compromise needs to be attained in the study area to achieve the beneficial “on-site” leaching of salts while minimizing the detrimental “off-site” export of salts., This study was partially supported by the European Commission (INCO-CT-2005-015031) and by an INIA (Instituto Nacional de Investigación y Tecnologia Agraria y Alimentaria, Spain) doctoral fellowship given to V. Urdanoz.

26 Pag., 6 Tabl., 6 Fig. The definitive version is available at: http://www.sciencedirect.com/science/journal/03784290, The increasing competition for good-quality waters is forcing to use saline waters for irrigation in many areas around the world. Maize (Zea mays L.) is considered a moderately sensitive crop to soil salinity, but its response to saline sprinkling irrigations and the potential benefits of irrigating at night to minimize leaf Na+ and Cl- uptake are not established. Our objective was to appraise plant ion concentrations and yields of maize subject to diurnal and nocturnal saline sprinkling irrigations. The work was performed in the Middle Ebro River Basin (NE Spain) during three years using a triple line source sprinkler system that diverts waters with an electrical conductivity gradient in-between 0.5 and 5 dS m-1. Na+ and Cl- concentrations in different plant tissues increased linearly with applied water ECaw. Plant Cl- was much higher than plant Na+ at low ECaw, but leaf ion uptake with increasing ECaw was higher for Na+ than for Cl-, and yields were more sensitive to plant Na+ than to plant Cl- accumulation. Grain yields were slightly affected by saline sprinkling irrigations in the first year, when soil salinity (ECe < 3 dS m-1) and irrigation water Na+ (12 meq l-1) and Cl- (26 meq l-1) concentrations were relatively low. Yields decreased drastically in the third year, due to increasing soil salinity (maximum ECe about 4.5 dS m-1) and irrigation water Na+ and Cl- concentrations (about 34 meq l-1). Yields in the diurnal and nocturnal sprinkler irrigations were similar, except in the second year where yield decline was somewhat lower in the nocturnal treatment. Plant Cl- was similar and plant Na+ was higher in diurnal than in nocturnal saline sprinkler irrigations, but no significant differences (P > 0.05) were found in general among the two irrigation treatments. Even though water evaporation rate was about ten times lower at night than at daytime, irrigating at night was not beneficial in maize in terms of reduced leaf Na+ and Cl- accumulation and increased yield., This study was supported by the Ministry of Education and Science of the Spanish Government (Project AGL2003-01942).

Little information is available on the quantitative effects on crops of saline sprinkler irrigations and the presumable beneficial effects of nocturnal versus diurnal irrigations. We measured crude protein content, carbon isotope discrimination and total dry matter (TDM) of alfalfa (Medicago sativa L.) subject to diurnal and nocturnal saline sprinkler irrigations. The work was carried out in Zaragoza (Spain) during the 2004–2006 growing seasons with a triple line source sprinkler system using synthetic saline waters dominated by NaCl with an irrigation water EC ranging from 0.5 to 5.6 dS m−1. The quality of alfalfa hay assessed through its crude protein concentration was not significantly affected by salinity. Carbon isotope discrimination, an indicator of the effect of osmotic stress on plant water status, tended to decrease with increases in salinity. Based on a piecewise linear response model, alfalfa grown under saline sprinkler irrigation was shown to be more tolerant (threshold soil salinity, ECe = 3.5 dS m−1) than in previous experiments under surface irrigation (threshold ECe = 2.0 dS m−1) at relatively low salinity values, but became more sensitive at higher salinity values as shown by the higher absolute slope (13.4%) for sprinkler as compared to surface irrigation (7.3%). No significant differences in TDM were found between diurnal and nocturnal saline sprinkler irrigations. The recommended practice of irrigating at night for sprinkler irrigation using saline water is therefore not supported by our results in alfalfa grown under semiarid conditions.

17 Pag., 2 Tabl., 4 Fig. The definitive version is available at: http://www.springerlink.com/content/0342-7188/, When using saline waters, sprinkling irrigation at night is a recommended practice to reduce evaporation, salt absorption by the wetted leaves and its negative effects on crops. We measured shoot ion concentrations (Cl−, Na+ and K+) and total dry matter (TDM) in alfalfa subject to diurnal and nocturnal saline sprinkler irrigations and established potential relationships among them. The work was carried out along the 2004–2006 growing seasons using EC waters from 0.5 to 5.6 dS m−1. Saline sprinkling irrigations linearly increased shoot Cl− and Na+ and decreased shoot K+. Even though daytime evaporation was much higher than nigh-time, shoot ion accumulation and TDM were similar in the diurnal and nocturnal irrigations. The salinity tolerance of alfalfa decreased in year 2006 due to increases in shoot Cl− and, particularly, shoot Na+. The lower threshold for shoot Na+ (276 meq kg−1) than for shoot Cl− (726 meq kg−1) shows that alfalfa is more sensitive to Na+ than to Cl−, and that Na+ accumulation is the preponderant cause of alfalfa yield decline after 3 years of sprinkling with saline waters., This study was supported by the Ministry of Education and Science of Spanish Government (Project AGL2003-01942).

24 Pag., 6 Tabl., 3 Fig. The definitive version is available at: http://www.springerlink.com/content/0032-079x/, We evaluated the salinity tolerance of young Tempranillo grapevines over a three year’s period, and the related effects on growth to leaf Na and Cl concentrations. Soil salinity, rootstock growth and leaf Na and Cl concentrations were measured in a drip-irrigated saline field. Salinity tolerance was determined using the slope (percent growth decline per unit increase in soil salinity) of the upper-boundary line fitted to the maximum growth-salinity observations. Based on a slope of 17.1% for the 3 years, Tempranillo was shown to be more sensitive to salinity than other reported varieties (slopes between 9.3% and 13.2%). The salinity tolerance of Tempranillo decreased along the study period. Tempranillo excluded Cl and, in particular, Na from the leaves more efficiently than other grape rootstock-scion combinations. Tempranillo was classified as moderately sensitive to salinity, and decreases in growth with increases in salinity were attributed to the osmotic effect rather than to specific ion toxicities., This study was partially supported by the European Commission (INCO-CT-2005-015031) and by an INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain) doctoral fellowship given to V. Urdanoz.

5 Pag., 1 Tabl. 2 Fig., As the pressure to use marginal or low-quality lands for crop production increases, it becomes increasingly necessary to determine the influence of stress factors such as salinity or waterlogging on crop growth and yield. This paper models the survival of olive trees (Olea europaea L. cv. Arbequina) under salinity and waterlogging field conditions. The effects of soil salinity [electrical conductivity of the saturation extract (ECe)] and waterlogging [relative ground elevation (RGE) and water table depth (WTD)] on the survival of 338 young olive trees were analyzed by logistic regression. The logit and probit models based on ECe, RGE, and WTD and their interactions were fitted to the data. Also, a nonlinear regression with 100% probability of olive survival (P) below a first ECe limit, 0% P above a second ECe limit, and a linear decrease in between (threshold-slope regression model) was fitted to the ECe data. The ECe and RGE were the two factors significantly affecting olive survival. The ECe was 7.7 dS m−1 for P = 50% (estimated median lethal ECe) and 3.7 dS m−1 for P = 95%. The threshold-slope model ECe estimates were 5.0 dS m−1 (upper threshold for unrestricted survival or P = 100%) and 10.3 dS m−1 (lower limit for the nonsurvival or P = 0%). Young olive trees were moderately tolerant to soil salinity, and their P under saline conditions was satisfactorily explained by both the logistic and the threshold-slope regression models., This study was partially supported by INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain). A Fulbright Grant and the financial sponsorship of the Spanish Ministry of Education supported Daniel Isidoro.

Irrigation return flows may induce salt and nitrate pollution of receiving water bodies. The objectives of this study were to perform a salt and nitrogen mass balance at the hydrological basin level and to quantify the salt and nitrate loads exported in the drainage waters of three basins located in a 15,500 ha irrigation district of the Ebro River Basin (Spain). The main salt and nitrogen inputs and outputs were measured or estimated in these basins along the 2001 hydrological year. Groundwater inflows in the three basins and groundwater outflow in one basin were significant components of the measured mass balances. Thus, the off-site impact ascribed solely to irrigation in these basins was estimated in the soil drainage water. Salt concentrations in soil drainage were low (TDS of around 400–700 mg/l, depending on basins) due to the low TDS of irrigation water and the low presence of salts in the geologic materials, and were inversely related to the drainage fractions (DF = 37–57%). However, due to these high DF, salt loads in soil drainage were relatively high (between 3.4 and 4.7 Mg/ha), although moderate compared to other areas with more saline geological materials. Nitrate concentrations and nitrogen loads in soil drainage were highest (77 mg NO 3 − /l and 195 kg N/ha) in basin III, heavily fertilized (357 kg N/ha), with the highest percentage of corn and with shallow, low water retention flood-irrigated soils. In contrast, the lowest nitrate concentrations and nitrogen loads (21 mg NO 3 − /l and 23 kg N/ha) were found in basin II, fertilized with 203 kg N/ha and preponderant in deep, alluvial valley soils, crops with low N requirements (alfalfa and pasture), the highest non-cropped area (26% of total) and with fertigation practices in the sprinkler-irrigated fields (36% of the irrigated area). Thus, 56% of the N applied by fertilization was lost in soil drainage in basin III, as compared to only 16% in basin II. In summary, a low irrigation efficiency coupled to an inadequate management of nitrogen fertilization are responsible for the low-salt, high-nitrate concentrations in soil and surface drainage outflows from the studied basins. In consequence, higher irrigation efficiencies, optimized nitrogen fertilization and the reuse for irrigation of the low-salt, high-nitrate drainage waters are key management strategies for a better control of the off-site pollution from the studied irrigation district.

20 Pag., 3 Tabl., 6 Fig. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1475-2743/, Diagnosis of soil salinity and its spatial variability is required to establish control measures in irrigated agriculture. This article shows the usefulness of electromagnetic (EM) and soil sampling techniques to map salinity. We analysed the salinity of a 1-ha plot of surface-irrigated olive plantation in Aragon, NE Spain, by measuring the electrical conductivity of the saturation extract (ECe) of soil samples taken at 22 points, and by reading the Geonics EM38 sensor at 141 points in the horizontal (EMH) and vertical (EMV) dipole positions. EMH and EMV values had asymmetrical bimodal distributions, with most readings in the non-saline range and a sharp transition to relatively high readings. Most salinity profiles were uniform (i.e. EMH=EMV), except in areas with high salinity and concurrent shallow water tables, where the profiles were inverted as shown by EMH > EMV, and by ECe being greater in shallow than in deeper layers. The regressions of ECe on EM readings predicted ECe with R2 > 84% for the 0–100 to 0–150 cm soil depths. We then produced salinity contour maps from the 141 ECe values estimated from the electromagnetic readings and the 22 measured values of ECe. Owing to the high soil sampling density, the maps were similar (i.e. mean surface-weighted ECe values between 3.9 dS m−1 and 4.2 dS m−1), although the electromagnetically estimated ECe improved the mapping of details. Whereas soil sampling is preferred for analysing the vertical distribution of soil salinity, the electromagnetic sensor is ideal for mapping the lateral variability of soil salinity., This article is a result of the project RTA01-001, funded by INIA (Ministry of Science and Technology of Spain). The second author was granted by Fundación Cándido Iturriaga - María Dañobeitia.

The analysis of irrigation and drainage management and their effects on the loading of salts is important for the control of on-site and off-site salinity effects of irrigated agriculture in semi-arid areas. We evaluated the irrigation management and performed the hydrosalinity balance in the D-XI hydrological basin of the Monegros Il system(Aragòn, Spain)by measuring or estimating the volume, salt concentration and salt mass in the water inputs(irrigation, precipitation and Canal scepage) and outputs(evapotranspiration and drainage)during the period June 1997—September 1998. This area is irrigated by solid-set sprinklers and center pivots, and corn and alfalfa account for 90% of the 470 ha irrigated land. The soils are low in salts(only 10% of the irrigated land is salt affected),but shallow (

Evaluation of the salt tolerance of crop cultivars under field conditions is greatly complicated by the typical temporal and spatial variability of soil salinity. We obtained the grain yield – salinity response functions of 124 barley genotypes by growing them in ten salinity treatments imposed by a Triple Line Source Sprinkler (TLS) system during five consecutive years. Additional objectives were to ascertain the consistency and reproducibility over years of these functions, to quantify the deleterious effects of saline sprinkling irrigations, and to assess correlations between salinity tolerance and leaf sap salt concentration. The consistency and reproducibility of the response functions within and between years were adequate (only 8% of the response functions were discarded for statistical reasons). The Ym (grain yield without salinity) and the EC50 (the ECe that reduces yield by 50%) estimates were not correlated (P > 0.05) suggesting that the most productive genotypes were not necessarily less salinity tolerant. Ym was positively and significantly (P < 0.01) correlated with Y6 and Y12 (fitted grain yields at ECevalues of 6 dS m-1, and 12 dS m-1, respectively), indicating that it is a useful statistic in the selection of barley genotypes most productive under medium and high salinities. Foliar salt uptake due to saline sprinkling irrigations decreased the EC50 by around 50% as compared with the salinity tolerance obtained with surface irrigation systems. No consistent relationships were found between either Ym or EC50 and the leaf sap osmotic potential, Cl, Ca, Na and K concentrations. They could not therefore be used in screening for salinity tolerance of barley. On the basis of the evidence from the present study, Ym is the best statistic for predicting the most productive barley genotypes in salt-affected soils.

11 Pags.- 4 Tabls.- 5 Figs., Limited knowledge of the physiological basis of the detrimental effects of soil salinity on growth and yield of barley and the consequent lack of suitable screening traits are two reasons for the limited success of plant breeding in saline environments. We assessed the relationships between grain yield, carbon isotope discrimination (Δ), canopy temperature, stomatal conductance, and grain ash content in a set of barley cultivars grown in a soil salinity gradient imposed by a triple-line-source sprinkler system. A linear increase in soil salinity produced significant (P0.05). A multiple linear regression of Δ, stomatal conductance and grain ash content on grain yield was highly significant (R2=0.77, P, This research was supported by a CICYT (Ministry of education, Spain) research project founds and a CONAI (Government of Aragón, Spain) fellowship to R. Isla.

8 Pags.- 3 Figs.- 1 Tabl., Soil mulching is a sensible strategy to reduce evaporation, accelerate crop development, reduce erosion and assist in weed control, but its efficiency for soil salinity control is not as well documented. The benefits of inorganic (plastic) and organic (grapevine pruning residues) mulching for soil salinity and sodicity control were quantified in a grapevine orchard (cultivars ‘Autumn’ Royal and ‘Crimson’) drip-irrigated with moderately saline waters. Soil samples were taken at the beginning and end of the 2008 and 2009 irrigation seasons in six vines of each cultivar and mulching treatment. Soil saturation extract electrical conductivity (ECe), chloride (Cle) and sodium adsorption ratio (SARe) values increased in all treatments of both grapevines along the irrigation seasons, but the increases were much lower in the mulched than in the bare soils due to reduced evaporation losses and concomitant decreases in salt evapo-concentration. The absolute salinity and sodicity daily increases in ‘Autumn’ and ‘Crimson’ 2008 and in ‘Crimson’ 2009 were on the average 44% lower in the plastic and 76% lower in the organic mulched soils than in the bare soil. The greater efficiency of the organic than the plastic mulch in ‘Crimson’ 2009 was attributed to the leaching of salts by a precipitation of 104 mm that infiltrated the organic mulch but was intercepted by the plastic mulch. Although further work is needed to substantiate these results, the conclusion is that the plastic mulch and, particularly, the organic mulch were more efficient than the bare soil for soil salinity and sodicity control., This work was financed by the CSD2006-00067project (CONSOLIDER-INGENIO 2010).

28 Pags., 4 Tabls., 6 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/03783774, Deficit irrigation strategies save water, but may enhance soil salinization and sodification when irrigated with low-quality waters. The objectives of this five-year study performed in the middle Ebro Basin (Spain) were to quantify these processes and assess their potential deleterious impact on the response of peach trees subjected to full irrigation (FULL), sustained deficit irrigation (SDI, irrigated at 62.5% of FULL) and regulated deficit irrigation (RDI, irrigated at 50% of FULL in Stage II of fruit development). In relation to FULL, water savings were 40% in SDI and 9% in RDI. Soil salinity (ECe), chloride concentration (Cle) and sodicity (SARe) measured in the saturation extract of 480 soil samples generally increased in the irrigation seasons, particularly in the more severe deficit irrigation strategy (SDI). These increases were counteracted by the leaching of salts induced by high leaching fractions (LF) and low water deficits (WD) attained during the non irrigation seasons. The changes in ECe, Cle and SARe measured between sampling dates were significantly correlated (p < 0.01) with WD and LF calculated for the periods between sampling dates. These parameters were therefore suitable to estimate the required irrigation depths for soil salinity and sodicity control. Peach trees were unaffected by the irrigation treatments, but yield productivity tended to decline above a threshold ECe of 4 dS m−1. Under the irrigation salinity (mean EC = 1.1 dS m−1) and the semiarid climatic characteristics of the study area, the three examined irrigation strategies proved to be sustainable in the five studied years., This work was financed by the CSD2006-00067 project (CONSOLIDER-INGENIO 2010).

The establishment of proper agronomical practices and plant breeding programs for saline environments is limited by the lack of adequate field screening methods. We assessed the relationships between leaf ion concentration and grain yield in a set of barley cultivars and compared their ranking for salinity tolerance established with a triple-line-source (TLS) sprinkler system, where the absorption of salts is through the leaves and the roots, with that obtained with a drip-irrigation (DI) system, where the absorption of salts is only through the roots. The saline solution in both systems was made up of sodium and hydrated calcium chloride (1:1 w/w). Except for the highest saline treatments, direct leaf absorption of toxic Na+ and Cl- was minor or negligible, but it was substantial for Ca2+. Irrespective of barley cultivar and leaf age, the accumulation of Cl- in the TLS was 1.5–2.5 times greater than Na+. There was no significant correlation between grain yield and leaf sap ion concentration among eighteen barley cultivars. Thus, leaf ion concentrations should not be used as screening tools in breeding programs for increasing salinity tolerance in barley. The highest-yielding cultivars under non-saline conditions were also most productive under moderately saline conditions, though not under high-saline conditions. Although grain yields of the eighteen barley cultivars in the TLS were substantially lower than in the DI, the salinity tolerances estimated in both systems were significantly correlated (P < 0.05), indicating that the simple and inexpensive TLS irrigation system could be successfully used in screening for salinity tolerance in barley.

13 Pags., 3 Tabls., [ES] El riego por goteo enterrado (RGE) ha despertado en los últimos años un interés creciente en España debido a que su baja presión de trabajo y su menor coste energético, junto con otras potenciales ventajascomparativas, puede hacerlo más rentable que otros sistemas de riego (aspersión en particular). Este trabajo revisa las principales ventajas y limitaciones del RGE, con un énfasis particular en los problemas dediseño, manejo y mantenimiento del sistema, así como en la salinización potencial del suelo superficialen zonas áridas o semiáridas regadas con aguas de baja calidad. El RGE bien diseñado, manejado y man-tenido, ha demostrado ser rentable y sostenible. Sin embargo, el RGE tiene inconvenientes relacionadoscon las características del agua de riego, del suelo y de los cultivos que pueden comprometer su sostenibilidad y rentabilidad. Las ventajas y limitaciones del RGE deben por lo tanto evaluarse en cada casoparticular con el objetivo de proporcionar recomendaciones sólidas a los agricultores., [EN] Subsurface drip irrigation (SDI) has attracted an increasing interest in Spain in the last years due to its low operating pressure and lower energy cost that, coupled to other potential advantages, can makeit more profitable than other irrigation systems (sprinkler systems in particular). This work reviews themain benefits and constraints of SDI, with special emphasis on design, management and maintenance problems, as well as on the potential salinization of surface soils in arid and semiarid areas irrigated with low quality waters. Well designed, operated and maintained SDI systems have shown to be profitable and sustainable. Never the less, SDI has drawbacks in relation to certain irrigation water, soil and crop characteristics that can jeopardize its sustainability and profitability. Therefore, the advantages and limitations of SDI must be evaluated on a case-by-case basis with the objective of providing solid recommendations to farmers.

9 Pags.- 3 Tabls.- 2 Figs., Brief pre- and post-irrigation sprinkling treatments using freshwater were tested to determine if these practices could reduce the uptake of salts through leaves when saline water is used to sprinkler irrigate crops. Maize and barley were sprinkler irrigated 2 to 3 times per week for 30 min with saline water (4.2 dS m−1, 30 mmol L−1 NaCl and 2.8 mmoles L−1 CaCl2 for maize and 9.6 dS m−1, 47 mmoles L−1 NaCl and 23.5 mmoles L−1 CaCl2 for barley) in separate experiments with plants grown in pots outdoors. The soil surface of all pots was covered to prevent salinization of the soil by the sprinkling water. One half of the sprinkled plants was grown in nonsaline soil to study the effects of pre-wetting and post-washing when ion uptake was primarily through leaves. The other half of the sprinkled plants was grown in soil salinized by drip irrigation, in order to evaluate the effects of pre-wetting and post-washing when Na+ and Cl- uptake was through both leaves and roots. Post-washing with freshwater (5 min) reduced the leaf sap concentrations of Cl- in saline-sprinkled plants from 56 to 43 mmol L−1 in maize and from 358 to 225 mmol L−1 in barley (averages for plants grown in nonsaline and saline soil). Na+ concentrations in leaf sap were reduced from 93 to 65 mmoles L−1 (maize) and from 177 to 97 mmoles L−1 (barley) by the post-washing. Pre-wetting had a small effect on ion uptake through leaves, the only significant reduction in seasonal means being in leaf Na+ concentrations for plants grown in nonsaline soil. Pre-wetting and post-washing, when combined, reduced leaf Cl- concentrations to levels similar to those of nonsprinkled plants grown in saline soil; however, Na+ concentrations in leaves remained 3.5 times (maize) and 1.5 times (barley) higher than those of nonsprinkled plants. When pre-wetting and post-washing were not applied, sprinkled barley plants grown in saline soil had grain yields which were 58% lower than nonsprinkled plants grown in saline soil, but the reduction in grain yield was only 17% when the freshwater treatments were given. We conclude that a brief period of post-washing with freshwater is essential when saline water is employed in sprinkler irrigation. By comparison, the benefits from pre-wetting were small in these experiments. ei]T J Flowers, This work was financially supported by the STD program of the European Union and by the Interministry Commission of Science and Technology of Spain. The first author was supported for two years by the Spanish government, through the fellowship ‘Temporary Stays of Foreign Scientists and Technical Experts in Spain’ of the Ministry of Education and Science.

50 Pags., 1 Tabl., 8 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/00221694, The measurement of the soil solution electrical conductivity (σw) is critical for a better management of irrigation water and the effective monitoring and control of soil salinity. The objective of this work is to present the design and validation of a new time domain reflectometry (TDR) probe (WECP) for accurate and non-destructive measurements of σw. The probe consists in 14 porous ceramics disks (0.5 bar bubbling pressure) arranged along the axis of a three-rod TDR probe. Using the Mualem and Friedman (1991) model, σw was estimated from the volumetric water content (θ) and the bulk electrical conductivity (σa) measured in the ceramic disk set of known pore-geometry. The τ and β factors, which describe the complex geometry of the ceramic matrix, were calculated by immersing the probe in NaCl solutions of different electrical conductivities, and in a pressure cell wetted and drained with these NaCl solutions, respectively. The reliability of the WECP was validated under laboratory and field conditions. The laboratory experiment consisted of the TDR probe inserted in a pressure cell packed with mixed sand and 2-mm sieved loam soil that was subsequently wetted and drained with different NaCl solutions at various pressure heads. The σw estimated by WECP was compared to the σw measured in the draining solutions after they stabilized in the soil porous system. The field experiment compared the σw estimated by WECP with the corresponding σw values measured in the soil solution extracted with three ceramic tension lysimeters (TLs) after successive wetting and drainage cycles. The τ and β factors calculated for the ceramic disks set were 1.957 and 4.282, respectively. High and significant correlations were found in both laboratory (R2 = 0.98; P < 0.001) and field (R2 = 0.97; P < 0.001) experiments between the σw estimated by the WECP and the corresponding σw values measured in the column-drainage or TL-extracted soil solutions, respectively. These results demonstrate that the WECP is a feasible instrument to accurately estimate soil solution salinity independently of the soil water content and the porous medium in which the TDR probe is installed., This research was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain (Grant AGL2010-22050-CO3-02/AGR). C. Peña was awarded with a FPI fellowship by the Spanish Ministry of Science and Innovation.

25 Pag., 6 Tabl., 1 Fig. The definitive version is available at: http://www.sciencedirect.com/science/journal/03783774, Irrigated agriculture is threatened by soil salinity in numerous arid and semiarid areas of the Mediterranean basin. The objective of this work was to quantify soil salinity through electromagnetic induction (EMI) techniques and relate it to the physical characteristics and irrigation management of four Mediterranean irrigation districts located in Morocco, Spain, Tunisia and Turkey. The volume and salinity of the main water inputs (irrigation and precipitation) and outputs (crop evapotranspiration and drainage) were measured or estimated in each district. Soil salinity (ECe) maps were obtained through electromagnetic induction surveys (ECa readings) and district-specific ECa–ECe calibrations. Gravimetric soil water content (WC) and soil saturation percentage (SP) were also measured in the soil calibration samples. The ECa–ECe calibration equations were highly significant (P < 0.001) in all districts. ECa was not significantly correlated (P > 0.1) with WC, and was only significantly correlated (P < 0.1) with soil texture (estimated by SP) in Spain. Hence, ECa mainly depended upon ECe, so that the maps developed could be used effectively to assess soil salinity and its spatial variability. The surface-weighted average ECe values were low to moderate, and ranked the districts in the order: Tunisia (3.4 dS m−1) > Morocco (2.2 dS m−1) > Spain (1.4 dS m−1) > Turkey (0.45 dS m−1). Soil salinity was mainly affected by irrigation water salinity and irrigation efficiency. Drainage water salinity at the exit of each district was mostly affected by soil salinity and irrigation efficiency, with values very high in Tunisia (9.0 dS m−1), high in Spain (4.6 dS m−1), moderate in Morocco (estimated at 2.6 dS m−1), and low in Turkey (1.4 dS m−1). Salt loads in drainage waters, calculated from their salinity (ECdw) and volume (Q), were highest in Tunisia (very high Q and very high ECdw), intermediate in Turkey (extremely high Q and low ECdw) and lowest in Spain (very low Q and high ECdw) (there were no Q data for Morocco). Reduction of these high drainage volumes through sound irrigation management would be the most efficient way to control the off-site salt-pollution caused by these Mediterranean irrigation districts., This study was supported by the European Commission research project INCO-CT-2005-015031.

22 Pag., 5 Tabl., 3 Fig. The definitive version is available at www.springerlink.com, Olive is considered moderately tolerant to salinity, but most studies are short in duration and report its tolerance on the basis of targeted irrigation water salinity (ECiw) rather than on measured root zone soil salinity (ECe). We evaluated the growth (tree height and trunk diameter) and yield (fruit and oil weights) response of two drip-irrigated young olive cultivars (Arbequina and Empeltre) subject to three ECiw treatments (2, 4 and 10 dS m−1). The ECe of 23 Arbequina and 20 Empeltre trees was intensively monitored during the 2003–2007 study period using an EM38 sensor and converting its readings into ECe through sensor calibration. For growth, the slopes of the linear regression equations (−3% to −5%) and the ECe50 estimates (12.5–14.0 dS m−1) were similar in both cultivars and vegetative traits. Likewise, for yield the slopes of the linear regression equations (−4% to −7%) and the ECe50 estimates (7.9–9.6 dS m−1) were similar in both cultivars and yield traits. Based on mean ECe50 estimates, olive vegetative growth was ranked as moderately tolerant (mean ECe50 = 13.2 dS m−1), whereas olive and oil yields were ranked as moderately sensitive (mean ECe50 = 8.7 dS m−1)., This study was financed by projects RTA01-001 and RTA04-050 of INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain).

Soil salinity is a major threat in irrigated agriculture because of its negative on-site (decreased productivity) and off-site (salinization of irrigation return flows) effects. The delineation of the spatial variability of soil salinity is best suited using non-invasive geophysical measurements of the apparent soil electrical conductivity (ECa) using mobile GPS-based systems. Two simple and cost-effective Mobile Georeferenced Electromagnetic Sensors (MGES) developed in Aragón and Navarra (Spain) are described. These devices involve electromagnetic instruments towed by all terrain vehicles and combined with GPS units and data acquisition systems that collect both ECa readings and GPS coordinates. Two applications of the MGES aimed at delineating ECa maps for (1) selecting the most suitable crops in a 43-ha saline site (Hondo de Espartosa) and (2) correlating ECa with drainage water salinity to ascertain the salinity-source areas in a new 715 ha irrigated basin (Barranco de Lerma) were examined. These examples demonstrate the MGES surveying capacities for management of salt-affected agricultural areas. La salinidad del suelo es una importante amenaza para la agricultura de regadío debido a sus efectos negativos internos (descenso de la productividad) y externos (salinización de los flujos de retorno del riego). El procedimiento más adecuado para delinear la variabilidad espacial de la salinidad edáfica es mediante la medida geofísica de la conductividad eléctrica aparente del suelo (ECa) efectuada con sistemas móviles georreferenciados. En este trabajo se describen dos Sensores Electromagnéticos Móviles Georreferenciados (MGES) sencillos y económicos desarrollados en Aragón y Navarra (España). Estos equipos incluyen instrumentos electromagnéticos arrastrados por un vehículo todo terreno, combinados con una unidad de GPS y un sistema de adquisición de datos que recopila las lecturas de ECa y las coordenadas geográficas. Se presentan dos aplicaciones del MGES en las que se levantan mapas de ECa para (1) seleccionar los cultivos más apropiados en un regadío salino de 43 ha (Hondo de Espartosa) y (2) correlacionar la ECa con la salinidad de las aguas de drenaje para identificar las áreas-fuente mas importantes de salinidad en una nueva cuenca de regadío de 715 ha (Barranco de Lerma). Estos ejemplos demuestran las capacidades de análisis del MGES para el manejo de áreas agrícolas afectadas por salinidad.

10 Pag., 4 Tabl., 9 Fig., Salt loading in irrigation return flows contributes to the salinization of the receiving water bodies, particularly when originated in salt-affected areas as frequently found in the middle Ebro River basin (Spain). We determined the salt loading in La Violada Gully from the total dissolved solids (TDS) and flows (Q) during the 1995 to 1998 hydrological years. Since this gully collects flows from various sources, an end-member mixing analysis (EMMA) was performed to quantify the drainage flow from La Violada Irrigation District (VID). Three flow components were identified in La Violada Gully: drainage waters from VID (Qd); tail-waters from irrigation ditches, spill-over, and seepage from the Monegros Canal (Qo); and ground water inflows (Qg) originating in the dryland watershed. Gypsum in the soils of VID was the main source for salts in La Violada Gully (flow-weighted mean TDS = 1720 mg L−1, dominated by sulfate and calcium). The contribution of Qg to the total gully flow during the 1996 irrigation season was low (6.5% of the total flow). The 1995 to 1998 annual salt load average in La Violada Gully was 78 628 Mg, 71% of which was exported during the irrigation season. The 1995 to 1998 irrigation season salt load average in Qd was 43 015 Mg (77% of the total load). Thus, irrigated agriculture in VID was the main source of salt loading in this gully, with a yield of 11.1 Mg of salts per hectare of irrigated land for the irrigation season. Efficient irrigation systems and irrigation management practices that reduce Qd are key factors for controlling off-site salt pollution of these gypsum-rich irrigated areas., This study was funded by the Spanish Institute of Agricultural Research and Technology (INIA). A Fulbright Grant and the financial sponsorship of the Spanish Ministry of Education supported Daniel Isidoro.

This work analyzes the effect of soil salinity on olive oil quality. The chemical composition of oils extracted from young ‘Arbequina' olives subject in the field to three soil salinity levels (low-L, medium-M and high-H) was determined throughout a period of three years. A total of 30 parameters were analyzed (moisture, oil content, acidity, peroxides, ultraviolet absorbances, poliphenols, aliphatic alcohols, sterols, waxes, and fatty acid composition). Soil salinity was measured on fourteen different dates with an electromagnetic sensor. Overall, salinity increased oil content (+15 % in H with respect to L) and decreased aliphatic alcohols (-29 %) and palmitoleic acid (-32 %) (values significant at P0,05). In summary, olive oil quality was practically independent of soil salinity and, according to the prevailing legislation, all the oils were classified as “extra virgin”. Este trabajo analiza el efecto de la salinidad edáfica sobre la calidad del aceite de oliva. Durante tres campañas se determinó la composición química de aceites provenientes de olivos jóvenes ‘Arbequina' sujetos en campo a tres niveles de salinidad (baja-B, media-M y alta-A). En total se analizaron 30 parámetros (humedad, grasa, acidez, peróxidos, lecturas en el ultravioleta, polifenoles, alcoholes alifáticos, esteroles, ceras y composición de ácidos grasos). La salinidad edáfica se midió en catorce fechas con un sensor electromagnético. La salinidad produjo un aumento del porcentaje de grasa (+15 % en A respecto a B), y un descenso de los alcoholes alifáticos (-29 %) y del ácido palmitoleico (-32 %) (valores significativos a P0,05). En conclusión, la calidad del aceite de oliva fue prácticamente independiente de la salinidad, clasificándose en todos los casos como “virgen extra” según la normativa vigente.

28 Pag., 10 Fig. The definitive version is available at: http://www.springerlink.com/content/0032-079x/, High-density olive orchards are increasing around the world, many of which may be potentially affected by salinity and waterlogging (hypoxia), two important stresses common in irrigated fields in arid and semi-arid climates. However, the response of olive to these stresses under field conditions is not well established. Therefore, our objective was to evaluate the vegetative growth response of young olive trees (Olea europaea L., cv. Arbequina) grown in a spatially-variable waterlogged, saline-sodic field. We monitored the growth in trunk diameter of 341 three-year’s old olives between September 1999 and September 2000. Field contour maps were developed delineating soil salinity (ECa), relative ground elevation (RGE) and water table depth (WTD). Soil samples were also collected and analyzed for ECe and SARe in order to characterize the salinity and sodicity profiles and develop the ECa-ECe calibration equation. The infiltration rate (IR) of the crusted and uncrusted soil and the penetration resistance (PR) were also measured. The field was characterized by spatially variable ECe (2 to 15 dS m-1), SARe (3 to 40), RGE (-4 to +4 cm) and WTD (0.5 to 1.9 m, with corresponding ground water EC values between 12 and 6 dS m-1). Steady-state IR of crusted soil was only 7% of the uncrusted soil. Since the field was heavily irrigated by flooding, waterlogging conditions were related to low RGE values. Soil salinity was negatively correlated (R2 = 0.83, P < 0.001) with RGE (ponded water) and WTD (upward flux), due to the evapo-concentration of water and salts at the soil surface. Thus, inverted salinity profiles developed in high salinity areas. Fifty five percent of the olives were dead 3.5 years after planted, and most of them were located in areas of high ECe (> 10 dS m-1), low RGE (< - 1.5 cm) and low WTD (< 1.2 m). The surviving trees had vegetative salinity tolerance values of ECe threshold = 4 dS m-1 and slope = -12% (i.e., percent decline per unit increase in ECe above the treshold), indicating that the Arbequina olive is moderately tolerant to salinity. The RGE and WTD thresholds for olive’s survival were > 0.1 cm and > 1.6 m, respectively. Thus, very small changes in ground elevation had a significant effect on olive’s survival or death. The coupled effects of salinity and waterlogging (hypoxia) stresses were most detrimental for olive’s growth., This study was partially supported by INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain).

22 Pag., 5 Tabl., 4 Fig. The definitive version is available at: http://www.springerlink.com/content/0014-2336/, The assessment of the level and spatial variability of soil salinity and the knowledge of the salinity-yield response functions of crops are required to ascertain the best management strategies aimed at optimizing crop's productivity in saline environments. This work analyzed the spatial distribution of ECe in six irrigated, salt-affected fields of the middle Ebro River Valley (Spain) using electromagnetic survey and geostatistical techniques, and the implications of this salinity variability in plant breeding strategies for increased productivity. The average field ECe varied between 4.9 and15.4 dS m-1, with within-field coefficients of variation between 37 and 79%. The yield simulation analysis of 20 barley and durum wheat cultivars showed that almost 60% of the total yield came from the less saline areas (ECe < 6 dS m-1). The model-estimate Ym (maximum yield under non-saline conditions)and the simulated yields were significantly correlated (p, The first author was granted by Consejo Asesor de la Investigación, Gobierno de Aragón.

12 Pags.- 4 Tabls.- 3 Figs., Above-canopy sprinkler irrigation with saline water favours the absorption of salts by wetted leaves and this can cause a yield reduction additional to that which occurs in salt-affected soils. Outdoor pot experiments with both sprinkler and drip irrigation systems were conducted to determine foliar ion accumulation and performance of maize and barley plants exposed to four treatments: nonsaline control (C), salt applied only to the soil (S), salt applied only to the foliage (F) and salt applied to both the soil and to the foliage (F+S). The EC of the saline solution employed for maize in 1993 was 4.2 dS m−1 (30 mM NaCl and 2.8 mM CaCl2) and for barley in 1994, 9.6 dS m−1 (47 mM NaCl and 23.5 mM CaCl2). The soil surface of all pots was covered so that in the F treatment the soil was not salinized by the saline sprinkling and drip irrigation supplied nutrients in either fresh (treatments C and F) or saline water (treatments S and F+S). Saline sprinkling increased leaf sap Na+ concentrations much more than did soil salinity, especially in maize, even though the saline sprinkling was given only two or three times per week for 30 min, whereas the roots of plants grown in saline soil were continuously exposed to salinity. By contrast, leaf sap Cl− concentrations were increased similarly by saline sprinkling and soil salinity in maize, and more by saline sprinkling than saline soil in barley. It is concluded that barley leaves, and to a greater extent maize leaves, lack the ability to selectively exclude Na+ when sprinkler irrigated with saline water. Moreover, maize leaves selectively absorbed Na+ over Cl− whereas barley leaves showed no selectivity. When foliar and root absorption processes were operating together (F+S treatment) maize and barley leaves accumulated 11–14% less Na+ and Cl− than the sum of individual absorption processes (treatment F plus treatment S) indicating a slight interaction between the absorption processes. Vegetative biomass at maturity and cumulative plant water use were significantly reduced by saline sprinkling. In maize, reductions in biomass and plant water use relative to the control were of similar magnitude for plants exposed only to saline sprinkling, or only to soil salinity; whereas in barley, saline sprinkling was more detrimental than was soil salinity. We suggest that crops that are salt tolerant because they possess root systems which efficiently restrict Na+ and Cl− transport to the shoot, may not exhibit the same tolerance in sprinkler systems which wet the foliage with saline water. ei]T J Flowers, This work was financially supported by the STD program of the European Union and by the Interministry Commission of Science and Technology of Spain. The first author was supported for two years by the Spanish government, through the feliowship ‘Temporary Stays of Foreign Scientists and Technicai Experts in Spain’ of the Ministry of Education and Science.

9 Pags.- 2 Tabls.- 4 Figs., Barley is a crop that has been classified as tolerant to soil salinity, but under sprinkler irrigation with saline water it can readily absorb salts through its leaves and develop injury. Experiments using a triple-line-source sprinkler system were conducted on barley between 1989 and 1991 to determine: (1) the specific effects of foliage wetting on the mass of different shoot components; (2) the relative contribution of root and foliar absorption processes to foliar Cl accumulation; and (3) the extent by which these processes affect Cl partitioning in the shoot at the end of the season. Some plants were covered with plastic during the irrigation process to prevent foliar wetting while others remained uncovered. Salinity affected the partitioning of dry matter in the shoots regardless of whether plants were covered during the irrigation process. The organs associated with reproduction, e.g., heads and peduncles, comprised a larger fraction of the total shoot biomass under high salinity than under low salinity, indicating that plants under salinity stress were able to redistribute their dry matter to favor reproductive growth. The Cl concentration of the young leaves sampled from uncovered plants was linearly related (i.e., r 2>0.71) to the Cl concentration of the irrigation water. Equivalent leaves from covered plants also contained a substantial amount of Cl but concentrations were weakly correlated (i.e., r 2, At low salinity, there were no differences in leaf Cl concentrations between covered and uncovered treatments. In young leaves, differences between these treatments progressively increased with increasing salinity, indicating that the relative contribution of Cl in the leaf from foliar absorbed salts increased with increasing Cl in the irrigation water. Only in the youngest leaves sampled at the end of the season from plants grown at high salinity was the Cl concentration in uncovered plants (foliar plus root-absorbed Cl) found to be more than twice that in covered plants (only root-absorbed Cl) indicating that most of the Cl in young leaves originated from foliar absorption. In addition, only in the youngest leaves (e.g., flag leaves) was the slope of the relationship between leaf-Cl concentration and Cl concentration of the sprinkling water of uncovered plants more than twice that of covered plants, also indicating that foliar-Cl absorption was more substantial than root-Cl absorption. At high salinity, the difference in leaf Cl concentration between covered and uncovered plants was maximum in the youngest leaf (flag leaf), but differences became progressively smaller with increasing leaf age until ultimately concentrations of chloride in leaves older than the flag leaf-2 were highest in covered plants. In older tissue, it was difficult to distinguish which process, foliar or root absorption, was most responsible for leaf-Cl accumulation. These processes may not be entirely independent of one another and much of the Cl in the oldest leaves of uncovered plants could have been derived from foliar sources during the first month of sprinkling, reaching maximal levels, and thereby restricting root-absorbed Cl. Furthermore, since these leaves at the end of the season are more injured and drier than those from covered plants, late-season sprinkler irrigations may have been responsible for leaching some of the Cl out of these necrotic leaves.

8 Pags.- 1 Tabl.- 6 Figs., Crops that are sprinkler irrigated with saline water often suffer greater yield losses than when they are irrigated by soil surface methods, because harmful levels of salts are directly absorbed through the wetted leaves. We investigated whether salt damage to barley, sprinkler irrigated with saline water, was minimized with a short pre-irrigation with fresh water. A triple line-source sprinkler system was used to test the influence of three irrigation treatments on harvested grain yield, leaf water content and Cl and Na concentrations of barley sampled at two different dates. These treatments were compared at five levels of applied water salinity and consisted of : (i) RO (root salt absorption only) : plants were covered to avoid salt spray on leaves and saline water was applied directly to the soil ; (ii) PREW (pre-washing with fresh water) : plants were pre-irrigated for 3 min with fresh water in addition to the regular 30 min irrigation with saline sprinkler water plus the 3 min post-washing with fresh water ; (iii) NOPREW (no pre-washing with fresh water), where the 3 min pre-irrigation was not applied. Exposure to saline spray plus soil salinity (PREW and NOPREW treatments) decreased grain yields more than soil salinity only (RO treatment). Increased salinity decreased grain yields substantially less in the PREW treatment than in the NOPREW treatment. The EC of the applied water that reduced grain yield by 50 per cent was 12.9 dS m-' in the PREW treatment and 10.8 dS m−1 in the NOPREW treatment. Differences in grain yield were associated with lower concentrations of foliar salt in leaves from the PREW treatment. The first several minutes of sprinkler irrigation are, therefore, critical in the foliar absorption of salts. Cl and Na accumulated in the leaves in the same proportion in the first sampling of 16 April, but plants absorbed Cl more readily than Na in the second sampling of 29 May. This preferential accumulation of Cl was greater in the RO treatment, indicating that roots absorbed Cl more readily than did leaves, in comparison with Na absorption. These results have important implications in the management of overhead sprinkler irrigation, since short pre-irrigations with good quality water may substantially reduce the adverse effects of saline sprinkling water., This research was supported by the Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA) and the European Community. The Spanish Ministry of Education partially financed the sabbatical leave of S. Granan.

The stability of 22 commercially available soil salinity sensors was studied: 23% were considered to be stable under the imposed experimental conditions during a period of 14 months. During the same time period, accuracy of sensors decreased from ±0.32 to ±0.98 mmho cm−1. Time response is adequate under saturated conditions (Fig. 3) but it may be extremely long for unsaturated soils (Fig. 4 and Table 2). Measurements of the soil solution electrical conductivity with salinity sensors and by the suction probe extraction technique demonstrated that the soil matrix affects the salt distribution near soil surfaces and within the pore space. Time response (63% of total change) of sensor thermistor is 0.9 min, with an estimated accuracy of ±0.3 °C.

24 Pags.- 5 Tabls.- 4 Figs. The definitive version is available at: http://link.springer.com/journal/271, Deficit irrigation (DI) strategies using moderately saline waters save water, but may enhance soil salinization. Based on data gathered during years 2007–2012 in three drip-irrigated grapevine, peach, and nectarine crops subjected to several irrigation and soil-mulching treatments, we assessed trends in root-zone soil salinity [saturation extract electrical conductivity (ECe)], related the changes in soil salinity (ΔECe) to field-wide leaching fraction (LF), evaluated management strategies for soil salinity control, and examined the sustainability of DI strategies under present and expected climate change (CC) scenarios in the Middle Ebro River Basin (ERB, Spain). ECe increased in 82 % of the irrigation seasons and decreased in 75 % of the non-irrigation seasons examined. Soil salinization trends were not apparent during the study years due to these annual salt accumulation–salt leaching cycles. ECe increases were higher in the more severe DI treatments and in the geotextile-mulched soil and lower in the full and less severe irrigation treatments and in the organic-mulched soil. As expected, ΔECe and LF were linearly and negatively correlated (P < 0.01), indicating that soil salinization increased with decreasing LF. These linear relationships provided a way to evaluate best management strategies (increased irrigation, rainfall harvesting, and soil mulching) for soil salinity control. These strategies decreased soil salinization, but did not guarantee the sustainability of severe DIs in the study area. The application of these relationships to the CC precipitation and crop evapotranspiration projections in the ERB shows that the examined DI strategies will be unsustainable due to soil salinization., This work was financed by the CSD2006-00067 project (CONSOLIDER-INGENIO 2010).

22 Pags., 5 Tabls., 7 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/03783774, Irrigation with moderately saline waters may provoke soil salinization and sodification. The objectives of this three-year study were (1) to quantify these processes in two seedless table grapevines (Vitis vinifera cvs. Autumn Royal and Crimson) subject to a full irrigation and two regulated deficit irrigations (RDI, irrigated at 80% and 60% of net irrigation requirements from post-veraison till harvest) with 1.7 dS m−1 electrical conductivity irrigation waters, and (2) to assess the impact of soil salinization on grapevine's response. Soil samples were taken three times along each irrigation season and soil solution samples were extracted weekly by suction cups. Soil saturation extract electrical conductivity (ECe) and sodium adsorption ratio (SARe) were high in Autumn Royal (4.4 dS m−1 and 6.1 (mmol l−1)0.5) and very high in Crimson (7.0 dS m−1 and 8.6 (mmol l−1)0.5) due to relatively low leaching fractions (LF) (0.20 in Autumn Royal and 0.13 in Crimson). Soil solution salinity and sodicity were generally higher in the more severe RDI than in the full irrigation treatment. Soil salinity and sodicity generally increased along the irrigation seasons and decreased along the non-irrigation seasons. Salt accumulation or leaching and LF were significantly correlated, so that LF estimates could anticipate the required irrigation depths for soil salinity control. Grapevine yield declined with increases in soil salinity. Leaf Na concentrations were very low (, This work was financed by the CSD2006-00067 project (CONSOLIDER-INGENIO 2010).

An irrigation system was developed for the establishment of salinity gradients in field experiments that are aimed at obtaining salinity-yield response functions of crops. The drip-injection irrigation system (DIS) consists of a parallel pump system (a centrifugal pump for fresh water and an injection pump for saline water) and a conventional drip irrigation system composed of various irrigation sectors. The number of emitters installed in each irrigation sector determines the discharge of the centrifugal pump that blends with the fixed discharge of the injection pump. So, for the rest of fixed variables, the number of emitters (N) installed in a given irrigation sector determines the salinity of the irrigation water (ECiw): , with a measured coefficient of determination of 99%. The DIS was validated in an experiment where the salinity-yield response functions of ten barley cultivars were obtained using nine ECiw salinity treatments, with two replications per treatment. The DIS proved to be accurate and robust in that: (i) the measured ECiw gradient was similar to the target ECiw gradient (r positively correlated at P < 0.0001); (ii) the soil salinity (ECe) horizontal and vertical (0–50 cm depth) uniformities within each salinity treatment were low (average coefficient of variation [CV] of the pooled salinity treatments equal to 16–22% for the horizontal soil salinity and equal to 10% for the vertical soil salinity) and the temporal variability of soil salinity was low to moderate (average CV of the pooled salinity treatments equal to 18% during the studied period); and (iii) ECiw and ECe were positively correlated (P < 0.001). We concluded that the DIS is an excellent, low cost irrigation system for conducting field crop salt tolerance evaluations.