Resposta de Populações de Plantas Daninhas ao Plantio e a Taxas Reduzidas de Herbicida e Nitrogênio na Produção de Trigo (Triticum aestivum)

Field experiments were carried out in 1999 and 2000 to investigate the effects of conventional (CT) and no-tillage (NT) systems, interacting with three herbicide dose levels and three nitrogen (N) levels on weed growth and wheat production of two varieties. There was a higher grain yield for NT system compared with CT in one year. CT weed biomass was lower than from NT weed biomass, in both varieties. No differences on wheat biomass and grain yield were observed between full and reduced herbicide rates. N fertilizer increased wheat biomass and grain yield significantly. Only N medium level had an effect upon weed biomass with respect to non-fertilized plots, while the highest fertilization rate lowered weed biomass. Conventional tillage, reduced herbicide rates and nitrogen fertilization were effective ways of limiting weed production in wheat.Experimentos foram conduzidos sob condições de campo em 1999 e 2000 a fim de investigar os efeitos dos plantios convencional (PC) e direto (PD), em combinação com três doses de herbicidas e três de nitrogênio (N), no crescimento de plantas daninhas e produção de duas variedades de trigo. Foi observada produção maior de grãos PD, comparado ao PC, durante um ano. A biomassa das plantas daninhas no PC foi menor do que no PD, para as duas variedades. Nenhuma diferença em biomassa e produção de grãos de trigo foi observada entre as doses de herbicida integral e reduzida. N aumentou a biomassa do trigo e produção de grãos significativamente. Apenas o nível médio de N teve efeito sobre a biomassa das plantas daninhas em relação à não-aplicação de N, enquanto uma taxa maior de N diminuiu a biomassa das plantas daninhas. No plantio convencional, doses reduzidas de herbicida e aplicação de N foram efetivos na limitação do crescimento das plantas daninhas no cultivo de trigo.Facultad de Ciencias Agrarias y Forestale

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Effect of landscape position on the acidification of loess-derived soils under Pinus radiata

Interactions between landscape position and the acidifying effect of trees planted into loess-derived grassland soils were studied in the Ventana region of Argentina. Forests of Pinus radiata planted at the end of 1940, were selected in two different positions from the landscape, plains and slopes. Samples of the soil surface mineral horizon were taken from landscape positions at four distances from the trees and compared with grassland soils. The values of the main soil chemical properties changed significantly with distance from trees, with a decrease in pH, base saturation, exchangeable Ca2+, Mg 2+ and K+, and increase in Na+, Al3+ and particularly H+ closer to the trees. This pattern confirms the prominent role of vegetation in bringing about changes in soil properties. Regression models showed high levels of explanation (r2 > 0.85) indicating that a high percentage of the spatial variability of soil chemical properties is systematic and predictable with distance from the trees. The pH in KCl proved an excellent tool for predicting the cationic composition of soils. Organic carbon and total nitrogen were significantly higher in the plains positions than in the slopes under the trees, whereas there was no difference under grassland. The slopes of the regression lines indicated that acidification is more intense in soils on the plains. Vegetation was the main factor influencing acidification of the studied soils. The landscape position regulates the bio-hydrological factor and thus the speed of acidification process.Fil: Amiotti, Nilda Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Bravo, Oscar Abel. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Zalba, Pablo. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Peinemann, Norman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentin

Moisture and temperature effect on soil phosphorus availability

The effect of desiccation temperature upon soil phosphorus availability was evaluated under laboratory conditions in soil samples of different texture. Soil samples of 1.4 g were weighed in 25 mL glass tubes and desiccated in an oven at 40, 60, 80 and 100o C using 2 different moisture levels: dry and wet. A total of 10 treatments were carried out with two replicates per treatment. Soil variables analyzed were: extractable phosphorus (Pe), organic phosphorus (Po), pH, organic carbon (OC), soil microbial activity (SMA), CaCO3 and texture (sand, silt and clay %). A marked increase in Pe was observed through the combined effect of moisture and temperature. Medium- and fine-textured soils showed higher Pe increments than coarser-textured soils. Whereas in medium-textured soils (loam) the increment in Pe varied between 4 mg kg-1 and 8 mg kg-1 as a result of the effect of temperature and temperature plus moisture, respectively, in the case of fine- and coarse-textured soils (clay loam and loamy sand) the increment was between 1 mg kg-1 and 6 mg kg-1. The soil variable analysis did not show any statistically significant relationships for Pe. However, high correlations were found between Po and SMA (r = 0.73, P <0.01) and between SMA and silt content (r = 0.86, P <0.01) . Thus, the results infer that soil microorganisms play an active role in the process of Po mineralization and the consequent increase in Pe.Fil: Zalba, Pablo. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Bravo, Oscar Abel. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Garay Schiebelbein, Maximiliano Miguel. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Peinemann, Norman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentin

Resposta de Populações de Plantas Daninhas ao Plantio e a Taxas Reduzidas de Herbicida e Nitrogênio na Produção de Trigo (Triticum aestivum)

Field experiments were carried out in 1999 and 2000 to investigate the effects of conventional (CT) and no-tillage (NT) systems, interacting with three herbicide dose levels and three nitrogen (N) levels on weed growth and wheat production of two varieties. There was a higher grain yield for NT system compared with CT in one year. CT weed biomass was lower than from NT weed biomass, in both varieties. No differences on wheat biomass and grain yield were observed between full and reduced herbicide rates. N fertilizer increased wheat biomass and grain yield significantly. Only N medium level had an effect upon weed biomass with respect to non-fertilized plots, while the highest fertilization rate lowered weed biomass. Conventional tillage, reduced herbicide rates and nitrogen fertilization were effective ways of limiting weed production in wheat.Experimentos foram conduzidos sob condições de campo em 1999 e 2000 a fim de investigar os efeitos dos plantios convencional (PC) e direto (PD), em combinação com três doses de herbicidas e três de nitrogênio (N), no crescimento de plantas daninhas e produção de duas variedades de trigo. Foi observada produção maior de grãos PD, comparado ao PC, durante um ano. A biomassa das plantas daninhas no PC foi menor do que no PD, para as duas variedades. Nenhuma diferença em biomassa e produção de grãos de trigo foi observada entre as doses de herbicida integral e reduzida. N aumentou a biomassa do trigo e produção de grãos significativamente. Apenas o nível médio de N teve efeito sobre a biomassa das plantas daninhas em relação à não-aplicação de N, enquanto uma taxa maior de N diminuiu a biomassa das plantas daninhas. No plantio convencional, doses reduzidas de herbicida e aplicação de N foram efetivos na limitação do crescimento das plantas daninhas no cultivo de trigo.Facultad de Ciencias Agrarias y Forestale

Évaluation directe de la compétitivité et de la tolérance à la défoliation des graminées vivaces

Stipa clarazii is a dominant, late-seral perennial grass species under exclosure or lightly grazed rangelands in semiarid Argentina, whereas S. tenuis and S. ambigua are earlier-seral perennial tussock grasses. Recent studies have demonstrated that late-seral species are more competitive and can have either similar or greater herbivory tolerance than earlier-seral species. We hyphothesized that (1) tolerance to defoliation is greater on defoliated plants of S. clarazii than on those of S. tenuis and S. ambigua, (2) competitive ability is greater in S. clarazii than in S. tenuis and S. ambigua when plants remain undefoliated or are exposed to a comparable defoliation intensity, and (3) competitive ability decreases in S. clarazii when this species is selectively defoliated within a non-defoliated, nearby neighbourhood of S. tenuis or S. ambigua. The study objectives included obtaining a direct measure of competitive ability and defoliation tolerance in the three perennial grasses when they grew either in isolation or in different neighbourhoods and were exposed to various defoliation patterns in the field. In 1998, two parallel studies were conducted within a 2-yr-old field exclosure during one growing season. In one study, responses were evaluated on either defoliated or undefoliated plants of all three species without neighbours. In a second experiment, four types of neighborhoods were selected such that a central (target) plant of one species was surrounded by five neighboring plants of a different species. Three different defoliation patterns were imposed on each neighbourhood type. Results led to acceptance of the first and second and rejection of the third hypothesis. When plants grew without nearby neighbours, greater growth rates for height, dry matter production and end-of-season daughter tiller production per parent tiller in S. clarazii relative to S. tenuis and S. ambigua contributed to greater regrowth in S. clarazii. Amounts of 15N atom excess were always greater in S. clarazii than in S. tenuis and S. ambigua independently of neighbourhood type and pattern of defoliation. However, uptake of 15N was similar in S. clarazii to that in S. tenuis or S. ambigua when S. clarazii was selectively defoliated within a non-defoliated, nearby neighbourhood of any of the other two species. Selective herbivory of S. clarazii, rather than factors associated with its competitive ability and defoliation tolerance, were found to be the major determinant driving its replacement by earlier-seral, less desirable perennial grasses in rangelands of central Argentina.Stipa clarazii est une graminée de transition vivace tardive mais dominante dans les exclos ou les grands parcours peu fréquentés des régions semi-arides de l’Argentine, où les vivaces de transition S. tenuis et S. ambigua peuplent plus hâtivement les buttes de tourbe. Des études récentes indiquent que les espèces de transition tardives sont plus compétitives et tolèrent autant ou mieux les herbivores que les espèces de transition plus précoces. Les auteurs ont formulé les hypothèses suivantes : (1) les plants de S. clarazii défoliés tolèrent plus la défoliation que ceux de S. tenuis et de S. ambigua; (2) S. clarazii est plus compétitive que les deux autres espèces quand ses plants ne sont pas défoliés ou sont exposés à une défoliation analogue; (3) la compétitivité de S. clarazii diminue quand on défolie cette espèce de manière sélective près de peuplements de S. tenuis et de S. amgigua. L’étude devait servir à mesurer directement la compétitivité et la tolérance à la défoliation des trois graminées vivaces, cultivées en isolement ou dans des milieux différents puis exposées à divers modes de défoliation observés sur le terrain. En 1998, les auteurs ont tenu deux études parallèles sur un champ de deux ans exclos durant la période végé- tative. Dans la première, ils ont évalué la réaction des plants défoliés et normaux des trois espèces en l’absence de plantes voisines. Dans la seconde, ils ont sélectionné quatre types d’environnement, de telle sorte que les plantes d’une espèce (cible) était entourée de cinq plants d’une espèce différente. Trois modes de défoliation ont ensuite été appliqués à chaque environnement. Les résultats ont amené les auteurs à retenir les deux premières hypothèses et à rejeter la troisième. Quand les plantes poussent sans voisin immédiat, un meilleur taux de croissance relatif pour la hauteur, une plus forte production de matière sèche et un plus grand nombre de talles filles en fin de saison concourent à une meilleure repousse de S. clarazii, comparativement à S. tenuis et à S. ambigua. La proportion d’atomes 15N en excé- dent était toujours plus élevée chez S. clarazii que chez les deux autres espèces, sans égard au type d’environnement ou au mode de défoliation. L’absorption du 15N chez S. clarazii était néanmoins semblable à celle observée chez S. tenuis ou S. ambigua quand on défolie sélectivement S. clarazii dans un peuplement non défolié d’une des deux autres espèces. On doit surtout la substitution de S. clarazii par des graminées vivaces de transition plus hâtives et moins désirables dans les grands parcours de l’Argentine à un broutage sélectif plutôt qu’à d’autres facteurs comme la compétitivité et la tolérance à la défoliation de l’espèce.Fil: Saint Pierre, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Busso, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Montenegro, Oscar Alberto. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; ArgentinaFil: Rodriguez, Gustavo Dionisio. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; ArgentinaFil: Giorgetti, Hugo Dosindo. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; ArgentinaFil: Montani, Tomás. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Bravo, Oscar Abel. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Soil resource acquisition mechanisms, nutrient concentrations and growth in perennial grasses

Species historically heavily grazed may have been selected for grazing-resistance traits associated with improved nutrient use efficiency (Chapin and Slack, 1979). Higher root length density (RLD) and vesicular-arbuscular mycorrhizae (VAM) colonization have been associated with greater nutrient acquisition in perennial grasses, thus contributing to competitive ability (Jackson and Caldwell, 1996). This is especially true in unproductive environments where competition for belowground resources is strong (Jackson and Caldwell, 1996). Mycorrhizal fungi can affect competitive interactions among plants by improving soil nutrient uptake (Marschner and Dell, 1994; Mohammad et al., 1998). However, lack of or even negative responses have been obtained under increased levels of mycorrhizal colonization (Fitter and Hay, 1983).Relationships among soil resource acquisition mechanisms and components of shoot tissue production were studied in the late-seral, grazing tolerant and competitive Stipa clarazii Ball and in the earlier-seral, less grazing tolerant and competitive S. tenuis Phil and S. ambigua Speg. History of grazing and/or fire determines abundance of these C3 perennial tussock grasses in temperate, semiarid rangelands of Argentina. We hypothesized lower values for root length density (RLD) and percentage vesicular-arbuscular mycorrhizal (%VAM) colonization on defoliated than on undefoliated plants, and also greater values for RLD and %VAM colonization on defoliated and undefoliated plants of S. clarazii than on those of the other two species, because of its greater competitive ability and defoliation tolerance. Field study was conducted within a 2-year exclosure to domestic herbivory. One group of plants was defoliated once to 5cm stubble height in early spring, while another group was defoliated twice, in early and mid-spring. A third group remained undefoliated (control). Measurements were conducted 6-10 days after each defoliation, and at the end of the growing season. RLD and %VAM colonization were similar on defoliated plants and on undefoliated controls in all three species. Greater regrowth production in S. clarazii was not associated with higher RLD and %VAM colonization in the more competitive species. The positive relationship between RLD and either dry weight production or tissue N and P concentration in these species suggests that their root activity must be maintained after defoliation to rapidly reestablish a photosynthetic canopy and keep resource supply at equilibrium. All perennial grasses showed consistently high %VAM colonization, suggesting they may function as obligate mycotrophs. The negative correlation between %VAM colonization and RLD or soil available P for S. clarazii could represent a mechanism to avoid shifts from mutualism to parasitism in the plant-mycorrhizae relationship.Estudaram-se as relações entre os mecanismos de aquisição de recursos do solo e os componentes de produção de tecido foliar na espécie de etapas serais tardias, tolerante ao pastoreio e competitiva Stipa clarazii Ball e nas espécies de etapas serais mais prematuras, menos tolerantes ao pastoreio e competitivas S. tenuis Phil. e S. ambigua Speg. A história de pastoreio e/ou fogo determina a abundância destas gramíneas perenes cespitosas C3 nos pastizais temperados semi-áridos da Argentina. A hipótese de trabalho foi de que as plantas desfolhadas teriam menor densidade de longitude de raízes (DLR) e porcentagem de colonização por micorrizas vesiculares-arbusculares (%MAV) que aquelas não desfolhadas, e também que as plantas desfolhadas e não desfolhadas de S. clarazii teríam maiores valores de DLR y %MAV que aquelas das outras espécies, por sua maior capacidade competitiva e tolerância à desfolhação. Se conduziu um estudo sob condições de campo em uma área excluída ao pastoreio por herbívoros domésticos durante 2 anos. Um grupo de plantas foi desfolhado uma vez a 5 cm do solo no início da primavera, enquanto que outro grupo foi desfolhado duas vezes, no início e na metade da primavera. Um terceiro grupo permaneceu não desfolhado. As medições se conduziram 6-10 dias depois de cada desfolhação, e no final da estação de crescimento. DLR y %MAV foram similares em plantas desfolhadas e não desfolhadas nas três espécies. A maior produção de rebrote em S. clarazii não esteve associado com maiores DLR y %MAV na espécie mais competitiva. A relação positiva entre DLR e produção de peso seco, ou a concentração de N e P no tecido nestas espécies, sugere que sua atividade radical deve se manter após a desfolhação para restabelecer uma superficie fotossintética e manter a distribuição de recursos em equilíbrio. Todas as espécies mostraram valores consistentemente altos de % MAV, sugerindo que podem ter uma associação mutualística obrigada com as micorrizas. A correlação negativa entre %MAV e DLR ou P disponível do solo para S. clarazii poderia representar um mecanismo para evitar mudanças de associação mutualística a parasítica na relação planta-micorriza.Fil: Saint Pierre, Carolina. Universidad Nacional del Sur; ArgentinaFil: Busso, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Montenegro, Oscar Alberto. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina. Universidad Nacional del Sur; ArgentinaFil: Rodriguez, Gustavo Dionisio. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; ArgentinaFil: Giorgetti, Hugo Dosindo. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina. Universidad Nacional del Sur; ArgentinaFil: Montani, Tomás. Universidad Nacional del Sur; ArgentinaFil: Bravo, Oscar Abel. Universidad Nacional del Sur; Argentin

Partition of arsenic in soils sediments and the origin of naturally elevated concentrations in groundwater of the southern pampa region (Argentina)

Excessive arsenic concentrations above the Argentinean and WHO guidelines for drinking water (10 μg L -1) affects shallow aquifers of the southern Pampean Plain (Argentina) hosted in the Pampean and the Post Pampean formations (loess and reworked loess; Plio-Pleistocene-Holocene). Health problems related to high As concentrations in drinking waters are known as Endemic Regional Chronic Hydroarsenicism. Hydrochemistry of shallow groundwaters and soil geochemistry were investigated aiming to (1) understand the partition of As in the solid phase and its relationship with unacceptable As concentrations in waters, (2) identify the provision source of As to groundwaters. Only 5% of the samples had As concentrations < 10 μg L -1; in 27% As concentrations ranged from 10 to 50 μg L -1 and in 58% it reached 60-500 μg L -1. The coarse fraction (50-2,000 μm) hosts about 27% of the total As in the solid phase, being positively correlated to Ba (p < 0.01; r 2 = 0.93). About 70% is included in the < 2 μm fraction and had positive correlations of As-Fe (p < 0.05; r 2 = 0.85) and As-Cr (p < 0.05; r 2 = 0.68). Soils and sediment sand fractions of vadose zones are the primary sources of As in shallow groundwater while adsorption-desorption processes, codisolution-coprecipitation, and evaporation during the dry seasons raise As concentrations in waters exceeding the guideline value for drinking water.Fil: Blanco, María del Carmen. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Paoloni, Juan Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Morrás, Héctor José María. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; ArgentinaFil: Fiorentino, Carmen. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Sequeira, Mario Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Amiotti, Nilda Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Bravo, Oscar Abel. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Díaz, Silvana Letisia. Ministerio de Ciencia. Tecnología e Innovación Productiva. Agencia Nacional de Promoción Cientifíca y Tecnológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Espósito, Martín Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentin