M. A. Herrero

Water Resources in the Salado River Drainage Basin, Buenos Aires, Argentina: Chemical and Microbiological Characteristics

Abstract Buenos Aires Province is located in the region of greatest agrarian importance in Argentina. Studies that have been carried out up to now are mainly hydrogeological, geological, and limnological and focused on localized specific problems. The aim of this article is to determine the chemical composition, including trace elements and the microbiological characteristics, of surface and shallow ground waters at a regional scale as a basis that may allow the relation of the dynamics of the natural systems with that of the economically productive systems. Groundwater and surface water were sampled in stations located with a global positioning system (GPS). Chemical and microbiological analyses were carried out using reference analytical methods. A representative group of samples was also analyzed with ICP-MS techniques for the determination of trace elements. Shallow groundwater is alkaline to strongly alkaline. The high sodium content is due to a cationic exchange process taking place in the clays of pampean loess. Surface waters, strongly alkaline and of sodium-chloride or sodium-sulfate type, come in part from the discharge of groundwater. The concentration of trace elements in shallow groundwater, does not respond strictly to the conditions of regional flow. Rather, their distribution is related to the morphology and distribution of several types of soils in the region. The microbiological analysis showed that in surface waters the number of total heterotrophic bacteria is within the usual ranges, fluctuating between 1 x 103 and 1 x 105 CFU/ml. The values of total coliforms and thermotolerant coliforms are in accordance with international established parameters for recreational waters.

Intensificación agropecuaria evaluada por indicadores de sustentabilidad ambiental

espanolSe compararon 19 establecimientos agropecuarios, (superficie total 3654 hectareas), mediante indicadores de sustentabilidad agro-ambiental, para evaluar como el proceso de adopcion de tecnologias de produccion influye en un agro-ecosistema con incipiente intensificacion en el uso de la tierra, en la zona semiarida central de Argentina. Se identificaron prioridades de capacitacion y extension para productores segun escala de produccion. Originariamente el area correspondia a pastizales y bosques de calden (Prosopis caldenia) con ganaderia vacuna. Se aplicaron como variables: uso de la tierra por cultivos anuales (CA), y como indicadores: consumo de energia fosil (EF) y eficiencia de su utilizacion (EEF), balances de nitrogeno (BN) y fosforo (BP), riesgo de contaminacion por plaguicidas (RPL), riesgo de erosion (RE), cambio de stock carbono en suelo (CSC) y balance de gases efecto invernadero (GEI), evaluandolos segun escala de gravedad. Los predios fueron analizados individualmente y agrupados segun tamano (81 ha). Se observaron diferencias significativas (p2 Mj EF utilizado/Mj EF producto) y valores negativos de BP en el 68% de los predios (hasta -14,4 kg P/ha/ano), relacionandolo a la incorporacion de soja sin restitucion por fertilizantes. Los BN no senalan riesgo de contaminacion (entre -4,7 a 41,7 kg N/ha/ano). El CSC presento valores problematicos en campos chicos, por la utilizacion de labranzas convencionales para cultivos forrajeros. El GEI reflejo las mayores emisiones de metano en los predios grandes, debido al sistema pastoril de alimentacion. Las actividades de capacitacion deberian orientarse segun escala. La utilizacion de indicadores permitio conocer el impacto de practicas agropecuarias a nivel de predio y de zona, segun escala de produccion, mostrando que la actual intensificacion del sector no ha impactado aun gravemente al medio. EnglishThe aim of the study was to evaluate how technology adoption processes influence agro-ecosystems with incipient land use intensification, in a rural semiarid area of San Luis province, Argentina, using environmental sustainability indicators at farm and regional level. For this purpose a comparison of 19 farms (3654 ha) was carried out. Training and extension priorities for producers were identified during this study. The original vegetation corresponded to grassland and Prosopis caldenia forests with beef cattle production. The environmental sustainability indicators were: Land use -% of annual crops (CA)- (a variable); Fossil energy use(EF); fossil energy use efficiency (EEF); nitrogen balance (BN); phosphorus balance(BP); pesticide contamination risk (RPL); soil erosion risk (RE); changes in soil carbon stock (CSC) and greenhouse gases balance (GEI), evaluated according to severity scale. Farms were analyzed individually and grouped by size (81 ha). Statistically significant differences (p2 Mj EF used/Mj EF product), and negative values of BP in the 68% of the farms (up to -14.4 kgP/ha/year). Both can be related to soybean introduction without extensive fertilizers use. Nitrogen balance do not indicate contamination risk (between -4.7 and 41.7 kg N/ha/year). Conventional tillage in forages is the cause of high CSC values in small farms. The methane emissions in big farms, were reflected by the higher values of GEI indicator because of their grazing systems. Training activities should be farm scale oriented . The use of these indicators has made it possible to understand the impact of agricultural practices at farm and at regional level in relation to production scale. These indicators show that todays Villa Mercedes farm area intensification has not had a serious impact on their environment yet.

Influence of Water Temperature and Heat Stress on Drinking Water Intake in Dairy Cows

Grazing animals are exposed to heat stress and there should be conditions to facilitate water intake. Three experiments were carried out to determine the relationship between water intake, water temperature, and heat stress for Holstein pastured dairy cows. Experiment 1: Drinking behavior of 13 cows was evaluated (for 3 consecutive days) and four time periods were established according to the temperature humidity index (THI): (H1:05:00 to 10:59 h, H2:11:00 to 16:59 h, H3:17:00 to 22:59 h, and H4:23:00 to 04:59 h). The highest mean percentage of drinking bouts (53.2%) was registered in H2 (THI: 74.91 to 83.95). Drinking bout means among time periods were different (p 0.05). Recorded water intake in T1 (18 L) was lower than in T2 (35.9 L), although body heat dissipation was higher (T1 = 672.64 kJ d -1 , T2 = 620.76 kJ d -1 ).

Dairy Manure Management Perceptions and Needs in South American Countries

Milk production is important in South American countries being based mainly on grazing systems. Dairy slurry management has become an important issue in these production systems because of the large volumes produced and the environmental effects. Thus, manure management regulations are emerging in the region. This research aims to identify priorities for management strategies and technology transfer by assessing perceptions, needs and barriers towards dairy manure management by stakeholders in South American countries. A questionnaire was prepared and distributed in Spanish and Portuguese in different formats: on paper and online (PDF format and SurveyMonkeyTM platform) between March 2015- November 2017. It was divided into two sections, the first addressed issues related to water quality and pollution, odour generation, fertiliser value, pathogens impact and biogas production. Responses were measured across a standard 5-point Likert type scales. Section two addressed needs and hindrances concerning about manure application. A total of 593 surveys were completed: Argentina (n=308, 52%), Brazil (n=217, 37%) and Chile (n=68, 11%). The majority of respondents were dairy farmers (31%), professional advisors and consultants (29%) and representatives of public institutions and researchers (31%). Some differences appear according the country. Overall, a large majority perceive that manure is a good fertiliser (91%), also they believe that it contributes to pathogen’s transmission and groundwater and shallow aquifers ´contamination. Stakeholders (60%) perceived biogas production as a good option for manure treatment. Most of respondents (79%) would use manure to replace mineral fertilisers, with little differences between countries (Argentina 79%, Brazil 80% and Chile 68%). The most selected needs were: a management handbook, increased investment in equipment and technologies and better access to laboratory analysis. The most chosen barriers were: cumbersome management, lack of knowledge and of specific laws, with differences between countries and respondents. The survey showed interest in dairy manure management as a source of nutrients for grassland and crops, especially among farmers and advisors whom requested guidelines for responsible management. Policymakers and stakeholders should focus on promoting manure reuse on dairy farms through incentives, technologies and/or appropriate strategies, in order to improve nutrient use and reduce pollution to the wider environment.

El aprendizaje servicio en universidades de Buenos Aires: avanzando hacia su institucionalización

El aprendizaje servicio esta teniendo una amplia difusion en el panorama internacional; si nos centramos en su desarrollo en el seno de la Educacion Superior, mas concretamente dentro del contexto Latinoamericano, indudablemente debemos hacer referencia a la universidad argentina. Una reciente estancia investigadora y formativa en la provincia de Buenos Aires nos ha permitido acercarnos a la realidad que diferentes universidades presentan en la insercion del aprendizaje servicio dentro de sus estructuras. La revision de documentacion institucional, la visita a diferentes proyectos y sobre todo, las entrevistas con diversos agentes implicados en su instauracion y desarrollo, han sido de ayuda para entender el nivel de institucionalizacion que esta propuesta esta alcanzando, asi como los retos que se presentan a futuro. Todo esto se refleja en el analisis realizado y en unas conclusiones que recogemos a modo de cierre