Short-term effects of nitrogen deposition on soil microbial biomass in Calluna heathlands NW Spain: critical loads

We evaluate the short-term effects of different N deposition loads on nutrient dynamic of soil microbial biomass in Cantabrian heathlands. A surplus of 10 kg N ha-1 yr-1 above N background deposition was required to increase soil microbial biomass N content in old Calluna heathlands, while a surplus of 20 kg N ha-1 yr-1 was required in young ones. The increase of atmospheric N deposition showed no change in soil microbial biomass C content. This caused a decrease in C:N ratio with the highest N deposition loads, being linked to a bacterial biomass dominance against fungal dominance

Evolution of the spherical cavity radius generated around a subsurface emitter

The emitter discharge in subsurface drip irrigation can be affected by soil properties. A positive pressure develops at the emitter outlet where a spherical cavity is assumed to form. In steady-state conditions, the pressure in the soil relates to soil hydraulic 5 properties, the emitter discharge, and the cavity radius. This pressure in the soil is very sensitive to the cavity radius. In this paper, the development of the cavity around the emitter outlet was measured for various emitter discharges in laboratory tests carried out in containers with uniform loamy soils. A trend between soil pressure and emitter discharge was established that illustrates the performance of buried emitters in the 10 field. Its application to the prediction of water distribution in subsurface drip irrigation units and its effect on the estimation of irrigation performance is also show

Propuestas metodológicas para motivar el aprendizaje de materias de ingeniería hidráulica: evaluación de resultados preliminares

Las universidades europeas están adaptándose a las directrices de la Declaración de Bolonia de 1999. Recientemente, se ha dado a conocer una encuesta, realizada a estudiantes graduados en ingeniería en diversos países europeos, en donde los españoles valoran por debajo del aprobado los apartados relacionados con su percepción tanto del aprendizaje como de las habilidades sociocomunicativas. Por otra parte, los alumnos de la UPM mostraron un nivel de satisfacción con sus estudios menor que la media. Para mejorar la eficiencia las actividades formativas se deberán cuidar aspectos como: hacer atractivas las enseñanzas de ingeniería sin descuidar la exigencia y motivar para su aprendizaje. Este trabajo propone varias estrategias metodológicas para motivar el aprendizaje y las habilidades comunicativas en las materias relacionadas con la Ingeniería Hidráulica. Se analizan los resultados de las primeras experiencias de su aplicación a la docencia de varias asignaturas y su comparación con la situación de partida

Water distribution in laterals and units of subsurface drip irrigation. II: Field evaluation.

The performance of drip irrigation and subsurface drip irrigation (SDI) laterals has been compared. Two emitter models (one compensating and the other noncompensating) were assessed. Field tests were carried out with a pair of laterals working at the same inlet pressure. A procedure was developed that recorded head pressures at both lateral extremes and inlet flow during irrigation. Both models showed similar behavior and soil properties affected their discharge. On the other hand, the performance of a field SDI unit of compensating emitters was characterized by measuring pressures at different points and inlet flow. Finally, the distribution of water and soil pressure in the laterals and the unit were predicted and irrigation uniformity and soil pressure variability were also determined. Predictions agreed reasonably well with the experimental observations. Thus, the methodology proposed could be used to support the decision making for the design and management of SDI system

Soil-plant relationship in Calluna heathlands after experimental burning and nitrogen fertilization, studies from NW Spain

We studied changes in the relationship between soil nutrient content and plant species richness in Calluna heathlands after seven years of experimental burning (B) and nitrogen fertilization (NF). Our results indicate that both the treatments (B, NF, B+NF) and modification of several soil characteristics (total N, available Na, and C:N ratio) reflected in a significant increase in plant species richness

Landscape Implications of Contemporary Abandonment of Extensive Sheep Grazing in a Globally Important Agricultural Heritage System

[EN], In Southern Europe, the abandonment of the traditional transhumant system where sheep graze lowland areas during winter and distant mountain systems during summer has led to an important cultural loss and still poorly understood ecological consequences. We investigate the landscape-scale implications of contemporary sheep grazing patterns in a Globally Important Agricultural Heritage System (GIAHS). Our analysis showed a heterogeneous use of mountain grazing areas between 1990 and 2020. The areas most used by sheep had more abundance of pasture, fewer forests, and structurally different landscapes than those that had been fully abandoned by sheep. Likewise, we have detected decreasing trends in landscape diversity in those areas not used by sheep over the study period, whereas landscape heterogeneity is maintained in those areas grazed by sheep. Our study constitutes an original analysis of landscape patterns and shifts in relation to extensive sheep grazing by using novel approaches that combine interviews, updated satellite time series, and state-of-the-art landscape analysis techniques. Likewise, our results constitute a benchmark as they inform on the importance of preserving extensive sheep grazing if we aim to maintain the cultural heritage, and traditional diverse landscape and the semi-natural grasslands in the Mountains of León.SIEuropean Union Next-Generation EU fundsCESEFORMAP

The role of prescribed fire in the provision of regulating ecosystem services of Spanish heathlands

We provide a synthesis of evidence of the effects of burning and N deposition on the provision of regulating ecosystem services of Cantabrian heathlands (NW Spain). We quantified carbon sequestration in litter, above and belowground biomass, root and soil compartments in heathlands after burning and burning plus N fertilization

Water use efficiency and water productivity in the Spanish irrigation district ¿Río Adaja?

A study of the assessment of the irrigation water use has been carried out in the Spanish irrigation District “Río Adaja” that has analyzed the water use efficiency and the water productivity indicators for the main crops for three years: 2010-2011, 2011-2012 and 2012-2013. A soil water balance model was applied taking into ccount climatic data for the nearby weather station and soil properties. Crop water requirements were calculated by the FAO Penman- Monteith with the application of the dual crop coefficient and by considering the readily vailable soil water content (RAW) concept. Likewise, productivity was measured by the indexes: annual relative irrigation supply (ARIS), annual relative water supply (ARWS), relative rainfall supply (RRS), the water productivity (WP), the evapotranspiration water productivity (ETWP), and the irrigation water productivity (IWP. The results show that in most crops deficit irrigation was applied (ARIS<1) in the first two years however, the IWP improved. This was higher in 2010-2011 which corresponded to the highest effective precipitation Pe. In general, the IWP (€.m-3) varied amongcrops but crops such as: onion (4.14, 1.98 and 2.77 respectively for the three years), potato (2.79, 1.69 and 1.62 respectively for the three years), carrot (1.37, 1.70 and 1.80 respectively for the three years) and barley (1.21, 1.16 and 0.68 respectively for the three years) showed the higher values. Thus, it is highlighted the y could be included into the cropping pattern which would maximize the famer’s gross income in the irrigation district

Evaluación de los sistemas de riego por aspersión en la Comunidad de Regantes "Río Adaja" y propuestas para la mejora del manejo del riego.

La evaluación en campo de los sistemas de riego permite conocer el funcionamiento del mismo y establecer criterios de manejo que mejoren la eficiencia y los resultados del riego. En este trabajo se evaluaron en campo trece sistemas de riego por aspersión: diez pivotes centrales, dos de cobertura total y un ramal de avance frontal. Además se analizó la carta de riego propuesta por el fabricante en ocho de los pivotes y en el ramal de avance frontal y se determinó la uniformidad de distribución de agua del sistema expresada como coeficiente de uniformidad de Christiansen (CU). Posteriormente, se seleccionaron las boquillas de los emisores con objeto de obtener una mayor uniformidad en la aplicación del agua considerando el supuesto de una distribución continua de caudal. Los resultados de la evaluación en campo mostraron que el 38% de los sistemas evaluados tienen una uniformidad de aplicación de agua del riego mala (CU<80). Asimismo, el rendimiento de aplicación Ra del 31% de los sistemas está por debajo de lo requerido (Ra <0,75) y el riego del 92% de los sistemas es deficitario. Por otra parte, la uniformidad de aplicación del agua calculada para las cartas de riego propuestas por el fabricante ofrecen valores de CU<80 estimándose que el cambio de boquillas propuesto aumentaría su valor en la mayoría de los sistemas estudiados

Emitter discharge variability of subsurface drip irrigation in uniform soils: effect on water-application uniformity

Emitter discharge of subsurface drip irrigation (SDI) decreases as a result of the overpressure in the soil water at the discharge orifice. In this paper, the variation in dripper discharge in SDI laterals is studied. First, the emitter coefficient of flow variation CVq was measured in laboratory experiments with drippers of 2 and 4 L/h that were laid both on the soil and beneath it. Additionally, the soil pressure coefficient of variation CVhs was measured in buried emitters. Then, the irrigation uniformity was simulated in SDI and surface irrigation laterals under the same operating conditions and uniform soils; sandy and loamy. CVq was similar for the compensating models of both the surface and subsurface emitters. However, CVq decreased for the 2-L/h non-compensating model in the loamy soil. This shows a possible self-regulation of non-compensating emitter discharge in SDI, due to the interaction between effects of emitter discharge and soil pressure. This resulted in the irrigation uniformity of SDI non-compensating emitters to be greater than surface drip irrigation. The uniformity with pressure-compensating emitters would be similar in both cases, provided the overpressures in SDI are less than or equal to the compensation range lower limit