Pig slurry incorporation with tillage does not reduce short-term soil CO2 fluxes

Tillage and organic fertilization impact short-term soil CO2 fluxes. However, the interactive effect of these two management practices has been rarely studied under field conditions. The objective of this study was to evaluate the impact of tillage (NT, no-tillage, and CT, conventional tillage) and fertilization strategy (PS, pig slurry, and MF, mineral fertilizer) on short-term soil CO2 fluxes in a rainfed Mediterranean agroecosystem. Soil CO2 fluxes were measured several times during two tillage and pre-sowing fertilization periods in 2012 and 2013 (7 and 6 times in 2012 and 2013, respectively). In the two years studied, tillage and fertilization significantly affected soil CO2 fluxes, but the interaction between both factors was not significant. The application of PS resulted in a sharp and immediate increase in the soil CO2 flux. One hour after the application of the organic fertilizer, soil CO2 emissions increased from 0.05 to 0.70 g CO2 m−2 h−1 and from 0.08 to 0.82 g CO2 m−2 h−1 in 2012 and 2013, respectively. Unlike fertilization, 1 h after tillage similar soil CO2 fluxes were observed in CT and NT plots. However, after 7 h, larger fluxes were observed in CT compared with NT in both years. Cumulative CO2 flux during the first 24 h after fertilization and tillage was about three- and two-fold greater in PS than in MF and in CT than in NT, respectively. The results of this study showed that in rainfed Mediterranean systems, soil management and fertilization have a noteworthy impact on short-term soil CO2 losses though no interactive effects were observed between both management practices.This research was supported by the Ministry of Economy and Competitiveness of Spain (AGL2010-22050-C03-01/02; AGL2013-49062- C4-4-R) and the COMET-Global project (FACCE-JPI grant)

Do no-till and pig slurry application improve barley yield and water and nitrogen use efficiencies in rainfed Mediterranean conditions?

Tillage and N fertilization strategies including mineral and organic sources need to be studied in combination given their importance on the production cost that farmers face and their potential interaction on crop performance. A four-year (2010–2014) experiment based on barley monocropping was carried out in NE Spain in a typical rainfed Mediterranean area. Two tillage treatments (CT, conventional tillage; NT, no-tillage) and three rates of N fertilization (0; 75 kg N ha−1, applied at top-dressing; 150 kg N ha−1, applied at pre-sowing and at top-dressing at equal rate), with two types of fertilizers (ammonium-based mineral fertilizer and organic fertilizer with pig slurry), were compared in a randomized block design with three replications. Different soil (water and nitrate contents) and crop (above-ground biomass, grain yield, yield components and N concentration in biomass and grain) measurements were performed. Water- and nitrogen use efficiencies (WUE and NUE) as well as other N-related indexes (grain and above-ground biomass N uptake; NHI, nitrogen harvest index; NAR, apparent nitrogen recovery efficiency) were calculated. Barley above-ground biomass and grain yield were highly variable and depended on the rainfall received on each cropping season (ranging between 280 mm and 537 mm). Tillage and N fertilization treatments affected barley grain yields. No-tillage showed 1.0, 1.7 and 6.3 times greater grain yield than CT in three of the four cropping seasons as a result of the greater soil water storage until tillering. Water scarcity during the definition of the number of spikes per m2 under CT would have compromised the compensation mechanism of the other two yield components. Pig slurry application led to the same (3 of 4 years) or higher (1 of 4 years) grain yield than an equivalent rate of mineral N fertilizer. Regardless the N origin, barley yield did not respond to the application of 150 kg N ha−1 split between pre-sowing and top-dressing compared to the 75 kg N ha−1 rate applied as top-dressing. A significant nitrate accumulation in the soil over the experimental period was observed under CT. Greater barley water use efficiency for yield (WUEy), N uptake and grain N content were found under NT than CT in three of the four cropping seasons studied. Moreover, for a given N rate, the use of organic fertilization increased significantly the WUEy as an average of CT and NT. When CT was used, a greater NHI was observed when using pig slurry compared with mineral N as an average of the four years studied. However, the use of different N fertilization treatments (rates or types) under CT or NT did not increase the NUE compared with the control. Our study demonstrates that the use of NT and the application of agronomic rates of N as pig slurry leads to greater barley yield and water- and nitrogen-use efficiencies than the traditional management based on CT and mineral N fertilization.We thank Silvia Martí, Carlos Cortés, Ana Bielsa, Maria José Salvador, Josan Palacio and Héctor Martínez for their technical assistance. Daniel Plaza-Bonilla received a Juan de la Cierva Postdoctoral Grant from the Ministerio de Economía y Competitividad of Spain. This research was supported by the Ministerio de Economía y Competitividad of Spain (grants AGL2007-66320-C02-01, AGL2010-22050-C03-01/02 and AGL2013-49062-C4). This paper has been produced within the context of the Red SIRENA network (Ref. AGL2015-68881-REDT) funded by the Ministerio de Economía y Competitividad of Spain

Sistema facilitador para la visualización superficial de puentes

Proyecto de graduación (Bachillerato en Ingeniería en Diseño Industrial) Instituto Tecnológico de Costa Rica. Escuela de Ingeniería en Diseño Industrial, 2013.La situación de las carreteras, vías y puentes del país, está en estado crítico. Ante esto es necesario la agilidad para reparar la infraestructura nacional que está en decadencia y abandono. Los puentes y pasos en altos son necesarios que se evaluen continuamente para proteger a los usuarios y asegurar el flujo continuo de vehículos. Ante esto el CIVCO del Instituto Tecnológico de Costa Rica, está a punto de adquirir la supervición de todos los puentes a cargo del MOPT. El proceso de la inspección cuenta de varios pasos, entre esos está la inspección visual. La inspección visual actualmente se realiza de forma manual, donde los operarios deben bajar a las partes inferiores de los puentes a tratar de tomar fotografias y ver las bases y estructuras de los puentes. Ante todo esto surgió la necesidad de crear un dispositivo que agilice el proceso de la inspección visual, que evite que los usuarios esten en riesgo de sufrir lesiones o caidas y que se amolde a las condiciones y entorno de los puentes en Costa Rica Para esto se realizo un proceso de diseño con varias etapas de análisis y desarrollo que dieron como resultado un dispositivo capaz de satisfacer las necesidades y requerimientos técnicos

Teoría fundamentada y Atlas.ti : recursos metodológicos para la investigación educativa

Revista Electrónica de Investigación Educativa, Vol. 16, Núm. 1Las prácticas investigativas en educación han experimentado muchos cambios, principalmente en los procedimientos de análisis. Estos cambios han sido motivados por la irrupción de la Teoría Fundamentada en la práctica investigativa, pero también por la presencia de software específico para análisis cualitativos de datos. Esta situación no está exenta de cuestionamientos y debates en torno al real aporte de los ordenadores en la investigación de tradición interpretativa. Sin embargo, esto se debería al desconocimiento de la relación método-software. En este trabajo se presentan los procedimientos analíticos propuestos por la Teoría Fundamentada, y las posibilidades que ofrece el software Atlas.ti para mejorar la práctica analítica cualitativa. La finalidad es contribuir a la fundamentación teórico-metodológica en la investigación educativa

Highway Bridge Assessment for Dynamic Interaction with Critical Vehicles

Dynamic vehicle-bridge interaction is often considered for the most common classes of vehicle such as the 5-axle articulated truck. However, the dynamic response of bridges to this type of trucks is quite different to the response to the vehicles more likely to feature in maximum-in-lifetime traffic loading events. This paper focuses on large (\u3e100 tonne) cranes and crane-type vehicles that have been recorded at Weigh-in-Motion sites in Europe. This paper analyses the total bending moment due to these vehicles on short to medium span bridges and compare them to 5- axle articulated trucks. To account for the variability in vehicle characteristics, more than 40,000 vehicle-bridge interaction events are computed using Monte Carlo simulation

Soil aggregation and organic carbon protection in a no-tillage chronosequence under Mediterranean conditions

Low-intensity soil management systems like no-tillage (NT) are being increasingly accepted as an essential part of sustainable farming systems. The objective of this work was to study the effects of NT maintenance over time on soil aggregation and soil organic carbon (SOC) protection on a semiarid Mediterranean agroecosystem. A NT chronosequence was established with five phases: (i) conventional tillage (CT); (ii) NT for 1 year (NT-1); (iii) NT for 4 years (NT-4); (iv) NT for 11 years (NT-11) and (v) NT for 20 years (NT-20). N fertilization was based on pig slurry for the whole experimental area. Soil samples were collected from four depths (i.e., 0–5, 5–10, 10–20, 20–30 cm). Dry and water-stable aggregates, SOC concentration and C concentration of water-stable aggregates were measured. SOC concentration reached its maximum value after 11 years under NT. However, the differences between NT phases were only found in the 0–5 cm soil depth. In soil surface (i.e., 0–5 cm), water-stable large macroaggregates (2–8 mm) were 0.02, 0.12, 0.32 and 0.31 g g− 1 dry soil for the NT-1, NT-4, NT-11 and NT-20 phases, respectively. C concentration of microaggregates increased in relation with the number of years under NT. SOC and water-stable macroaggregate stratification were greatest with the increase in the years under NT, emphasizing the close relationship between SOC and aggregation. In Mediterranean semiarid agroecosystems, the increase in the proportion of stable macroaggregates and the enrichment of C concentration within microaggregates are two main mechanisms of SOC protection when NT is maintained over time.This research was supported by the Comision Interministerial de Ciencia y Tecnologia of Spain (AGL 2004-07763-C02-02 and AGL 2010-22050-C03-01). D. Plaza-Bonilla was awarded with a FPU fellowship by the Spanish Ministry of Education. Jorge Álvaro-Fuentes acknowledges the Consejo Superior de Investigaciones Científicas (CSIC) for his contract within the “Junta para la Ampliación de Estudios” (JAE-DOC) programme co-financed by the European Social Fund