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Predicting the regional net greenhouse gas emissions (Net GHG) of grasslands is increasingly important, as these are one of the most globally widespread vegetation types, providing several ecosystem services. In this study, we assessed the regional soil organic carbon (SOC) change over a 30-year period (1981–2010), and the annual GHG balance for 405,000 ha of moist temperate Spanish grassland associated with dairy cow production. To do this we used the following: (i) an integrated modelling framework comprising geographic information systems (GIS); (ii) the RothC model to simulate SOC changes in managed grasslands under moist temperate conditions; and (iii) Tier 2 recent IPCC methods to estimate emissions. The results showed an average regional SOC change rate of 0.16 Mg C ha−1 year−1, associated with the initial SOC and livestock density. The annual GHG balance was positive, contributing to global warming by 5.6 Mg CO2-e ha−1 year−1. Livestock density was the main factor affecting net GHG emissions in the grasslands associated with dairy production in northern Spain. We determined a livestock density threshold of 0.95 LU ha−1, below which there is no SOC accumulation, and a threshold of approximately 0.4 LU ha−1, above which net GHG per livestock unit (LU) are reduced. In conclusion, our study confirms the importance of dairy cow grazing systems in preserving and/or enhancing SOC stocks in the grasslands of northern Spain. It is therefore crucial to optimise the livestock density considering large variety of feed intake and alternative manure management mitigation options to reduce the net GHG emissions.

Temperate grassland soils store significant amounts of carbon (C). Estimating how much livestock grazing and manuring can influence grassland soil organic carbon (SOC) is key to improve greenhouse gas grassland budgets. The Rothamsted Carbon (RothC) model, although originally developed and parameterized to model the turnover of organic C in arable topsoil, has been widely used, with varied success, to estimate SOC changes in grassland under different climates, soils, and management conditions. In this paper, we hypothesise that RothC-based SOC predictions in managed grasslands under temperate moist climatic conditions can be improved by incorporating small modifications to the model based on existing field data from diverse experimental locations in Europe. For this, we described and evaluated changes at the level of: (1) the soil water function of RothC, (2) entry pools accounting for the degradability of the exogenous organic matter (EOM) applied (e.g., ruminant excreta), (3) the month-on-month change in the quality of C inputs coming from plant residues (i.e above-, below-ground plant residue and rhizodeposits), and (4) the livestock trampling effect (i.e., poaching damage) as a common problem in areas with higher annual precipitation. In order to evaluate the potential utility of these changes, we performed a simple sensitivity analysis and tested the model predictions against averaged data from four grassland experiments in Europe. Our evaluation showed that the default model’s performance was 78% and whereas some of the modifications seemed to improve RothC SOC predictions (model performance of 95% and 86% for soil water function and plant residues, respectively), others did not lead to any/or almost any improvement (model performance of 80 and 46% for the change in the C input quality and livestock trampling, respectively). We concluded that, whereas adding more complexity to the RothC model by adding the livestock trampling would actually not improve the mod

En este trabajo se ha modificado y recalibrado el modelo de RothC para simular la dinámica del COS en pastos de clima templado húmedo.

Soil organic C (SOC) stock assessments at the regional scale under climate change scenarios are of paramount importance in implementing soil management practices to mitigate climate change. In this study, we estimated the changes in SOC sequestration under climate change conditions in agricultural land in Spain using the RothC model at the regional level. Four Intergovernmental Panel on Climate Change (IPCC) climate change scenarios (CGCM2-A2, CGCM2-B2, ECHAM4-A2, and ECHAM4-B2) were used to simulate SOC changes during the 2010 to 2100 period across a total surface area of 2.33 × 104 km2. Although RothC predicted a general increase in SOC stocks by 2100 under all climate change scenarios, these SOC sequestration rates were smaller than those under baseline conditions. Moreover, this SOC response differed among climate change scenarios, and in some situations, some losses of SOC occurred. The greatest losses of C stocks were found mainly in the ECHAM4 (highest temperature rise and precipitation drop) scenarios and for rainfed and certain woody crops (lower C inputs). Under climate change conditions, management practices including no-tillage for rainfed crops and vegetation cover for woody crops were predicted to double and quadruple C sequestration rates, reaching values of 0.47 and 0.35 Mg C ha−1 yr−1, respectively.

• El cambio climático limitará la capacidad futura de secuestrar C en los suelos agrícolas de Aragón. • Esta limitación será mayor en suelos de regadío y menor en suelos de secano. • En condiciones futuras, la adopción de determinadas prácticas de manejo (como la siembra directa o los cultivos cubierta) puede contribuir a incrementar las tasas de secuestro.

Agriculture in the Mediterranean basin is currently contributing to greenhouse gas emissions (GHG) and in the future is expected to be strongly affected by climate change. Increasing soil organic carbon (SOC) via soil organic matter (SOM) improvement is widely regarded as a way to both mitigate and adapt to climate change. Using as a case study the Mediterranean coastal area in Spain, which is regarded as one of the most intensively managed areas in Europe for orchards and horticultural cropping, we analyzed the potential for climate change mitigation of introducing different practices that are expected to increase SOC. We selected both as a single measure and in combination, cover cropping and application to the soil of the available underutilized exogenous organic matter (EOM), treated (e.g. composted or digested) or non-treated. These practices were compared against a baseline scenario that intended to reflect the current practices in the area (e.g. all livestock manure produced in the area is applied to the agricultural soil). We carried out a modelling exercise at the regional scale using the agricultural activity data and current climatic conditions as inputs. Modelling runs were performed coupling a widely used dynamic model of SOC turnover (RothC) with a model to simulate the GHG emissions from EOM processing or storage prior to soil application (SIMSWASTE). Results indicate that the most promising practice, considered as a single measure and with respect to the baseline, was introducing cover crops in woody cropping systems. This practice resulted in an increase of 0.44 Mg C ha−1 yr−1 during the first 20 years (range 0.41–0.52 Mg C ha−1 yr−1) and led to a total SOC accumulation of about 30 Tg C after 100 years. Amendment of all agricultural land with available underutilized EOM resulted in an increase of up to 0.09 Mg C ha−1 yr−1 (range 0.07–0.16 Mg C ha−1 yr−1) as a single measure (urban waste) and 0.13 Mg C ha−1 yr−1 (range 0.11–0.21 Mg C ha−1 yr−1) as a

An integrated assessment of the potential of different management practices for mitigating specific components of the total GHG budget (N2O and CH4 emissions and C sequestration) of Mediterranean agrosystems was performed in this study. Their suitability regarding both yield and environmental (e.g. nitrate leaching and ammonia volatilization) sustainability, and regional barriers and opportunities for their implementation were also considered. Based on its results best strategies to abate GHG emissions in Mediterranean agro-systems were proposed. Adjusting N fertilization to crop needs in both irrigated and rain-fed systems could reduce N2O emissions up to 50% compared with a non-adjusted practice. Substitution of N synthetic fertilizers by solid manure can be also implemented in those systems, and may abate N2O emissions by about 20% under Mediterranean conditions, with additional indirect benefits associated to energy savings and positive effects in crop yields. The use of urease and nitrification inhibitors enhances N use efficiency of the cropping systems and may mitigate N2O emissions up to 80% and 50%, respectively. The type of irrigation may also have a great mitigation potential in the Mediterranean region. Drip-irrigated systems have on average 80% lower N2O emissions than sprinkler systems and drip-irrigation combined with optimized fertilization showed a reduction in direct N2O emissions up to 50%. Methane fluxes have a relatively small contribution to the total GHG budget of Mediterranean crops, which can mostly be controlled by careful management of the water table and organic inputs in paddies. Reduced soil tillage, improved management of crop residues and agro-industry by-products, and cover cropping in orchards, are the most suitable interventions to enhance organic C stocks in Mediterranean agricultural soils. The adoption of the proposed agricultural practices will require farmers training. The global analysis of life cycle emissions associated to

Silicon samples were implanted with high Ti doses and subsequently processed with the pulsed-laser melting technique. The electronic transport properties in the 15-300 K range and the room temperature spectral photoresponse at energies over the bandgap were measured. Samples with Ti concentration below the insulator-metal (I-M) transition limit showed a progressive reduction of the carrier lifetime in the implanted layer as Ti dose is increased. However, when the Ti concentration exceeded this limit, an extraordinary recovery of the photoresponse was measured. This result supports the theory of intermediate band materials and is of utmost relevance for photovoltaic cells and Si-based detectors.

A sample of the investigations that are currently being carried out concerning GHG mitigation in the Spanish agricultural, livestock and forestry sector, but nevertheless give a taste of the research that is being developed in Spain to an international audience.

Recientemente, Jorge Álvaro-Fuentes y sus colegas del Consejo Superior de Investigaciones Científicas (CSIC, Estación experimental de Aula Dei) y de la Universidad de Lleida han llevado a cabo en España un estudio de cronosecuencia para estimar cuándo se produce la tasa de secuestro de C más alta después de la adopción de la siembra directa en condiciones de secano mediterráneas (Álvaro-Fuentes et al., 2014). Así, compararon campos adyacentes de siembra directa con diferente antigüedad (1, 4, 11 y 20 años). Este experimento de cronosecuencia reveló que 5 años después de la adopción de la siembra directa el suelo acumulaba C a su máxima velocidad y que después de 11 años el secuestro de C en el suelo era ya mínimo. Por tanto, estos resultados muestran la importancia de los primeros años después de la adopción de la práctica de manejo (en este caso la siembra directa) como potencial sumidero de C.

A principios de este mes de Diciembre tuvo lugar en el Basque Centre for Climate Change (BC3, Bilbao) el primer taller de modelización de emisiones de gases de efecto invernadero (GEI) en agrosistemas españoles. Enmarcada dentro de la red REMEDIA, esta actividad contó con la participación de un grupo de modelizadores de distintos centros de investigación y universidades españoles (BC3, UPM, CSIC, UdL y CIFA) que presentaron su trabajo en este ámbito y elaboraron un plan de trabajo a seguir en el futuro inmediato.