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Double-cropping is increasingly embraced for its economic advantages in irrigated crops within the Ebro Valley region. However, the implications of this practice for soil carbon dioxide (CO2) and methane (CH4) emissions remain poorly understood. This study aimed to assess the impact of legume-maize double-cropping on soil CO2 and CH4 emissions and to identify optimal tillage systems and nitrogen fertilization rates for enhancing soil carbon budget. Conducted in Agramunt (NE Spain), the research transformed a long-term tillage and nitrogen fertilization field experiment initiated in 1996 under rainfed conditions. It transitioned into a maize monocrop system in 2015 and a diversification experiment in 2018. Maize monocrop was compared to a legume-maize double-cropping with two tillage systems (conventional tillage and no-tillage) and three mineral nitrogen fertilization rates (zero, medium and high). The legumes used were pea for grain (2019), vetch for green manure (2020) and vetch for forage (2021). The use of legumes in the double-cropping system had a significant impact on CO2 fluxes. CO2 emissions in the double-cropping ranged from 250 to 8070 mg CO2-C m−2 day−1, while in the monocropping, the fluxes were in the range of 150–5790 mg CO2-C m−2 day−1. Due to the higher biomass production and extended crop cycle in the double-cropping, along with increased residue decomposition due to the higher amount of residue provided, the cumulative CO2 emissions were higher in the double-cropping. Within the double-cropping, the response of cumulative soil CO2 emissions to tillage depended on the legume used and residue management. For legumes with a low nitrogen content, conventional tillage resulted in lower cumulative CO2 emissions, while for legumes with a high nitrogen content, the lowest emissions were observed in the no-tillage system. The increased incorporation of crop residues in the combined approach of double-cropping and no-tillage led to a greater net ecosystem c

Winter legume cover crops or double-cropping in high N-fertilizer maize-based sprinkler-irrigated systems enhance agroecosystem diversity and potentially increase yields. However, the effects on direct N2O emissions and global warming potential (GWP) have not been fully established. For two years, in the Ebro Valley (Spain), four maize-based systems consisted of: long-season maize (Zea mays) with winter fallow period (F-LSM) the reference system; or after a leguminous cover crop (common vetch, Vicia sativa) (CC-LSM); and short-season maize after a cereal crop (barley, Hordeum vulgare) (B-SSM) or after a leguminous crop (pea, Pisum sativum) (P-SSM). They were assessed in terms of productivity, direct greenhouse gasses emissions (GHG: N2O, CH4, CO2), and global warming potential (GWP). Direct GHG emissions were measured using the static chamber technique, while soil parameters were monitored. Crop yields and nitrogen uptake were also quantified. GHG emissions linked to management and inputs were calculated to obtain GWP and greenhouse gas intensity (GHGI). The most productive system (B-SSM) obtained the highest direct (79 %, 35 %, and 30 % higher than the F-LSM, P-SSM, and CC-SSM, respectively) and scaled N2O emissions. The P-SSM system had similar N-uptake-scaled emissions to the monocropping (MC) systems. Irrigation, fertilizer, and farm operations accounted for the 26 %, 31 %, and 27 % of the total indirect emissions, respectively. Fertilizer production-related emissions in B-SSM and F-LSM systems were 172 % and 45 % higher than the average emissions in the systems with legumes (461 kg CO2eq. ha−1). Diversified systems lead to slightly higher GHGI values than the reference system (F-LSM). However, no differences were found between the F-LSM and P-SSM systems in GWP (4521 and 5512 kg CO2-eq. ha−1, respectively) or GHGI (144 and 158 kg CO2-eq. ha−1, respectively). The P-SSM system may be a potential alternative for increasing the diversification of maize-based irriga

La Estación Experimental de Aula Dei (EEAD) es un instituto de investigación perteneciente al Área de Ciencias Agrarias del Consejo Superior de Investigaciones Científicas (CSIC), organismo público de investigación del Ministerio de Ciencia e Innovación. La EEAD-CSIC forma parte del Campus de Aula Dei, un Campus único en España en el estudio, enseñanza y diseminación de las ciencias agrarias y medioambientales.

Microbial communities inhabiting hypersaline wetlands, well adapted to the environmental fluctuations due to flooding and desiccation events, play a key role in the biogeochemical cycles, ensuring ecosystem service. To better understand the ecosystem functioning, we studied soil microbial communities of Salineta wetland (NE Spain) in dry and wet seasons in three different landscape stations representing situations characteristic of ephemeral saline lakes: S1 soil usually submerged, S2 soil intermittently flooded, and S3 soil with halophytes. Microbial community composition was determined according to different redox layers by 16S rRNA gene barcoding. We observed reversed redox gradient, negative at the surface and positive in depth, which was identified by PERMANOVA as the main factor explaining microbial distribution. The Pseudomonadota, Gemmatimonadota, Bacteroidota, Desulfobacterota, and Halobacteriota phyla were dominant in all stations. Linear discriminant analysis effect size (LEfSe) revealed that the upper soil surface layer was characterized by the predominance of operational taxonomic units (OTUs) affiliated to strictly or facultative anaerobic halophilic bacteria and archaea while the subsurface soil layer was dominated by an OTU affiliated to Roseibaca, an aerobic alkali-tolerant bacterium. In addition, the potential functional capabilities, inferred by PICRUSt2 analysis, involved in carbon, nitrogen, and sulfur cycles were similar in all samples, irrespective of the redox stratification, suggesting functional redundancy. Our findings show microbial community changes according to water flooding conditions, which represent useful information for biomonitoring and management of these wetlands whose extreme aridity and salinity conditions are exposed to irreversible changes due to human activities.

The irrigation systems of the Ebro valley can lead to high N2O emissions. The effects that crop diversification, such as double-cropping in combination with conservation tillage and different N fertilizer ratios, has on soil N2O emissions have not been extensively studied in this region. The goal of this research was to measure N2O soil emissions and determine the tillage practices and N fertilization rates that provide the lowest emissions when combined with double-cropping systems. The work compared monocropping maize (MC) versus legume-maize double-cropping (DC) with two tillage systems (conventional tillage, CT; and no-tillage, NT), and three mineral N fertilization rates (zero, medium and high). Pea for grain (2019), vetch for green manure (2020), and vetch for forage (2021) were the legumes employed. The N2O emissions ranged from 0 to 15.5 mg N2O-N m−2 d−1 and were concentrated in the fertilization periods. Soil temperature and water filled pore space (WFPS) content significantly influenced soil N2O emissions. For both cropping systems, the conditions with the highest N2O emissions were soil temperatures above 20 °C and a WFPS of 50–60 %. The use of legumes facilitated reduced N fertilization in DC without affecting crop yield and led to reduced N2O emissions in this cropping system. DC reduced the emission factor (EF), which in all cases was lower than the default IPCC EF (1 %). With DC, a medium N fertilization rate produced similar yields to the high rate commonly applied by farmers, and also entailed lower N2O emissions. The no-tillage system, although producing higher levels of N2O, achieved lower yield-scaled N2O emissions due to greater crop yields. This work underlines the advantages of using double-cropping no-tillage systems combined with medium rates of N fertilization to reduce soil N2O emissions.

Maize is a major irrigated crop in Mediterranean areas and its typical intensive management may impact soil nitrous oxide (N2O) emissions. In these irrigated continuous maize systems, the legumes incorporation as well as adjusted nitrogen (N) fertilization might be interesting strategies to reduce soil N2O emissions. The objective of this study was to assess the impact of cropping diversification and different N rates on soil N2O emissions in flooded irrigated maize under Mediterranean conditions. To achieve this, two cropping systems (maize monoculture system, MC; and pea -maize rotation, MP) and 3N rates (unfertilized, 0N; medium rate, MN; and high rate, HN) were evaluated in a field experiment established in NE Spain during 2 years (2019; 2020). During the studied period, the N rate had a significant effect on soil N2O emissions, with a non-linear positive response of cumulative soil N2O emissions to N rates. In both systems, quick and high increases of soil N2O fluxes were observed immediately after the N application reaching 55 and 100 mg N2O-N m−2 day−1 in MC and MP, respectively. Both years, the pea phase of the MP rotation showed greater cumulative N2O emissions than the fallow of MC. However, N2O losses in the maize phase were similar (2019) or even higher (2020) in MC than in MP. Moreover, in both seasons, the MN treatments showed lower yield-scaled N2O emissions and N emission factor than the HN treatments, being this last lower than 1% in all cases. The results obtained showed that in irrigated Mediterranean conditions the replacement of a fallow by a legume, together with an adjusted N fertilization are favourable strategies to mitigate soil N2O emissions in high-yielding maize systems.

Sustainable agriculture has been identified as key to achieving the 2030 Agenda for the Sustainable Development Goals, which aims to end poverty and hunger and address climate change while maintaining natural resources. Soil organic carbon (SOC) sequestration is a key soil function for ecosystem services, and storing carbon (C) in soil by changing traditional management practices can represent an important step toward the development of more sustainable agricultural systems in Europe. Within the European project Diverfarming, the process-based ecosystem model ECOSSE was modified and evaluated in four long-term experiments (>8 years) to assess the impact of crop diversification and agricultural management in SOC dynamics. ECOSSE was able to simulate SOC under dry conditions in Mediterranean regions in Spain and Italy. In the site of Murcia, Spain, the addition of manure and cover crop in the diversified systems produced an increase of SOC in 9 years, when compared with the conventional management (16% measured increase, 32% simulated increase). The effect of tillage management on SOC stock in dry soil, in Foggia, Italy and Huesca, Spain, was also modeled, and a positive impact on SOC was predicted when no tillage was practiced. Finally, ECOSSE was used to understand the impact of diversifications in Boreal regions, Finland, where different proportions of legumes and grass were considered in a 4-year crop rotation compared with conventional cereal rotations. Experiments and modeling showed that the loss of SOC in conventional cereal was compensated when grass was introduced in the rotations. A good agreement (NRMSE <10%) and a nonsignificant bias were observed between model and experimental data for all sites. Mitigation scenarios considered in the modeling analysis for the test site Huesca showed that an integrated management of no tillage and manure is the best strategy to increase SOC, ∼51% over 20 years, compared with the baseline scenario (current farmers practic

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.

In lieu of an abstract, this is an excerpt from the first page. Agricultural intensification is a highly specialized agri-food system that has contributed to raising food production worldwide due to progress in agricultural machinery and technologies, the use of improved cultivars, and external inputs such as fertilizers, irrigation, and pesticides. Nevertheless, agricultural intensification and unsustainable soil management negatively influence the environment through a decrease in air and water quality, soil erosion, depletion of soil organic matter, resistance of weeds, pests, and pathogens to pesticides, and a decrease in soil quality and agrobiodiversity. It is well-known that some changes in agricultural systems are needed for their sustainability through balancing socio-economic food production aspects with environmental goals. In this context, appropriate diversification strategies and management practices are crucial for promoting the re-design of intensive agricultural systems. Several authors agree that crop diversity can improve crop productivity and resource use efficiency by delivering multiple ecosystem services. Coupling agricultural diversification including crop rotation, cover crops, multiple cropping and/or intercropping with low-input management strategies such as, agroecology, conservation agriculture, and organic farming contributes to increasing crop productivity and cropping system resilience in the long-term. Despite the large scientific consensus on the potential agro-ecological and socio-economic benefits of crop diversification, some financial instruments might be necessary to favour the adoption of combined agricultural diversification strategies since the economic costs in the short-term can offset the environmental and ecological benefits in the long-term. Particularly, the re-design and diversification of agricultural intensification imply specific transition costs that must be considered by farmers and advisors in the short- and med

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

In croplands, the adoption of certain management practices may increase soil organic carbon (SOC) levels. In this study, we evaluated the short-term impact of crop stover management and the interaction between crop stover and irrigation method on SOC change in a continuous maize (Zea mays L.) system in Spain. Four years after the beginning of the experiment, total SOC and C fractions (particulate organic matter carbon, POM-C; and mineral-associated organic matter carbon, Min-C) contents, SOC stocks and SOC stock changes were measured in four different soil layers (0−5, 5−10, 10−25 and 25−50 cm) in an experiment with two irrigation methods (sprinkler and flood) and three stover management systems (conventional tillage with all the stover incorporated, CT; no-tillage maintaining the stover, NTr; and no-tillage removing the stover, NT). Stover management resulted in significant differences in SOC and POM-C but not in Min-C. In particular, NT reduced SOC and POM-C contents compared with CT and NTr (about 10 and 60 %, respectively). After 4 years, SOC change was not affected by the interaction between stover management and irrigation. Concurrently, both CT and NT showed SOC losses, reaching 0.11 and 1.22 Mg ha−1 yr−1 in CT and NT, respectively. However, NTr showed SOC gains at a rate of 0.09 Mg ha−1 yr−1. Consequently, the removal of crop stover has been demonstrated as a detrimental strategy to store SOC in the short-term in irrigated continuous maize systems.

The aim of this study was to evaluate the impact of 21 years of tillage and N fertilization and the conversion from a rainfed to an irrigated cropping system on soil organic C (SOC). The study was carried out in northeastern Spain in a long‐term tillage and N rate field experiment established in 1996 under barley rainfed conditions, which in 2015 was converted into irrigation with corn. Three types of tillage (conventional tillage, CT; reduced tillage, RT; no‐tillage, NT) and three mineral N fertilization rates (0, 60, and 120 kg N ha−1 under barley, and 0, 200, and 400 kg N ha−1 under corn) were compared. Annual C‐inputs as aboveground crop residues and annual SOC sequestration rate (∆SOCrate) (0–40 cm depth) were calculated in three different periods (P1, P2 and P3) under rainfed (‐R) and irrigated (‐I) conditions (P1‐R, from 1996 to 2009; P2‐R, from 2009 to 2015; P3‐I, from 2015 to 2017). At the end of P3‐I, particulate organic C (POC) was measured from the 0–5, 5–10, 10–20, 20–30, and 30–40 cm depths. Averaged over all treatments, ∆SOCrate was 492, 222, and 969 kg C ha−1 yr−1 for P1‐R, P2‐R, and P3‐I, respectively. In P1‐R and P3‐I, C‐input explained 70% of the variability of ∆SOCrate. In P1‐R, ∆SOCrate followed the order NT > RT > CT, while for N rate, order was high > medium > 0. In P3‐I at the highest N rate, ∆SOCrate followed the order NT > RT > CT. In P2‐R, ∆SOCrate did not show differences between tillage and/or N rate treatments. The increase in SOC after conversion from a rainfed to an irrigation system was mainly explained by POC, which was increased by 75% compared to the previous rainfed period. The modification of the cropping system through the introduction of irrigation and adequate crop management practices under no‐tillage and adjusted N fertilizer rates can contribute to the sequestration of large amounts of atmospheric CO2.

[ES] El riego y el manejo del suelo son prácticas agrícolas que pueden afectar a los procesos de producción, consumo, transporte y emisión de gases de efecto invernadero (GEI) del suelo. Por tanto, resulta necesario evaluar y documentar el impacto de estas prácticas sobre las emisiones de estos GEI. El objetivo general de esta Tesis doctoral ha sido cuantificar el efecto del sistema de manejo del suelo y el sistema de riego y su gestión sobre la producción, transporte y emisión de GEI del suelo a la atmósfera en sistemas de monocultivo de maíz bajo condiciones mediterráneas. Para alcanzar este objetivo, entre los años 2015 y 2017 se realizaron dos ensayos de campo en la finca experimental de la Estación Experimental de Aula Dei (EEAD-CSIC) ubicada en la depresión central del Valle del Ebro., [EN] Irrigation and soil management are agricultural practices that can affect the processes of production, consumption, transport and emission of greenhouse gases (GHG) in soils. Therefore, it is necessary to assess the impact of those practices on soil GHG emissions. The general aim of this PhD Thesis was to quantify the effects of the soil management system and the irrigation system and its management on the production, transport and emission of soil GHG emissions in maize (Zea mays L.) monoculture systems under Mediterranean conditions. To achieve this objective, two field trials were conducted in 2015-2017 in the experimental farm of the Aula Dei Experimental Station (EEAD-CSIC) located in the central depression of the Ebro River Valley., [CA] El reg i el maneig del sòl són pràctiques agrícoles que poden afectar als processos de producció, consum, transport i emissió de gasos d’efecte hivernacle (GEH) del sòl. Per tant, resulta necessari avaluar i documentar l’impacte d’aquestes pràctiques sobre les emissions d’aquests GEH. L’objectiu general d’aquesta Tesi doctoral ha sigut el de quantificar l’efecte del sistema de maneig del sòl i el sistema de reg i la seva gestió sobre la producció, transport i emissió de GEH del sòl a l’atmosfera en sistemes de monocultiu de panís sota condicions mediterrànies. Per assolir aquest objectiu, entre els anys 2015 i 2017 es van realitzar dos assajos de campo a la finca experimental de la Estación Experimental de Aula Dei (EEAD-CSIC) ubicada a la depressió central de la vall del riu Ebre.

In the European Union, various crop diversification systems such as crop rotation, intercropping and multiple cropping, as well as low-input management practices, have been promoted to sustain crop productivity while maintaining environmental quality and ecosystem services. We conducted a data analysis to identify the benefits of crop associations, alternative agricultural practices and strategies in four selected regions of Europe (Atlantic, Boreal, Mediterranean North and Mediterranean South) in terms of crop production (CP). The dataset was derived from 54 references with a total of 750 comparisons and included site characteristics, crop information (diversification system, crop production, tillage and fertilization management) and soil parameters. We analyzed each effect separately, comparing CP under tillage management (e.g., conventional tillage vs. no tillage), crop diversification (e.g., monoculture vs. rotation), and fertilization management (e.g., mineral fertilization vs. organic fertilization). Compared with conventional tillage (CT), CP was higher by 12% in no tillage (NT), in fine- and medium-textured soils (8–9%) and in arid and semiarid sites located in the Mediterranean Region (24%). Compared to monoculture, diversified cropping systems with longer crop rotations increased CP by 12%, and by 12% in soils with coarse and medium textures. In relation to fertilization, CP was increased with the use of slurry (40%), and when crop residues were incorporated (39%) or mulched (74%). Results showed that conversion to alternative diversified systems through the use of crop rotations, with NT and organic fertilization, results in a better crop performance. However, regional differences related to climate and soil-texture-specific responses should be considered to target local measures to improve soil management.

In irrigated Mediterranean conditions there is a lack of knowledge about the best combination of tillage and N fertilization practices to reduce soil nitrous oxide (N2O) emissions while maintaining maize productivity. The aim of this work was to investigate the effects of different soil management practices and synthetic N fertilization rates on soil N2O emissions and their relationship with maize grain yield to determine the best management system to reduce yield-scaled N2O emissions (YSNE) in a semiarid area recently converted to irrigation under Mediterranean conditions. A long-term tillage and N rate field experiment established in 1996 under barley (Hordeum vulgare L.) rainfed conditions, was converted to irrigated maize (Zea mays L.) in 2015. After the transformation to irrigation, the field experiment maintained the same tillage treatments and N fertilization rates. Three types of tillage (conventional tillage, CT; reduced tillage, RT; no-tillage, NT) and three mineral N fertilization rates (0, 200, 400 kg N ha−1) were compared during three years (2015–2017) in a randomized block design with three replications. Soil N2O emissions, water-filled pore space, soil temperature, mineral N content (as NH4+ and NO3−), denitrification potential and maize grain yield and above-ground N uptake were quantified. Moreover, the emission factor (EF) and YSNE were calculated. The results showed that the combination of NT and the highest rate of N fertilization led to greater N2O emissions. Furthermore, the lowest N2O fluxes were observed in CT when WFPS was below 40% and the highest N2O fluxes were seen in NT when WFPS was above 60% coinciding with the greatest denitrification potential. Cumulative N2O emissions in 2017 and 2015 followed the order 400 > 200 > 0 kg N ha−1, while in 2016, rate of 400 and 200 kg N ha−1 showed greater cumulative N2O emission compared to the control. Only RT showed differences between growing seasons on cumulative N2O emissions, with greater value

Irrigation as well as soil tillage management are considered two possible strategies to reduce carbon dioxide (CO2) and methane (CH4) emissions from the soil in Mediterranean agroecosystems. The objective of this work was to assess the impact of the irrigation system (i.e. flood, F; and sprinkler, S) and the soil tillage system (i.e. conventional tillage, CT; no-tillage maintaining the maize stover, NTr; and no-tillage removing the maize stover, NT) on CO2 and CH4 emissions from the soil during three growing seasons (2015, 2016 and 2017) and two fallow periods between growing seasons (15–16 fallow and 16–17 fallow) in a maize (Zea mays L.) monoculture system. Soil temperature and water-filled pore space (WFPS) had a great influence on daily soil CO2 fluxes but not on daily soil CH4 fluxes. In all tillage-irrigation treatments, daily soil CO2 fluxes showed an increase with soil temperature, being this increment greater when soil temperature was above 15 °C in coincidence with the maize plant growth. In contrast, soil WFPS differently affected daily soil CO2 fluxes depending on the irrigation system. Under S irrigation, daily soil CO2 fluxes increased with soil WFPS, whereas under F irrigation a threshold value of 60% WFPS was found, with a positive or negative effect on CO2 fluxes for values below or above this threshold value, respectively. Over the three maize growing seasons, CT-S presented the greatest cumulative soil CO2 emissions with a seasonal average value of 3.28 Mg CO2-C ha−1. In contrast, for the same period, NTr-S cumulative soil CO2 emissions were up to 42% lower than the CT-S cumulative soil CO2 emissions. Cumulative CH4 emissions were only affected by soil tillage during the 16–17 fallow period, resulting both NTr and NT in greater net CH4 uptake compared with CT. This work highlights the importance of irrigation and soil tillage systems as key agricultural practices to minimize soil CO2 and CH4 emissions under Mediterranean conditions.

El Departamento de Suelo y Agua de la Estación Ex­perimental de Aula Dei, instituto perteneciente te al Consejo Superior de Inves­tigaciones Científicas (CSIC), está investigando el impacto de las ac­tividades agrícolas en las comuni­dades microbianas de los hume­dales salinos del arco mediterrá­neo. En España, concretamente, están centrando sus trabajos en la zona de Gallocanta y Monegros de Aragón. A través de un enfoque integrado y multidisciplinar, el tra­bajo está orientado a conocer las características físico-químicas y microbiológicas de las aguas y el suelo de los humedales. El fin es investigar la transferencia de sus­tancias químicas a las masas de agua y al suelo.

The work shows, through results from different long-term experiments and some insights on crop rotation performance in commercial farms, how the adoption of conservation tillage, rational use of N fertilizers, sowing date delay and crop diversification, as integrated cropping system approach, can make wheat-based production systems more sustainable under Mediterranean conditions.

• Maize monocropping is the main cropping system under irrigated conditions in Spain. • Typical management includes high N fertilizer rates and irrigation with the concomitant impact on soil greenhouse gas emissions (GHG). • This study evaluates the impact of alternative diversified cropping systems to maize monocropping and varying N fertilization rates on soil GHG emissions.

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

Major constraints to rainfed production systems in the world’s drylands include low and highly variable rainfall, nutrient deficiencies and land degradation by wind and water erosion. Although the same principles to cope with these limitations could be in theory applied to all dryland situations, there is no a universal recipe for sustainable dryland agriculture. In this chapter, the authors recall some of the challenges that have been identified for semiarid rainfed farming systems, namely soil conservation, water use efficiency, nutrient use efficiency and climate change mitigation, as well as some sustainable cropping and management strategies that have been formulated and recommended to address them appropriately. To this end, the authors provide examples supporting those practices mainly from semiarid Mediterranean agroecosystems. Among all the strategies discussed in this Chapter, and despite their limitations, the maintenance of a protective crop residue cover and the reduction of tillage operations appear to be the simplest technological options not only to control soil erosion but also to improve water and nutrient use efficiency and mitigate greenhouse gas emissions. The authors conclude that sustainable agricultural management in drylands should be primarily based on conservation agriculture practices and associated local-based crop residue management systems.

For quite a long time, soil organic carbon stock (SOCS) has reduced from reconverting forest areas into agricultural land or by inadequate agronomic practices. However in recent decades in Mediterranean areas, abandonment of agricultural areas due to lack of economic profits and to promoting tourism has fostered a change in land use that has impacted edaphic carbon. In line with this, the Majorca Island (Spain) could be a good scenario to evaluate temporary changes in carbon stocks in soils in areas with a Mediterranean climate. For 11 years, the present study analysed the spatial distribution of SOCS and assessed temporal changes in agricultural soils in relation to the influence of human activities and land use. The global carbon budget on the Majorca Island was estimated at 31.23 Tg C, and showed wide spatial variability. As expected, SOCS was higher in the forest areas of the Tramuntana Mountain Range (more than 100 tC ha-1), while the lowest contents were found in agricultural use (79.3 tC ha-1 ), located mainly in the centre and south of this island.The total C stored from 2006 to 2017 increased by 2.62 Tg C (15%) in agricultural areas on the island. We noted a major increase in SOCS in the agricultural zones on mountain slopes (> 2-9 fold higher), associated with abandoned crops in terrace cultivation, but grassland systems also increased. Nonetheless, the present study shows a sharp drop in SOCS in the centre and south of this island. This decrease was more pronounced in annual crops (-14.5%), which could be attributed to intensive soil management and increased irrigated land. Land abandonment has been indicated as the main potential to carbon sequestration in soil, but this SOC sequestration is no infinite process. Certain changes in agricultural practices on Majorca, and in rural Mediterranean areas in general, are necessary to avoid carbon loss in crop soils. Adoption of conservation agriculture practices, e.g. cover crops, crop rotation, organic addition

Tras la Cumbre del Clima celebrada en Madrid, este experto destaca el protagonismo del sector agrario en la lucha contra el cambio climático.

In newly irrigated Mediterranean agroecosystems, the combined effect of tillage and N fertilization on soil carbon dioxide (CO2) and methane (CH4) fluxes is at present poorly understood. The goal of this study was to quantify both soil CO2 and CH4 emissions as well as crop performance under different tillage systems and N fertilization rates during three maize (Zea mays L.) growing seasons (2015–2017) in a semiarid area converted to irrigated. Three types of tillage (conventional tillage, CT, reduced tillage, RT, and no-tillage, NT) and three mineral N fertilization rates (0, 200, and 400 kg N ha−1) were compared in a randomized block design with three replications. Weekly soil CO2 and CH4 emissions, soil temperature and gravimetric moisture were measured. Moreover, maize above-ground biomass, grain yield, and above-ground C-inputs were quantified. Carbon dioxide emissions ranged from 173 to 4378 mg CO2-C m-2 d-1. No-tillage showed a greater mean soil CO2 flux than CT when applying the highest rate of N (400 kg N ha-1). Although some emissions of CH4 were observed, all treatments acted as net CH4 sinks during most of the experimental period. A linear multiple relationship between soil CO2 fluxes and soil gravimetric moisture (0–5 cm depth) and temperature (10 cm depth) were found. In the 2015 growing season, greater cumulative CO2 emissions were found under NT and RT compared with CT, while in 2016 N T showed the highest values compared to CT with intermediate values in RT. Differently, in 2017 no differences between tillage systems were found. When applying N fertilizer, NT and RT increased maize grain production and above-ground C-inputs compared to CT, since a severe soil crusting occurred in this last, which caused crop water deficit. The results suggest that tillage intensity and N fertilization rate reduction can increase maize biomass production and yield which leads to greater C-input that returns to the soil.

Threshold friction velocity (u⁎t) is a very important parameter, which represents wind erosion potential. Because of the difficulty of measuring u⁎t, it would be advantageous if u⁎t could be estimated indirectly from its effecting factors that can be easily measured. The main purpose of this research was to quantify relationships between u⁎t and various topsoil features using inexpensive approaches. To prepare a reliable dataset, we used a portable wind tunnel for measuring u⁎t at a total of 118 observation points in Kerman province, southeast Iran. We developed a non-dominated sorting genetic algorithm II (NSGA-II), specifically designed to operate with artificial neural network (ANN) to select the most determinant properties that influence u⁎t. A permutation of nine input features including surface crust (SC), gravel coverage (GC), very fine sand (VFS), fine sand (FS), very coarse sand (VCS), electrical conductivity (EC), sodium adsorption ratio (SAR), calcium carbonate equivalent (CCE), and mean weight diameter (MWD), was introduced as explanatory variables. We also examined the potential power of using a Multi-Layer Perception (MLP) neural network for prediction of u⁎t changes in response to spatial variation of the selected features. The results of constructed MLP model revealed the ability of the model for u⁎t prediction and showed that the coefficient of determination (R2) values were 0.91 and 0.89 for training and testing data, respectively. Furthermore, acceptable level of the statistical validation criteria verified reliable performance of the MLP model. This research provided a powerful basis for prediction of u⁎t from topsoil features and surface roughness in arid and semi-arid areas of Iran; however, its generic framework could be used to other arid and semi-arid regions with similar challenges.

Irrigation management may influence soil greenhouse gas emissions (GHG). Solid-set sprinkler irrigation systems allow to modify the irrigation time and frequency. The objective of this study was to quantify the effect of two irrigation times (daytime, D; nighttime, N) and two irrigation frequencies (low, L; high, H) on soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions in a solid-set sprinkler-irrigated maize (Zea mays L.) field located in NE Spain during 2015 and 2016 growing seasons and the fallow period between growing seasons. Compared with D irrigation, N irrigation increased soil water content (0–5 cm) in both growing seasons. Irrigation management did not affect CH4 emissions and the soil acted as a sink of CH4. Cumulative CO2 emissions were affected by the measurement period (growing season vs fallow) with the greatest values in 2015 growing season, being 81 and 32% higher over the fallow period and over the 2016 growing season, respectively, due to the effect of the preceding crop, alfalfa, and a better soil moisture conditions for the microorganism activity. Similarly, cumulative N2O emissions showed the highest values in 2015, reporting values 90 and 51% greater than the fallow period and the 2016 growing season, respectively. Moreover, N irrigation increased cumulative N2O emissions by 29% compared with D irrigation, but irrigation frequency did not affect cumulative N2O emissions. Irrigation time did not affect cumulative N2O emissions scaled per grain yield or per N uptake because N irrigation increased maize yield by 11% compared with D irrigation. Due to the lack of differences in the scaled N2O emissions, N irrigation should be consider as an appropriate strategy to optimize grain yield without compromising soil GHG emissions per unit of grain yield in Mediterranean agroecosystems.

Actividad institucional divulgativa celebrada durante la "Jornada sobre la Historia de la EEAD-CSIC" realizada el 7 de junio en el Salón de Actos del Instituto Agronómico de Zaragoza perteneciente al Centro de Altos Estudios Mediterráneos (CIHEAM-IAMZ). Forma parte, junto con otras actividades divulgativas de naturaleza histórica, del II Ciclo de Exposiciones y conferencias del 75 Aniversario EEAD-CSIC (junio 2019), dentro del programa general de actividades organizadas con motivo del 75 Aniversario de la EEAD-CSIC. La conferencia, finalmente, se impartió por la autora con otro título: "Cereales, cromosomas y colchicina: Aula Dei y la citogenética en la década de 1950".

The soils of the Mediterranean Basin are the products of soil processes that have been governed by a unique convergence of highly differentiated natural and anthropogenic drivers. These soils are expected to be dramatically affected by future climate and societal changes. These changes imply that suitable adaptive management strategies for these resources cannot simply be transposed from experiments that are performed in other regions of the world. Following a framework that considers the chain of “drivers-soil process-soil capital-ecosystem services/disservices,” the paper review the research undertaken in the Mediterranean area on three types of Mediterranean soil degradation than can be expected under global change: (i) soil losses due to the increase of drought and torrential rainfall; (ii) soil salinization due the increase of droughts, irrigation, and sea level; and (iii) soil carbon stock depletion with the increase of temperature and droughts. The possible strategies for mitigating each of these degradations have been largely addressed and are still studied in current research projects. They should include changes in agricultural practices, soil water management, and vegetal material. As a pre-requisite for the site-specific adaptations of such mitigation strategies within viable Mediterranean agrosystems, it is highlighted that methodological advances are necessary in integrated assessment of agricultural systems and in finer resolution soil mapping.

En los sistemas de producción de cultivos herbáceos extensivos con siembras otoñales, las operaciones de fertilización representan un importante coste de producción. La eficiencia en el uso de los fertilizantes es fundamental, ya que estudios actuales indican que como media, la eficiencia en el uso de los fertilizantes nitrogenados no alcanza el cincuenta por ciento, incluso es más baja para el fosforo y el potasio. Se muestran tres ejemplos prácticos de fertilización de cultivos de siembra otoñal en distintas condiciones de cultivo.

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.

El cambio climático representa, sin duda, uno de los principales retos mundiales, con graves repercusiones no solo ambientales sino también sociales y económicas. Debido al papel decisivo que el clima juega en la agricultura, el cambio climático es, actualmente, una de las principales amenazas en el sector agrario. En esta conferencia se analizará, en primer lugar, el impacto del cambio climático en la producción de alimentos, se examinarán las estrategias de adaptación al cambio climático existentes y, por último, se presentarán algunas de las alternativas disponibles para mitigar el cambio climático a través de la actividad agraria.

Human occupation and transformation of land are a root cause of ecosystem services degradation. For example, land use (LU) and land use change (LUC) are drivers of soil organic carbon (SOC) change, decreasing the biotic production potential of soils. In Life Cycle Assessment (LCA) there is a growing trend towards accurate and regionalized impact assessment of LU∖LUC. Available impact assessment models apply statistical procedures to a simplified static characterization framework, including a limited set of aggregated LU classes. In this paper we propose process-based modelling as the basis for LU/LUC Life Cycle Impact Assessment (LCIA) and calculate midpoint process-based characterization factors (CFs) using SOC depletion as the impact indicator. This forecast or scenario-based approach included climate change scenarios for the study region. Temperature and precipitation changes are likely to affect the role of LU in SOC accumulation, which should influence LUC choices today. As proof of concept we used the region of Alentejo, Portugal, which was divided in more than 1500 unique homogeneous territorial units (UHTU). We used the process-based model RothC to establish the likely dynamic SOC evolution after LUC in each UHTU. Our work suggests that process-based models are necessary to move beyond the calculation of CFs for generic LU classes. We provide CFs for individual crops and discriminated LU classes and management practices. We additionally provide insights and indication for future work leading up to the production of global CFs using similar soil models and an updated procedure for CF calculation.

El cambio climático se genera por el incremento de la concentración de determinados gases presentes en la atmosfera. Estos gases, denominados ‘gases de efecto invernadero’, tienen la capacidad de absorber parte de la radiación, incrementando la temperatura de la superficie terrestre. Estos gases han existido siempre de manera natural en nuestra atmósfera, permitiendo la vida en nuestro planeta. El problema sucede cuando los niveles de estos gases aumentan sustancialmente a consecuencia de la actividad del ser humano y, de manera paralela, se acelera el incremento de la temperatura en la superficie terrestre.

¿Qué hacemos? • Sistema “suelo-agua-cultivo-atmósfera” • con énfasis en el riego, la agronomía y el medio ambiente, • con un enfoque de investigación aplicada., Líneas prioritarias: 1- Uso sostenible de los recursos agua y suelo; 2- Impacto ambiental de las actividades agrarias; 3- Agronomía de cultivos.

La metodología para el muestreo de gases de efecto invernadero (GEI) mediante cámaras estáticas debe estandarizarse para una correcta comparación. Objetivo: Evaluar y comparar los flujos de CO2 y N2O medidos con cámaras estáticas dejando la planta en su interior o eliminándola.

There is a strong need to identify agricultural management practices that maintain agronomic productivity while diminishing soil N2O emissions. The yield-scaled N2O emissions (YSNE) indicator can help to evaluate the adequacy of a given agricultural practice under both aspects. Long-term (18-yr) soil water and mineral N dynamics, crop biomass and yields, and 2011–2012 soil N2O emissions and ancillary variables were measured on barley (Hordeum vulgare L.) production in a tillage (conventional tillage, CT; no-tillage, NT) and N rate (0, 60 and 120 kg N ha−1) combination under rainfed Mediterranean conditions (NE Spain). Once evaluated, the STICS soil-crop model was used to simulate the 18-yr soil N2O emissions of each tillage system under increasing N rates (0, 30, 60, 90 and 120 kg N ha−1) in order to identify optimum management to reduce YSNE, being initialized with observed data. Cropping season precipitation was highly variable during the experiment, being a key regulating mechanism for crop yields and simulated soil N2O emissions. Crop yield under NT with N outperformed CT in 11 years. STICS performed reasonably well when simulating cumulative N2O emissions and ancillary variables with model efficiencies greater than 0.5. The 18-yr average simulated cumulative N2O emissions were 0.50, 0.82 and 1.09 kg N2O-N ha−1 yr−1 for CT-0, CT-60 and CT-120, respectively, and they were 0.53, 0.92 and 1.19 kg N2O-N ha−1 yr−1 for their counterparts under NT. These averages mask a large variability between years, according to precipitation. The 18-yr mean yield-scaled N2O emissions were 2.8–3.3 times lower under NT, compared to the corresponding CT treatments. Under CT, N application would increase YSNE in most years while YSNE would be more resilient to the application of increasing N rates under NT. Our work demonstrates that in rainfed Mediterranean systems NT is a win-win strategy for the equilibrium between agricultural productivity and low soil N2O emissions.

Los resultados que se presentan en este documento corresponden a los 4 primeros años de experimento (campañas 2010-2011, 2011-2012, 2012-2013 y 2013-2014) en los que el sistema de cultivo fue un monocultivo de cebada. El tratamiento LC consistió en el manejo tradicional de la zona con un pase de grada de discos seguido de uno de cultivador antes de la siembra. En el caso de la SD no se realizó ninguna labor de preparación del suelo, aplicándose glifosato a una dosis de 1,5 L ha-1, antes de la siembra.

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.

[ES] Los cambios en los usos del suelo han contribuido de manera importante al incremento de gases de efecto invernadero en la atmósfera, especialmente de dióxido de carbono, aumentando sus emisiones desde 1970 en un 80%. Estos cambios causan la alteración de los suelos provocando un impacto sobre el ciclo del carbono, aumentando las tasas de descomposición de la fracción orgánica creando así un flujo de CO2 a la atmosfera. Entre las recomendaciones del Panel Intergubernamental de expertos sobre el Cambio Climático (IPCC, en inglés), y contemplado en el Protocolo de Kyoto, se encuentra el proceso de secuestro de carbono en suelos, que implica la eliminación del CO2 atmosférico por parte de las plantas y su almacenamiento como materia orgánica del suelo. Para poder favorecer dicho proceso, en un determinado tipo de ecosistema, es fundamental conocer cuáles son los factores que gobiernan la respiración del suelo y el impacto que tienen los diferentes usos en la emisión de CO2. En el presente trabajo se han estudiado 4 usos del suelo representativos del secano aragonés: un monocultivo de cebada en siembra directa (NT), un suelo abandonado labrado (AC), un suelo abandonado no alterado (AU) y un suelo forestal (FR) con el objetivo de conocer sus tasas de respiración, la influencia de diferentes parámetros edáficos en ellas, y proponer cambios en el uso del suelo que ayuden a mitigar estas emisiones. Además, se ha dedicado un apartado para conocer cómo influyen diferentes técnicas de fertilización nitrogenada (mineral y orgánica) en la respiración de un monocultivo de cebada en siembra directa. En cuanto a los usos, los resultados obtenidos tanto in situ como en laboratorio muestran una mayor respiración en AC, siendo los valores más bajos los de NT y FR. Una de las principales conclusiones es que la supresión del laboreo y del periodo de barbecho largo, así como la conversión de tierras abandonadas y marginales a cultivos y zonas forestales se presentan en este tipo de e, [EN] Land use changes have contributed significantly to increase the concentration of greenhouse gases in the atmosphere, especially carbon dioxide, whose emissions have grown since 1970 by 80%. These changes cause an alteration of soil inducing an impact on the global carbon cycle that accelerates the soil organic matter decomposition rates generating CO2 fluxes to the atmosphere. A process recommended by the Intergovernmental Panel on Climate Change (IPCC), and recognized in the Kyoto Protocol, is the carbon sequestration that implies removal of atmospheric CO2 by plants and storage as soil organic matter. In order to implant this practice in a particular ecosystem, studies are necessary to understand the factors that govern soil respiration and the impact of different land uses on CO2 emissions. In this study, it was studied 4 different types of land uses representative of semiarid rainfed Aragón: a cropping system of barley under no-tillage (NT), an abandoned agricultural plowed field (AC), an abandoned uncultivated field (AU) and a forest area (FR). The objective of the present study was to evaluate the respiration rates, the environmental factors that influence these rates and to propose land use changes to mitigate CO2 emissions. Additionally, it is included a section to explore the response of soil respiration to nitrogen fertilization (mineral and organic) in a barley system. In the study of land uses, the obtained results in situ as well as in laboratory have shown the highest soil respiration in AC and the lowest in NT y FR. Thus, one of the main conclusions is that the suppression of tillage and the fallow period, and the conversion from abandoned and marginal soils to forest areas or crops are carbon sequestration practices in this ecosystem. In the study of nitrogen fertilization, there was no change in soil respiration rates after application of mineral nitrogen. In contrast, soil fertilized with manure showed peaks in CO2 emissions during the hours f