Biological and chemical factors controlling the patchy distribution of soil water repellency among plant species in a Mediterranean semiarid forest

Natural soil water repellency is a property that has already been observed in forest soils and is characterized by its patchy distribution. There are many factors involved in its development. In this work, we have studied a large number of chemical and biological factors under the influence of different plant species (. Pinus halepensis, Quercus rotundifolia, Cistus albidus and Rosmarinus officinalis) to learn which has the greatest responsibility for its presence and persistence in the top-soil layer. We observed strong and significant correlations between ergosterol, glomalin related soil protein (GRSP), extractable lipids, soil organic matter (SOM) content and water repellency (WR). Our results suggested lipid fraction as the principal factor. Moreover, apart from Pinus, fungal biomass seems to be also related to the SOM content. Soil WR found under Pinus appears to be the most influenced by fungi. Quality of SOM, to be precise, lipid fraction could be responsible for WR and its relationship with fungal activity.Ministerio de Economía y Competitividad CGL2010- 21670-C02-01, CGL2012-38655-C04-0

Biological and chemical factors controlling the patchy distribution of soil water repellency among plant species in a Mediterranean semiarid forest

Natural soil water repellency is a property that has already been observed in forest soils and is characterized by its patchy distribution. There are many factors involved in its development. In this work, we have studied a large number of chemical and biological factors under the influence of different plant species (. Pinus halepensis, Quercus rotundifolia, Cistus albidus and Rosmarinus officinalis) to learn which has the greatest responsibility for its presence and persistence in the top-soil layer. We observed strong and significant correlations between ergosterol, glomalin related soil protein (GRSP), extractable lipids, soil organic matter (SOM) content and water repellency (WR). Our results suggested lipid fraction as the principal factor. Moreover, apart from Pinus, fungal biomass seems to be also related to the SOM content. Soil WR found under Pinus appears to be the most influenced by fungi. Quality of SOM, to be precise, lipid fraction could be responsible for WR and its relationship with fungal activity.Peer Reviewe

Analytical Pyrolysis of Soil Easily-Extractable Glomalin (EEG) fraction.

Póster (P-EA-23) presentado en la XVIII Reunión de la Sociedad Española de Cromatografía y Técnicas Afines (SECyTA 2018), Granada, del 2 al 4 de Octubre de 2018.Easily Extractable Glomalin (EEG) represents an organic fraction of the soil that contains mainly glomalin-related soil proteins (GRSP), a glycoprotein abundantly found in soils produced by arbuscular mycorrhizal fungi in the phylum Glomeromycota [1]. The EEG fraction is confirmed to have multiple ecological functions in soils, including the improvement of soil stability and resilience to degradation, facilitate aggregate formation and contribute to soil carbon storage [2]. Given its potential for soil C immobilization, a detailed molecular characterization "fingerprint" of pyrolysis products of EEG fraction extracted from a Mediterranean soil under different plant covers, affected and unaffected by forest fire and at different times is conducted. A total of 16 samples were extracted from soils in Gorga (NE Alicante, Spain). Further information about the sampling process and EEG extraction protocols are described elsewhere [3]. In short, samples were taken from the surface (to 2.5 cm depth; A horizon) under pine and shrub covers, immediately after a forest fire (July 2011), and at 4, 8 and 12 months after the fire. Surrounding soils with similar characteristics but unaffected by fire were taken as control. The EEG samples were analysed using pyrolysis-gas chromatography coupled to mass spectrometry (Py-GC/MS). Pyrolysis temperature was 400 ºC for 1 minute and detailed chromatographic conditions and compound assignment procedure were as described in [4]. A total of 139 compounds were identified and grouped according to their probable biogenic origin: polysaccharides (PS), lignin and polyphenols (LIG), proteins and polypeptides (PRO), non-specific aromatic compounds (ARO), hydro-aromatics (HAR), lipids (LIP), polycyclic aromatic hydrocarbons (PAH) and terpenes (TER). A remarkable high similarity was found between EEG samples from different plant covers, both affected and unaffected by forest fire and at different time over a year after the fire. This fact indicates that EEG is a structurally stable soil organic fraction, very homogeneous and highly resistant if temperatures remain below 200-250ºC [5]. Its chemical structure mainly accounted for PS (42 ± 5%), ARO (24 ± 3%) and HAR (12 ± 3%). The remaining 20% included PAH (8 %), LIP (7 %), LIG (5 %) and PR (2 %). Comparison with previous results prove EEG to be rich in aromatic carbon [6, 7] and this reinforces the idea of EEG having a role in carbon sequestration.[1] Janos, D.P., Garamszegi, S., Beltran, B. (2008). Glomalin extraction and measurement. Soil Biol. Biochem, 40: 728-739. [2] Wright, S.F., Upadhyaya, A. (1996). Extraction of an abundant and unusual protein from soil and comparison with hyphal protein of arbuscular mycorrhizal fungi. Soil Sci. 161: 575–586. [3] Lozano, E., Jiménez-Pinilla, P., Mataix-Solera, J., Arcenegui, V., Mataix-Beneyto, J. (2016). Sensitivity of glomalin-related soil protein to wildfires: Immediate and medium-term changes. Sci Total Environ. 572: 1238–1243. [4] González-Pérez, J.A., Almendros, G., de la Rosa, J.M., González-Vila, F.J. (2014). Appraisal of polycyclic aromatic hydrocarbons (PAHs) in environmental matrices by analytical pyrolysis (PyGC/MS). J. Anal. Appl. Pyrolisis 109: 1-8. [5] Lozano, E., Chrenková, K., Arcenegui, V., Jiménez-Pinilla, P., Mataix-Solera, J., Mataix-Beneyto, J. (2016). Glomalin-related soil protein response to heating temperature: a laboratory approach. Land Degrad. Dev. 27: 1432–1439. [6] Schindler, F., Mercer, E., Rice, J. (2007). Chemical characteristics of glomalin-related soil protein (GRSP) extracted from soils of varying organic matter content. Soil Biol. Biochem. 39: 320–329. [7] Zhang, J., Tang, X., Zhong, S., Yin, G., Gao, Y., He, X. (2017). Recalcitrant carbon components in glomalin-related soil protein facilitate soil organic carbon preservation in tropical forests. Sci. Rep. 7: 2391Projects “POSTFIRE” (CGL2013- 47862-C2-1-R), “POSTFIRE_CARE” (CGL2016-75178-C2-1-R) and “INTERCARBON” (CGL2016-78937-R) co-financed by ‘Ministerio de Ciencia, Innovación y Universidades’ and FEDER Funds. Layla M. San Emeterio ‘Ministerio de Ciencia, Innovación y Universidadaes’ grant BES-2017-079811.Peer reviewe

Application of soil quality indices to assess the status of agricultural soils irrigated with treated wastewaters

The supply of water is limited in some parts of the Mediterranean region, such as southeastern Spain. The use of treated wastewater for the irrigation of agricultural soils is an alternative to using better-quality water, especially in semi-arid regions. On the other hand, this practice can modify some soil properties, change their relationships and influence soil quality. In this work two soil quality indices were used to evaluate the effects of irrigation with treated wastewater in soils. The indices were developed studying different soil properties in undisturbed soils in SE Spain, and the relationships between soil parameters were established using multiple linear regressions. These indices represent the balance reached among properties in "steady state" soils. This study was carried out in four study sites from SE Spain irrigated with wastewater, including four study sites. The results showed slight changes in some soil properties as a consequence of irrigation with wastewater, the obtained levels not being dangerous for agricultural soils, and in some cases they could be considered as positive from an agronomical point of view. In one of the study sites, and as a consequence of the low quality wastewater used, a relevant increase in soil organic matter content was observed, as well as modifications in most of the soil properties. The application of soil quality indices indicated that all the soils of study sites are in a state of disequilibrium regarding the relationships between properties independent of the type of water used. However, there were no relevant differences in the soil quality indices between soils irrigated with wastewater with respect to their control sites for all except one of the sites, which corresponds to the site where low quality wastewater was used

Molecular characterization of the soil organic fraction Easily-Extractable Glomalin (EEG)

4 páginas.-- 2 figuras.-- 7 referencias.-- Comunicación presentada en el VIII Congreso Ibérico de las Ciencias del Suelo. VIII Congresso Ibérico de Ciências do Solo. DONOSTIA-SAN SEBASTIÁN. 20 - 22 junio 2018..-- El documento completo se encuentra para su descarga en http://www.cics2018.com/libro-de-abstracts/[EN]: Easily Extractable Glomalin (EEG) is an operational term applied to an organic fraction of the soil supposed to contain mainly glomalin-related soil proteins (GRSP), a glycoprotein abundantly found in soils that is produced in the hyphae and spores of arbuscular mycorrhizal fungi (AMF). The EEG fraction is the most immunoreactive to glomus monoclonal antibody MAb32B11 and is related to relavant soil characteristics, such as its stability and resilience to degradation, formation of aggregates and stabilization of organic carbon. In this study we carried out a detailed molecular characterization >fingerprint> of the pyrolysis products of the GFE fraction extracted from a Mediterranean soil beneath different plant covers, affected and not affected by fire and at different times of the year. A total of 139 compounds were identified and grouped according to their probable biogenic origin. There is little variation between samples, indicating that the EEG is a structurally stable soil organic fraction, composed mainly of polysaccharides (42 ± 5%), non-specific aromatic compounds (24 ± 3%) and hydro-aromatics (12 ± 3%). The remaining 20% contains aromatic polycyclic hydrocarbons (8%), lipids (7% fatty acids and alkane/alkene pairs), lignin (5%) and protein/peptide derivatives (2%).[ES]: Glomalina Fácilmente Extraible (GFE) es un término operacional aplicado a una fracción orgánica del suelo que se supone contiene principalmente proteínas del suelo relacionadas con glomalina (PSRG), una glicoproteina abundante en los suelos y producida en las hifas y esporas de hongos micorrícicos arbusculares (HMA). La fracción GFE es la más inmunoreactiva al anticuerpo monoclonal MAb32B11 de glomus y está relacionada con características relavantes de los suelos, como su estabilidad y resiliencia a la degradación, formación de agregados y estabilización de carbono orgánico. En este estudio realizamos una caracterización molecular detallada “fingerprint” de los productos de pirólisis de la fracción GFE extraidas de un suelo mediterráneo bajo diferentes cubiertas vegetales, afectado y no afectado por un incendio y en distintas épocas del año. Se identificaron un total de 139 compuestos que se agruparon dependiedo de su probable origen biogénico. Se observa escasa variación entre muestras, indicando que la GFE es una fracción estructuralmente estable, compuesta principalmente de polisacáridos (42 ± 5 %), compuestos aromáticos no específicos (24 ± 3 %) e hidroaromáticos (12 ± 3 %). El 20 % restante lo componen hidrocarburos policíclicos aromáticos (8 %), lípidos (7 % ácidos grasos y pares alcano/alqueno), lignina (5 %) y derivados de proteina/péptidos (2 %).Los autores agradecen la financiación de los proyectos “POSTFIRE” (CGL2013- 47862-C2-1-R), “POSTFIRE_CARE” (CGL2016-75178-C2-1-R) e “INTERCARBON” (CGL2016-78937-R) financiados por la Agencia Estatal de Investigación (AEI) y por la Unión Europea a través del Fondo Europeo de Desarrollo Regional (FEDER),Peer Reviewe

Thermal alteration of soils belonging to highly diverse forest ecosystems: what’s behind the non-univocal aggregate stability and water repellency response?

Climate change drawbacks have recently induced major variations in fire regimes, and projections for future years forecast even more frequent and disruptive events [1]. As wildfires impose deep modifications on soil organic matter (OM) and mineral phase [2,3], soil water repellency (WR) and aggregate stability (AS) can be heavily affected, with fallouts on fertility and erosion. Yet, the extent of these alterations may vary according to soil type and development degree. Thirty topsoils representative of a wide variety of forest ecosystems across the globe (from savannah to tropical, Mediterranean, temperate and boreal forests) were subjected to laboratory heating at temperatures of 200° and 300°C (for 30 minutes) and characterized for WR, AS, and main drivers of organomineral interactions, such as pH, texture, organic C (OC) and total N content, and abundance of Fe oxyhydroxides. Selected samples were also analyzed by FT-IR, GC/MS, TGA-DSC and XRD. Water repellency, despite being highly variable among the samples, was always drastically lost when samples were exposed to temperatures>200°C. After separation into macro (2–0.250 mm) and micro (<0.250 mm) aggregate size classes, determination of macro-aggregate stability revealed that, upon growing temperatures, OM-rich high-elevation soils (from temperate and boreal forests) were far more subjected to AS loss than highly-developed Mediterranean and savannah soils, where aggregation is possibly ruled mostly by clay and heat induced Fe-Al oxyhydroxides re-crystallization phenomena [4]. In tight interlink with ecosystem resilience, the present study clearly evidenced the vulnerability of certain biomes towards thermal-induced soil degradation

Soil Easily-Extractable Glomalin (EEG): molecular characterization.

Easily Extractable Glomalin (EEG) is an operational term applied to a soil organic fraction supposed to contain mainly glomalin-related soil protein (GRSP) a glycoprotein abundantly found in soils that are produced in the hyphae and spores of arbuscular mycorrhizal fungi (AMF). This fraction is a significant component of SOM which effectively has multiple ecological functions including the facilitation of soil aggregate formation and its stability and resilience to degradation contributing to SOC storage. Given its potential as soil perturbation indicator here a detailed molecular characterization "fingerprint" was performed using analytical pyrolysis (Py-GC/MS) of the EEG fraction extracted from a Mediterranean soil beneath different plant covers (pine and shrubs) affected and unaffected by forest fire and at different times. 60 Soils (16) under pine and shrub covers from Gorga (NE Alicante Spain) were studied. Surface soil (2.5 cm depth; A horizon) samples were taken immediately after a forest fire that occurred in July 2011 and 4 8 and 12 months after the fire. EEG was extracted and measured using the Bradford assay and the lyophilized extracts analysed by PyGC/MS. A total of 139 compounds were identified and grouped according to their probable biogenic origin. Py-GC/MS did not show any clear differences between samples. Only minor differences could be detected between samples under pine and shrub covers regardless of the effect of fire. This fact indicates that the EEG is a structurally stable soil organic fraction very homogeneous and highly resistant in soil if temperatures remain below 200-250ºC. The main compounds found were polysaccharides (PS); polyphenols (LIG); proteins and polypeptides (PRO); non-specific aromatic compounds (ARO); hydro-aromatics (HAR); lipids (LIP); polycyclic aromatic hydrocarbons (PAH) and terpenes (TER). Surface density plots (also known as 3D van Krevelen diagrams) were built up from average values of pyrolytic products. The spatial distribution of these compounds supports similar pyrolytic patterns for the main factors studied: vegetation and fire. The results provide insight into the role of EEG in soils under high-level perturbations such as fire events. Due to their chemical similarity with humic acids EEG may play a relevant role in soil carbon storag

The impact of the farming, abandonment and agricultural intensification on loss of water and soil. the example of the northern slopes of the Serra Grossa, Eastern Spain

[EN] Land abandonment throughout the twentieth century led to an intense landscape transformation in the mountain areas of the Iberian Peninsula. In some cases, and after 50 years of abandonment, agriculture returned with the development of commercial farms and the intensification of the agrarian activities. In the Easter Iberian Peninsula, following the abandonment of olive groves, vineyards and cereals during the 50’s, has been in the past two decades the expansion of intensive citrus production on sloping terrain. Geomorphological transects and simulated rainfall experiments have quantified the impact of traditional rainfed cultivation of the 50’s, abandonment, and the intensification of farming on the processes and landforms of erosion on the northern slopes of the Serra Grossa, south of the province of Valencia. It was found that the citrus groves have the highest number of rills and gullies. These erosive morphologies were not in the traditional crop tillage, and when they formed in the abandoned fields were soon controlled by the growth of vegetation. The abandonment of the crops reduced the soil losses, but the intensification of the agriculture with the citrus production has accelerated the soil erosion rates that exceed by several orders of magnitude (x4) the soil erosion rates measured during the abandonment and multiply by 17 the quantified traditional rainfed agriculture soil losses. Tillage of traditional rainfed orchards reduced runoff, but increased the concentration of sediments of the surface wash.[ES] El abandono del campo a lo largo del siglo XX supuso una intensa transformación paisajística en las zonas de montaña en toda la Península Ibérica. En algunos casos, y tras 50 años de abandono, la actividad agrícola ha regresado con explotaciones comerciales y con una intensificación de la actividad agrícola. En el Este Peninsular, tras el abandono de olivares, viñedos y cereales, se ha producido en las dos últimas décadas la expansión de la citricultura intensiva en ladera. Mediante transectos geomorfológicos y experimentos con lluvias simuladas se ha cuantificado el impacto del cultivo tradicional de secano de los años 50, el abandono y posterior recuperación, y la intensificación de la explotación agrícola sobre los procesos y formas de erosión en la vertiente norte de la Serra Grossa, al sur de la provincia de Valencia. Se ha comprobado que los campos de cítricos presentan el mayor número de regueros y cárcavas. Estas morfologías erosivas no existían en el cultivo tradicional por el laboreo, y cuando se formaron en los campos abandonados pronto fueron controlados por el crecimiento de la vegetación. El abandono de los cultivos redujo la pérdida de suelo, pero la citricultura intensiva ha vuelto a reactivar los procesos erosivos hasta tasas que superan en varios órdenes de magnitud el abandono (x4) y que multiplican por 17 las cuantificadas en la agricultura tradicional de secano. El laboreo del secano tradicional reducía las escorrentías, pero aumentaba la concentración de sedimentos de la arroyada.Los proyectos CGL2008-02879/BTE y LEDDRA 243857 financiaron esta investigaciónCerdà, A.; Giménez Morera, A.; Burguet, M.; Arcenegui, V.; González Peñaloza, FA.; García Orenes, F.; Pereira, P. (2012). El impacto del cultivo, el abandono y la intensificación de la agricultura en la pérdida de agua y suelo, el ejemplo de la vertiente norte de la Serra Grossa en el este Peninsular. Cuadernos de Investigación Geográfica. I(38):75-94. https://doi.org/10.18172/cig.1276S7594I3