Microbiological characterization of a semi-arid meadow soil seeded with different proportions of orchard grass and alfalfa

1 póster donde se muestran los resultados de su investigación.-- Póster presentado al XV Congress of the Spanish Society of Nitrogen Fixation, and the IV Portuguese-Spanish Congress on Nitrogen Fixation. En León (España). 16, 17 y 18 de junio de 2015Soil is a pivotal component of the environment and the maintenance of soil quality is critical for ensuring the sustainability of the biosphere. The use of fertilizers has increased at a faster rate than global food production. Modern agriculture is dependent on phosphorus derived from phosphate rock, which is a non‐renewable resource. It is needed to improve P acquisition efficiency for both low input and intensive agroecosystems. However, few studies have focused on cereal‐legume interactions with regard to soil P. The objective of this work was to study the effects of grass‐legume mixtures and phosphorus fertilization on soil microbial community structure and biomass [determined by fatty acid methyl ester (FAME) profiling] as well as on the soil nitrogen (N) mineralisation rate.Peer reviewe

Mulching and seeding treatments for post-fire stabilization techniques in Laza (NW Spain): medium-term effects on soil quality and effectiveness

The impact of fire and different post-fire stabilisation treatments like mulching and seeding on some selected physical, chemical biochemical and microbiological properties as well as the efficacy of these treatments on control of post-fire erosion was evaluated in a burnt area affected by a high severity wildfire located in Laza (NW Spain). Soil samples were collected from the A horizon (0-2 cm) of the burnt soil 8 and 12 months after the wildfire as well as from the unburnt soil located in an adjacent plot used as control; sediments were periodically collected after precipitation events in the burnt soil with and without different post-fire stabilisation treatments. The results clearly showed that a significant medium-term impact of the wildfire on most soil properties analyzed was still observed 12 months after the fire event and that mulching and seeding treatments did not affect the overall soil quality (physical, chemical, biochemical and microbiological properties) of this burned soil. Sediments data indicated that both stabilisation treatments were effective to control post-fire erosion since, compared to the burnt control, soil losses were reduced by 85% in the mulching treatment and by 30% in the seeding treatment

Recovery of a soil under different vegetation one year after a high intensity wildfire

Studies on soil recovery in fragile ecosystems following high intensity wildfires are scarce. The aim of the present investigation is to evaluate the impact of a high intensity wildfire in an ecosystem under different vegetation (shrubland and pinewood) located at Vilardevós (Galicia, NW Spain) and highly susceptible to suffer soil erosion due to the steep relief and high erositivity of the rainfall. Soil samples were collected from the A horizon (0-5 cm) 1 year after the fire and soil quality was evaluated by analysis of several physical, chemical and biochemical properties measured in the fraction < 2 mm. The results showed marked effects of the wildfire on most properties analyzed even 1 year after the fire; however, a different effect both in the trend (positive, negative) and magnitude were observed, depending on the soil property analyzed. In general, the sensitivity to detect fire induced changes followed the order: biochemical properties > chemical properties > physical properties. The data also showed that the fire impact was different depending on the soil vegetation considered (shrubland and pinewood). Moreover, the data confirmed the slow soil recovery in this fragile ecosystem and, therefore, the need of adopting post-fire stabilisation and rehabilitation treatments in order to minimize the post-fire erosion and soil degradation

Effect of Long-Term Zinc Pollution on Soil Microbial Community Resistance to Repeated Contamination

The aim of the study was to compare the effects of stress (contamination trials) on the microorganisms in zinc-polluted soil (5,018 mg Zn kg−1 soil dry weight) and unpolluted soil (141 mg Zn kg−1 soil dw), measured as soil respiration rate. In the laboratory, soils were subjected to copper contamination (0, 500, 1,500 and 4,500 mg kg−1 soil dw), and then a bactericide (oxytetracycline) combined with a fungicide (captan) along with glucose (10 mg g−1 soil dw each) were added. There was a highly significant effect of soil type, copper treatment and oxytetracycline/captan treatment. The initial respiration rate of chronically zinc-polluted soil was higher than that of unpolluted soil, but in the copper treatment it showed a greater decline. Microorganisms in copper-treated soil were more susceptible to oxytetracycline/captan contamination. After the successive soil contamination trials the decline of soil respiration was greater in zinc-polluted soil than in unpolluted soil

Comparative Toxicity of Nanoparticulate CuO and ZnO to Soil Bacterial Communities

The increasing industrial application of metal oxide Engineered Nano-Particles (ENPs) is likely to increase their environmental release to soils. While the potential of metal oxide ENPs as environmental toxicants has been shown, lack of suitable control treatments have compromised the power of many previous assessments. We evaluated the ecotoxicity of ENP (nano) forms of Zn and Cu oxides in two different soils by measuring their ability to inhibit bacterial growth. We could show a direct acute toxicity of nano-CuO acting on soil bacteria while the macroparticulate (bulk) form of CuO was not toxic. In comparison, CuSO4 was more toxic than either oxide form. Unlike Cu, all forms of Zn were toxic to soil bacteria, and the bulk-ZnO was more toxic than the nano-ZnO. The ZnSO4 addition was not consistently more toxic than the oxide forms. Consistently, we found a tight link between the dissolved concentration of metal in solution and the inhibition of bacterial growth. The inconsistent toxicological response between soils could be explained by different resulting concentrations of metals in soil solution. Our findings suggested that the principal mechanism of toxicity was dissolution of metal oxides and sulphates into a metal ion form known to be highly toxic to bacteria, and not a direct effect of nano-sized particles acting on bacteria. We propose that integrated efforts toward directly assessing bioavailable metal concentrations are more valuable than spending resources to reassess ecotoxicology of ENPs separately from general metal toxicity

Differential clinical characteristics and prognosis of intraventricular conduction defects in patients with chronic heart failure

Intraventricular conduction defects (IVCDs) can impair prognosis of heart failure (HF), but their specific impact is not well established. This study aimed to analyse the clinical profile and outcomes of HF patients with LBBB, right bundle branch block (RBBB), left anterior fascicular block (LAFB), and no IVCDs. Clinical variables and outcomes after a median follow-up of 21 months were analysed in 1762 patients with chronic HF and LBBB (n = 532), RBBB (n = 134), LAFB (n = 154), and no IVCDs (n = 942). LBBB was associated with more marked LV dilation, depressed LVEF, and mitral valve regurgitation. Patients with RBBB presented overt signs of congestive HF and depressed right ventricular motion. The LAFB group presented intermediate clinical characteristics, and patients with no IVCDs were more often women with less enlarged left ventricles and less depressed LVEF. Death occurred in 332 patients (interannual mortality = 10.8%): cardiovascular in 257, extravascular in 61, and of unknown origin in 14 patients. Cardiac death occurred in 230 (pump failure in 171 and sudden death in 59). An adjusted Cox model showed higher risk of cardiac death and pump failure death in the LBBB and RBBB than in the LAFB and the no IVCD groups. LBBB and RBBB are associated with different clinical profiles and both are independent predictors of increased risk of cardiac death in patients with HF. A more favourable prognosis was observed in patients with LAFB and in those free of IVCDs. Further research in HF patients with RBBB is warranted

Laboreo de conservación: efectos a largo plazo sobre la fracción orgánica de un suelo de la zona semiárida

Trabajo presentado en la XXIX Reunión de la Sociedad Española de la Ciencia del Suelo (SECS), celebrada en Mallorca (España), del 3 al 6 de septiembre de 2013Se estudiaron los cambios a largo plazo (23 años) en el contenido de materia orgánica de un suelo (C total, N total) de la zona semiárida sometido a distintos sistemas de laboreo en una rotación cereal-leguminosa y comparados con los valores obtenidos para un suelo de referencia con barbecho (B). El estudio se realizó en la finca experimental >La Higueruela> perteneciente al CSIC, localizada en Santa Olalla (Toledo) con parcelas experimentales de 9 m de ancho y 40 m de largo en un diseño experimental de bloques al azar con tres repeticiones. Se analizaron anualmente e ininterrumpidamente desde el inicio del experimento en el año 1987 hasta el año 2010 muestras de suelo a 3 profundidades diferentes (0-10, 10-20 Y 20-30 cm) en los siguientes tratamientos: laboreo convencional (LC) con vertedera, nolaboreo (NL), no-laboreo con descompactador (NLD), mínimo laboreo con chisel, distinguiendo si la parcela provenía de NL (ML 1) o de LC (ML2). Se observó, por una parte, una clara reducción del contenido de materia orgánica (C total, N total) con el cultivo, efecto que era más acusado en los 0-10 cm superiores y, por otra, una estratificación de la materia orgánica con la profundidad en el suelo con barbecho y en todos los suelos cultivados excepto en LC. La adopción de sistemas de laboreo de conservación tendía a recuperar los niveles de materia orgánica en los 0-10 cm superiores y, por consiguiente, la estratificación del contenido de materia orgánica a lo largo del perfil, efecto que era más acusado en los sistemas NL y NLD. Los datos también demostraron que los cambios en el contenido de materia orgánica del suelo se producen muy rápidamente dado que los valores se estabilizaron al cabo de 6 años y no variaron hasta el final del experimento. Los resultados obtenidos ponen de manifiesto que la dinámica de la materia orgánica y, por consiguiente, los beneficios de la adopción de las prácticas de laboreo de conservación originados por el secuestro de carbono en este suelo de la zona semiárida, vienen condicionados, en gran medida, por las condiciones de equilibrio del agroecosistema (tipo de suelo, clima, sistema de manejo).Trabajo financiado por el Ministerio Español de Economía y Competitividad (CICYT AGL20l2-39929-C03-02 AGR) y por la Junta de Comunidades de Castilla-La Mancha (POIIlO-0115-2863