Rentabilidad económica de explotaciones agrarias de secano según tamaño y tipo de laboreo

[EN] The objective of the present study was to assess, in semiarid conditions of central Spain, the economic feasibility of chisel ploughing and no-tillage compared to mouldboard ploughing for rainfed winter wheat and forage legume production on different farm sizes. A decision support system was used to solve for the least-cost machinery selection for each farm enterprise and tillage system considered. No differences were observed in either wheat or forage vetch crop yields averaged across several years, irrespective of the tillage system used. The economic performance was found to depend on the tillage system adopted and farm size.[ES] El objetivo de este trabajo es evaluar, desde un punto de vista económico, el efecto que supone pasar de un sistema de laboreo tradicional a uno de laboreo reducido en explotaciones cerealistas de la meseta castellana. Se utilizan datos experimentales de campo para estimar las producciones, así como un sistema de decisión experto para seleccionar el parque de maquinaria que conlleva el menor coste de utilización. La rotación de cultivos que se ha considerado ha sido trigo/leguminosa. No se encontraron diferencias significativas entre los rendimientos obtenidos en los tres sistemas de laboreo comparados. Los resultados económicos se muestran condicionados por el sistema de laboreo empleado y el tamaño de la explotación.Los autores quieren agradecer los comentarios realizados por los evaluadores anónimos.Este trabajo forma parte del proyecto AGL2007-65698-C03-01 financiado por la CICYT.Serrano, A.; Suárez De Cepeda, M.; Sánchez-Girón, V. (2011). Economics of reduced tillage systems on rainfed farm enterprises of different sizes. Economía Agraria y Recursos Naturales - Agricultural and Resource Economics. 8(2):73-91. https://doi.org/10.7201/earn.2008.02.04SWORD73918

Prevalence, concordance and determinants of human papillomavirus infection among heterosexual partners in a rural region in central Mexico

Background: Although human papillomavirus (HPV) infection in heterosexual couples has been sparsely studied, it is relevant to understand disease burden and transmission mechanisms. The present study determined the prevalence and concordance of type-specific HPV infection as well as the determinants of infection in heterosexual couples in a rural area of Mexico. Methods: A cross-sectional study was conducted in 504 clinically healthy heterosexual couples from four municipalities in the State of Mexico, Mexico. HPV testing was performed using biotinylated L1 consensus primers and reverse line blot in cervical samples from women and in genital samples from men. Thirty-seven HPV types were detected, including high-risk oncogenic types and low-risk types. Multivariate logistic regression models were utilized to evaluate factors associated with HPV. Results: The prevalence of HPV infection was 20.5% in external male genitals and 13.7% in cervical samples. In 504 sexual couples participating in the study, concordance of HPV status was 79%; 34 partners (6.7%) were concurrently infected, and 21 out of 34 partners where both were HPV positive (61.8%) showed concordance for one or more HPV types. The principal risk factor associated with HPV DNA detection in men as well as women was the presence of HPV DNA in the respective regular sexual partner (OR = 5.15, 95% CI 3.01-8.82). In men, having a history of 10 or more sexual partners over their lifetime (OR 2.5, 95% CI 1.3 - 4.8) and having had sexual relations with prostitutes (OR 1.7, 95% CI 1.01 - 2.8) increased the likelihood of detecting HPV DNA. Conclusions: In heterosexual couples in rural regions in Mexico, the prevalence of HPV infection and type-specific concordance is high. High-risk sexual behaviors are strong determinants of HPV infection in men

Global Retinoblastoma Presentation and Analysis by National Income Level.

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs

A comparison between seasonal changes in soil water storage and penetration resistance under conventional and conservation tillage systems in Aragón

The definitive version is available at: http://www.sciencedirect.com/science/journal/01671987Low and extremely variable precipitations limit dryland crop production in the semi-arid areas of Aragón (NE Spain). These areas are also affected by high annual rates of topsoil losses by both wind and water erosion. A long-term experiment to determine the feasibility of conservation tillage in the main winter barley production areas of Aragón was initiated in 1989 at four locations, three on loam to silt loam soils (Xerollic Calciorthid) and one on a silty clay loam (Fluventic Ustochrept), receiving between 300 and 600 mm of average annual rainfall. In this study, we compared, under both continuous cropping and cereal-fallow rotation, the effects of conventional tillage (mouldboard plough) and two conservation tillage systems, reduced tillage (chisel plough) and no-tillage, on soil water content and penetration resistance during the first two growing seasons. Whereas reduced and conventionally tilled treatments generally had similar soil water content during the experimental period, the effects of no-tillage were inconsistent. No-tilled plots had from 26% less to 17% more stored soil water (0–80 cm) than conventional tilled plots at the beginning of the growing season. In contrast to the conventional and reduced tillage treatments, penetration resistances were between 2 and 4 MPa after sowing in most of the plough layer (0–40 cm) under no-tillage at all sites. Fallow efficiencies in moisture storage in the cereal-fallow rotation, when compared with the continuous cropping system, ranged from −8.7 to 12%. The highest efficiencies were recorded when the rainfall in the months close to primary tillage exceeded 100 mm. Since this event is very unlikely, long fallowing (9–10 months) appears to be an inefficient practice for water conservation under both conventional and conservation management. Our results suggest that, up to now, only reduced tillage could replace conventional tillage without adverse effects on soil water content and penetration resistance in the dryland cereal-growing areas of Aragón.The authors wish to thank the Consejo Asesor de Investigaci&-DGA (Grants nos. PCA-9/89 and BCA-35/89) and the Comisi6n Interministerial de Ciencia y Tecnologia (Grant no. AGF93-0613-C02-02) Spanish Agencies for financial support.Peer reviewe

Performance and emissions of an agricultural diesel engine fuelled with differente diesel and methyl ester blends

This paper shows the results of an investigation carried out to assess the application of different fuels produced by blending diesel fuel with methyl ester obtained from mixture of 75% (v/v) sunflower oil and 25% (v/v) used cooking oil on a Kubota agricultural indirect injection diesel engine, natural aspirated, and with a rated horsepower of 19.7 kW. Seven fuels, namely diesel fuel; 90:10, 80:20, 70:30, 50:50, 25:75 and 0:100 (%v/v) blends were prepared and tested for the performance of the diesel engine in accordance with the standardised OECD test code 2. The test results showed that the performance of the engine was satisfactory without a significant reduction in power output and torque with blends smaller than 50%. Fuel consumptions with biodiesel were higher than that when fuelled with diesel but differences were not very marked up to 30% blends. As the reduction of the engine thermal efficiency was less than the corresponding reduction in heating value of the different biodiesel blends, the latter resulted in a more complete combustion in comparison with diesel fuel. The oxides of nitrogen (NOx) emissions were found to be reduced as the biodiesel concentration increase, particularly with 70% and 100% blends. The emissions of carbon monoxide (CO) were lower and increased at a lower rate with the oxygen concentration of the exhaust as the biodiesel blends were equal or higher than 50%.En este trabajo se evalúan las prestaciones de un motor Kubota diésel de uso agrícola, de inyección indirecta de combustible y con una potencia nominal de 19,7 kW, cuando se utilizan como combustibles gasóleo comercial (100:0), biodiésel puro (0:100), obtenido por mezcla de metil éster procedente en un 75% (v/v) de aceite de girasol y en un 25% (v/v) de aceite de freír, y diferentes mezclas de biodiésel que se corresponden con las siguientes proporciones de esos dos combustibles: 90:10; 80:20; 70:30; 50:50; 25:75 (%v/v). Las prestaciones del motor se determinaron siguiendo la metodología establecida en el código 2 de ensayos de la OCDE. Los resultados obtenidos pusieron de manifiesto que los valores de la potencia y del par motor medidos en los puntos de ensayo con mezclas de biodiésel inferiores al 50% fueron similares a los obtenidos con gasóleo. Los consumos de combustible fueron ligeramente superiores a los alcanzados con gasóleo cuando se utilizó biodiésel con un contenido en metil éster que no superó el 30%, observándose los aumentos más acusados de los mismos con mezclas iguales o superiores al 50%. El rendimiento térmico de las diferentes mezclas de biodiésel disminuyó en menor medida que su poder calorífico, indicando con ello que su combustión fue más completa que la del gasóleo. Las emisiones de óxidos de nitrógeno (NOx) se redujeron a medida que aumentó el contenido de biodiésel en el combustible, particularmente con las mezclas del 70% y del 100%. Por lo que respecta a las emisiones de monóxido de carbono (CO), se observó que fueron menores, y crecieron a una menor tasa con la concentración de oxígeno de los gases de escape, cuando el contenido de biodiésel del combustible superó el 50%

Sobrecompactación del suelo agricola parte I: influencia diferencial del peso y del número de pasadas Overcompaction of agricultural soil part I: differential influence of axle load and number of passes

Han sido objetivos principales de este trabajo, tanto el discriminar la responsabilidad de las variables independientes, peso y número de pasadas, en la distribución vertical de la compactación inducida, como obtener evidencia que permita decidir la conveniencia entre conjuntos ligeros que rueden muchas veces sobre la superficie trabajada, o conjuntos más grandes y pesados que resuelvan la tarea con menos pasajes. Se trabajó sobre un suelo de textura fina, con alta humedad presente. Las variables experimentales independientes configuraron dos tratamientos, tractor pesado y ligero, y tres diferentes número de pasadas, 1, 5 y 10, resultaron en seis subtratamientos de diferente intensidad de tráfico, más una parcela testigo sin tráfico. Los resultados no mostraron diferencias entre los tratamientos pesado y ligero, en el rango más superficial evaluado, sin embargo siempre fueron muy significativas las diferencias si se considera el rango de mayor profundidad. Disminuciones del rendimiento del pastizal del orden de 7 a 25% fueron medidas en las zonas adyacentes a las huellas, mientras que esas pérdidas ascendieron al rango de 52 a 76% dentro de la impronta dejada por las huellas del tráfico. Se pudo concluir que, el número de pasadas reiteradas sobre la misma senda, puede emular, e incluso reemplazar, al factor peso sobre el eje, en la responsabilidad principal de inducir compactaciones en el subsuelo. Diez pasadas, es el número crítico de rodadas, a partir del cual se pierden las ventajas de traficar con un tractor ligero, como alternativa a uno pesado con menos pasadas.<br>The main objectives of this research were: to determine the responsability of weight, number of passes and independent variables, on the vertical distribution of subsoil compaction and to obtain evidence to decide upon the convenience of matching equipments with light or heavy tractors, according to their differences in passes on the field. Field tests were carried out on grassland, on a typic Argiudol with a soil moisture below, but near to field capacity. The dependent experimental variable was the induced soil compaction and was related to bulk density (assessed with gamma probe), penetration resistance (measured with an electronic cone penetrometer), and remaining grassland yield, six and eight months after traffic treatments were applied. Data from two tests, with two phases of data logging were analysed, totalizing a three year period of assessment pursuit. Results did not show differences between heavy and light treatments in the shallower depth range. Nevertheless, highly significant differences were shown if the deepest range is considered. Decrease in grassland yields ranging from 7 to 25% were measured in out-of-track areas, and 52 to 76% in intrack areas. It was concluded that the number of repeated passes on the same tramlines of a light tractor, can do as much or even greater damage than the heavier tractor with fewer passes. Ten is the critical number of passes, beyond it, advantages taken from the use of a light tractor are lost

Waterbird detritus impair seedling root growth in a unique centenarian cork oak population : implications for forest regeneration

4 páginas.-- Working Group “Integrated Protection in Oak Forests”. Proceedings of the 7th meeting of the IOBC-WPRS (Avignon, France), 07 – 11 October, 2013.Field studies have shown than soil-mediated effects of nesting wading birds may be a main cause of the decline of centenarian cork oaks (Quercus suber L.) in the Doñana Biological Reserve (SW Spain). The aim of this work was to experimentally investigate whether soil modification by bird detritus significantly affected the first stages of development of Q. suber. Seedlings were growing under controlled conditions in three types of natural soils with different levels of wading bird influence. Our results showed that main root length was strongly reduced by bird influence. Birdinfluenced soils significantly decreased both the above-ground and the below-ground seedling dry biomass. Guano seems to harm primary root meristem stopping the main root growth, which becomes thickened (root stunting). This impedes the quick initial main root growth that this species usually exhibits prior to shoot emergence. Since the presence of a well-developed main root is essential to explore deep soil layers and extract additional water over the dry season, we predict that guanoaffected seedlings will suffer a higher mortality in summer. We concluded that even low levels of wading bird influence could strongly hamper cork oak regeneration in the studied area. Thus, both natural and assisted cork oak regeneration will fail in these bird-influenced soilsPeer reviewe

Les détritus d'échassiers nuisent a la croissance des racines des semis d'une population de chéne-Iiege centenaire unique : implications pour la régénération des forêts

Trabajo presentado al citado Congreso, celebrado del 8-11 octubre 2013, en Domaine de Bousquety Belambra, L'Isle-sur-la-Sorgue (Vaucluse), Francia.-- Los autores pertenecen al Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC); Estación Biológica de Doñana (EBD-CSIC) y al Departamento de Agronomía, Patología Agroforestal de la Universidad de Córdoba, España.[EN]: Field studies have shown than soil-mediated effects of nesting wading birds may be a main cause of the decline of centenarian cork oaks (Quercus suber) in the Doñana Biological Reserve (SW Spain). The aim of this work was to experimentally investigate whether soil modification by bird detritus significantly affected on the first stages of development in Q. suber. Seedlings were growing under controlled conditions in three types of natural soils with different levels of wading bird influence. Our results showed that root length was strongly reduced by bird influence, unlike shoot length. Bird influenced soils significantly, decreasing both the aboveground and the below-ground seedling dry biomass. We concluded that even low levels of wadding bird influence could strongly hamper cork oak regeneration in the studied area. Guano seems to harm primary root meristem stopping the main root growth, which becomes thickened (root stunting). This impedes the quick initial main root growth that this species usually exbibits prior to shoot emergence. Since the presence of a well-developed main root is essential to explore deep soil layers and thereby survive the dry season, we predict that guano-affected seedlings would suffer higher mortality in summer and fails in natural or assisted cork oak regeneration in bird-influenced soils.[FR]: Des études au terrain ont montré que l' impact sur le sol des échassiers nicheurs peut être une des causes principales du dépérissement des chênes lièges centenaires dans la Réserve Biologique de Doñana (SW Espagne). Le but de ce travail était de déterminer expérimentalement si une modification du sol par les détritus des échassiers affecte de manière significative les premiers stades de développement de Q. suber. Les semis ont été maintenus dans des conditions contrôlées dans trois types de sol naturel avec différents niveaux d'influence des échassiers. Nos résultats montrent que la longueur des racines a été fortement réduite par l'influence des oiseaux, contrairement à la longueur des pousses. Sur les sols influencés par échassiers la biomasse sèche aérienne et souterraine des semis a diminué sensiblement. Nous avons conc1u que même de faibles niveaux d'influence des oiseaux pouvaient fortement affecter la régénération du chêne-liège dans la zone étudiée. Le guano semble nuire au méristème de la racine primaire, en arrêtant sa croissance. Cela empêche le développement rapide de la racine principale que cette espèce présente habituellement avant d'émerger. Sachant que le bon developpement de la une racine principale est indispensable à la plante pour explorer les couches plus profondes du sol et survivre à la saison sèche, nous prévoyons que les plants affectés par le guano vont subir une mortalité plus élevée en été el faire échouer les reboisements naturels ou assistés de chêne-liège sur les sols occupés par ces échassiers.Peer reviewe