Decomposition of and nutrient release from ruminant manure on acid sandy soils in the Sahelian zone of Niger, West Africa

In ago-pastoral systems of the semi-arid West African Sahel, targeted applications of ruminant manure to the cropland is a widespread practice to maintain soil productivity. However, studies exploring the decomposition and mineralisation processes of manure under farmers' conditions are scarce. The present research in south-west Niger was undertaken to examine the role of micro-organisms and meso-fauna on in situ release rates of nitrogen (N), phosphorus (P) and potassium (K) from cattle and sheep-goat manure collected from village corrals during the rainy season. The results show tha (1) macro-organisms played a dominant role in the initial phase of manure decomposition; (2) manure decomposition was faster on crusted than on sandy soils; (3) throughout the study N and P release rates closely followed the dry matter decomposition; (4) during the first 6 weeks after application the K concentration in the manure declined much faster than N or P. At the applied dry matter rate of 18.8 Mg ha^-1, the quantities of N, P and K released from the manure during the rainy season were up to 10-fold larger than the annual nutrient uptake of pearl millet (Pennisetum glaucum L.), the dominant crop in the traditional agro-pastoral systems. The results indicate considerable nutrient losses with the scarce but heavy rainfalls which could be alleviated by smaller rates of manure application. Those, however, would require a more labour intensive system of corralling or manure distribution.

Organic inputs and farmers' management strategies in millet fields of western Niger

Research on soil fertility management in sub-Saharan Africa was criticized lately for largely ignoring farmers’ management strategies and the underlying principles. To fill this gap of knowledge, detailed interviews were conducted with 108 farm households about their rationale in managing the soil fertility of 307 individual fields in the agro-pastoral village territory of Chikal in western Niger. To amplify the farmers’ information on manuring and corralling practices, repeated measurements of applied amounts of manure were carried out within six 1-km^2 monitoring areas from February to October 1998. The interviews revealed that only 2% of the fields were completely fallowed for a period of 1–15 years, but 40% of the fields were at least partially fallowed. Mulching of crop residues was mainly practiced to fight wind erosion but was restricted to 36% of the surveyed fields given the alternative use of straw as livestock feed. Manure application and livestock corralling, as most effective tools to enhance soil fertility, were targeted to less than 30% of the surveyed fields. The application of complete fallow and manuring and corralling practices were strongly related to the households’ endowment with resources, especially with land and livestock. Within particular fields, measures were mainly applied to spots of poor soil fertility, while the restoration of the productivity of hard pans was of secondary importance. Given the limited spatial coverage of indigenous soil fertility measures and their strong dependence on farmers’ wealth, supplementary strategies to restrict the decline of soil fertility in the drought prone areas of Niger with their heavily weathered soils are needed.

Construcción de la estrategia contra - terrorista española entre 2004 - 2010 frente al Yihadismo Internacional

El fenómeno del terrorismo de carácter trasnacional,Especialmente aquel que hace referencia a la vertiente yihadista, ha despertado preocupación dentro de la comunidad internacional, específicamente dentro de aquellos centros de poder occidentales que se han visto vulnerados por algún tipo de acción llevada a cabo por grupos de esta índole. Organizaciones como Al–Qaeda, que mediante la concentración y labor de múltiples células vinculadas en su haber, operan y ejecutan acciones terroristas en varias regiones del mundo, son identificadas hoy en día, como una nueva amenaza no estatal dentro de los sistemas de seguridad occidentales. El caso español representa un claro ejemplo de la transnacionalización del terrorismo, en particular aquel que se denomina de carácter yihadista dentro de territorio europeo, puesto que es a partir de los atentados perpetuados en el metro de Madrid, que se activan las alarmas hacia el interior de la Unión Europea y se inician una serie de reformas pertinentes a enfrentar dicha amenaza dentro de los sistemas de seguridad de la mayoría de Estados miembros de la unión.De esta manera, y dentro del campo de estudio que ofrecen las Relaciones Internacionales, la amenaza que el terrorismo de carácter yihadista representa para la seguridad española, puede ser comprendida, a partir del análisis de elementos claves tales como: España como escenario directo de la amenaza terrorista, proximidad geográfica con las regiones del Mediterráneo, Magreb y Sahél, ideología de los grupos yihadistas y finamente la ampliación de la agenda de seguridad española a partir del 11-M, entre otros. Los alcances del terrorismo yihadista son definitivamente percibidos dentro de la comunidad internacional, de allí reside la importancia del estudio de la estrategia contra terrorista elaborada por España para combatir este fenómeno, puesto que no solo se encuentra al interior de su territorio sino además en las regiones aledañas.

El apoyo de Argelia a la independencia del grupo étnico saharawi como fachada para el alcance de su interés geopolítico (2008-2012)

El objetivo principal del presente estudio de caso es determinar el interés geopolítico que impulsa a Argelia a apoyar las intenciones de independencia de la República Árabe Saharawi Democrática (RASD). Como consecuencia del proceso de descolonización del Sahara Occidental que ha sido negado por las potencias colonizadoras que allí se encontraban y por Marruecos, país que reivindica su posesión del territorio; Argelia se ha apadrinado de la causa saharawi mediante la transferencia de armamento y envío de alimentos al Frente Polisario de Liberación y ha logrado que 26 países de la Unión Africana reconozcan la existencia de la RASD. Sin embargo, detrás de la vocación argelina sobre la promoción al respeto del principio de autodeterminación se esconden una serie de intereses geopolíticos, comerciales y de seguridad que pueden ser satisfechos con un Sahara Occidental independiente.

Securitización en el desierto: Una respuesta al terrorismo en Malí y en Níger, 2009 - 2013.

Este es un estudio sobre las dinámicas de seguridad en Malí durante el periodo de 2009 a 2013. La investigación busca explicar de qué manera se ha dado un proceso de securitización de los grupos insurgentes frente a la amenaza generada por la proliferación de grupos armados no estatales en el territorio comprendido entre Malí y Níger. Se toma a Níger con el ánimo de ver la existencia de un subcomplejo regional de seguridad entre este país y Malí. De esta manera se afirma que el aumento de las actividades insurgentes y terroristas en la zona compuesta por Malí y Níger se da por la proliferación de actores armados no estatales, entre los cuales se encuentran los grupos seculares e insurgentes Tuareg, las agrupaciones islamistas fundamentalistas y los grupos que se componen entre rebeldes Tuareg, criminales e islamistas, éstos actores han afectado la percepción que tiene Malí sobre su seguridad.

Noaga, com podem aturar el desert?. 'Noaga, ¿cómo podemos parar el desierto?'.

El documento es un cuaderno de trabajo que ofrece actividades y tareas para trabajar y profundizar más en el conocimiento sobre África y las personas y culturas que viven en ella. En este caso se centra en la zona de Sahel.

Noaga, la nena de Burkina Faso. 'Noaga, la niña de Burkina Faso'.

Resumen del documento en catalán. También disponible en castellano

Problemes del Tercer Món : Àfrica. 'Problemas del Tercer Mundo : África'.

Resumen del autor. Vídeo disponible en beta

Problemas del Tercer Mundo : África.

En el vídeo se presentan tres tipos de problemáticas que acontecen en el llamado Tercer Mundo; uno de ellos es el problema del hambre y la sed en el Sahel mostrando desde el difícil equilibrio entre la economía y las sociedades tradicionales hasta los problemas de desarrollo actual. Otra de las problemáticas entra directamente en el problema de la dependencia económica de los países del sur. Finalmente, plantea el conjunto de problemas con los que choca un país al principio de su industrialización, poniendo como ejemplo el caso de Egipto.

El Sáhara y los cambios climáticos.

Resumen tomado de la publicación

Módulo educativo sobre la desertización.

Se presenta un módulo educativo experimental en torno a los problemas de desertización en la zona del Sahel, con el objetivo de proporcionar material didáctico para el estudio del medio ambiente en enseñanza primaria y secundaria. El contenido se compone de 3 partes y dos anexos. La primera parte proporciona elementos a los profesores para que organicen sus actividades y prácticas. La segunda recoge datos sobre el proceso de desertización en el Sahel. La tercera está dedicada al desarrollo de diversos temas medioambientales para realizar en clase con los alumnos..

A importância da revisão estratégia europeia de segurança : desafios pós-2008

O processo de construção de uma comunidade europeia de segurança iniciou-se em 1953. Apenas em 2003 foi adotada uma Estratégia Europeia de Segurança e só em 2010, com a entrada em vigor do Tratado de Lisboa, se criou uma política comum de segurança e defesa. Desde 2003, nestes 10 anos de PESD/PCSD, foram lançadas cerca de 30 missões em regiões diferentes como os Balcãs, a África Subsahariana, o Sahel e o espaço da ex-União Soviética, tocando áreas tão vastas como a reforma do setor da segurança, a formação e controlo alfandegário, o combate à pirataria ou a formação militar. Portugal participou em 11 dessas missões. O elenco de riscos e ameaças constantes da Estratégia Europeia de Segurança, revisto e atualizado em 2008, é exaustivo e mantém-se ajustado à presente situação internacional. As dificuldades da UE, no domínio da PCSD, prendem-se sobretudo com um conjunto de défices, em particular de vontade política e de recursos materiais e finanaceiros e não com a revisão da EES. Uma abordagem pragmática, que passe pela melhor definição de prioridaddes, de estratégias regionais, do reforço das capacidades e das industriais de defesa, seria a melhor orientação que o Conselho EUropeu de Dezembro de 2013 poderia dar às Instituições Europeias e aos Estados membros, no sentido de um esforço conjunto com vista a manter e a reforçar o papel da União Europeia enquanto fornecedor de segurança no sistema internacional.

Sampling uncertainties in surface radiation budget calculations in RADAGAST

In the Radiative Atmospheric Divergence Using ARM Mobile Facility GERB and AMMA Stations (RADAGAST) project we calculate the divergence of radiative flux across the atmosphere by comparing fluxes measured at each end of an atmospheric column above Niamey, in the African Sahel region. The combination of broadband flux measurements from geostationary orbit and the deployment for over 12 months of a comprehensive suite of active and passive instrumentation at the surface eliminates a number of sampling issues that could otherwise affect divergence calculations of this sort. However, one sampling issue that challenges the project is the fact that the surface flux data are essentially measurements made at a point, while the top-of-atmosphere values are taken over a solid angle that corresponds to an area at the surface of some 2500 km2. Variability of cloud cover and aerosol loading in the atmosphere mean that the downwelling fluxes, even when averaged over a day, will not be an exact match to the area-averaged value over that larger area, although we might expect that it is an unbiased estimate thereof. The heterogeneity of the surface, for example, fixed variations in albedo, further means that there is a likely systematic difference in the corresponding upwelling fluxes. In this paper we characterize and quantify this spatial sampling problem. We bound the root-mean-square error in the downwelling fluxes by exploiting a second set of surface flux measurements from a site that was run in parallel with the main deployment. The differences in the two sets of fluxes lead us to an upper bound to the sampling uncertainty, and their correlation leads to another which is probably optimistic as it requires certain other conditions to be met. For the upwelling fluxes we use data products from a number of satellite instruments to characterize the relevant heterogeneities and so estimate the systematic effects that arise from the flux measurements having to be taken at a single point. The sampling uncertainties vary with the season, being higher during the monsoon period. We find that the sampling errors for the daily average flux are small for the shortwave irradiance, generally less than 5 W m−2, under relatively clear skies, but these increase to about 10 W m−2 during the monsoon. For the upwelling fluxes, again taking daily averages, systematic errors are of order 10 W m−2 as a result of albedo variability. The uncertainty on the longwave component of the surface radiation budget is smaller than that on the shortwave component, in all conditions, but a bias of 4 W m−2 is calculated to exist in the surface leaving longwave flux.

Examining the interaction of growing crops with local climate using a coupled crop-climate model

This paper examines to what extent crops and their environment should be viewed as a coupled system. Crop impact assessments currently use climate model output offline to drive process-based crop models. However, in regions where local climate is sensitive to land surface conditions more consistent assessments may be produced with the crop model embedded within the land surface scheme of the climate model. Using a recently developed coupled crop–climate model, the sensitivity of local climate, in particular climate variability, to climatically forced variations in crop growth throughout the tropics is examined by comparing climates simulated with dynamic and prescribed seasonal growth of croplands. Interannual variations in land surface properties associated with variations in crop growth and development were found to have significant impacts on near-surface fluxes and climate; for example, growing season temperature variability was increased by up to 40% by the inclusion of dynamic crops. The impact was greatest in dry years where the response of crop growth to soil moisture deficits enhanced the associated warming via a reduction in evaporation. Parts of the Sahel, India, Brazil, and southern Africa were identified where local climate variability is sensitive to variations in crop growth, and where crop yield is sensitive to variations in surface temperature. Therefore, offline seasonal forecasting methodologies in these regions may underestimate crop yield variability. The inclusion of dynamic crops also altered the mean climate of the humid tropics, highlighting the importance of including dynamical vegetation within climate models.

Climate impacts of recent multidecadal changes in Atlantic Ocean Sea Surface Temperature: A multimodel comparison

During the twentieth century sea surface temperatures in the Atlantic Ocean exhibited prominent multidecadal variations. The source of such variations has yet to be rigorously established—but the question of their impact on climate can be investigated. Here we report on a set of multimodel experiments to examine the impact of patterns of warming in the North Atlantic, and cooling in the South Atlantic, derived from observations, that is characteristic of the positive phase of the Atlantic Multidecadal Oscillation (AMO). The experiments were carried out with six atmospheric General Circulation Models (including two versions of one model), and a major goal was to assess the extent to which key climate impacts are consistent between the different models. The major climate impacts are found over North and South America, with the strongest impacts over land found over the United States and northern parts of South America. These responses appear to be driven by a combination of an off-equatorial Gill response to diabatic heating over the Caribbean due to increased rainfall within the region and a Northward shift in the Inter Tropical Convergence Zone (ITCZ) due to the anomalous cross-equatorial SST gradient. The majority of the models show warmer US land temperatures and reduced Mean Sea Level Pressure during summer (JJA) in response to a warmer North Atlantic and a cooler South Atlantic, in line with observations. However the majority of models show no significant impact on US rainfall during summer. Over northern South America, all models show reduced rainfall in southern hemisphere winter (JJA), whilst in Summer (DJF) there is a generally an increase in rainfall. However, there is a large spread amongst the models in the magnitude of the rainfall anomalies over land. Away from the Americas, there are no consistent significant modelled responses. In particular there are no significant changes in the North Atlantic Oscillation (NAO) over the North Atlantic and Europe in Winter (DJF). Additionally, the observed Sahel drying signal in African rainfall is not seen in the modelled responses. Suggesting that, in contrast to some studies, the Atlantic Multidecadal Oscillation was not the primary driver of recent reductions in Sahel rainfall.