Self-Organizing Maps Applied to Soil Conservation in Mediterranean Olive Groves

International audienceSoil degradation and hot climate explain the poor yield of olive groves in North Algeria. Edaphic and climatic data were collected from olive groves and analyzed by Self-Organizing Maps (SOMs). SOM is a non-supervised neural network that projects high-dimensional data onto a low-dimension topological map, while preserving the neighborhood. In this paper, we show how SOMs enable farmers to determine clusters of olive groves, to characterize them, to study their evolution and to decide what to do to improve the nutritional quality of oil. SOM can be integrated in the Intelligent Farming System to boost conservation agriculture

Self-Organizing Maps Applied to Soil Conservation in Mediterranean Olive Groves

International audienceSoil degradation and hot climate explain the poor yield of olive groves in North Algeria. Edaphic and climatic data were collected from olive groves and analyzed by Self-Organizing Maps (SOMs). SOM is a non-supervised neural network that projects high-dimensional data onto a low-dimension topological map, while preserving the neighborhood. In this paper, we show how SOMs enable farmers to determine clusters of olive groves, to characterize them, to study their evolution and to decide what to do to improve the nutritional quality of oil. SOM can be integrated in the Intelligent Farming System to boost conservation agriculture

Atmospheric deposition of particulate matter between Algeria and France: Contribution of long and short-term sources

Large worldwide sources of dust, such as the Saharan desert, play a key role in the amounts and composition of atmospheric particulate deposition (APD), but their relative contribution compared to other sources remain unclear. Our study aimed to apportion Saharan, regional, and anthropogenic sources of APD in three sampling along a long transect affected by Saharan outbreaks. We quantified total APD, and analyzed its mineralogical and chemical composition between 2011 and 2012.. Strong markers of Saharan dust, such as large amounts of APD and of a low Al2O3:CaO ratio allowed identifying clear periods influenced by Saharan outbreaks. Nitrogen and phosphorus reflected soil affected by agricultural practices, while Cd, Pb, Sb and Sn tracked traffic and industrial sources-as confirmed by enrichment factors. Then, we designed a conceptual model including sensitivity analyses to estimate the contribution of unanalyzed (10-11%, likely chlorites or sulfates), organic (34-41%), anthropogenic (11-22%), mineral-regional (5-25%) and mineral-Saharan (10-38%) matter over our entire study period. Our study shows the rapidly decreasing contribution of Saharan outbreaks-and the decreasing flux of Ca and Mg, from 40 to 0.4 kg.ha(-1) over the study period between Algeria and France. Yet, Saharan outbreaks were still noticeable in APD at a site 1500 km away. Our study also shows the large relative contribution of organic and anthropogenic sources to APD in the three sampling sites, and their possible influence on nutrient budgets

Hierarchization of factors driving soil macrofauna in North Algeria groves

The current study gathers new data on soil macro-invertebrates in North Algerian orchards in order to evaluate their seasonal dynamics. Invertebrate samples were collected from three sites in Kabylie: two from sub-humid areas (Nezla and Guendoul) and one from a semi-arid area (Bouira). The objectives were to determine levels of soil macrofauna abundance and to rank the factors controlling their distribution in order of importance. We particularly focused on the effects of site (climate), season and type of orchard (Ficus carica L. and Olea europaea L.). We collected 24 taxa, of which 70% were ants and 16% earthworms. Site and seasonal factors as well as the interaction between these two elements were found to significantly influence total soil macro-invertebrate abundance. In particular, earthworms were found to be highly sensitive to aridity. In contrast, the type of grove explained only a small part of earthworm variance, whereas it had a significant influence on ant abundance. In order to be able to say whether these conclusions are typical for other comparable orchards in North Africa, more studies of this kind are needed

Dust deposits along the North Sahara-Europe axis: consequence on forest ecosystem fertilization

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Transductive Information Maximization For Few-Shot Learning

International audienceWe introduce Transductive Infomation Maximization (TIM) for few-shot learning. Our method maximizes the mutual information between the query features and their label predictions for a given few-shot task, in conjunction with a supervision loss based on the support set. Furthermore, we propose a new alternating-direction solver for our mutual-information loss, which substantially speeds up transductiveinference convergence over gradient-based optimization, while yielding similar accuracy. TIM inference is modular: it can be used on top of any base-training feature extractor. Following standard transductive few-shot settings, our comprehensive experiments 2 demonstrate that TIM outperforms state-of-the-art methods significantly across various datasets and networks, while used on top of a fixed feature extractor trained with simple cross-entropy on the base classes, without resorting to complex meta-learning schemes. It consistently brings between 2% and 5% improvement in accuracy over the best performing method, not only on all the well-established few-shot benchmarks but also on more challenging scenarios, with domain shifts and larger numbers of classes

Influence of Olea europea L. and Ficus Carrica L. fine root activity on the K biodisponibility and clay mineralogy of the rhizosphere

The objective of this study was to compare the effect of fine root activity of Olea europea L. and Ficus carrica L. of soil in its immediate vicinity (in the so-called rhizosphere zone). The study was conducted on two stations in Northern Algeria: Guendoul and Bouira. Olea europea L. and Ficus carrica L. roots significantly modified some chemical properties of rhizosphere soil. Increases of soil carbon, KNH4+ and KHNO3- were observed in the Olea europea L. and Ficus carrica L rhizosphere soil at both stations. Bulk and rhizosphere soil clay mineralogy was similar. Interstratified illite-smectite, smectite-illite and illite were predominant in the clay fraction. Chlorite and kaolinite were less represented. The decomposition of XRD diffractograms of two soil clay fractions using the Decomp program revealed that Olea europea L. roots promote nK+ storage in interlayer position. Indeed, the lower abscissa position of the gravity center (cg) of the X-ray patterns, the peak displacement of clays populations PCI, I/S, S/I toward illite peak position indicates an increase of “illite-like” layer content in the vicinity of Olea europea L. roots. Olea europea L. roots appeared to have more influence on the rhizosphere soil than Ficus carrica L. roots probably because of its higher root biomass and the greater activity of the tree in winter (contrary to Ficus Carrica L., Olea europea L. keep their leaves in winter). The two species underground activity seems to be well reflected in their respective rhizosphere