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Description of the subject. Farmers' knowledge is a significant source of information about cultivated soil knowledge. Objectives. This paper focuses on farmers in the Alaotra Lake Region in Madagascar to identify their knowledge of the soil and soil fertility and to propose a conceptual framework for developing participatory approaches. Method. The methodology is based on surveys conducted with 100 farmers randomly selected within five Communes (villages) to (i) study their knowledge on soil, (ii) design local soil map, and (iii) identify local soil fertility assessment. For each task, an exploratory survey with non-directive individual interviews followed by more in-depth surveys with semi-directive individual interviews and restitution workshops were conducted. Results. The results revealed two types of local soil classifications according to toposequence. Twelve and nine local soil types were identified respectively in the southern zone and in the northern zone. Moreover, farmers used 14 main local indicators to assess the fertility of these soils. Farmers' soil classification was found to comply with previous pedological studies and even provided complementary details to the reference French Soil Classification (CPCS). Finally, the local soil fertility indicators have been proved to be identical to those used by other farmers in other countries and are scientifically validated to be effective. Conclusions. This paper offers a new conceptual framework that may be effective for agricultural development service and scientific research in other contexts. It provides a foundation for supporting a common language between farmers and researchers, one that may prove instrumental in future projects including the co-conception of sustainable, innovative agricultural practices.

Cosmogenic nuclide analysis of river sediment provides insight into catchment-wide erosion rates and dynamics. Here, we investigate spatial patterns and controls on 10Be-inferred erosion rates in Madagascar, a moderately seismically active microcontinent surrounded by passive margins with locally steep topography and a climate that varies from humid tropical to semiarid. We use a compiled dataset of 99 detrital 10Be measurements, 63 of which are new, covering more than 30% of the country and a wide range of topographic, bioclimatic and geologic characteristics. Overall, 10Be erosion rates are low (2.4–51.1 mm kyr−1), with clear differences between regions. The lowest rates are measured on the central highlands ( 8 mm kyr−1), in the Alaotra–Ankay graben ( 11 mm kyr−1) and in the large north-central catchments ( 11 mm kyr−1). Higher rates are found on the steep eastern escarpment ( 20 mm kyr−1), in the northwest ( 31 mm kyr−1) and in the southwest ( 29 mm kyr−1). A stepwise linear regression model identified elevation as the main factor associated with variations in 10Be erosion rates (lower rates for higher catchments). Random within-between statistical models (REWB), on the other hand, indicated that the differences between different regions can be explained by differences in river concavity, seismic events and gully (lavaka) densities, whereas additional variation within regions is only linked to seismicity. We find no correlation between catchment or river steepness and 10Be-inferred erosion rates. Our results indicate that in Madagascar, long-term erosion rates are overall low and that simple topography-based models do not explain variations in rates of landscape change inferred from 10Be concentrations in river sediment. We demonstrate that identifying different regions aids in interpreting spatial patterns of erosion rates and that REWB models can be a powerful tool in deciphering environmental controls on 10Be erosion rates.

Organic wastes originating from livestock, agro-industry or urban activities may represent true resources when recycled for new uses, for example, as soil improvers, organic fertilizers or bioenergy sources. The compositional characteristics of these organic resources (ORs) can vary considerably depending on origin, nature, processing, stage, and state. Despite being of potential interest to different stakeholders in a circular economy, the variability in OR characteristics and the difficulty of accessing reliable, fast and inexpensive analysis methods may curb the recycling of OR in the agriculture or bioenergy sectors. As is the case in other low-income countries, scarcity of data on OR characteristics and the difficulty in assessing these data (due to cost and the sparsity of laboratories) is particularly acute in Madagascar, thus impairing the rational utilization of OR in the agricultural or bioenergy sectors. Visible-near infrared spectroscopy (VIS-NIR) has proven to be suitable for the fast, reliable and low-cost determination of the composition of different ORs, usually through the development of calibration models based on one type of OR by single research or lab groups. It is challenging to develop VIS-NIR models based on several types of ORs encompassing a wide range of target characteristics. Another challenging issue is the extension of databases containing spectra acquired on different spectrometers to increase model genericity. In both cases, standardization can be performed to resolve the problem of developing models for diverse ORs whose spectra originate from different laboratories. To assess the ability to develop VIS-NIR models with as much genericity as possible, we built a large database containing a wide diversity of ORs produced in Madagascar. The data presented in this paper were obtained by chemical and spectral analyses of 1,000 ORs collected from five districts in Madagascar. The data are accompanied by fine-grained metadata defined by 32

Le secteur agricole à Madagascar représente 80 % de la population active et contribue à 33 % du PIB. Pourtant, le pays affiche des rapports " alarmants " sur la faim. Plus de 75 % de la population malgache vit en dessous du seuil de pauvreté. La faible productivité agricole est une des principales causes de ce problème. De ce fait, la Politique Générale de l'État malgache (PGE) a inscrit l'autosuffisance alimentaire parmi les objectifs à atteindre d'ici 2023. Face à ce défi, le pays a un besoin urgent de trouver des solutions pour améliorer la productivité agricole. Des solutions de gestion durable conciliant les services écosystémiques fournis par la biodiversité avec les besoins des acteurs et les enjeux du développement économique s'affichent dans le plan de la plateforme " Initiative Émergence de Madagascar (IEM) ". Des Solutions Fondées sur la Nature : valoriser au mieux les vers de terre et leurs fonctions Les vers de terre sont des organismes clés du sol qui fournissent une multitude de services écosystémiques pour améliorer l'agriculture et assurer la résilience du système. Ils améliorent la fertilité du sol et favorisent la croissance des plantes, la séquestration du carbone et la résistance du sol à l'érosion. Ils constituent également un aliment de choix, source de protéines pour de nombreux animaux d'élevage (e.g. volailles, poissons). Ils sont aussi un bioréacteur naturel pour la production de lombricompost, considéré comme un engrais organique performant. L'utilisation des vers de terre et du lombricompost permettrait d'améliorer la productivité et la durabilité de la rizipisciculture et de l'agriculture pluviale des petites exploitations agricoles.