Search

Fulfilling both “Water and soil conservation” and “Integrated rural development” objectives, hillside reservoirs are very popular components of water and/or rural management strategies. In Central Tunisia, more than 800 reservoirs have been built since the 1950s. These have been the subject of an abundant literature by both social and physical scientists. However, this literature, which is highly segmented and often centred on the technical and economic assessment of development programs, does not help understand the different logics at work in the appropriation of these technical objects by the different actors involved. To achieve this goal, our research based on a "sociohydrological negotiation", articulates the methods and research questions of hydrology and anthropology on a same case study in Central Tunisia. An initial survey of water use and management practices around hillside reservoirs in the Merguellil Catchment revealed the wide variety of the infrastructures and the multiple functions they fulfil. These initial observations underpinned the process of negotiating an interdisciplinary framework to analyze the social, physical and technical dimensions of hillside reservoirs. To trace the history of watershed development policies implemented in the Merguellil Catchment, we first examined the multiple embedded logics underlying Tunisian hillside reservoir planning. This led to the production of “sociohydrological narratives” for four hillside reservoirs that both combined and enabled us to analyze the inhabitants’ own accounts of their reservoir history. This ethnographical material was then examined through the lense of a “resource making process”. Considering the way in which hydraulic objects function in a landscape that is both socio-political and hydrological enabled us to analyze the different aspects of this resource making process, from water valuation to the production of “hydraulic localities”.

International audience; This paper deals with an exhibition: “Fertile soils and secret lives” designed at the initiative of Senat to raise public awareness of the soil resources knowledge and preservation issues. Exhibited for the first time in the Orangeries of the Luxembourg gardens in 2014,its design and diffusion involved the collaboration of numerous organizations, among which the French Soil Science Society. This very diverse exhibition attracted a very large and diverse public, with an estimated 50,000 persons involved between September 2014 and December 2019. The pedagogic posters designed on this occasion were further enriched, thanks to a collaboration with the CESE (Economic, Social and Environmental Council), with complementary posters about the links between soils and climate change. Then, they have been made available by the senate to AFES and declined in various formats (roll-ups, posters…) and presented in very numerous events (scientific congress of soil science, World Soil Day in France, open doors of agricultural high schools, libraries, …) to a very diverse public including professionals, students, general public and policy-makers. In this paper, we describe their dissemination and impact. These posters are still, and will be again, used. They are very good means to discover soils and to raise awareness about the major issues and challenges to which they contribute.; Cet article présente une exposition, "Sols fertiles, vies secrètes", conçue à l'initiative du Sénat pour sensibiliser le grand public aux enjeux de la connaissance et de la préservation de nos ressources en sol. Exposée pour la première fois dans l'Orangerie des jardins du Luxembourg en 2014, sa conception et sa diffusion a mis à contribution de nombreux organismes, dont l'Association Française pour l'Etude du Sol. Cette exposition d'une grande diversité a touché un public nombreux et très divers avec selon nos estimations plus de 50 000 personnes touchées entre septembre 2014 et décembre 2019. Des panneaux pédagogiques ont été réalisés à cette occasion puis ont ensuite été enrichis grâce à une collaboration avec le CESE par des panneaux complémentaires sur le lien entre le sol et le climat. Ils ont été mis à disposition par le Sénat à l'AFES pour être déclinés sous différentes formes (roll-ups, affiches...) et présentés en de très nombreuses occasions (colloques de sciences du sol, Journée Mondiales des Sols, portes ouvertes de lycées agricoles, bibliothèques, …), en touchant un public varié (professionnels, étudiants, grand public, élus…). Nous décrivons ici leur diffusion et leur impact. Ces panneaux continuent, et continueront, d'être utilisés et constituent un excellent moyen de découverte des sols et de sensibilisation aux grands enjeux auxquels ils contribuent.

International audience

As a response to the worldwide challenge raised by soil degradation, Conservation Agriculture (CA) was proposed to help restoring the three main soil functions, i.e. carbon transformation, nutrient cycling and structure maintenance. However, there is still a lack of integrative studies that assess the overall impact of CA on soil health. To fill the gap, Biofunctooll (R), a set of in-field indicators, was developed to monitor changes in soil biological functioning. In this study, Biofunctool (R) was used to assess the impact of a conventional tillage (CT) and three CA annual-based cropping systems on soil health on a Cambodian Oxisol. Eight indicators related to the three soil functions were monitored and integrated into a Soil Quality index (SQI), i.e. the Biofunctool (R) Index. Overall, we found that soil health was twice higher under the CA treatments than under CT treatment. Although it was similar in the three CA treatments, the contribution of each soil function to the soil health diverged. An analysis of soil carbon dynamics also showed that CA support short-term soil organic carbon stabilization compared to CT. This study demonstrates that Biofunctool (R) is a robust, relevant, time-and cost-effective in-field assessment tool that can be used in multiple ways including cropping system management, capacity building of local stakeholders, and policy dialogue.

International audience; The natural fragility of the environment (relief with steep slopes, aggressive rain, fragile substrates) associated with human fragility (poverty, insecurity) lead to the development and the extension of soil degradation. Water erosion concerns all Moroccan mountains and affects land productivity. This has prompted farmers to design and implement land management techniques, which optimize water use and promote rainwater harvesting. Land management institutions in these areas have also carried out soil protection and restoration (DRS) and soil and water conservation (SWC) projects for the same purposes. This study aims to inventory most of soil and water conservation techniques in Morocco through a literature review. It tracks a set of techniques adopted by farmers to remedy the lack of agricultural land, to enhance land conservation and improve its productivity. Many traditional soil and water conservation systems have been described and classified according to local water balance, topography, operation and objectives: impluvium runoff management, water infiltration increase, diversion of excess-runoff and runoff energy dissipation.Perhaps there exist still other installations not quoted here. Their effectiveness depends on multiple factors, which vary in time and space such as the climatic conditions (dryness) and socio-economic (emigration of youth).; La fragilité naturelle du milieu (relief accidenté, pluies agressives, substrats fragiles) associée à une fragilité humaine (pauvreté, précarité) conduisent à l'apparition et l'extension de phénomènes de dégradation des sols spectaculaires. L'érosion hydrique concerne affecte la productivité une grande partie des terres marocaines. Cette situation a incité les paysans à concevoir et à réaliser des aménagements pour réduire les pertes de terres, optimiser l'utilisation des eaux et valoriser les eaux pluviales. Des projets de Défense et Restauration des Sols (DRS) et de Conservation des Eaux et des Sols (CES) ont également été conduits par les institutions d'aménagement des terres dans ces zones pour les mêmes objectifs. Cette étude vise, à travers une recherche bibliographique, à inventorier les techniques de conservation des eaux et des sols au Maroc. Elle retrace un ensemble de techniques adoptées par les agriculteurs pour remédier au manque de terres agricoles, leur conservation et l'amélioration de leur productivité. De nombreux systèmes traditionnels de conservation de l'eau et des sols ont été décrits et classés en fonction du bilan hydrique local, de la topographie, de leur fonctionnement et de leurs objectifs : la capture du ruissellement sous impluvium, l'infiltration totale de l'eau, la diversion des excédents d'eau et la dissipation de l'énergie du ruissellement. Il existe peut-être encore d'autres aménagements non cités ici. Leur efficacité dépend de multiples facteurs qui varient dans le temps et dans l'espace comme les conditions climatiques (sécheresse) et socio-économiques (émigration des jeunes).

International audience; El petróleo, "sangre de la tierra", es la principal fuente de energía fósil en el mundo. La Amazonía ecuatoriana, tierra de explotación petrolera y de colonización agrícola, es símbolo de la riqueza natural del planeta pero también un testigo del daño causado por las actividades humanas. En el corazón de este bosque, de su biodiversidad, de sus recursos y de sus habitantes, se teje el hilo de un viaje científico e interdisciplinario. Este libro comparte saberes, conocimientos e imágenes sobre los impactos y riesgos de las actividades petroleras en el medio ambiente, la salud, la sociedad y refleja las condiciones de vida en la Amazonía.; Le pétrole est le « sang de la terre » et la principale source d’énergie fossile au monde. L’Amazonie équatorienne, terre d’exploitation pétrolière et de colonisation agricole, est un symbole des richesses naturelles de la planète mais aussi un témoin des dommages causés par les activités humaines. Au cœur de cette forêt, de sa biodiversité, de ses ressources et de ses habitants, se tisse le fil d’un voyage scientifique et interdisciplinaire. Ce livre partage des savoirs, des connaissances et des images sur les impacts et risques liés aux contaminations pétrolières sur l’environnement, la santé et la société et comment on « vit avec ».

L'application de la connaissance des services écosystémiques rendus par les sols passe par leur meilleure connaissance dans des contextes divers. La Guyane cherche à allier un développement local à un maintien des services environnementaux rendus par les écosystèmes. La déforestation, lorsque pratiquée hors de cahiers de charges bien établis, conduit à la destruction partielle ou totale de l'horizon de surface des sols, donc au principal réservoir de carbone (C) des sols. La connaissance actuelle du carbone des sols de Guyane est limitée. Les données collectées ici permettent d'approcher la spatialisation des contenus de C même si la variabilité des stocks reste forte. Les modélisations du devenir des stocks de C suite à la déforestation ont été réalisées à partir des données collectées dans le projet CarSGuy et le site expérimental de Terres Inovia ; s'ajoutent à ces valeurs la compilation de données issus de campagnes précédentes : Réseau de Mesures de la Qualité des Sols (RMQS) et ValSol. Ces modélisations indiquent l'importance de la prise en compte du stock initial (T0) pour le devenir des stocks. Enfin ce travail a testé une méthodologie de mesures spectrales (visible et proche infra-rouge) de terrain des sols pour l'évaluation du stock. Les données collectées à partir de 236 sites permettent de quantifier et spatialiser les stocks (0-0,3/0-0,5/0-1 m). La modélisation permet de constater que la mise en culture induit de fortes baisses des stocks, 16 % du stock initial à court terme (~ année) après défriche. L'essai expérimental du site de Combi, montre que les stocks ont tendance à croître avec la mise en place d'une prairie de fauche intensive (Urochloa ruziziensis). Enfin, l'étude méthodologique de mesure du stock par spectroscopie-spectrométrie sur le terrain n'a pas été concluante, car testée sur un échantillon à forte diversité pédologique.

International audience; Persistent pesticides led to long term pollution of soils and consequently contaminate rivers, groundwater, ecosystems and finally human beings. Volcanic soils (andosols) are generally more polluted than the other kinds of tropical soils but data show that andosols release less pesticides to percolating water and crops. Andosols contain amorphous clays (allophane) which present unique structures and physical properties compared to crystalline clays. Allophane aggregates have physical features very close to that of nano porous materials like synthetic gels: large pore volume and water content, a broad pore size distribution, a high specific surface area and a fractal structure. The aim of the study was to show the influence of the features (nano materials structure, shrinkage during drying) of these natural gels on the pesticide retention. Our study confirms that the soil to crop pesticide transfer is lower in andosols compared to other volcanic soils. Associated to high organic matter content, the allophane microstructure favor pollutants (chlordecone) accumulation in soils. We put forth the importance of the nano porous features of allophane (the associated tortuous microstructure) but also the pore collapse during drying, for pollutant trapping in soils.

In semiarid Sahelian region, the dynamics of soil organic carbon (SOC) and water are key to sustainable land management. This work focuses on the behaviour of carbon. A total of 33 soil profiles in four polders, ranging from 10 to 65 years in age, were sampled, analysed (0–1 m), and matched with marsh soil profiles in recent sediments considered as reference (t0) for carbon stocks determination. SOC and soil inorganic carbon (SIC) stocks show a spatial variability between polders. SOC stocks were t0 200 ± 0.8; t60 183 ± 34; and t65 189 ± 1.1 MgC·ha−1, whereas the SIC stocks were negligible. These results show the highest stocks of soil carbon observed for this climatic region. The SOC stocks were also calculated for the equivalent soil mass at a defined depth (0–0.3 m); the corrected calculation of SOC stocks (Scorr) for 2450 Mg·ha−1 of equivalent soil mass is t0 64 ± 1.9, t60 59 ± 9.8, and t65 53 ± 2.2 MgC·ha−1; the stocks decrease by −7.8% and −17.2% from t0 to t60 and t65. Carbon was inherited from the pre-existing·marsh and the polders have conserved high stock values.

Les Tanala, paysans de l'Est de Madagascar, pratiquent une culture temporaire sur défriche-brûlis appelée tavy, souvent perçue comme une cause d'érosion du sol L'accroissement de l'activité cyclonique, facteur d'érosion et d'inondations, appelle alors des stratégies d'adaptation. Supposant que les pratiques de tavy comportaient une stratégie pour faire face aux aléas cycloniques, nous avons étudié les sols, les processus d'écoulements et d'érosion dans le paysage, les pratiques agricoles et les savoirs liés dans plusieurs terroirs et bassins villageois choisis selon l'importance des reliques forestières. Les pratiques observées sont adaptées au risque érosif, aux échelles parcelle et paysage : choix raisonné des sols, pratiques culturales précautionneuses et accordées au risque saisonnier, mosaïques paysagères et agroforesterie sur les terrains à risque. La collecte des classifications paysannes confirme la profondeur des savoirs locaux et l'existence de "principes de gestion" derrière les pratiques. Mais à long terme, et sous pression de la population et du nouveau marché du gingembre, les dernières forêts disparaissent, des écosystèmes dégradés apparaissent, et l'érosion s'accroît. Ce savoir est désormais moins opérationnel et un nouveau savoir adapté doit être co-construit.

Smallholder farmers in the Taita hills and Mount Kilimanjaro recognize the need to conserve soil nutrients of fields and farms located in the upper, middle and lower zones of mountainous areas. These mountain communities depend on rain-fed subsistence agriculture which means that for sustainable subsistence crop production, they also depend on nutrient availability and use efficiency in farming households. A study under way in the area has looked at loss of land cover and infestations of plant pests and diseases and is using this information to raise farmers’ awareness of soil fertility and to introduce best cropping practices.

Jusqu’au milieu du siecle passe, les savanes d’Amerique du Sud ont ete relativement peu concernees par l’activite agricole et sylvicole, etant un lieu d’elevage bovin extensif. Depuis, tant dans le Cerrado au Bresil que dans les Llanos de Colombie et du Venezuela, pâturages cultives, cereales et legumineuses a grains se sont imposes sur de grandes surfaces. L’occupation des terres est egalement sylvicole avec l’introduction d’especes exogenes. Ce developpement de nouvelles activites a ete possible avec des schemas de fertilisation inorganique importants. Apres une revue comparative du mecanisme de colonisation agricole des Llanos et du Cerrado et de l’examen de quelques caracteristiques biogeochimiques des sols, nous montrons l’importance de la relation de ces milieux avec des enjeux environnementaux actuels et la necessite de produire de nouveaux indicateurs pour l’usage des savanes.

The paper presents results of a field experiment designed to investigate the potential use of forage legume Stylosanthes hamata (stylo) to ameliorate the structure of a compact layer in sandy soils of Northeast Thailand. Sandy and acidic soils that are common to Northeast Thailand have restricted agronomic potential due to inherent chemical and physical properties. A compact layer at 20–40 cm reduces root elongation for most crops, thereby restricting the quantity of nutrients and water available for the plant growth. Deep ploughing and subsoiling are costly and have not been shown to be effective in overcoming compaction since these soils are unstable and collapse after the first heavy rainfall event. A three-year study was conducted in order to evaluate the effect of continuous stylo on the porosity of the compact layer and its influence on root elongation and yield of a subsequent maize crop. Continuous stylo was grown for two years in experimental plots and compared to a currently used stylo-maize rotation. Root distribution and macropore density were measured under the two cropping systems. After 24 months of continuous stylo, roots were able to penetrate the compact layer, resulting in a significant improvement in the macroporosity of this layer. The subsequent maize crop developed a deeper and more extensive root system using macropores created after 24 months of continuous stylo when compared to the stylo-maize rotation treatment. This study demonstrates the potential role of Stylosanthes hamata in structural amelioration of sandy compact layers.

Depuis plusieurs décennies, sous l’effet du défrichement, du surpâturage et de la pression démographique, les milieux naturels et les aires cultivées des régions semi-arides sont soumis à d’importantes dégradations. Malgré la mise en œuvre des grands projets de lutte antiérosive depuis les années 1950, les espaces ruraux nord-africains ont notamment connu d’importantes baisses de productivité accompagnées d’une augmentation du risque de ruissellement et d’érosion des versants. Devant ce constat et face à la nécessité d’optimiser concrètement la gestion de l’eau et de restaurer la fertilité des terres, l’amélioration des techniques traditionnelles est la voie recommandée dans cet ouvrage pour mettre en œuvre des projets intégrés de développement en milieu rural. Soutenue par le réseau érosion de l’AUF, l’équipe franco-marocaine de géographes, d’agronomes et de forestiers réunie pour cet ouvrage a analysé une trentaine de techniques traditionnelles de gestion de l’eau et des sols au Maroc. Testées dans différentes zones agro-écologiques et en tenant compte des facteurs économiques et humains, les techniques paysannes de lutte antiérosive sont présentées et commentées à la lumière des derniers acquis scientifiques. À partir de ces expériences, l’ouvrage propose des combinaisons de techniques traditionnelles de gestion des sols, optimisées et adaptées aux conditions locales. Il s’adresse aux enseignants, aux étudiants et aux chercheurs, mais également aux ONG et aux décideurs en charge des programmes de développement rural au Maghreb et dans les régions semi-arides.

The intensive farming practices that have been developed over the past 60 years are based mainly on the use of chemical inputs such as fertilisers and pesticides, mechanical tillage and monoculture. The limitations of these methods are now clear: long-term degradation of soil fertility, impacts on the environment and human health, high consumption of fossil fuels, low efficiency of inputs and threats to food security in a context of climate change. Would farming practices that rely on the activation of ecological processes be an alternative to achieve a balance between high productivity and environmental preservation? While many studies suggest a positive relationship between soil biodiversity and ecosystem services, there is considerable debate on the form such agricultural systems should take. This study reviewed the state of current knowledge and identified aspects requiring further research to achieve the aim of sustainable intensification of agriculture. The following major points emerged: (i) Most studies focused on the evaluation of individual practices. However, changes in farmers’ cropping practices to take advantage of soil biodiversity services would need to manage not only the interactions between various practices but also the trade-off between the technical and socio economic constraints of cropping systems. Advances in agricultural system design approaches may help to ensure appropriate trade-offs. (ii) More attention should be given to drawing on knowledge from different sources: laboratory studies focusing on the ecological functions of soil biodiversity, experimental surveys on farmers’ fields to rank the farming practices and processes to be included in site-specific models, and on- station experiments to test hypotheses and acquire additional reference material. (iii) Whereas advances in technical and scientific knowledge provide an increasing number of relevant indicators for characterizing biodiversity and ecological functions, studies are rarely targeted at the development of indicators that are accessible to farmers or their technical advisors. The lack of indicators accessible to grassroots players for evaluating the impacts of their decisions on soil biodiversity remains a serious obstacle to the development of innovative agro-ecological systems.

International audience; Earthworms provide key soil functions that favour many positive ecosystem services. These services are important for agroecosystem sustainability but can be degraded by intensive cultural practices such as use of pesticides. Many literature reports have investigated the effect of pesticides on earthworms. Here, we review those reports to assess the relevance of the indicators of earthworm response to pesticides, to assess their sensitivity to pesticides, and to highlight the remaining knowledge gaps. We focus on European earthworm species and products authorised in Europe, excluding natural compounds and metals. We consider different organisation levels: the infra-individual level (gene expression and physiology), the individual and population levels (life-history traits, population density and behaviour) and the community level: community biomass and density. Our analysis shows that earthworms are impacted by pesticides at all organisation levels. For example, pesticides disrupt enzymatic activities, increase individual mortality, decrease fecundity and growth, change individual behaviour such as feeding rate and decrease the overall community biomass and density. Insecticides and fungicides are the most toxic pesticides impacting survival and reproduction, respectively.

International audience; An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment , socioeconomic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score todesertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient,plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation.

Metal-rich soils, especially heavy metal-polluted soils and ultramafic soils, are generally toxic to non-adapted plants and microorganisms. The role of mycorrhizal fungi in the metal tolerance of adapted plant species has become clear in the last decade. This review aims to synthesize the findings of representative studies of the effects of mycorrhizas on the alleviation of heavy metal toxicity on plants and on the absorption/accumulation of heavy metals in their roots and shoots. The adaptation to heavy metals by mycorrhizal symbionts is associated with their efficiency in metal-rich soils. More than 80 % of the studies have indicated a positive role of mycorrhizal fungi in the adaptation of plants to heavy metals in these soils, but the relationships between plant tolerance to heavy metals and the absorption of metals are complex and depend on a range of biological, physical and chemical factors.

In Northern Vietnam, organic fertilization programmes are being tested to restore soil fertility and reduce soil erosion. However, the amendment of organic matter in soil is also associated with the development of the invasive earthworm species Dichogaster bolaui. The objective of this study was to investigate the influence of organic matter amendment quality (compost vs. vermicompost) on D. bolaui. Our study confirmed D. bolaui development in organic patches in the field. However, we also observed that the flat-backed millipede Asiomorpha coarctata proliferated in these organic patches. Native to Asia, this millipede species is also considered as invasive in America. Both D. bolaui and A. coarctata more rapidly colonized compost than vermicompost patches. A laboratory experiment confirmed this trend and showed the limited development of D. bolaui in vermicompost. This is probably because of the decreased palatability of this substrate to soil fauna. In conclusion, any restoration practice that aims to increase the organic stocks in soils degraded by erosion should consider the quality of the organic amendment. In Northern Vietnam, vermicompost may be the preferred substrate for restoring soils while limiting the spread of D. bolaui. (C) 2014 Elsevier Masson SAS. All rights reserved.

La dégradation de l'environnement en particulier la ressource sol ne cesse de s'amplifier, entrainant une diminution de sa fertilité. Face à ce problème, une étude d'interaction plante-vers de terre a été initiée pour déterminer s'il existe un partenariat bénéfique pour la plante, car les vers de terre contribuent beaucoup à l'amélioration de la structure et de la composition physico-chimique du sol. Cette étude a été menée dans le site d'URP-SCRiD à Andranomanelatra en collaboration avec le FOFIFA et l'IRD. L'essai a été conduit sous deux dispositifs sur terrain : i) en mésocosme, vase de végétation (en pots) et ii) au champ. Les traitements testés sont l'apport de Dichogaster saliens dans les pots ou au champ avec un nombre croissant de 0, 4, 8, 12 vers de terre. Le riz et l'éleusine sont les plantes testées. Après 6 mois de culture, le nombre de D.saliens augmente dans la rhizosphère du riz. Par contre, il diminue chez l'éleusine. Les résultats montrent qu'il n'y a pas de différences significatives sur la productivité en grains du riz due à une grande variabilité entre les blocs ainsi que sur la biomasse racinaire des plantes. Cependant, une corrélation positive est obtenue entre le poids de Dichogaster saliens et le poids en grains plein du riz. Des contaminations d'autres vers non étudiés, Pontoscolex corethrurus et Amynthas minimus, ont été observées. Malgré cela, le phénomène de compétitivité entres les espèces n'a pas eu lieu.