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Comparison of methods to aggregate climate data to predict crop yield: an application to soybean
No full textInternational audienceAbstract High-dimensional climate data collected on a daily, monthly, or seasonal time step are now commonly used to predict crop yields worldwide with standard statistical models or machine learning models. Since the use of all available individual climate variables generally leads to calculation problems, over-fitting, and over-parameterization, it is necessary to aggregate the climate data used as predictors. However, there is no consensus on the best way to perform this task, and little is known about the impacts of the type of aggregation method used and of the temporal resolution of weather data on model performances. Based on historical data from 1981 to 2016 of soybean yield and climate on 3447 sites worldwide, this study compares different temporal resolutions (daily, monthly, or seasonal) and dimension reduction techniques (principal component analysis (PCA), partial least square regression, and their functional counterparts) to aggregate climate data used as inputs of machine learning and linear regression (LR) models predicting yields. Results showed that random forest models outperformed and were less sensitive to climate aggregation methods than LRs when predicting soybean yields. With our models, the use of daily climate data did not improve predictive performance compared to monthly data. Models based on PCA or averages of monthly data showed better predictive performance compared to those relying on more sophisticated dimension reduction techniques. By highlighting the high sensitivity of projected impact of climate on crop yields to the temporal resolution and aggregation of climate input data, this study reveals that model performances can be improved by choosing the most appropriate time resolution and aggregation techniques. Practical recommendations are formulated in this article based on our results
Efficiency assessment of a novel automatic mosquito pupae sex separation system in support of area-wide male-based release strategies
No full textInternational audienceThis study provides a comparative analysis of two state-of-the-art automatic mosquito pupae sex sorters currently available: the ORINNO and the WOLBAKI Biotech pupae sex separation systems, which both exploit the sexual size dimorphism of pupae. In Aedes aegypti , the WOLBAKI sex sorter and the ORINNO with a sieve mesh size of 1.050 mm achieved sex separation with female contamination rates below 1%, low pupae mortality rates and high male flight capacity. However, in Ae. albopictus , there was more variability, with female contamination rates above the 1% threshold and pupae mortality reaching 27% when using the ORINNO sorter. On the other hand, the WOLBAKI sorter achieved a male pupae recovery of 47.99 ± 8.81% and 50.91 ± 11.77% in Ae. aegypti and Ae. albopictus, respectively, while the ORINNO sorter with a smaller sieve size achieved male pupae recoveries of 38.08 ± 9.69% and 40.16 ± 2.73% in Ae. aegypti and Ae. albopictus, respectively. This study provides valuable information for researchers and practitioners in the field, assisting in the selection of the most suitable system for mosquito control, management and research programs depending on their specific requirements
Viticulture et agroécologie - Variabilité de développement des couverts végétaux selon les conditions climatiques et les itinéraires techniques dans un réseau de parcelles de viticulteurs en Languedoc-Roussillon
No full textNational audienceLa viticulture fait aujourd’hui face à de nombreux enjeux climatiques, environnementaux et agronomiques : qualité des sols, résilience aux aléas climatiques, dépendance aux phytosanitaires, préservation de la biodiversité etc. . Les pratiques viticoles intensives impactent fortement la multifonctionnalité des sols et mènent à une diminution problématique de la matière organique, clé de voûte de la fertilité des sols, notamment par érosion. Les couverts végétaux, ou cultures de services, permettent de répondre à ces enjeux. Par l’amélioration de la porosité et de l’infiltration et par la couverture végétale qu’ils forment, ils limitent le lessivage et l’érosion des sols. La fertilité physique n’est pas la seule à être améliorée : les couverts végétaux accroissent le carbone organique des sols via leur décomposition en alimentant l’humus stable, améliorant ainsi la fertilité chimique des sols. L’effet engrais vert d’apport d’azote par les couverts de fabacées est également un service d’intérêt pour les viticulteurs ou les viticultrices. La fertilité biologique – dernier aspect du triptyque de fertilité des sols — bénéficie également de l’implantation de couverts végétaux, l’activité biologique du sol étant stimulée par la hausse de matière organique. Si les cultures de services sont des leviers pour l’amélioration des sols viticoles, des questions quant à leur mise en place persistent. Le pilotage des couverts végétaux demeure complexe et les potentielles concurrences pour les ressources avec la vigne en contexte méditerranéen freinent les viticulteurs. En outre, les amendements organiques sont connus depuis très longtemps pour leur capacité à améliorer les propriétés des sols et leur association à des couverts pourrait modérer les potentielles concurrences. Bien que les enherbements progressent en Languedoc-Roussillon, les couverts semés représentent encore une minorité de ces pratiques. Il est donc nécessaire de produire des références techniques sur le pilotage des couverts semés et leurs effets sur la viticulture languedocienne. Le projet RESAMOVITI (RESeau d’Acquisition de références et d’accompagnement des pratiques d’amélioration de la Matière Organique des sols VITIcoles, 2020-2024) est le fruit d’une demande de la filière sur la problématique de la qualité des sols et des couverts végétaux. Les résultats de RESAMOVITI présentés dans cet article apportent des éléments de réponse à cette problématique, en termes de compréhension des déterminants de la réussite du semis en biomasse et en composition carbone et azote
Protection of straw cereals, sugar beet and oilseed rape against aphid-borne viruses using varietal and biocontrol solutions
No full textAlternatives aux néonicotinoïdes Rendu des projets réunissant des contributions des projets scientifiques d'Ecophyto et du Plan National de Recherche et Innovation-betterave avec, selon les projets, les soutiens financiers de l'Office français de la biodiversité (OFB), l’Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE) et de l'Institut technique de la betterave (ITB).International audienceThree viral diseases transmitted by aphids can cause significant yield losses in beet, straw cereal and oilseed rape production. For a long time, these crops were protected against yellows by targeting aphids using plant protection products that have recently been banned (neonicotinoid family) or are still authorised, but whose effectiveness may be inadequate following the appearance of aphid populations resistant to certain insecticide active substances. Academic researchers, technical institutes and companies have worked together as part of the ABCD_B research project, with the aim of evaluating new solutions for protecting these crops against viruses. Work was carried out on the three species, both in natural field conditions and under controlled conditions. The results highlighted and quantified differences in varietal sensitivity within each of the crop species (wheat, oilseed rape, sugar beet). At the same time, a major effort to evaluate biocontrol products has produced encouraging results for two active substances (azadirachtin and paraffin oil), even though their efficacy remains significantly lower than that of reference solutions
A construção da governabilidade da água no Ceará: avanços e desafios após quatro décadas de reformas
No full textInternational audienceThe management of water resources in the Brazilian state of Ceará has been widely praised for its governance,commonly regarded as remarkably participatory and integrated. However, this model, whose essentialcontours were designed between 1987 and 1993, also included a governability project. The democratizationof governance was conceived as a tool to better know about, control, and direct the uses of water by stateagencies, at different scales. After three decades of implementation, what has this project of governabilitythrough democratic means achieved? In this paper, we argue that governance arrangements were, on the onehand, fundamental to furthering water governability at the “meso” level of watersheds; but, on the other hand,that they were much less conducive to strengthening governability at the more “micro”, local level. We attributethese ambivalent effects to two mechanisms. First, the implementation of the model raised many issues relatedto the institutional organization of watersheds, which consequently monopolized stakeholders’ attention, tothe detriment of the challenges that emerged at the local level. Second, governance arrangements eventuallyconfined municipalities to a subordinate role, even though local governments remain indispensable actors toadvance local governability. Thus, we foreground two unexpected effects of governance on governability: themonopolization of attention and the marginalization of an influential actor. Insofar as these effects may wellend up destabilizing the governance architecture itself, we conceptualize them as ‘negative’ policy feedback,which the paper thus contributes to identify. In conclusion, we argue that only more inclusive and deliberativeforms of governance at the local level may strenghten the local governability of water resources, therebyopening a new chapter for the “Ceará model”
Nodulating another way: what can we learn from lateral root base nodulation in legumes?
No full textInternational audienceCertain legumes provide a special pathway for rhizobia to invade the root and develop nitrogen-fixing nodules, a process known as lateral root base (LRB) nodulation. This pathway involves intercellular infection at the junction of the lateral roots with the taproot, leading to nodule formation in the lateral root cortex. Remarkably, this LRB pathway serves as a backbone for various adaptative symbiotic processes. Here, we describe different aspects of LRB nodulation and highlight directions for future research to elucidate the mechanisms of this as yet little known but original pathway that will help in broadening our knowledge on the rhizobium-legume symbiosis.To improve our understanding of how legumes interact with nitrogen-fixing rhizobia, we highlight the importance of studying an original lateral root base nodulation process present in certain legumes
It's not all about drought: What “drought impacts” monitoring can reveal
No full textInternational audienceDrought impacts monitoring has been called the missing piece in drought assessment. The potential to improve drought management is high but uncertain due to rare analyses of impacts datasets, predominantly because there are few impacts monitoring programmes to generate the datasets. Drought impacts monitoring is conducted on the ground in much of Brazil by local observers at monthly and municipality scale to support the Brazilian Drought Monitor. In Ceara state, within drought-prone semiarid northeast Brazil, over 3600 drought impacts reports were completed by agricultural extension officers from 2019 to 2022. We investigated, through manual coding and observer interviews, the reported drought impacts and impact drivers. Analysis provided a catalogue of the experienced impacts and showed that impacts still occur, and are often normalised, during non-drought periods, sometimes as lingering effects of previous droughts. The impact drivers were predominantly non-extreme hydrometeorological conditions or a result of socio-technical vulnerabilities such as insufficient water infrastructure. The normalisation of "impacts" included, in particular: a generally accepted high level of crop losses and consistently low reservoir levels around which the agricultural and domestic systems are adapted. Conventional drought indices often did not align with experienced impact severity, highlighting the limitations of relying solely on these indices for emergency response. Continual impacts monitoring could be extremely valuable anywhere in the world for identifying vulnerabilities and informing proactive measures to reduce drought and other hazard risk, in addition to guiding targeted mitigation efforts
Acquisitions et déploiement international des firmes multinationales issues des pays émergents : Étude du cas de l’entreprise brésilienne JBS
No full textInternational audienceThe internationalization’s process of emerging countries’ multinational firms (EMNF) challenges the theoretical approaches in international business. This work aims to identify the specificities of EMNF’s internationalization through the study of the internationalization of JBS, a Brazilian firm world leader in meat production. Based on internal company data and a collection of secondary information, we have traced around fifty acquisition operations in Brazil and abroad. Our results confirm that the EMNFs’ internationalization process follows a specific trajectory compared to those revealed by last internationalization models (Born Global, Springbaord, Casino). It reveals a particular logic: strong financial dimension, acquisitions of subsidiaries of international groups, then used to acquire other firms, controlled geographical expansion and aimed at securing supply and distribution, and strong support from financial and political institutions in the origin country.Les processus d’internationalisation des firmes multinationales des pays émergents (FMNE) interrogent les approches théoriques en management international. L’objet de ce travail est d’identifier les spécificités de l’internationalisation des FMNE à travers l’étude de JBS, firme brésilienne leader mondiale des viandes. En partant des données internes de l’entreprise et d’un recueil d’informations secondaires, nous avons retracé l’ensemble des opérations d’acquisition que JBS a réalisé au Brésil et à l’étranger. Nos résultats confirment que l’internationalisation des FMNE suit une trajectoire spécifique par rapport à celles explicitées par les modèles récents (Born Global, Springboard ou Casino). Elle a des logiques particulières : forte financiarisation, acquisitions de filiales de groupes internationaux servant à acquérir d’autres firmes, expansion géographique visant la sécurisation des approvisionnements et de la distribution, et fort appui des institutions politico-financières du pays d’origine
AMG_base
No full textAMG_base simulates topsoil soil organic carbon stock evolution in arable cropping systems. It is a basic R version of the AMGv2 model (without calculation of C3 and C4 stocks)
Long-term soil organic carbon and crop yield feedbacks differ between 16 soil-crop models in sub-Saharan Africa
No full textInternational audienceFood insecurity in sub-Saharan Africa is partly due to low staple crop yields, resulting from poor soil fertility and low nutrient inputs. Integrated soil fertility management (ISFM), which includes the combined use of mineral and organic fertilizers, can contribute to increasing yields and sustaining soil organic carbon (SOC) in the long term. Soil-crop simulation models can help assess the performance and trade-offs of a range of crop management practices including ISFM, under current and future climate. Yet, uncertainty in model simulations can be high, resulting from poor model calibration and/or inadequate model structure. Multi-model simulations have been shown to be more robust than those with single models and help understand and reduce modelling uncertainty. In this study, we aim to perform the first multi-model comparison for long-term simulations of crop yield and SOC and their feedbacks in SSA. We evaluated the performance of 16 soil-crop models using data from four longterm maize experiments at sites in SSA with contrasting climates and soils. Each experiment had four treatments: i) no exogenous inputs, ii) addition of mineral nitrogen (N) fertilizer, iii) use of organic amendments, and iv) combined use of mineral and organic inputs. We assessed model performance in two steps: through blind calibration involving a minimum level of experimental data provided to the modeling teams, and subsequently through full calibration, which included a more extensive set of observational data. Model ensemble accuracy was greater with full calibration than blind calibration. Improvement in model accuracy was larger for maize yields (nRMSE 48 vs 18%) than for topsoil SOC (nRMSE 22 vs 14%). Model ensemble uncertainty (defined as the coefficient of variation across the 16 models) increased over the duration of the long-term experiments. Uncertainty of SOC simulations increased when organic amendments were used, whilst uncertainty of yield predictions was largest when no inputs were applied. Our study revealed large discrepancies among the models in simulating i) crop-to-soil feedbacks due to uncertainties in simulated carbon coming from roots, and ii) soil-tocrop feedbacks due to large uncertainties in simulated crop N supply from soil organic matter decomposition. These discrepancies were largest when organic amendments were applied. The results highlight the need for long-term experiments in which root and soil N dynamics are monitored. This will provide the corresponding data to improve and calibrate soil-crop models, which will lead to more robust and reliable simulations of SOC and crop productivity, and their interactions