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The objective of the ACME (Agile Crop Model Ensemble) software is to facilitate the simulation of large virtual experiments using an ensemble of crop models on personal computers running Windows OS. These simulations can either be point-based or spatially explicit. The package includes an ensemble of three crop models (executable files and input and output data) and two databases: 'MasterInputOutput' which contains the input and output variables of the models, and 'ModelDictionary', which contains the connections and required transformations between variables of the different models. In addition, an executable code 'DataMill' applies these transformations and manages the data flow between the MasterInputOutput database and the file system of each model, before (input parameters) and after (output parameters) running the virtual experiment.

Sub-Saharan Africa (SSA) faces significant food security risks, primarily due to low soil fertility leading to low crop yields. Climate change is expected to worsen food security issues in SSA due to a combined negative impact on crop yield and soil fertility. A common omission from climate change impact studies in SSA is the interaction between change in soil fertility and crop yield. Integrated soil fertility management (ISFM), which includes the combined use of mineral and organic fertilizers, is expected to increase crop yield but it is uncertain how this advantage is maintained with climate change. We explored the impact of scenarios of change in soil fertility and climate variables (temperature, rainfall, and CO2) on rainfed maize yield in four representative sites in SSA with no input and ISFM management. To do so, we used an ensemble of 15 calibrated soil-crop models. Reset and continuous simulations were performed to assess the impact of soil fertility vs climate change on crop yield. In reset simulations, SOC, soil N and soil water were reinitialized each year with the same initial conditions. In continuous simulations, SOC, soil N and soil water values of a given year were obtained from the simulation of the previous year, allowing cumulative effects on SOC and crop yields. Most models agreed that with current baseline (no input) management, yield changed by a much larger order of magnitude when considering declining soil fertility with baseline climate (-39%), compared with considering constant soil fertility but changes in temperature, rainfall and CO2 (from -12% to +5% depending on the climate variable considered). The interaction between change in soil fertility and climate variables only marginally influenced maize yield (high agreement between models). The model ensemble indicated that when accounting for soil fertility change, the benefits of ISFM systems over no-input systems increased over time (+190%). This increase in ISFM benefits was greater

Damages caused by various pathogens, animal pests, and weeds in rice crops can result in important yield losses (Oerke, 2006). In order to limit these damages, farmers use large amounts of pesticides, especially in Cambodia (Flor et al., 2019). This leads to high health and ecological risks. Two major challenges must be completed to support farmers in the agroecological transition, and to limit the use of pesticides on rice crops: i) to link pest populations and pest injuries with the associated risks of crop losses (yield and/or quality) in a given production situation and for given cropping practices; ii) to understand which agroecological levers can prevent pest development and damages. We calibrated the Decision Support System DSSAT using the CERES-Rice model to simulate the impact of different cropping systems (e.g. number of cycles per year, cultivars, fertilization practices) representing various farming systems (e.g. conservation agriculture) on rice growth and yield in Cambodia. The simulated growth dynamics represent potential crop growths in the considered agroenvironmental conditions. The impacts of multiple pests are then integrated using coupling points and damage functions. This presentation introduces the structure, parameterization, model's goodness of fit, and potential use of the model to help adapt crop management strategies in different environments.

Agriculture in semi-arid Burkina Faso is dominated by mixed crop-livestock smallholder farms with limited investment capacity in production factors, such as improved seeds, fertilizer and equipment. Hence, to make a living, farmers try to make the best use of available resources based on principles of agro-ecology, including crop diversity and nutrient and biomass recycling. We investigated farm-level management of resources (soil, crops and livestock) through time to assess whether the current management options were able to sustain crop and livestock production and fulfil household food requirements. We ran a one-year detailed farm monitoring campaign in collaboration with 22 volunteer farmers representing the diversity of the farming system in our study area. We quantified inputs and outputs in the cropping system (177 fields) for one rainy season. In addition, the weekly dynamics of crop residues left on field were quantified. Moreover, inflow and outflow of resources at farm level were quantified weekly. The cropping system was characterized by a negative nitrogen balance of about 12 kg N/ha/year, with market-oriented farms and large livestock owners having the most negative balance. Legumes grown (sole and intercropping) contributed to alleviate the nitrogen depletion by adding 15 kg N/ha/year to the nitrogen inputs through atmospheric fixation. However, cereal-legume intercropping did not significantly reduce the nitrogen deficit in comparison to sole cereal cropping mainly because of the small proportion of legumes (8%) in intercropped fields. Livestock grazed crop residues left on the soil (739 kg dry matter/ha on average) at a rate of 26 − 76 kg/ha/week, thus strongly reducing the potential for mulching in the region. Livestock protein requirements were rarely met from farm-produced feed with average feed gaps ranging between 40% and 89% of the daily requirements for small and large herd keepers respectively. Large livestock (cattle) owners relied on trans

En Haïti, les systèmes agricoles sont fortement vulnérables au changement climatique. Cette étude vise à analyser la pertinence d'une démarche de co-conception de stratégies d'adaptation des exploitations agricoles au changement climatique dans une zone hautement vulnérable telle que Haïti. Menée à Saint Michel de l'Attalaye, l'étude reposait : (i) sur la réalisation d'un diagnostic des performances technico-économiques de 24 exploitations représentatives des trois principaux types de stratégies d'adaptation observées, et (ii) sur la co-conception de stratégies innovantes avec un échantillon plus réduit de 9 agriculteurs. Les résultats de l'étude montrent que les performances initiales des 24 exploitations en termes de couverture des besoins caloriques du ménage, revenus, et émissions de gaz à effet de serre sont différentes pour les trois types de stratégies. La diversification des systèmes de production agricole joue un rôle crucial dans les performances mesurées. Les stratégies proposées par les 9 producteurs visent à accroître cette diversification tout en renforçant la place de la canne à sucre dans les systèmes de production, mais les changements pensés sont incrémentaux. D'autres boucles de co-conception pourraient être envisagées pour explorer avec les producteurs des changements de rupture articulant augmentation des capacités de production des exploitations et adaptation au changement climatique. Cette étude pilote en Haïti pourrait être répliquée dans d'autres zones hautement vulnérables afin de co-concevoir des systèmes innovants tenant compte des contraintes spécifiques auxquelles sont exposés les agriculteurs.

The year 2023 will likely be the hottest ever recorded on our planet. Adapting to climate change and climate extremes is increasingly becoming a day-to-day concern for African farmers, along with food security and income issues. Agricultural adaptations like varietal choice and fertilizer doses have deserved great attention from the crop modeling community, and are overall well accounted for by crop models. Agroecological practices, for example residue mulching, rotation and intercropping with legumes and application of organic amendments offer great potential to adapt to climate change. Yet, they have deserved less attention when it comes to the modeling of their performance in tropical context. In this abstract, we describe a collective research effort to update and test the Stics soil-crop model to account for the impact of agroecological practices on cropping system performance in the tropics. We built on multiple years of measurements in contrasting experimental sites from cool to warm, semi-arid to sub-humid subtropical environments, in Senegal, Zimbabwe, Mali, Burkina Faso, Kenya, Brazil and Madagascar. We assessed the skills and pitfalls of the model to simulate i) new cereal and legume crops ii) cereal-legume intercropping, iii) crop residue decomposition and feedbacks on crop growth and iv) crop residue mulching. We calibrated a new set of parameters for tropical maize (Falconnier et al., 2020), sorghum (Traoré et al., 2022, Ganeme et al., in revision), millet (Sow et al., forthcoming), rice (Ranaivoson et al., 2022), and legumes like cowpea (Traoré et al., 2022, Ganeme et al., in revision) and groundnut (Civil, 2022). Model accuracy (rRMSE) for end-of-season variables like aboveground biomass and grain yield was in the range of 20 to 50%. The scrutiny of in-season soil water and plant leaf area index (LAI) indicated that water stress was often underestimated, possibly because of underestimation of soil evaporation, and underestimation of the impact of wat

Purpose To support the sustainable development of smallholder farms, bridging the gap between generic scientific knowledge and local knowledge relevant to farmers' socio-ecological niches represents a challenge for advisory services. We explore two approaches supporting farmers in the tailoring of technical options to their own farm systems. Design/Methodology/Approach We present two case studies in which farmers are supported in the adaptation of sustainable cropping practices and describe the mechanisms at play for the tailoring of technical options using the concept of tailoring effort. Findings In the case of Farmer Field Schools (FFS), the tailoring occurs during discussions with the farmers, when the facilitator contextualizes technical options to suit farmers' expressed priorities and constraints. Each farmer can then choose what is relevant to their situation. In the case of crop models (CM), the tailoring happens when researchers parametrize the model as closely as possible to farmers' environments and practices, and then use simulation results in discussions with farmers. Practical implications Possible complementarity between FFS and CM could be explored for advisory services. Advisors need to acquire the skills for collaboration with farmers and facilitation approaches that support the tailoring of generic knowledge to farmers' priorities and constraints. Theoretical implications We highlight the importance of considering what is required from the different stakeholders to make the tailoring process to a socio-ecological niche effective, when supporting farmers in transition towards sustainable agricultural systems.

La diversification des cultures est un des leviers qui pourraient contribuer à stabiliser, voire améliorer, les rendements dans les régions soudano-sahéliennes contraintes par des conditions climatiques semi-arides et des sols très faiblement fertiles. Elle peut permettre aussi d'atténuer les risques liés aux marchés. Cette diversification peut être mise en oeuvre par la pratique des associations et des rotations ainsi que par l'enrichissement de celles-ci avec de nouvelles espèces. Pendant trois années d'expérimentation, nous avons comparé sept espèces, dont quatre légumineuses y compris le haricot mungo, cultivées seules ou en association avec le sorgho. Le haricot mungo est apparu comme une espèce très bien adaptée aux conditions semi-arides du Burkina Faso. Parmi les sept espèces testées, c'est celle qui a produit le plus de grains, entre 0,8 et 1,8 t ha−1 en culture pure et entre 0,35 et 0.9 t ha−1 en association avec le sorgho. Nos résultats confirment aussi le gain de rendement de la culture de sorgho associée avec les légumineuses par rapport à la culture pure. Vingt-cinq producteurs du centre nord du Burkina Faso ont testé le haricot mungo dans leurs parcelles et apprécié sa productivité et sa rusticité. Ils ont obtenu un rendement moyen de 0,7 t ha−1. Toutefois, l'absence de marché, par comparaison au niébé, reste un frein à sa diffusion.

Adapting rice cropping systems to climate change requires new tolerant varieties. Harnessing genetic diversity is crucial to adapt to contrasting environments. We present results from a global rice array (GRA) network built to evaluate 50 varieties nominated by breeders in 52 trials carried out by CG centers, CIRAD, IRD and NARES institutions, in 21 sites across Asia, Africa, and Latin America, from 2018 to 2020. Grain yield varied greatly among varieties, sites, and seasons. Seven Mega-environments (ME) were determined depending on whether abiotic and/or biotic constraints prevailed. ME1 and ME2 showed the highest grain yield, along with high cumulative radiation, while differing in relative humidity and maximum temperatures. In these ME, varieties like Kinandang Pathong, Tequing, and TN1, selected for deep root systems, high yield, and disease sensitivity respectively, showed their potential. Abiotic stresses led to significant yield losses: 10% in ME3, 40% in ME4, and 52% in ME6 compared to ME1 and ME2, due to high frequencies of maximum temperatures above 33°C and night temperatures surpassing 24°C during the reproductive and grain filling stages. Elevated night temperatures led to reduced grain yields for majority of varieties except Nanhi, an Aus Landrace variety. In ME5 and ME7 biotic stresses reduced grain yield. Bacterial blight and blast had the highest damage scores, together with high relative humidity during reproductive and grain filling stages and yield losses of 40% and 52%. However, Chomrong Dhan, one of the tested disease-tolerant variety, consistently demonstrated stable grain yields in both ME5 and ME7. Overall, disease-tolerant varieties performed better than others in MEs with biotic stress. However, Abiotic stress-tolerant varieties did not exhibit a consistent pattern of superiority in ME's with abiotic stress conditions. The GRA network enabled the definition of ME with stress profiles that are likely to occur in the mid to long-term future

Smallholder farming systems face many adversities including poor soil fertility, poor access to inputs, and high dependence on climate variability. On top of that, ongoing climate change is expected to exacerbate the effect of abiotic and abiotic stresses on farm performances, and poses additional challenges of adaptation to climate change. This chapter presents the effect of climate change on the different components of the farming systems (crop, livestock, grassland and tree), in the context of low-input systems. After this account, we argue on the need to have a more integrative approach to assess the effect of climate change on farming systems as a whole. We expose different approaches: coupling of models, use of optimization model. We finally highlight the importance of involving farmers in the process of using models to co-design relevant adaptations to climate change in the context of low input systems.

In the semi-arid zone of Burkina Faso, farmers practice intercropping to minimize climatic risk by ensuring at least one crop in case of particular stress. Crop models are useful tools for evaluating the effect of abiotic stresses on crop performances. Our study aimed to evaluate the contribution of intercropping to the resilience to climate change. An experiment was conducted in 2017 and 2018 at the Saria research station. Two pairs of varieties of sorghum and cowpea were evaluated in intercropping and sole crop. The STICS model was used and calibrated on the 2018 sole crop experimental data, which represented the most optimal cropping situation. Two CO2 pathway emission scenarios and five probable future climate models were used to analyze the climate impact for the middle of the century. The results showed that the model satisfactorily simulated the phenology and grain yield of both crops with NRMSE values within the observation errors. Consistent with observed data, simulated yields were higher in sole crop systems, followed by the ones in intercropping systems. Climate analysis showed that crop yields were more sensitive to changes in rainfall and temperature than CO2. The relatively cold-dry (+0.83°C and -12.5% by 2050) future climate was most favorable to grain yields with yield increases averaging from +3.6% to +7.8% for cowpea when intercropped, and from +7% to +107% in both cropping systems for sorghum. In contrast, the relatively cold-wet (-0.21°C and +30.2% by 2050) future climate was the most unfavorable with grain yield reductions averaging from 0.4 to 29% for both crops. Furthermore, our study showed that intercropping systems stabilized grain yields for most varieties with lower coefficients of variation than in sole crops systems. Overall, the results suggested that intercropping can contribute to the resilience of crops to climate change in the semi-arid zones of Burkina Faso.

Document technique de synthèse des résultats d'un dispositif longue durée mis en place au Cambodge avec une comparaison de 4 systèmes de culture à base de riz avec 3 niveaux de fertilisation. Le document présente le bilan des indicateurs de croissance et développement des cultures de riz mais aussi de plantes de couverture en rotation, évolution de la fertilité du sol, de la pression des bioagresseurs (dispositif géré sans insecticides ni fongicides).

CONTEXT: The semi-arid zone of Burkina Faso is characterized by strong climate variability and declining soil fertility associated with low biomass production. OBJECTIVE: The main objective of this study was to identify key levers to improve biomass management in semi-arid Burkina Faso for diverse farm types. METHODS: Farm diversity was captured with a statistical typology complemented by a participatory typology established with local farmers. Biomass management was described for the different farm types based on survey information obtained from 228 households across two villages. Fuzzy Cognitive Mapping (FCM) was conducted to represent biomass production strategies of each farm type. After a sensitivity analysis which revealed model robustness, scenario analysis was performed with the FCMs to explore farm type-specific options for alleviating biomass scarcity. Two contrasting scenarios were built based on observations and insights from the survey and focus group discussions with farmers and included (1) deliberate exchange of crop residue with manure, and (2) a subsidies policy allowing a reduction in prices of 30% for farm inputs coupled with increased off-farm revenue for the subsistence-oriented farms. RESULTS AND CONCLUSIONS: The statistical typology identified four farm types, distinguishing between subsistence or market-oriented farms and crop or livestock-oriented production. The participatory typology partly confirmed these four main types, even though other criteria of distinction were given by farmers. Different farm types used contrasted strategies in biomass production and management which were mainly driven by the total cultivated area and the herd size. The farm type with the largest herd and smallest cultivated land was the only one to rely on grain inflow from outside the farm to meet its household food requirement. The inflow of crop residue was also largest for this farm type. In contrast, crop residue outflow was mainly observed for the subsiste

Sorghum is a water-efficient crop and an important cereal in semiarid and arid environments where water availability limits production. Providing farmers with sorghum genotypes with specific agro-morphological characteristics of high double production (grains and biomass) would help to maintain or obtain high yields in these environments. The SAMARA model was used to define dual-purpose sorghum ideotypes for different target environments. Model calibration and evaluation were carried out with experimental data collected in Nioro du Rip in 2015 and Sinthiou Malem from 2013 to 2016 on 10 contrasting sorghum genotypes. Daily weather conditions from 1950 to 2016 were used for the simulations. Also considered were the different environmental (soil and climate) conditions of Bambey, Nioro du Rip, and Sinthiou Malem (Senegal). Simulations for the identification of optimal genotypic parameters in these target environments highlighted three ideotypes showing performances for a dual-purpose (grain and fodder) production superior to the reference genotype Nieleni. This was thanks to their strong capacity to colonize the soil (long roots) and to maintain green leaves (stay-green) throughout the cycle. Hence, long roots and staygreen trait should be strongly considered while selecting or developing dualpurpose genotypes of sorghum for the target environments, especially in less-watered areas like Bambey.

Agriculture in semi-arid Burkina Faso is dominated by mixed crop-livestock smallholder farms with limited investment capacity in production factors (e.g. improved seeds, fertiliser and equipment). Hence, to maintain production, farmers try to make the best use of available resources based on principles of agro-ecology, including crop diversity and nutrient and biomass recycling). We investigated farm-level management of resources (soil, crops, manure, fertiliser and livestock) through time to assess whether the current management options were able to sustain crop and livestock production and fulfil household food requirements. We ran a one-year detailed farm monitoring campaign in collaboration with 22 volunteer farms representing the diversity of the farming system in our study area. We quantified inputs and outputs in the cropping system (244 plots) for one rainy season. In addition, the weekly dynamics of crop residues left on field was quantified up to 12 weeks after harvest. Moreover, inflow and outflow of resources at farm-level were quantified weekly. The cropping system was characterised by a negative nitrogen balance of about 10 kg N ha-1 at the farm level. At the field level, cereal-legume intercropping significantly reduced the nitrogen deficit from -23.7 kg N ha-1 (sole cereals) to -4.8 kg N ha-1. Dry season livestock grazing caused the amount of crop residue left on the soil after harvest (739 kg DM ha-1 on average) to quickly reduce at a rate of 26–76 kg DM ha-1 per week, leaving very little mulch as organic amendment. Livestock protein requirements were rarely met from farm-produced feed with average feed gaps ranging between 22 and 94 % of the requirements for small herd and large keepers respectively. Large livestock (cattle) owners relied on transhumance during the rainy season, grazing and frequent purchase of crop residues and concentrates to feed their livestock. Concerning food availability in the household, the amount of grain produced (89–175

Sorghum is an important staple crop in Sub-Saharan Africa. In the Sudano-Sahelian zone of West Africa, sorghum is mainly intercropped with cowpea, but these intercropping systems are facing low-productivity problems. The overall aim of this research was to identify sorghum varieties with different agro-morphological and physiological traits that could improve the performance of the intercropping systems. We followed a two-step methodology comprising (i) identification of varieties and plant traits of interest in intercropping systems, using participatory methods, and (ii) agro-morpho-physiological characterization of 50 sorghum varieties, to examine the range of variation in traits of interest. The results show that landraces are the varieties most widely used by farmers, and that 82.5% of farmers consider the variety type they choose for intercropping to be important. Farmers mentioned plant height, number of leaves and stem diameter as important traits to consider. Analysis of variance showed significant differences between varieties for half of the 24 agro-morpho-physiological traits studied. Hierarchical clustering identified three main groups of varieties, distinguished by morphological traits such as stem diameter, total number and size of leaves (group 1), root traits (depth, growth angle, dry matter) and relative chlorophyll content (groups 2 and 3). Based on this classification, we recommend several varieties from each of the three groups, exhibiting contrasting traits, for an assessment of their performances in intercropping systems.

Production of cereals (maize, sorghum, millet) in southern Mali is challenged by several hazards that affect yield and yield variability. The research aims to inform decision making towards effective risk management by quantifying cereal yield losses at field level due to production hazards under different management strategies. Five hazards relevant for farmers were analysed: late onset of rains, insufficient total rainfall, dry spells, low fertiliser quality and sudden lack of labour. The frequency and impact on yield of these hazards were assessed by combining a long term weather database (1965–2019) with outputs of the DSSAT crop model (baseline and optimised variety, fertiliser rates and sowing dates), and visualised in a risk matrix. The prevalence of the weather hazards was common, with all of them occurring at least once every five years. Frequency of non-weather hazards were perceived to occur once every five years (labour hazards) and once every ten years (fertiliser hazards). Under baseline conditions maize (3.39 t / ha) outperformed sorghum (1.74 t / ha) and millet (1.33 t / ha), except in cases of fertiliser hazard when sorghum yielded more than maize. Maize responded relatively well to N application, and sorghum performed relatively well without N application. The benefit of millet resided in low yield variability, and lower sensitivity to the weather hazards. Changing management to optimise yields generally involved early sowing (22 days, 2 days and 27 days after onset for maize, sorghum and millet), increased N applications (66 kg N / ha, 27 kg N / ha and 111 kg N / ha for maize, sorghum and millet), and using short duration varieties. For millet the long duration variety was more beneficial. For maize there was opportunity to increase the yield without affecting the risk of yield loss, while for sorghum there was a synergy and for millet a trade-off between yield and risk. The different interactions between hazards and management for the three cerea

CONTEXT: The semi-arid zone of Burkina Faso is characterized by strong climate variability and declining soil fertility associated with low biomass production. OBJECTIVE: The main objective of this study was to identify key levers to improve biomass management in semi-arid Burkina Faso for diverse farm types. METHODS: Farm diversity was captured with a statistical typology complemented by a participatory typology established with local farmers. Biomass management was described for the different farm types based on survey information obtained from 228 households across two villages. Fuzzy Cognitive Mapping (FCM) was conducted to represent biomass production strategies of each farm type. After a sensitivity analysis which revealed model robustness, scenario analysis was performed with the FCMs to explore farm type-specific options for alleviating biomass scarcity. Two contrasting scenarios were built based on observations and insights from the survey and focus group discussions with farmers and included (1) deliberate exchange of crop residue with manure, and (2) a subsidies policy allowing a reduction in prices of 30% for farm inputs coupled with increased off-farm revenue for the subsistence-oriented farms. RESULTS AND CONCLUSIONS: The statistical typology identified four farm types, distinguishing between subsistence or market-oriented farms and crop or livestock-oriented production. The participatory typology partly confirmed these four main types, even though other criteria of distinction were given by farmers. Different farm types used contrasted strategies in biomass production and management which were mainly driven by the total cultivated area and the herd size. The farm type with the largest herd and smallest cultivated land was the only one to rely on grain inflow from outside the farm to meet its household food requirement. The inflow of crop residue was also largest for this farm type. In contrast, crop residue outflow was mainly observed for the subsiste