Exploring opportunities for diversification of smallholders' rice-based farming systems in the Senegal River Valley

CONTEXT: Policy-based or technological interventions are more likely to be effective if aligned with farmers' objectives, constraints, and decision-making processes. OBJECTIVE: The objective of this study was to explore trade-offs and synergies of farming systems in response to innovative rice cultivation activities by understanding current farming systems, main drivers impacting farm management and farmers' perspectives on rice intensification. Understanding these interrelations is key in rice production areas, where smallholder farmers largely depend on growing rice to subsist. METHODS: A rapid system analysis was conducted interviewing 20 farmers in 4 villages along the Senegal River Valley (SRV) to obtain a general view on farm functioning and farmers' perspectives on farming systems. A detailed system analysis with four farmers was subsequently conducted to provide an insight into the underlying processes regulating farm management. A multi-objective optimization model was used to quantitatively evaluate and explore farm performances based on four selected indicators representing: rice production, household agricultural profit, household labour and farm nutrient balance. RESULTS AND CONCLUSIONS: The results of this study showed that government programmes and farmers' Unions were strongly influencing farmers' decision-making in agricultural production. Farmers also reported that although rice was still essential for their livelihoods, there were transitions towards less rice production in the wet season with short duration rice varieties and more vegetable production. Both farmers' interviews and the modelling results suggested that farmers would be unlikely to increase or even maintain the area of rice double cropping, which has been strongly promoted by the Senegalese government. Instead, farmers would rather keep investing in vegetable production. SIGNIFICANCE: This modelling study shows the consequences of policy-based and technological interventions for farming systems and may inform both policy makers and farmers in situations where objectives are strongly divergent. Hence, modelling outcomes may be used to inspire discussion and innovation in order to align the government priority of ensuring national food security and farmers' objectives and constraints in the SRV

Analysing spatial–temporal changes in rice cultivation practices in the Senegal River Valley using MODIS time-series and the PhenoRice algorithm

In this study we used the PhenoRice algorithm to track recent variations of rice cultivation practices along the Senegal River Valley. Time series of MODIS imagery with 250m spatial resolution and a nominal 8-days frequency were used as input for the algorithm to map the spatial and temporal variations of rice cultivated area and of several important phenological metrics (e.g., crop establishment and harvesting dates, length of season) for the 2003–2016 period in both the dry and the wet rice cultivation seasons. Comparison between PhenoRice results and ancillary and field data available for the Senegal part of the study area showed that the algorithm is able to track the interannual variations of rice cultivated area, despite the total detected rice area being consistently underestimated. PhenoRice estimates of crop establishment and harvesting dates resulted accurate when compared with field observations available for two sub-regions for a period of 10 years, and thus allow assessing interannual variability and tracking changes in agronomic practices. An analysis of interannual trends of rice growing practices based on PhenoRice results highlighted a clear shift of rice cultivation from the wet to the dry season starting approximately from 2008. The shift was found to be particularly evident in the delta part of the SRV. Additionally, a statistically significant trend was revealed starting 2006 towards a longer dry season (r2=0.81; Slope=1.24 days y−1) and a shorter wet season (r2=0.65; Slope=0.53 days y−1). These findings are in agreement with expert knowledge of changes ongoing in the area. In particular the shorter wet season is attributed to shortage of labor and equipment leading to a delay in completion of harvesting operations in the dry season, which led to the adoption of short-duration rice varieties by farmers in the wet season to avoid risk of yield losses due to climatic constraints. Aforementioned results highlight the usefulness of the PhenoRice algorithm for providing insights about recent variations in rice cultivation practices over large areas in developing countries, where high-quality up to date information about changes in agricultural practices are often lacking