Groundnut Basin Research Articles

Study of the Cassava Production System in the Department of Tivaouane, Senegal

Cassava plays an important role in improving food security and reducing poverty in rural areas. Despite its importance, its production in Senegal remains low compared to other African countries. Nowadays, it is confronted with numerous constraints. It is in this context that a study was conducted on the cassava production system in the Thiès "cassava granary" region, with the objective of examining farmers' cultivation practices. It was conducted in eight communes located in the department of Tivaouane, some of which are located in the Niayes agro-ecological zone and others in the central-northern groundnut basin. Surveys were conducted among the largest cassava producers in these communes. Analysis of the results showed that cassava is only grown in the rainy season with the same cultivation practices that have been used for years. Of the five varieties listed by the President of the Senegalese Cassava Interprofession, only four are grown in the areas surveyed. The Terrasse (43%) and Kombo (36%) varieties are grown more by our respondents in the Niayes area. Soya (75%) and Wallet "Parydiey" (20% of our sample) dominate in the central-northern groundnut basin.

Estimation Of The Value Of Goods And Services Produced By Protected Areas: Case Of The Ndock Sare Community Forest In Senegal

The community forests of Senegal, and particularly those of the Groundnut Basin, play an important role in the lives of rural populations. They are significant sources of supply of various products and services. But despite their economic and ecological importance, community forests have never been the subject of an economic evaluation. This is likely to obscure the decision-making auspices of sustainable management of community forests. This study, based on vegetation surveys and socio-economic surveys, assessed the value of ecosystem goods and services. The results of the analysis showed that the forest has 21 species distributed among 08 families and that this diversity varies from one area to another. With this specific diversity, the basal area is evaluated at 2.64 m2/ha and the cover of 6081.17 m²/ha for a density of 327 individuals per hectare. The forest has a carbon storage capacity evaluated at 15.32 tons. The goods and services of the forest were estimated at 3,391,757 F CFA/year. This value is divided between direct uses estimated at 1,236,575 F CFA/year, indirect uses of 168,495 F CFA/year and an existence value of 1,986,687 F CFA/year. The study also showed that the exploitation of the forest is the most viable management option, as strict conservation imposes a social cost of 370,058 CFA francs per year on the population. In the context of decentralization, these results can serve as a basis for policy dialogue and decision-making processes on the sustainable management of forest resources

Benchmarking statistical modelling approaches with multi-source remote sensing data for millet yield monitoring: a case study of the groundnut basin in central Senegal

ABSTRACT In Sub-Saharan Africa, smallholder farms play a key role in agriculture, occupying most of the agricultural land. Design policies for increasing smallholder productivity remains a safe way to establish sustainable food systems and boost local economies. However, efforts are still needed in order to achieve accurate and timely monitoring in smallholder farming systems. With the advent of modern Earth Observation programmes such as the Sentinel satellites, which provide quasi-synchronous and high-resolution multi-source information over any area of the continental surfaces, new opportunities are opened up to accurately map crop yields in smallholder farming systems. This study intends to estimate and forecast millet yields in central Senegal, making the use of multi-source (synthetic-aperture radar (SAR) and optical) image time series and state-of-the-art machine learning models. A Random Forest (RF) model explained up to 50% of the millet yield variability, while deep learning models such as Convolutional Neural Network (CNN) showed promise results but performed lower. We also found that the concatenation of SAR polarizations and vegetation indices improved our crop yield modelling, but such improvement was tightly related to the modelling approach, namely RF and CNN. Using RF to forecast millet yields, we achieved stable and satisfactory accuracy 2 weeks before the harvest period.

Analysis of Genotype-Environment Interaction and Yield Stability of Introduced Upland Rice in the Groundnut Basin Agroclimatic Zone of Senegal

Identification of highly performing varieties under Senegalese environment is crucial to sustain rice production. Genotype-environment interaction and stability performance on the grain yield of ten upland rice genotypes were investigated across 11 environments in Senegal during the rainy seasons of 2016 and 2017 to identify adapted varieties. The experiment was conducted using a randomized complete block design with three replications at each environment. Data on grain yield were recorded and analyzed using the additive main effects and multiplicative interaction (AMMI) model. The combined analysis of variance revealed that the grain yield was significantly affected by environment (67.9%), followed by genotype × environment (G × E) interaction (23.6%) and genotype (8.5%). The first two principal component axes were highly significant with 37.5 and 26% of the total observed G × E interaction variation, respectively. GGE biplot grouped the environments into four potential megaenvironments. Based on the yield stability index parameter and ranking GGE biplot, NERICA 8 and ART3-7-L9P8-1-B-B-1 were stable and high-yielding varieties compared to the local check NERICA 6. These varieties should be proposed for cultivation in order to sustain the rice production in the southern part of the groundnut basin of Senegal and used as parental lines in rice breeding program for grain yield improvement.

Analyse expérimentale du comportement des producteurs de céréales sèches face au risque financier dans un contexte de changement climatique

Cette étude a un double objectif : caractériser les exploitants agricoles suivant leur niveau d’aversion au risque financier et analyser les facteurs explicatifs de leur propension à prendre un risque financier. En utilisant un système de loteries inspiré des travaux d’Allais (1953) sur 540 exploitants agricoles choisis dans le Bassin arachidier du Sénégal, les résultats montrent que 81,38 % des producteurs présentent une aversion au risque financier et seulement 8,57 % sont « risquophiles ». Les estimations avec le modèle probit binomial montrent également que la propension à prendre un risque financier diminue si l’exploitant agricole se fixe un niveau élevé de perte de production tolérable. Ces résultats suggèrent de prendre en compte les composantes de la demande dans les politiques publiques de financement et d’assurance agricole.

Farmers’ perception on the benefits and constraints of Farmer Managed Natural Regeneration and determinants of its adoption in the southern groundnut basin of Senegal

Farmers’ perception on the benefits and constraints of Farmer Managed Natural Regeneration and determinants of its adoption in the southern groundnut basin of Senegal

Effect of salinity on the physiology of peanut variety 73-33 (Arachis hypogaea L.)

Peanut (Arachis hypogaea, L.) is an annual papilionaceous oilseed legume cultivated on nearly 25 million hectares in tropical and temperate zones due to its remarkable plasticity to temperature and water requirements. In Senegal, peanut is produced in rural areas where they are the main source of agricultural income. Variety 73-33 is cultivated in the river valley and the groundnut basin is subject to the influence of salinization affecting four of Senegal's ecogeographic zones. Studies conducted with randomized full-block experimental set-up in the laboratory and under semi-controlled greenhouse conditions have shown the effect of different concentrations of NaCl on the peanut variety 73-33: 0mM; 25mM; 50mM; 100mM; 200mM; 300mM; 400mM; 500mM for germination and 0mM; 25mM; 50mM; 100mM for growth growth and chlorophyll production. The parameters which were measured are: the germination rate (ten days after sowing), the number of nodules, the number of gynophores, the dry biomass and the production of chlorophyll at twenty, forty and seventy-five days after sowing. Germination is significantly negatively affected from 400mM. Twenty days after sowing there is a significant difference between the control and the other treatments for the production of chlorophyll a (Chla) only. Forty days after sowing, the production of chlorophyll a and total chlorophyll shows a very highly significant difference between all the treatments. The dry biomass only shows a significant difference from 100mM. Seventy-five days after sowing, the dry biomass and the number of gynophores are significantly reduced by the salinity from 25mM.

Agricultural Land Transition in the “Groundnut Basin” of Senegal: 2009 to 2018

The study aims to reveal the transition features of agricultural land use in the Groundnut Basin of Senegal from 2009 to 2018, especially the impact of urbanization on agricultural land and the viewpoint of farmland spatiotemporal evolution. Integrated data of time series MCD12Q1 land-use images of 2009, 2012, 2015, and 2018 were used to provide a land transition in agricultural and urban areas through the synergistic methodology. Socio-economic data was also used to serve as a basis for the argument. The results highlight that: (1) Agricultural land increased by 14.53%, with a dynamic index of 1.45 from 2009–2018. (2) Over the same period, urbanization increased by 2.80%, with a dynamic index of 0.28. (3) In different regions, the transition of agricultural land in Kaffrine is most intense (expansion rate: 22.80%). The same situation of urbanization happened in Thiès Region with a value of 7.94%. Except for Thiès, agricultural land in other regions has not yet been subject to major pressure due to urbanization. Overall, the farming system in Groundnut Basin is an extensive model, the recommendations from the point of view of land-use planning and land law are necessary to ensure efficient agricultural land management in the area.

Estimates of carbon stocks in sandy soils cultivated under local management practices in Senegal’s groundnut basin

Soil organic carbon (SOC) is essential for the productivity of agroecosystems and for mitigating climate change. Because the SOC contents of sandy soils are usually small, the effects of agricultural management upon SOC stocks in such soils have been insufficiently studied. In West sub-arid Africa, the coarse-textured soils (mostly Arenosols) are diversely managed by smallholders. In this study, we aimed to quantify SOC stocks in cultivated soils of that region, in a context where agricultural practices rely mainly upon organic inputs derived from various integrated crop-livestock systems. SOC stocks were estimated for the 0–30 cm depth in 1,813 plots in Senegal’s groundnut basin. We found that SOC stocks in farmers’ fields varied between 2.3 and 59.8 Mg C ha-1 (mean ± standard deviation, 14.6 ± 0.14 Mg C ha-1). SOC stocks were influenced slightly by soil type, but were only weakly correlated to soils’ clay and silt contents. SOC stocks differed significantly among the three studied village territories due to contrasting livestock-raising systems. Average stocks were significantly higher in plots close to housings (home-fields), which receive larger amounts of organic inputs, than in plots farther from the village (out-fields). Thus, the organic inputs to home-fields improves soil C stocks of these sandy soils in the short term. Innovative agricultural practices in the studied area probably need to target options for managing all fields optimally. Those options will require continuous application of organic products—a measure that will in turn require solutions for improving availability or management of local organic resources.

Performance of dry and wet spells combined with remote sensing indicators for crop yield prediction in Senegal

Studying the relationship between potential high-impact precipitation and crop yields can help us understand the impact of the intensification of the hydrological cycle on agricultural production. The objective of this study is to analyse the contribution of intra seasonal rainfall indicators, namely dry and wet spells, for predicting millet yields at regional scale in Senegal using multiple linear regression. Using dry and wet spells with traditional indicators i.e. proxies of crop biomass and cumulated rainfall, hereafter called remote sensing indicators (NDVI, SPI3, WSI and RG), we analysed the ability of dry and wet spells alone or combined with these remote sensing indicators to provide intraseasonal forecasts covering the period 1991–2010. We analysed all 12 regions producing millet and found that results vary strongly between regions and also during the season, as a function of the dekad of prediction. At the spatial scale, the strongest performing combinations include the dry spell indicators DSC20 and DSxl in the peanut basin. While in the south of the country, the combination of wet period indicators WS1 or WSC5 with the RG is fairly reliable. Focussing on Thies, our best region in the groundnut basin, we showed that dry and wet spells indicators can explain up to 80% of yield variations, alone or in combination with remote sensing indicators. Regarding the timing of prediction, millet yield can be forecast as early as July with an accuracy of 40% of the mean yield but the best forecast is obtained in early September, at the peak of crop development (accuracy of 100 kg/ha i.e. 20% of the mean yield). Although, the estimated yields show biases over some years identified as extremely deficient or in oversupply in terms of agricultural yields.

Evaluation of Quantitative and Qualitative Losses on Millet and White Rice in Storage Grains Caused by <i>Corcyra cephalonica</i> (Stainton) in Senegal

In Senegal, millet (Pennisetum glaucum (L.) R. Br.) and rice (Oryza sativa (L., 1753)) are the most widely consumed foods. This study is part of improving the conservation of these two cereals in Senegal by assessing the quantitative and qualitative losses caused by a lepidopteran, Corcyra cephalonica (Stainton) subservient to millet and rice stocks. For this purpose, samples of millet and rice from an area of the center of the groundnut basin (Diourbel) were collected, sterilized in the cold and infected with C. cephalonica eggs from the same locality. These infected samples were tracked during a development period of two successive generations. The samples were scrutinized before being infected and after a larval cycle of codling moth. The results showed that rice grains are richer in water (10.75% ± 0.4249%, on average) than millet (9.40% ± 0.3944%, on average) and the difference in rank is very significant (p-value = 0.0001 Moreover, the attack percentage on millet grains is three times higher (36.31% ± 25.18%) than rice (12.95% ± 6.69%) with a non-significant difference (p-value = 0.296 > 0.05). A similar trend is observed at the loss percentage, which is four times higher with millet grains (8.67% ± 5.07%) than rice (2.86% ± 2.75%) with a non-significant difference (p-value = 0.835 > 0.05). A multiple linear regression showed a generation effect on millet for the attack percentage and a generation and cereal effect for the percentage of weight loss on rice.

English

Niayes and Groundnut basin areas are among the largest strongholds of rainfed agriculture in Senegal. In the agricultural holdings of both agro-ecological areas, main speculations are far from optimizing their agronomic production potential. In order to analyze the organizational capacity and decision-making processes of producers, a global agronomic diagnostic work was undertaken out on the scale of 180 agricultural holdings through socio-economic and technical descriptions, while taking into account endogenous and exogenous factors of the agrarian environment. The results revealed technical and biophysical failures of the resources in their availability and/or use, but also a plethora of constraints which hinder the increase of agricultural activity and the dynamical transition of the unit. These constraints are justified by a precarious technical framework (-15%), a modest size of the agricultural unit (7.45 ha) and a small to medium crop rotation of which 42% of UAA for the first speculation, pearl millet. For the dry cereal, 19% N.P.K phosphate fertilizers use is rated with 26.05 kg ha-1, and 0.46 t ha-1 of background manure for an average yield of 0.59 t ha-1. These conjunctures point to a system of peasant production with low market capital, limited to the satisfaction of family needs. Key words: Family farms, farming practices, pearl millet, Niayes, groundnut basin, Senegal.

Object-Based Multi-Temporal and Multi-Source Land Cover Mapping Leveraging Hierarchical Class Relationships

European satellite missions Sentinel-1 (S1) and Sentinel-2 (S2) provide at high spatial resolution and high revisit time, respectively, radar and optical images that support a wide range of Earth surface monitoring tasks, such as Land Use/Land Cover mapping. A long-standing challenge in the remote sensing community is about how to efficiently exploit multiple sources of information and leverage their complementarity, in order to obtain the most out of radar and optical data. In this work, we propose to deal with land cover mapping in an object-based image analysis (OBIA) setting via a deep learning framework designed to leverage the multi-source complementarity provided by radar and optical satellite image time series (SITS). The proposed architecture is based on an extension of Recurrent Neural Network (RNN) enriched via a modified attention mechanism capable to fit the specificity of SITS data. Our framework also integrates a pretraining strategy that allows to exploit specific domain knowledge, shaped as hierarchy over the set of land cover classes, to guide the model training. Thorough experimental evaluations, involving several competitive approaches were conducted on two study sites, namely the Reunion island and a part of the Senegalese groundnut basin. Classification results, 79% of global accuracy on the Reunion island and 90% on the Senegalese site, respectively, have demonstrated the suitability of the proposal.

Agronomic Performances and Nutritional Assessment of Three Sweet Potato Varieties (Ipomoea batatas (L) Lam.) Introduced in an Agro-ecological Zone of Groundnut Basin in Senegal

Aims: To evaluate the agronomic and nutritional performances of three varieties of sweet potato (Kandee, Caromex and Gandiol1) cultivated for the first time in the agro-ecological zone of the groundnut basin in Senegal.
 Study Design: The experiment was arranged in Randomized Completely Block Design.
 Place and Duration of Study: The study was conducted during two growing seasons from April to August 2017 and from October 2018 to February 2019 in Sagna village (Kaffrine, Senegal).
 Methodology: The planting of the cuttings was done with a density of 0.3 x 1 m or 3333.3 cuttings ha-1. Drip irrigation was used and mineral fertilization with 15-15-15 was applied. In each elementary plot, 5 plants were checked monthly for growth and phytosanitary monitoring. The harvest took place at 145 days after planting. The yields and agro-morphological characteristics of the roots were determined as well as their nutritional value and the incidence of bio-aggressor attacks.
 Results: The success percentage of cuttings was 90.1, 90.5 and 88% for Kandee, Caromex and Gandiol1, respectively. The length development of sweet potato stems was variable between the 3 varieties. The Gandiol1 variety with stems longer than 1.6 m was very spread out contrary to Caromex whose average stem length did not exceed 0.5 m. The marketable tuber yields obtained were comparable between the varieties and were 21.5, 22.5 and 13.4 t ha-1 respectively for Kandee, Caromex and Gandiol1. The morphology of the tubers was different in shape (diameter and length) but also in flesh color. Kandee had orange flesh, rich in carotenoids (101.1 mg/kg; P<0.001), Caromex a cream color with carotenes of 43.2 mg kg-1 and Gandiol1 a white flesh. Caromex had the best proportion of dry matter (40.6%; P<0.001) compared to the other varieties. This amount of dry matter was correlated with the marketable root yield (r=0.54; P=0.04) and the carbohydrates amount (r = 0.52; P=0.05). Bio-aggressor incidence on tubers was lower for the Kandee variety (10.3%; P=0.01).
 Conclusion: Sweet potato varieties performed well in the agro-ecological conditions of the groundnut basin and showed comparable agronomic performance. The three varieties can be discriminated on the level of their nutritional quality, particularly on their β-carotene content.

The Rock-Eval® signature of soil organic carbon in arenosols of the Senegalese groundnut basin. How do agricultural practices matter?

Soil organic carbon (SOC) ensures soil quality and productivity of cultivated systems in the Sahelian region. This study uses Rock-Eval® pyrolysis to examine how cultural practices impact the quantity of SOC and quality of SOM in cultivated sandy soils in the Senegal groundnut basin. This cost-effective method provides information on SOC thermal stability, which has been shown to be related qualitatively to biogeochemical stability of SOC. We sampled soils within two villages in agricultural plots representative of local agricultural systems, and in two local preserved areas (tree plantation and shrubby savanna). SOC concentrations ranged from 1.8–18.5 g.kg−1 soil in the surface layer (0−10 cm) and from 1.5–11.3 g.kg−1 soil in the 10−30 cm layer. SOC contents of cultivated soils decreased significantly (p-value < 0.0001) according to field amendment, in the following order: addition of organic wastes> addition of manure > millet residues left after harvest > no organic input. We found that the quantity and the quality of SOC are linked, and that both depend on land-use and agricultural practices, especially upon the type of organic inputs. Quantity of SOC and quality of SOM are correlated strongly in the tree plantation (R² = 0.98) and in the protected shrubby savanna (R² = 0.97). They are also correlated significantly in cultivated soils receiving organic wastes (R² = 0.82), manure (R² from 0.74 and 0.91), or millet residues (R2 = 0.91) but not in soils that receive no organic inputs. Indexes based upon Rock-Eval® pyrolysis were represented in an I/R diagram that illustrates the level of SOC stabilization. The indexes of the studied soils were plotted against comparable results from literature. Thermal signatures of the Senegalese Arenosols show an inversion of I and the R indexes compared to data from the literature. This result highlights SOC stabilization as a function of soil depth. Indeed, the refractory pool in the studied soils (where refractory pool ranged from 7.7–21.3 % in the 0−10 cm layer, and from 12.5–24.3 % in the 10−30 cm) was more abundant than in Ferralsols in natural conditions, where refractory pool ranged from 2 to 9%. The soil organic matter in these Arenosols while positively affected by organic inputs, is dominated by more or less labile forms that mineralize quickly: a quality that is excellent for productivity of these agrosystems, but not for mitigation of climate change in the long term.

Assessing the Sustainability of Horticultural Farms in Central Senegal: An Adaptation of the IDEA Method

This paper evaluates the sustainability of the different forms of horticulture farms (individual and collective) in the Groundnut Basin of Senegal using an adapted version of the IDEA method to the Senegal context. Results show that collective farms have higher sustainability scores than individual farms. Also, collective farms are more sustainable in the agroecological scale while individual farms are more sustainable in the economic scale. Results also suggest that although IDEA can be adapted to both individual and collective horticulture farms of Senegal, there is a need to include a fourth scale that will integrate the institutional and organizational features of collective farms as well as the socio-political and research context that can enable or hinder the adoption of sustainable farm practices.

Ecological niche modelling to estimate the distribution of Culicoides, potential vectors of bluetongue virus in Senegal

BackgroundVector-borne diseases are among the leading causes of morbidity and mortality in humans and animals. In the Afrotropical region, some are transmitted by Culicoides, such as Akabane, bluetongue, epizootic haemorrhagic fever and African horse sickness viruses. Bluetongue virus infection has an enormous impact on ruminant production, due to its high morbidity and mortality rates.MethodsA nationwide Culicoides trapping campaign was organized at the end of the 2012 rainy season in Senegal. A Maximum Entropy approach (MaxEnt), Boosted Regression Tree (BRT) method and Ecological Niche Factor Analysis (ENFA) were used to develop a predictive spatial model for the distribution of Culicoides, using bio-climatic variables, livestock densities and altitude.ResultsThe altitude, maximum temperature of the warmest month, precipitation of the warmest quarter, mean temperature of the wettest quarter, temperature seasonality, precipitation of the wettest quarter and livestock density were among the most important factors to predict suitable habitats of Culicoides. Culicoides occurrences were, in most of the cases, positively correlated to precipitation variables and livestock densities; and negatively correlated to the altitude and temperature indices. The Niayes area and the Groundnut basin were the most suitable habitats predicted.ConclusionWe present ecological niche models for different Culicoides species, namely C. imicola, C. oxystoma, C. enderleini and C. miombo, potential vectors of bluetongue virus, on a nationwide scale in Senegal. Through our modelling approach, we were able to determine the effect of bioclimatic variables on Culicoides habitats and were able to generate maps for the occurrence of Culicoides species. This information will be helpful in developing risk maps for disease outbreaks.

‘Latent’ surplus populations and colonial histories of drought, groundnuts, and finance in Senegal

Amidst growing concern about the displacement of rural populations exposed to climate change, new financial instruments are increasingly being presented as key tools for the management of climate risks. Index-based agricultural insurance (IBAI) is a particularly key example. Recent critical work has pointed to the deeply neoliberal character of IBAI and like interventions. However, the promotion of new financial instruments in response to crises of agrarian production has a much longer history in Africa and elsewhere. This article draws on Marx’s concept of ‘latent’ surplus populations to trace out and explain parallels between IBAI and colonial interventions in Senegal’s groundnut basin. Approaching the question in this way, the article highlights the long-run historical co-production and interdependence of the Senegalese state and a political ecology of groundnut production in which relations of indebtedness and the exposure to variable rainfall of a fragile relative surplus population has often been crucial to the mobilization of cheap labour for groundnut production. IBAI is thus positioned as part of a recurrent trajectory of emergency financial interventions aimed at smoothing out the contradictions implicit in this socio-ecological configuration.

Efficacy of augmentative release of the parasitoid wasp Bracon hebetor against the pearl millet headminer

The yield losses in pearl millet, estimated to be about 85%, are mainly due to millet headminer, Heliocheilus albipunctella . This study is aimed at determining the status of this serious insect pest in the pearl millet production system within the groundnut basin of Senegal and to assess the efficacy of augmentative releases of its parasitoid wasp, Bracon hebetor , to control it. The study area was divided into three homogenous blocks (Northern, Southern and Eastern parts) where a set of three villages was selected for release of the parasitoid and another three as control villages where no releases were made. The results revealed that in all the villages where the parasitoid was released, an increase in larval mortality due to parasitism ranging between 9% and 26% was recorded in comparison with the control villages. Consequently, damages recorded were significantly lower in the villages with parasitoid releases.

Evaluation of Extra-early Maturing Maize Genotypes for Grain Yield and Stability in the Groundnut Basin Agro-ecological Zone of Senegal

Maize is a highly valuable staple food crop in Sub-Saharan Africa regions. Its production is hampered by both biotic and abiotic stress. Early-maturing genetic resources appear as an excellent choice to manage adverse climatic change’s effects. This study aimed to find the best extra-early maize genotypes based on genotype by environment interactions in the groundnut agro-ecological zone of Senegal. The trials were conducted in Paoskoto, Ndiedieng, Nioro and Keur Sene during the rainy seasons of 2016 and 2017. Six extra-early maize genotypes were evaluated following a randomized complete block design with three replications. Data on grain yield were recorded and analysed using additive main effect and multiplicative interaction and genotype plus genotype by environment biplot methods. Analysis of variance revealed a significant (P &lt; 0.01) genotype by environment effect on grain yield. The sum of squares variation was higher (77.2%) explained by the environment effect. The genotype 2008-TZEE-W-STR showed the highest yield performance (3299 kg ha-1) and lowest yield stability index (3). This genotype can be suggested to farmers for its cultivation and a good candidate for early maturing maize breeding program in Senegal.