Index based crop insurance in senegal and west africa: some concerns based on on-going experiments

Agricultural insurance is just starting in West Africa (WA) with the recent launching of some index based insurance pilot projects. However it is already possible to stress some important issues based on those experiments and also considering previous knowledge on climate and agriculture in WA. As regards climate issues, the main problem is the basis risk due to the huge spatio-temporal variability of rainfall. This reality pleads for the development of remote sensing methods. Other important issues are the local rainfall gradients and the recent trend of increasing rainfall. Climatic issues also stress the question of the fair management of level of protection and cost of premium. The only way to ensure equity between farmers is to use subsidies of different values in order to provide the same protection for the same price to all farmers. That is the case in Senegal but it is the only country where Government provides subsidies for insurance. But the main issue to be solved will be to find an acceptable solution with all the stakeholders to the trade-off between "protection" and "premium cost". While people in Mali and Burkina Faso have accepted so far to buy very cheap insurance policies, without knowing how they protect them, we faced a totally opposite situation in Senegal where farmers' organizations analysed the indices in detail and asked for good protection at a low price. Major efforts will be necessary everywhere to allow stakeholders to analyse insurance issues together and decide which kind of system will be more appropriate. (Résumé d'auteur

Root architecture of two sorghum varieties differ than drought stress tolerance : [Abstract, P 7.17]

Root architecture of two sorghum varieties, fitted in #Durra race# and with different response in drought conditions, has been studied on hydroponic system, pot and in situ on field. These varieties have similar aerial agro-morphological characteristics in optimal growth conditions. In pre-flowering drought stress condition, tolerant variety (SSM1611), has a stable and higher yield than the non-tolerant one (IS16101). On hydroponics conditions and pot growth, varieties are studied at young stage. On field, observations concerned the whole plant cycle. Frequent observations of the aerial system have been made in all the trials, with counting of emerged leaves number and measuring stem height. Adventitious roots number and adventitious roots ranks number have been daily observed on hydroponic system and observations was not destructive. Spatial root disposition on stem was observed on hydroponic condition. On pot and field, these observations were destructive and realised once a week. Adventitious root and their different regions growth (basal none branched region, branched region, apical none branched region) were studied in hydroponic system and in pot. The distribution of the root length density according depth in situ condition was studied using passage model from root impacts to length density. Results show that, the development and the growth of aerial system are practically similar for both of varieties whatever trials conditions. However, for the root system there are some differences in favour of the drought stress tolerant varieties (SSM1611). All the trials showed that, SSM1611 presents a higher adventitious roots number and adventitious roots ranks number than IS16101. Adventitious roots number per rank varies according to the rank and the variety. The distribution of the adventitious roots around the stem seems to be leaded by the same low. Adventitious root of the same rank are balanced distribution around the stem. Until three roots per adventitious root rank, adventitious roots of two successive ranks are distributed in a complementary way around the stem. The growth of adventitious roots and their different regions ((basal none branched region, branched region, apical none branched region)e) present similarity for both of varieties. On hydroponic system, adventitious root length increase first time and then stop their growth to maximal level. However in pot, adventitious root growth seems to bee unlimited. SSM1611 variety reveals a root length density according to depth more important than IS16101 variety one in field. Adventitious roots number, adventitious roots ranks number, and root length density could constitute pertinent and easily accessible drought stress tolerance criterions. (Texte intégral

How farmers permanently adapt to climate evolution by testing new options and caring for food security: case of long-cycle sanyo millet comeback in Serer area in Senegal. [P-3330-58]

During the last decade, Serer farmers of the Sine region in the central and western part of Senegal have started to grow again the sanyo millet (Pennisetum glaucum), a long cycle (110-140 days) and photoperiodic traditional variety that had disappeared for 30 years from this region due to the rainfall decrease which has affected the Sahelian and Sudano-Sahelian zones starting from 1970, leaving only the short-cycle (90 days) souna millet in the fields. We made the assumption that the reintroduction of the sanyo millet could be an agronomic “marker” of the increase in rainfall observed in Senegal since the mid-1990s (Salack and al., 2011) attesting to the capacity of farmers to adapt to the evolution of their environment. We wanted to check, however, whether this necessary climatic opportunity was sufficient to explain farmers choices. We investigated how important was the sanyo comeback in local farming systems, its geographical diffusion, and its biophysical, economic, social and cultural drivers. We carried out (a) simulations of souna and sanyo annual development during the 1950-2013 period using the SarraH©Cirad model; (b) several Focus Group Discussions with farmers; (c) a large survey by questionnaire on farming systems among 1,061 farms in the 30 villages of the IRD human and health observatory zone of Niakhar (monitored since 50 years); and (d) a rapid survey in 240 villages of the region located between Bambey and Diourbel in the North and Fatick in the South (about 1000 km2) on whether the sanyo millet was grown and its date of reintroduction. The SarraH©Cirad crop model was parametered according to previous works. Survey data were carefully analysed using relevant statistics to assess the factors underlying sanyo reintroduction. Crop model simulations confirmed that sanyo reappearance is due to the recent rainfall improvement which now allows getting again grains with this variety whereas since 1970 grains production was only possible with souna. But simulations also show that sanyo yields remain very risky due to the rainfall interannual variability whereas souna yields are higher and surer. They also show that sanyo provides important biomass (stalks and straw). Farmers comments and surveys data analysis complement and confirm the results of the simulations. First, peasants report that they prefer the taste of sanyo and above all the quality of its stems rather than those of souna. In addition, adopting sanyo does not require any specific know-how or investment as it is grown like souna. Its qualities explain why it has quickly spread throughout the area. Sanyo was present in 61% of the sites surveyed in 2013 compared with 23% in 2000. But farmers stress that it is a risky cultivation and that they will not endanger their food security by substituting souna with sanyo. Souna and groundnuts still remain their main staple and cash crops, respectively. They also deplore that sanyo (similarly to souna) cannot provide cash, unlike groundnuts or watermelon that has also expanded in recent years. Statistical analyses highlight some social and family influences since farmers belonging to the “warrior caste” and those whose fathers formerly cultivated sanyo are more likely to cultivate it. But “land resources” appear to be the key factor. Yet, farmers explain they would plant fields dedicated to sanyo only if they were sure to produce enough souna. This is why sanyo is mainly cropped in association with souna, in an average proportion of 1 line of sanyo for 4-5 lines of souna. Moreover farmers point out that they would easily stop sanyo if they had other opportunities, particularly if they provide cash. Thus, despite its spectacular diffusion, sanyo cover very little surfaces: in the zone of Niakhar it was present in 2013 on 2.8% of the cropped areas and on 7.3% of millet areas. Sanyo reappearance and its important and rapid diffusion is clearly an agronomic “marker” of the recent climate evolution (rainfall increase) observed in Senegal. It attests to the adaptive capacity of farmers to quickly and autonomously adapt to the evolution of their environment by permanently looking and trying new options, but underlines how cautious they are to not endanger their food security, and confirms that a climatic opportunity is not sufficient to account for farmers' choices. Comparisons can be made with recent watermelon emergence in the same area and developments of maize and rainfed rice areas in the southern areas of Senegal, which have been enabled by the rainfall evolution but benefit of solid economical drivers. (Texte intégral

Yield gap and the shares of climate and crop management in yield and yield variability of staple crops in West Africa. [O-3330b-01]

" Yield gap " (Yg) is a key concept of agricultural science for identifying the room for improvement of yields through better management of the agroecosystem. in rainfed agriculture Yg is the difference between actual yield (Ya) and the theoretical water limited yield (Yw) that would be achieved if solar radiation, temperature and precipitations were the only factor limiting the crop's growth and yield. Changes in Yw over regions and years are due to climate-soil interactions that are not easily modified by crop management, whereas changes in Yg are due to limiting factors that are typically within the scope of crop management such as nutrient availability, weeds, and pests. We provide an example of yield gap estimates in semi-arid a frica, using yield and other agronomic data collected in famers' fields of Senegal in 1990 and 1991 and from 2006 to 2012. i t illustrates how contrarily to what most people would expect climate is not, on average, what most limits yields in that region: yet, actual yields are on average a quarter of water limited yield, and this is due to constraints whose reduction is technically possible albeit subject to the economic and environmental relevance of doing so. Most studies dealing with the impact of climate change on agriculture in West a frica compare Yw under present and future climate as predicted by climate models. t he magnitude of those predicted long term changes in Yw by 2050 is down to –20% in the worst scenario combining a +6°C change with a -20% rainfall change. s uch changes in water limited yields are certainly concerning, but they are remarkably small compared to the potential +390% increase that would result from closing the current yield gap. When considering yield variations observed across plots and years, and not anymore regional averages over a few years, what strikes is the stability of observed yields compared to variations of Yw. We used crop model simulations with historical series of 20 years of weather data to compare yield distributions over years of a crop grown using 3 contrasted levels of fertilisation and no incidence of weeds, pests or diseases. For each fertilisation level, the simulated yield reached a maximum value the 'best year' of the series. t he three fertilisation levels were chosen so that the maximum simulated yield reached 0.25 Yw, 0.5 Yw, and 0.75 Yw respectively. t he resulting simulated yield distributions show that even if management allows increasing the median yield, in many years the climate is the main limiting factor and fertilising has no or a slight impact only. i n other words, the way the current climate limits crop production in this region is by making uncertain the output of investing for high yields. Buying fertilizers or working hard for manure collection, transport and distribution do not translate, a certain number of years, into more production. For farmers struggling for the daily subsistence of their family, that kind of risk may not be justified while alternative use of family resources in cash and labour force provide less risky ways to produce subsistence means. Until recently, in many farming systems of West africa, the growth in food needs due to population growth in rural areas was matched thanks to increases in cultivated or pasted areas rather than increases in crop yields or livestock pressure on land (i.e extension rather than intensification of crop or livestock activities). When rural families reached the limits of this strategy, migrations of many kinds of distance and duration became the adjustment variable to the gap between resources available from farming and population needs. T his suggests that for many, it is less risky to leave home than to intensify cropping or livestock systems. Anyway, as job opportunities for migrants from the rural zones are currently low in West african cities and elsewhere, there are legitimate concerns about the way this strategy may soon reach its limit as well. i n terms of climate change, the worst scenario for farmers of that region would be if crop intensification became even more risky under future climate than at present. t here is thus an urgent need for joint agronomic and climate research to go beyond the prediction of Yw or of yield under unchanged crop management and determine whether or not the future climate will increase the yield risks associated with crop intensification in that region. But this should not divert from designing and implementing policies incentive to such intensification under present climate, as this might be much easier now than later. (Texte intégral

Phenological responses of irrigated rice in the Sahel

Worldwide rising temperatures are already being observed and are expected to increase within the next decades. In the Sahel cool periods cause yield losses due to spikelet sterility in late sown rice and thus Sahelian rice production systems might benefit from increasing temperatures. Higher temperatures during the vegetative phase will lead to shortened crop duration and during the reproductive phase higher temperatures during cool periods might reduce sterility. For the hot periods negative effects on biomass production and increased sterility due to heat stress are expected. The complexity of those phenomena requires well validated crop models able to precisely assess development and yield according to genotype and climate for predictive conclusions and adaptive decisions (choice of genotype, sowing date) under changing climatic conditions. In the early 90s for a wide range of germplasm phenology was observed and yield components were determined in staggered planting dates at AfriceRice's Sahel station in Ndiaye, Senegal. Based on this, a model (RIDEV) was developed by Dingkuhn et al. (1995) to estimate duration and sterility for multiple rice varieties in the Sahel as a function of sowing date. Until now, it has been used by the operational services. However, differences between crop cycles observed in farmers' fields and assessed by RIDEV have been reported. This could be explained either by model deficiencies, varietal evolution and/or climatic changes. Presently in Ndiaye (coastal-semi-arid) and Fanaye (continental-semi-arid), 10 strongly contrasting rice varieties are grown year-around in monthly-staggered planting dates in order to determine duration, leaf appearance rate and sterility under current climatic conditions. Those varieties include some of the formerly observed genotypes as well as heat- and cold-tolerant reference varieties. Results will be used to improve RIDEV thus allowing for predictions of crop responses to climate change. Preliminary results with a focus on derivation of photo-thermal constants will be presented for the first completed year and compared to results from former years. (Texte intégral

Policies to favour crop intensification and farm income under climatic risk in West Africa. [P-3330-32]

In West African countries, agricultural production per capita has decreased over the past half century. With continued population growth and the diminishing availability of marginal arable land, pressure on land is rapidly increasing and there is now a common view that crop yield must be increased in this region, especially as there is a wide gap between actual and potential yields. Although there are several factors which may explain this yield gap, the fact that agricultural production takes place in resource-constrained farm households exposed to risk is widely recognized as being important. Indeed, risk discourages the adoption of high-risk, high-return agricultural technologies, which in turn impedes the improvement of yields. In order to assess how climatic risk constrains intensification strategy in West Africa, we built and calibrated a bioeconomic farm simulation model predicting the choice to intensify crops or livestock as depending on the availability of key policies in the economic environment of farms, for typical cases in the groundnut basin of Senegal. These cases include two regions contrasted in terms of rainfall (Sine and Saloum) and in each region two typical farms, representing poor and less poor farmers. The model features uncertainty in weather (hence yields) and crop prices, farmer's risk aversion, nine cropping systems representing millet, maize and groundnut with various intensification levels, and the main interactions between crop and livestock: draught animal power, the feeding of animals with suitable crop products (groundnut haulms, cereal straw) and the production of farm manure. Farmers are constraint by land, labour, cash and credit availability. 180 households were surveyed to build the socio-demographic and economic dataset used by the model, and agronomic data were collected from 206 fields. These key policies analysed are (i) weather index insurances against drought impact on crop yields, either subsidised or not, (ii) subsidies to short term credit for purchasing farm inputs, (iii) subsidies to fertilizer, and (iv) direct payments to farmers. In our simulations, under the current climate and prices of agricultural products and inputs, all these policies appear favourable to the increase of farmers' expected utility for typical farms representing the vast majority of farms in the groundnut basin. Apart for insurance, all of them appear also favourable to intensification of coupled crop and livestock activities for those typical farms. Insurance appears favourable to this intensification strategy only for farms located in the northern part of the region studied, where climatic risk is higher. Among the scenario tested, for most typical farms, combining unsubsidized insurance with subsidized credit appeared as the best use of a given amount of public funds in support of crop intensification: subsidized credit allows the farmers to buy costly inputs while insurance reduces the risk that a drought prevents them from reimbursing the credit. Direct payments also rank high in this respect, because they efficiently mitigate the cash constraint. The amount of subsidies required to obtain a given increase of the value of farm production varies across farm types and subzones in the region, but is relatively reasonable. These results suggest that crop intensification is currently relatively close to becoming a relevant option for farmers and that public policies may favour it by improving the economic environment of farms. (Texte intégral

Can legume crop residues contribute to sustainable intensification of rainfed rice production in Madagascar?

Rainfed agriculture on smallholder farms across the tropics is crucial for food security and livelihoods when availability of irrigated land is limited. Coarse-textured soils with low organic carbon and poor inherent fertility prevail in these systems (Tittonell and Giller,2013). In the absence of sufficiently remunerative market, small holders cannot afford mineral fertilizers so that nutrient inputs are generally limited to manure. Integrated soil fertility management, e.g. integration of legumes combined with additional supply of mineral fertilizers, is required to sustainably increase rainfed agriculture productivity (Vanlauwe et al. 2014). In Madagascar, most small holders do not use mineral fertilizer under rainfed agriculture. Incorporation of Nitrogen (N) rich crop residues could increase nutrient supply and improve N use efficiency(Aggarwal et al.,1997). Nutrient supply from residues is a complex process related to decomposition rates of residue, which is impacted by residue type and climate variability, e.g increased temperatures can accelerate residue decomposition while intense rainfall can increase the loss of the precious mineralized N through leaching. The potential contribution of N rich crop residues to increase staple crop productivity is therefore complex to anticipate. Soil-crop models can account for such complexity. This study aims at(i) calibrating the STICS crop model for rice yield modeling in the smallholder context of cool humid uplands in Madagascar and (ii) use the model to explore the effect of incorporation of rice and legume residues for low (25kgN ha-1) and high (160kg N ha-1) fertilizer inputs with a variable climate. The soil-crop model STICS (Brisson et al., 2003) was chosen for its capacity to account for soil water and nutrient dynamics during crop cycle for various climates and crop management. Rice experiments (cultivar NERICA 4) carried out in 2016-2017 and 2017-2018 cropping season in Ivory(19°33'S, 46°24'E, 950 m a.s.l)on Ferral sols were used for model calibration and testing. Two previous crops were compared: (i) rice and (ii)Mucuna cochinchinensis-Crotalaria spectabilis intercropping, combined with two levels of nutrient input, i.e. manure only (25kgN ha-1) or manure and mineral fertilizer (160kg N ha-1). Residues were incorporated at plowing. Measured data include rice phenology, above ground biomass and plant N, grain yield and in-season soil moisture and soil N. The calibrated STICS model reproduced adequately rainfed rice emergence, flowering and maturity, with on average an error of less than four days. Simulated in-season soil N and rice biomass agreed with the observations with a relative Root Mean Square Error from 33% to 36% (see Figure 1for rice residues with high N input treatment). The model could reproduce the additional mineral N supply and plant uptake associated with the incorporation of N rich legume residue for the two fertilizer treatments. Calibration for grain yield and scenario analysis using historical climate (1980-2010) are on-going and will allow to determine the profitability and risk associated with the different simulated options. This study will contribute to gain new insights on the relevancy of legume residue for sustainable intensification of cropping systems in a tropical smallholder context