Targeting rural development interventions : empirical agent-based modeling in Nigerien villages

International audienceThe aim of this article is to analyze the impact of development interventions on the population of three Nigerien villages that differ in terms of their agro-ecological, social and economic characteristics. This is performed by simulating the behavior of individuals in an agent-based modeling framework which integrates the village characteristics as well as the family internal rules that condition access to economic and production activities. Villagers are differentiated according to the social and agro-ecological constraints they are subjected to. Two development project interventions are simulated, assuming no land scarcity: increasing the availability of inorganic fertilizers for farmers and an inventory credit technique based on millet grain. Two distinct approaches were used to model the rationale of farmers' decision making: gains or losses in economic value or gains or losses in within-village ''reputation''. Our results show that village populations do not respond en masse to development interventions. Reputation has little effect on the population behavior and should be considered more as a local proxy for wealth amongst villagers, suggesting the monetization of these societies. Populations involve themselves in the two simulated development interventions only at sites where savings are possible. Some level of household food security and investment capacity is actually required to take part in the development interventions, which are largely conditioned by family manpower and size. As long as uncultivated land remains available in the village territory, support for inorganic fertilizers has little impact in the absence of any intensification process. Inventory credit engages a maximum of 25% of the population at the site with medium agro-ecological conditions. Therefore, both interventions should be viewed as a potential support tool for a limited part of the population capable of going beyond the survival level, but not as a generic poverty-alleviation panacea

Benchmarking humanitarian support : empirical agent-based modeling of development action types in Nigerian villages

International audienceThe purpose of this article is to simulate and analyze the impacts of development interventions on the population of three different sites in Sahelian millet-cropping Niger (Sahelian Africa), taking account the differentiation of social and agro-ecological constraints on the different types of villagers. The work is based on a previous article (Saqalli, 2006), which has shown that using an individual Agent-based model (ABM) is a relevant approach to integrate agro-ecological, social and economic characteristics of a system and that family internal rules have strong impacts on village and environment evolutions. Two development project interventions are simulated in a context of no land scarcity: inorganic fertilizers availability for farmers and an inventory credit technique based on millet yields that some villagers may choose to use. Two rationalities are tested, one upon economic values and the second upon the intra-village "reputation" gains. Our results illustrate that a village cannot be considered as a whole and project operators must take in account the precise target population rather than all adult villagers. Project involvements concern only sites where savings for securization or intensification are possible: These proposals need actually some food security and investment capacities that are largely conditioned by family manpower and size. Inorganic fertilizers have little success without any intensification process in a context of good land availability. Inventory credit intervention engages a maximum of 25% of the population in the site with medium agro-ecological conditions. Reputation has little effect on the population behavior and should be considered more as a local wealth estimation factor between villagers. Therefore, one should consider these proposals as a potential support tool for a limited part of the population capable to go beyond the survival level,but not as a global poverty-alleviation panacea

Testing Social-driven Forces on the Evolution of Sahelian Rural Systems: A Combined Agent-based Modeling and Anthropological Approach

International audienceThis article presents the results of a methodology combining an extensive fieldwork, a formalization of field-based individual rules and norms into an agent-based model and the implementation of scenarios analyzing the effects of social and agro-ecological constraints on rural farmers through the study of three different sites in Nigerien Sahel. Two family transition processes are here tested, following field observations and literature-based hypotheses: family organizations can evolve between a patriarchal mode and a non-cooperative one because of family income redistribution tensions. Family inheritance systems can shift between a "customary" mode and a "local Muslim" one through family land availability tensions. Our results show that both agro-ecological and socio-economic characteristics determine the simulated family type distribution and consequently the allocation of resources. Results from simulations with no evolution processes show that villages specialize themselves on different economic activities according to natural resources: An intensification gradient is observed from the most favored site, with more local productions and improved ecological indicators, to the less-favored one, with a growing proportion of the population wealth coming from migration remittances and "off-shore" livestock. Once introducing such processes, the differentiation also occurs within the population level, subdividing it into specializing groups according to their size, their assets and their social status. Emerging individualistic family types increase the village populations' robustness through different and site-specific evolutions

Reconstituting family transitions of Sahelian western Niger 1950-2000 : an agent-based modelling approach in a low data context

International audienceThis research analyses the impacts of the family organization on the diversity of income sources and the sustainability and the dynamics of rainfed farming systems of Sahelian Niger, through an individual-centred agent-based model which variables were defined through anthropological investigation. Results show that family organisation has strong effects on wealth levels and distribution and on demographic growth. They also suggest a historic shift from the patriarchal mode to a mono-nuclear mode in the 70's in this specific area, due to a higher resilience of the latter thanks to a broader diversification and a better adequacy between wealth and family demograph

Extent and Severity of Wind Erosion in West and Central Africa

The West African Sahel (WAS) is the transition zone between the Sahara desert in the north of Africa and the more humid Sudanian zones in the south. Although diverse in many ways, the WAS countries have in common a fragile agricultural sector, brought about by poor soil, limited rainfall, frequent drought, and wind erosion that accelerates soil degradation and desertification, compounded by rapidly' growing populations. Erosive winds '"occur during two distinct seasons. During the dry season (October- April) the region is invaded by strong northeasterly winds, known as harmattan, resulting in moderate wind erosion. The second and most important wind-erosion period is the early rainy season (May-July), when rainfall comes with heavy thunderstorms . that move westward through the Sahel. Wind erosion can be controlled by soil cover, such as a mulch of crop residue, soil roughening, and the reduction of wind speed by annual or perennial grass barriers, artificial barriers, strip cropping, and windbreaks. Based on the strong relationship between the incidence of wind erosion and soil properties, it may be possible to map the incidence of potential wind erosion in the West African Sahel, and hence tell farmers where ameliorative measures can be used to best advantage

Pearl millet growth on an erosion-affected soil in the sahel

The residual effects of three years’ mulch application and the associated erosion processes, such as soil loss or deposition, on pearl millet (Pennisetum glaucum) growth have been investigated on a Sahelian sandy soil in field and pot studies. The smallest millet yields were found on unmulched eroded plots despite mineral phosphorus (P) applications, whereas stover mulching or manure and urine consistently resulted in larger yields. Bioassays revealed that aluminium (Al) by itself was not growth-limiting. Neither nematodes nor lack of micronutrients contributed to the small millet yields. On soil from eroded plots, millet dry matter yield tripled after P addition, and increased by a factor of 13.5 when additional nitrogen (N) was applied. High P availability was found to be the key to reversing decline in yields on erosion-affected fields, but the addition of organic material is a prerequisite to prevent acidification.Manure was more effective than straw because of the large amounts of N and P it contained. The addition of small quantities of lime (CaCO3) may partly compensate for organic matter addition by increasing soil pH and reducing P fixation. P-Bray was not a suitable indicator of plant available P on degraded sandy acid soil

Toward farm specific recommendations for the use of mineral fertilizers in sahelian crop-livestock systems

Low soil fertility is recognized as the major constraint to rainfed cereal production in the Sahel. Given that most farmers can not afford enough fertilizer to cover all their fields, it is important to fine-tune the recommendations to maximize the fertilizer economic return at farm level while minimizing economic risks linked to climate fluctuations. This study was designed to help draw site/year/farm specific recommendations regarding hill placed application of mineral fertilizer either combined or not with organic amendments. A three year, multi-factorial experiment was conducted on-farm on three sites from 2003 to 2005 to test the effect of hill-placed application of small doses of DAP fertilizers on three pearl millet (Pennisetum glaucum (L.) R. Br.) genotypes for a range of organic amendments. Results showed a consistent grain yield increase due to fertilizer application for the no-manure plots on 2 sites, the fertility level of the third site being good enough to mask to effect of mineral fertilizer with the exception of 2004, marked by an early drought. In normal conditions, no synergism was detected between organic and mineral fertilizer. However it became apparent in the case of re-sowing or late sowing with a larger effect of mineral fertilizer on manure plots

Wind Erosion Research in Niger: The Experience of ICRISAT and Advanced Research Organizations

In the Sahelian zone of Niger, wind erosion constitutes one, of the major causes of land degradation. This results from low vegetation cover at a time when the most erosive winds are blowing in combination with sandy; easily erodible soils. Through their effect on soil cover, overgrazing by cattle and the rapid expansion of agricultural land have further enhanced the impact of wind erosion on the Sahelian agro-ecosystem. Wind-erosion-induced damage includes direct damage to crops through sandblasting, seedling burial following sand deposition, and topsoil loss..

SAFE - a Tool for Assessing the Sustainability of Agricultural Systems: an Illustration

SAFE (Framework for Assessing Sustainability levels) is a tool for evaluating the sustainability of agricultural systems and uses a hierarchical framework populated with indicators objectively selected by multicriteria evaluation. Indicators are measured at field, farm and landscape scales and progressively integrated into a global sustainability index (SI). SAFE is illustrated below with results on a field scale from a farm site

Effects of livestock grazing on physical and chemical properties of sandy soils in Sahelian rangelands

The effects of 4 years grazing by sheep and goats at various stocking rates on soil surface features, bulk density, organic C, N and P contents and pH were investigated in Sadoré, Niger. Studies were also conducted in a fallow subjected to 9 years of intensive grazing. Although grazing reduced (P<0.001) and fragmented the area of crusted soil, the infiltration index increased with moderate grazing, and decreased at high stocking rates. The bulk density of topsoil was lower under shrub canopy but remained unchanged in deeper horizons. Organic C, N and P contents, water infiltration and biological activity were greater in soils sheltered by shrubs than in bare soil. On the site intensively grazed for 9 years, P content was lower and N and organic C contents higher than after 4 years under controlled grazing. Compaction occurred only in the topsoil beneath shrub canopy and vegetated patches under intensive grazing