Et demain l'agriculture? : options techniques et mesures politiques pour un developpement agricole durable en Afrique subsaharienne : cas du Cercle de Koutiala en zone sud du Mali

Global situation in Sub-Saharan countriesEconomic development in the Sub-Saharan countries is strongly linked to the agricultural sector, which constitutes the major part of gross national product (GNP) in most of these countries. However, agricultural productivity and production in the area are very low due to erratic rainfall and especially the low level of soil fertility (Penning de Vries & Djitèye, 199; van Keulen & Breman, 1990). Considered world-wide, it is one of the regions with the most unfavourable combination of low agricultural productivity and high population growth. The potential for economic development is limited, because of environmental, agro-technical, socio-economic and institutional constraints.Natural resource degradation is most directly linked to (Oldeman et al., 1991)practicing non-sustainable land use systems, particularly agricultural production techniques without application of mineral or organic fertilisers (24% of the crop land);over-exploitation of pasture (49% of the area);over-exploitation of woody resources (27% of the woody land).The most important single cause of degradation is the depletion of soil nutrients, including organic matter. Land degradation has serious consequences for agricultural productivity and production, and the availability of arable land. It has been estimated that the availability of arable land will decrease from the current 0.28 ha per capita to 0.17 ha in 2025 (WRI, 1990) and 0.15 ha in 2050 (FAO 1991)The situation in MaliThe economic situation in Mali is characterized by a low GNP per capita (around $270 per annum). The primary sector is the most important one, contributing 46% to GNP, mainly from arable farming and livestock activities (DNSI, 1992). More than 80 % of the work force is employed in the agricultural sector, which generates around 75% of the export revenues.Low soil fertility and degradation of natural resources are the most important constraints for agricultural development in Mali. For example, in Southern Mali, the value of the nutrients (at current fertilizer prices, based on replacement value) lost in traditional cropping systems has been estimated (van der Pol, 1992) at about half the value of the gross margin. Hence, a large part of farmers' income originates from soil depletion.The study area is the 'Cercle de Koutiala' in Southern Mali, with a total area of 9075 km 2and 286 244 inhabitants, i.e. a population density of about 31 per km 2(BCR, 1991). The Cercle de Koutiala is located at the border of the Soudano-Sahelian zone with monomodal rainfall at an average of 980 mm/year (Sivakumar et al. , 1984). Six main types of soils have been distinguished, with shallow gravelly soils, not suitable for arable farming, occupying the largest area (62%).Study objectives and methodologyThe specific objectives of the study are:definition of agricultural production techniques at different levels of sustainability;formulation and analysis of a scenario for sustainable agricultural development in the Cercle de Koutiala;exploration of the potentials and constraints for future land use in the Cercle de Koutiala, based on optimum natural resource management;analysis of the actual situation, including non-sustainable production techniques at farm household level;comparison between development options (in terms of production and land use) for situations with and without the possibilities for practicing non-sustainable production techniques;identification of policy measures to stimulate adoption of sustainable agricultural production techniques at farm household level.The research methodology is based on a systems-analysis approach, using linear programming at regional (aggregate) and farm (micro) level. Model structure and procedures are presented in Chapter 3. The different steps followed in the analysis of the results are:a scenario based on sustainable intensive agricultural production techniques is analysed with a regional model in Chapter 4 to explore the agricultural development perspective for the Cercle de Koutiala;results of the Farm Household Model, based on non-sustainable agricultural production techniques, are analysed in Chapter 5, with emphasis on the structure of production, (land use), the level of production and the degree of sustainability of the land use systems practiced by different household types;results at farm level have been aggregated to the regional level on the basis of the total number of different types of farm households in the region for comparison with the development perspectives under sustainable conditions;policy measures aiming at stimulating the adoption of sustainable technical options are defined, and their impact on farm household behaviour is analysed in Chapter 6;the influence of some policy measures on aggregate production of cereals at the regional level is analysed as well as its effect on market and price equilibrium.Sustainable production systemsThe basic question in the present study is: how to realise the transition from the current non-sustainable practices (associated with ' soil mining ' ) to sustainable intensive cropping systems? To answer that question, a sustainable agricultural development scenario has been defined, based on sustainable agricultural production techniques. For definition of those production techniques, sustainability has been operationalized as 'equilibrium of nutrient balances (including soil organic matter)' to avoid soil nutrient depletion. The resulting land use systems are characterized by strong integration of arable farming, animal husbandry and forestry. Sensitivity analyses have been carried out to analyse the effects of variation in 'level of sustainability' on the level of productivity of cropping systems. The scenario based on "absolutely (no soil nutrient depletion allowed)" sustainable intensive production techniques (SP1) results in the highest level of agricultural production and net revenue, despite higher expenditures on inputs, especially for chemical fertilizer. With increasing levels of soil nutrient depletion (application of 25, 50 and 75 % of the chemical fertilizer needed for equilibrium), productivity and net revenue decrease, the cultivated area increases (extensification), and net revenue per unit area and per capita decrease.Non-sustainable production systemsThe farm household model was applied to analyse the effects of the inclusion of non-sustainable production techniques on regional development. The results indicate large differences among farm household types in terms of agricultural productivity and farm management strategy. Farm household types were defined on the basis of access to resources and the degree of mechanisation (animal traction). When maximising net revenue and utility, the level of production and net revenue are appreciably higher for households of type A (well-endowed) than for those of types B and C (less endowed). Comparison of the results of the absolutely sustainable scenario (SP1) with those of scenario SB1 (actual situation) shows large differences in allocation of natural resources (land use), production and level of sustainability. Adoption of intensive, sustainable production techniques requires some major actions at farm household level:efficient land resource management, i.e. land use adapted to land qualities and suitability;integration of silviculture to satisfy wood requirements;intensification of livestock systems through introduction of high-quality supplementary feed. This leads to the conclusion that complementary policy measures are indispensable to stimulate adoption of sustainable and intensive technical production techniques.Policy measuresPolicy measures have been identified and their impact on farm household behaviour has been analysed using a farm household model. The policy measures considered include: price policy, market development policy, credit policy, natural resources management policy, and agricultural intensification policy. The policy measures could be classified in four main types on the basis of their effects on net revenue and sustainability level:policy measures having a strong positive effect on both net revenue and sustainability level;policy measures having a moderately positive effect on net revenue and sustainability level;policy measures having a moderately positive effect on net revenue and a negative effect on sustainability level;policy measures having a negative effect on both net revenue and sustainability level.Results indicate that several policy measures can have a strong effect on farm household behaviour. However, farm households vary strongly in their reactions to policy measures. Farm households of type A, for example, show an adoption rate of sustainable intensive production techniques of about 40% (expressed as the proportion of the area cultivated with these techniques) compared to 20% and 11% for types B and C, respectively. However, even when implementing the most effective policy measures, farm households generally combine non-sustainable and sustainable production techniques. The rate of adoption of sustainable intensive techniques strongly depends on their profitability. Hence, all policy measures that contribute to improved profitability of the alternative production techniques, by reducing their cost/benefit ratio, will stimulate increased rates of adoption at the farm household level. At the regional level, the most effective policy measures have a strong impact on development objectives through increasing the level of production and net revenue per ha and per capita. These policy measures also have a strong positive impact on the rate of adoption of sustainable and intensive production techniques at the farm household level. Some policy measures also induce changes in total production and hence in the demand/supply balance of cereals at the regional level. This may lead to price changes causing a new market equilibrium.The analyses of the effects of policy measures at farm household and regional level illustrate the potential role of such models in policy support in the macro-economic policy formulation process.From non-sustainability to strong sustainability: what are the possibilities for on-farm practices?The results from the regional model indicate that when sustainable intensive cropping systems are introduced, using high input levels, particularly of chemical fertilizers, high levels of production can be attained. However, such sustainable intensive systems cannot be adopted in the short term because of technical, socio-economic and institutional constraints. These constraints are mainly linked to availability of mineral fertilizers and profitability of their use.Therefore, what is required to realize the transition from the current non-sustainable practices to strong or absolute sustainability? Sustainable agricultural development requires at least a change in farm household behaviour by adopting sustainable and intensive production techniques.In the short and medium term, farm households can adapt by introducing improved, intensified forage production techniques (leguminous species), which will have a positive impact on soil fertility and livestock feed supply. For the long term, the results of the analysis of effects of policy measures have indicated that the rate of adoption of sustainable technologies can be increased through appropriate policy measures.Thus, a set of policy measures is necessary to stimulate introduction of sustainable agriculture practices at the farm level such as: increasing profitability of the use of mineral fertilizers, land improvement, improved land tenure regulations, decentralization of the responsibilities for implementation of development measures, coordination of development activities at regional level, stimulation of investments in rural areas, and of scientific and technical research oriented towards sustainable agricultural development.The Cercle de Koutiala is one of the regions in Mali with high agricultural potential, but agricultural production growth should not be realised on the basis of soil nutrient depletion, since that will trigger land degradation and environmental problems in the long term. Macro-economic policy measures are necessary to provide incentives to farm households to adopt sustainable and intensive production techniques. Only in that way will it be possible for the Cercle de Koutiala to maintain its important place in Mali's sustainable agricultural development process.