Agroecology-based aggradation-conservation agriculture (ABACO): Targeting innovations to combat soil degradation and food insecurity in semi-arid Africa
Highlights
► Farmers engage in co-innovation platforms to design and implement locally suited conservation agriculture (CA) practices. ► Agro-ecological principles and soil rehabilitation measures are put in practice to restore biomass productivity. ► Local knowledge and practices are central in the design of locally suitable CA practices. ► Suitability of CA interventions is evaluated across spatial and temporal scales through integrated model-based assessments. ► ABACO contributes to inform the development of policies that propend towards enabling contexts for smallholders.
Introduction
Poor soil fertility and land degradation are major limitations to food security in sub-Saharan Africa, placing many smallholder farmers in a vulnerable position. Rural poverty and the environment in developing countries have been linked as a ‘downward spiral’ by many, with population growth, economic marginalisation, and more recently climatic variability and change leading to environmental degradation (Scherr, 2000). The rural poor, and rural poor women even more so, who depend on agriculture for their livelihood and food security are particular vulnerable to such a downward spiral as they have limited access to inputs (e.g. fertilisers, irrigation) to improve soil productivity. These processes are particularly severe in semi-arid areas, where rainfall variability exacerbates crop failure risks and resource degradation, often forcing farmers to abandon their land or liquidate their assets to face unfavourable periods.
Conservation agriculture (CA) is increasingly promoted as an alternative to address soil degradation resulting from agricultural practices that deplete the organic matter and nutrient content of the soil, aiming at higher crop productivity with lower production costs (e.g. Kassam et al., 2009). In areas of climatic variability, CA may represent a low-investment strategy to increase water productivity and mitigate risks, by breaking the vicious cycle of low rainfall, poor yields, low investment and soil degradation. In spite of experimental evidence showing increased water productivity and crop yields under CA, its adoption by smallholder farmers in sub-Saharan Africa seems to be hampered by (Giller et al., 2009): (i) concerns on initial yield decreases often observed (or perceived) with CA; (ii) lack of sufficient biomass for effective mulching due to poor crop productivity or to competing uses for crop residues in crop-livestock systems; (iii) increased labour requirements when herbicides are not used, putting an extra burden on female labour for weeding; (iv) Lack of access to, and use of, external inputs such as mineral fertilisers and herbicides. A fundamental problem with the adoption of CA is its promotion as an indivisible package that farmers find hard to adopt in full, ignoring farmers’ participation in the design/selection of CA alternatives, overlooking the fact that the process through which innovation emerges are complex and non-linear (i.e., not as unidirectional research-extension-farmer flows).
It has become evident that conservation agriculture has to be tailored to local conditions to make it more suitable to resource-constrained smallholder farmers in sub-Saharan Africa (Giller et al., 2011). This is best done by collaborating with local smallholders, both male and female, improving their innovation capacity, sharing technological knowledge in co-innovation platforms, and overcoming adoption barriers through gender-sensitive technological solutions and supportive policy measures.
Section snippets
The ABACO initiative
An EU-funded1 project on agro-ecology based aggradation-conservation agriculture (ABACO, 2011–2014) for semi-arid regions emerged as a need for action
Aggradation-conservation agriculture in semiarid areas
The term ‘aggradation’ has been coined in physical geography to refer to the raise in grade or level of a river valley or a stream bed by depositing detritus or sediments. Aggradation is also used in soil physical chemistry to refer to the neo-formation of clay minerals, which is gradual, and the aggraded clays may have the same lattice than the original but not necessarily the same properties. Aggradation in forest ecology refers to the phase of re-colonisation of open spaces in forest after
Intensification of agroecological services and tradeoffs
Increasing agroecosystem primary productivity implies intensifying the basic agroecological functions of photosynthesis, water capture and nutrient cycling. ABACO seeks to enhance ecological functions and services through biodiversity management in order to increase resource use efficiency, reducing the need for external (synthetic) inputs. Diversification of the cropping system takes place through (i) use of intercrops (space) and cover crops or crop rotations (time) associated with the main
Co-innovation platforms: the Learning Centre
The emergence and diffusion of knowledge elements (technical, scientific) and their translation into production processes and practices describe feedback mechanisms and interactions between science, learning, policy and technology demand (Edquist, 1997). This opposes the traditional linear model of knowledge transfer in agriculture, the research-extension-farmer continuum, through which most technologies are promoted. The participation of farmers in technology development through action
Concluding remarks
The ABACO initiative places strong emphasis on local farmer selection and adaptation of CA technologies and principles. This does not guarantee that all technical, environmental and socio-economic constraints to CA in Africa would be automatically solved. The few examples of typical tradeoffs shown here, from the scale of the plot and the competition between associated species, to the village scale impact of crop residue allocation to mulching or livestock feeding, indicate that challenges are
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