Conservation agriculture and smallholder farming in Africa: The heretics’ view

Abstract

Conservation agriculture is claimed to be a panacea for the problems of poor agricultural productivity and soil degradation in sub-Saharan Africa (SSA). It is actively promoted by international research and development organisations, with such strong advocacy that critical debate is stifled. Claims for the potential of CA in Africa are based on widespread adoption in the Americas, where the effects of tillage were replaced by heavy dependence on herbicides and fertilizers. CA is said to increase yields, to reduce labour requirements, improve soil fertility and reduce erosion. Yet empirical evidence is not clear and consistent on many of these points nor is it always clear which of the principles of CA contribute to the desired effects. Although cases can be found where such claims are supported there are equally convincing scientific reports that contradict these claims. Concerns include decreased yields often observed with CA, increased labour requirements when herbicides are not used, an important gender shift of the labour burden to women and a lack of mulch due to poor productivity and due to the priority given to feeding of livestock with crop residues. Despite the publicity claiming widespread adoption of CA, the available evidence suggests virtually no uptake of CA in most SSA countries, with only small groups of adopters in South Africa, Ghana and Zambia. We conclude that there is an urgent need for critical assessment under which ecological and socio-economic conditions CA is best suited for smallholder farming in SSA. Critical constraints to adoption appear to be competing uses for crop residues, increased labour demand for weeding, and lack of access to, and use of external inputs.

Introduction

Conservation agriculture (CA) is proposed as a panacea to agricultural problems in smallholder farming systems in the tropics (Hebblethwaite et al., 1996, Steiner et al., 1998, Fowler and Rockström, 2001, Derpsch, 2003, Hobbs, 2007, Hobbs et al., 2008). It specifically aims to address the problems of soil degradation resulting from agricultural practices that deplete the organic matter and nutrient content of the soil and, moreover, it purports to address the problem of intensive labour requirements in smallholder agriculture (African Conservation Tillage Network, 2008). Proponents of CA suggest that it offers a solution to these problems by providing “the means that can prevent further destruction of precious soils, increase rainwater use efficiency and labour productivity, thereby ensuring higher and more stable yields while […] reduc[ing] production costs”. Given the continuing poor-productivity of smallholder agriculture in sub-Saharan Africa (SSA), and the alarming reports of soil degradation due to nutrient depletion and soil erosion (Stoorvogel and Smaling, 1998, Drechsel et al., 2001) CA appears to offer great potential to address these problems.

Zero-tillage was born out of a necessity to combat soil degradation and has been widely adopted by farmers of different scale in North and South America (Bolliger et al., 2006, Triplett and Warren, 2008). Brazil's “Zero-tillage revolution”, in particular, is viewed as an attractive potential solution to reversing soil degradation and increasing land productivity in SSA (Fowler and Rockström, 2001, Hobbs, 2007). Zero-tillage, together with crop residue management (mulches) and crop rotation are the pillars of CA as it is now actively promoted by a growing number of research and extension programmes, supported by major international initiatives (e.g. FAO – Benites and Ashburner, 2003, FAO, 2008a; the Direct-sowing, Mulch-based, Conservation agriculture (DMC) – systems initiative under the Global Forum on Agricultural Research (GFAR), the European Conservation Agriculture Federation (ECAF), etc.). Yet, apart from a few recent articles (Erenstein, 2002, Erenstein, 2003, Bolliger et al., 2006, Knowler and Bradshaw, 2007, Affholder et al., 2008, Lahmar, 2009), it appears that CA has escaped critical analysis. The more critical publications (Bolliger et al., 2006, Bolliger, 2007, Gowing and Palmer, 2008) address pertinent issues such as: (a) Which principles of CA, and under which conditions, actually contribute to the effects sought?; (b) What are the trade-offs of implementing CA?; (c) Does CA addresses a need identified by the farmer or one mainly identified by scientists and policymakers?; and (d) Do the preconditions for adoption by smallholder farmers exist in SSA?

In our work that addresses problems of soil fertility and productivity of smallholder farmers in SSA we often see that options for soil management that show great promise under controlled experimental conditions gain little foothold in practice (Tittonell et al., 2008). Most often this is not due to technical problems of the new options. More commonly the lack of uptake occurs because farmers are constrained in resources, such that investment in a new technology not only influences what must be done in one field, but involves trade-offs with other activities from which the farmers generate their livelihood (Benoit-Cattin et al., 1991, Scoones, 2001, Giller et al., 2006). Key resources that are constrained are land, labour at key periods during the cropping cycle, feed for livestock, manure for soil amendment, money to invest in external inputs, and lack of markets for produce.

Conservation agriculture is commonly regarded as appropriate for a wide range of smallholder conditions (FAO, 2008a, FAO, 2008b), but often this assumption goes without rigorous evaluation or detailed testing. The recent FAO (2008a) framework for action on CA states that “The plough has become the symbol of agriculture and many, including farmers, extension agents, researchers, university professors and politicians have difficulty in accepting that agriculture is possible without tillage.” We do not doubt that agriculture is possible without tillage, yet when we question whether CA is the best approach, or whether the suitability of CA in a given setting has been established, the reactions are often defensive. It seems as if we assume the role of the heretic – the heathen or unbeliever – who dares to question the doctrine of the established view.

In this article we first consider the diverse benefits and claims concerning CA to explore possible constraints that may assist us in understanding when and where CA is most likely to provide substantial benefits. Second we discuss the issue of which farmers, in which settings are likely to be able to make most use of CA approaches to assist in targeting of CA initiatives in African smallholder agriculture. In addressing these questions we aim to enrich the debate around CA and smallholder agriculture to assist in identification of ‘windows of opportunity’ in space and time to which efforts on CA could be focused.