Conservation Agriculture

For smallholder farmers in Africa?

Conservation Agriculture (CA) increasingly dominates debates on agricultural development policy in Africa. Over the past decade lots of (donor) money has been spent on the promotion of CA to smallholder farmers and often such interventions have been hailed as a success. Yet, we think there is need to question the emergent consensus on Conservation Agriculture in development policy. This page, which provides links to critical and dissenting analyses that tend to be ignored, explains why.

Identifying where Conservation Agriculture fits

As CA promotion is often combined with input support, the assessment of its success is difficult. Is CA uptake by resource poor farmers really caused by the benefits of the technologies promoted or are they the effect of the additional inputs provided? And how sustainable is the uptake of CA when input support is discontinued? These are pertinent questions that need to be addressed.

Evidence from the field also suggests that the core principles of Conservation Agriculture (see FAO),

(1) minimal soil disturbance (zero or reduced tillage)

(2) permanent soil cover provided by a growing crop and/or a mulch of organic residues

(3) diversification of crop species grown in sequence (crop rotation) and/or associations (intercropping) are often difficult to realize within African smallholder farming systems. Some practices can work in particular circumstances, others not. Rather than assuming the universal suitability of these principles or doing away with Conservation Agriculture altogether, we need to identify what CA practices suit where, and whether applying them makes sense for farmers.

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As the introductory video shows, constraints for CA uptake manifest themselves at the field-level, the farm and farming system-level, and the wider socio-economic (and policy) context.

If you are interested to read more on the suitability and promotion of CA in African smallholder farming, the following papers may be of interest.

On CA’s suitability in diverse African farming systems

Giller, K.E, E. Witter, M. Corbeels and P. Tittonell (2009) ‘Conservation agriculture and smallholder farming in Africa: The heretics’ view’, Field Crops Research 114(1): 23-34.

This review article questions the suitability of CA principles in diverse African smallholder farming systems. The article sparked-off the debate on Conservation Agriculture in Africa, including an internet debate on:

On key issues for research on Conservation Agriculture in Africa

Giller, K. E., M. Corbeels, J. Nyamangara, B. Triomphe, F. Affholder, E. Scopel, P. Tittonell (2011) A research agenda to explore the role of conservation agriculture in African smallholder farming systems. Field Crops Research 124, 468–472.

For various reasons, all of the CA principles are not always fully implemented by farmers and results not as favourable as expected. Constraints at field, farm, village land regional levels are discussed, as are trade-offs in the allocation of resources that determine how CA may fit into a given farming system. At each level, opportunities or difficulties emerge that enhance or impede development, adaptation and adoption of CA. The article provides suggestions on how research can targeted to determine whether CA is appropriate and to search for the best-fits for CA in smallholder farming systems.

On CA practices at field-level

Rusinamhodzi, L., M. Corbeels, M.T. van Wijk, M.C. Rufino, J. Nyamangara, K.E. Giller (2011) 'A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions’, Agronomy for Sustainable Development pp. 1-17

This analysis of some 26 long-term studies on Conservation Agriculture focuses on the effects of different CA practices (no-till, mulch, rotation and combinations thereof) on maize grain yield under rain-fed conditions. No immediate response in maize yield to Conservation Agriculture practices such as reduced and no-tillage where found, but when combined with rotation and high N input levels in low rainfall areas, yields increase.

Baudron, F., Tittonell, P., Corbeels, M., Letourmy, P., Giller, K.E. (2011) Comparative performance of conservation agriculture and current smallholder farming practices in semi-arid Zimbabwe.Field Crops Research, Elsevier.

This study compares the performance of CA with smallholder farming practice (which typically uses limited fertilization) during three consecutive seasons. Crop productivity was found to respond more to adequate fertilization and crop protection than to reduced tillage and mulching. CA was also found to 'shed' rather than harvest water, on the study area's soil crusting and compaction prone, coarse-textured soils.

On the performance of CA on smallholder fields of different soil fertility status

Guto, S.N., P. Pypers, B. Vanlauwe, N. de Ridder, K.E. Giller (2011) Socio-ecological niches for minimum tillage and crop-residue retention in continuous maize cropping systems in smallholder farms of Central Kenya. Agronomy Journal 103, 1-11.

Experimental research over four seasons on fields across soil fertility gradients on 16 smallholder farms showed marked differences in crop yields. On fields that were initially fertile neither mulch retention nor tillage had significant effects. Crop residue retention was beneficial on fields of moderate fertility. On degraded, poor fertility fields minimum tillage resulted in decreased yields while crop residue addition had no effect. The results highlight the problems of applying Conservation Agriculture where soils are degraded as there is insufficient mulch available and tillage helps to roughen the soil surface and encourage infiltration of rainwater, thus giving better yields.

On CA at the farming systems and policy-level

Baudron, F., J.A. Andersson, M. Corbeels and K.E. Giller (2012) ‘Failing to Yield? Ploughs, conservation agriculture and the problem of agricultural intensification An example from the Zambezi Valley, Zimbabwe’, Journal of Development Studies, 48(3), pp.393-412.

The promotion of Conservation Agriculture in many ways resembles earlier, colonial policy interventions aiming to intensify land-use in African smallholder farming. This article analyses policy models for agricultural intensification, illuminating why African smallholder farmers are often predisposed towards extensification rather than intensification. It is suggested that the widespread adoption of Conservation Agriculture is therefore unlikely.

On the socio-economic context of CA promotion (CA policy)

Andersson, J.A. and K.E. Giller (2012) On heretics and God’s blanket salesmen: Contested claims for Conservation Agriculture and the politics of its promotion in African smallholder farming, in: J. Sumberg and J. Thompson (eds) Contested Agronomy: Agricultural Research in a Changing World, (eds J. Sumberg & J. Thompson), pp. 22-46. Routledge, London.

This book chapter investigates the promotion of Conservation Agriculture (CA) for smallholder farmers in southern Africa and its apparent policy success, despite contestations regarding the suitability of specific CA technologies for smallholders’ farming systems.