Conservation Agriculture

On-farm CA experiment, Zambia.png

For smallholder farmers in Africa?

Conservation Agriculture (CA) has dominated debates on agricultural development policy in Africa for over a 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. At the same time, however, there are numerous reports on low and slow uptake by of CA by smallholder farmers. 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 Conservation Agriculture promotion is often combined with input support, the assessment of its success is difficult. Is Conservation Agriculture 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 Conservation Agriculture when input support is discontinued? These are pertinent questions when assessing smallholder farmer’s use of Conservation Agriculture practices.

Evidence from the field also suggests that the core principles of Conservation Agriculture (see also 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, there is aneed to identify what Conservation Agriculture practices suit where, and whether applying them makes sense for farmers.


Constraints for Conservation Agriculture uptake manifest themselves at the field, farm-, and farming system-level, as well as in the wider socio-economic (and policy) context. If you are interested to read more on the suitability, promotion, uptake and impacts of Conservation Agriculture in African smallholder farming, the following papers may be of interest:

On the poverty impacts of CA with herbicides (farming system level)

Bouwman, T.I., Andersson J.A., Giller, K.E. (2020) Herbicide Induced Hunger? Conservation Agriculture, Ganyu Labour and Rural Poverty in Central Malawi. Journal of Development Studies 57(2): 244-63. Herbicide use is increasing in sub-Saharan Africa, and often promoted to enable CA. While there are concerns about the health and environmental risks of herbcides, their socio-economic implications have been largely ignored. In rural Malawi, weeding other people’s fields is a major coping strategy during the hunger season/growing season. We find that where CA promotion incentivised herbicide use, herbicides became common and substituted much of this casual labour. While herbicides mainly benefited the better-off who could afford them, these benefits occurred at the expense of the poor and food insecure. This study thus demonstrates the danger of neglecting the social equity implications of technology promotion – a lesson pertinent to the sustainable intensification agenda, including the promotion of CA.

On CA uptake and the policy context of CA promotion

Andersson, J.A. and D'Souza, S. (2014) From adoption claims to understanding farmers and contexts: A review of Conservation Agriculture (CA) adoption among smallholder farmers in southern Africa. Agriculture, Ecosystems and Environment 187: 116–132. -- This review of CA adoption among smallholder farmers in southern Africa analyses the historical background of the upsurge in CA promotion, the various definitions of CA that have emerged, the barriers to its adoption, as well as uptake figures and adoption studies. It shows that different definitions of what constitutes CA complicates the assessment of its adoption and casts doubts on the validity of CA adoption figures. Current CA adoption studies are methodologically weak as they are often biased by the promotional project context in which are carried out.

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, pp. 22-46. Routledge, London. -- This book chapter investigates the promotion of 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.

On CA at the farming system and policy-level

Bouwman, T.I., Andersson J.A., Giller, K.E. (2021). Adapting yet not adopting? Conservation agriculture in Central Malawi. Agriculture, Ecosystems and Environment 307:107224. -- This study, which focuses on areas considered to have a relatively high uptake of CA, investigates how smallholder farmers have adapted CA in their farming practice. It reveals that the CA principles are hardly practiced as intended by its promoters. For instance, most farmers added large volumes of crop residues to their CA plots to suppress weeds. This practice severely restricts not only the size of CA plots, but also CA’s scalability in smallholder farming systems. CA did not seem to provide substantial benefits for overall farm productivity, labour-savings or soil conservation.

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): 393-412. -- The promotion of CA 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 pre-disposed towards extensification rather than intensification. It is suggested that the widespread adoption of CA is therefore unlikely.

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 31: 657. -- This analysis of some 26 long-term studies on CA 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 CA 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 132:117-128. -- 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 104 (1):188-198. -- 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 CA 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 key issues for research on CA 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(3):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’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 CA in Africa, including an internet debate on: