268 – Conservation agriculture in developing countries

Is “Conservation Agriculture” really a win-win for farmers and the environment? It reduces the losses of soil and nutrients from agricultural land, but are farmers who adopt it better off or worse off? In asking this, my focus is on developing countries, where soil erosion remains a serious problem.

Soil erosion reduces farmers’ livelihoods, but also causes off-farm damage, particularly to rivers, lakes and dams, and “Conservation Agriculture” has been promoted as a solution. A particular Conservation Agriculture (CA) package of three farming practices has been widely promoted in developing countries as a win-win option for farmers and the environment. It consists of zero tillage, retention of crop residues for soil cover (mulching), and rotation of cereal crops with legumes, which fix nitrogen and so increase soil fertility.

Something close to this package has been widely adopted in North America, South America and Australia, but its adoption by poor farmers in Africa and South Asia has generally been disappointing, despite years of active promotion by international organisations.

Does this mean that poor farmers can’t recognise a good thing when they see it, or is the problem that benefits of Conservation Agriculture to these farmers are not sufficient to outweigh the costs? Given the massive differences between small subsistence farms in southern Africa and large commercial farms in North America, we should be open to the possibility that a practice could be very attractive to one group of farmers but not the other.

Photo: Marc Corbeels

Photo: Marc Corbeels

In 2012 I was invited to review the evidence on the economics of Conservation Agriculture in Africa and South Asia, and to present my findings as part of a workshop on Conservation Agriculture held in Lincoln Nebraska that year.

Part of the motivation for the workshop was to try to address issues of controversy about Conservation Agriculture in developing countries. Some people had been critical of what they saw as promotion of CA as a silver bullet solution without sufficient consideration of circumstances where it did and didn’t work for farmers. Others hit back at these criticisms and defended CA as the best available option.

The workshop marshaled the evidence on various facets of CA. The results have recently been published in a special issue of the journal Agriculture, Ecosystems and Environment. All the papers can be accessed for free here.

Looking at past literature on the economics of CA for poor farmers, my co-authors and I found that there wasn’t all that much literature, but what there was tended to indicate that CA (or its components) should be economically attractive to small farmers. However, looking critically, little of this evidence was based on sophisticated analysis. Many of the economic models used seemed too simplistic to be reliable. 

So we set out to build a model of our own and apply it to a case study in northern Zimbabwe. Marc Corbeels from CIRAD joined the team, providing his data and extensive experience for the case study.

A key finding is that the farm-level economics of CA are highly case-specific. In some situations it is competitive with traditional agriculture, but in others it falls far behind. Organisations promoting CA need to be quite careful and discriminating about where it is actually a viable strategy if they are not to waste their own and farmers’ resources.

We didn’t find any scenarios where CA was substantially better than traditional agriculture. Where it was better, it was only slightly better, but where it was worse, it was sometimes dramatically worse. This would be important to farmers who are worried about risk.

CA tends to be more attractive for larger, wealthier farmers and to be much less profitable for the smallest, poorest farmers. No wonder many of them have been reluctant to adopt it.

There are several elements that can reduce the benefits of CA for small farmers. One is that zero tillage can increase the number of weeds in the crop. This either reduces crop yield or requires additional effort for weed control. A second factor is that some of the benefits take about a decade to kick in (increased yields from zero tillage combined with mulching). The poorest farmers might not be able to afford to look that far ahead when they make their farming decisions. Thirdly, crop residues may not be available for mulching. They may be harvested to feed to livestock, or in some cases farmers cannot keep other people’s cattle off their crop residues even if they want to. (The community doesn’t allow it, and there are no fences anyway.) Fourthly, legume crops may or may not be profitable enough to be worth including in the rotation. It depends on their yields and sale prices.

Some extension programs have emphasised the importance of farmers adopting all elements of the CA package. This is quite naive, as full adoption of farming packages rarely happens anywhere. Farmers almost always pick and choose the elements that they think will work for them, and leave the rest. We found that the economics tend to favour this approach in the case of CA – partial adoption tended to be more attractive than full adoption.

So, overall, this is one of those cases where the farm-level economics pose a barrier to changes that people would like to see, at least in some cases. There are good and bad ways to respond to this information. The bad ways include ignoring the information and continuing to promote CA in an untargeted way, or thinking that the adverse economics could be overcome by better or more intensive efforts to promote CA. The good ways include using the information to target CA promotion to situations where it is likely to be adoptable, and redoubling efforts to develop more appropriate soil conservation practices for situations where it is not. In some cases it might be feasible to subsidise CA to increase its uptake, but this won’t overcome adverse economics unless the subsidies can be maintained indefinitely. If they are to be maintained indefinitely, we would want to have confidence that the system will result in large enough reductions in the off-farm costs of soil erosion. 

Further reading

Pannell, D.J., Llewellyn, R.S. and Corbeels, M. (2014). The farm-level economics of conservation agriculture for resource-poor farmers, Agriculture, Ecosystems and Environment 187(1), 52-64. Journal web site (access to the paper is free) ◊ On-line video presentation ◊ IDEAS page for this paper


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