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What impact does promoting modern seed varieties among small farmers have on deforestation in Democratic Republic of Congo?

Improved agricultural technologies can help improve households’ well-being. However, do these potential gains have a negative effect on the environment? This is a vital question in the Congo Basin which is home to fragile populations and threatened by deforestation. To evaluate the environmental effects of a government policy supporting family farming, researchers at INRAE, the University of Bordeaux and the World Bank have conducted a large-scale experimental study. Their results show that the promotion of modern seed varieties did not lead to an increase in overall deforestation by small farmers. However, farmers cleared more primary forest and less secondary forest. These results show that, unless combined with interventions to maintain soil fertility, policies to promote modern seed varieties may come at the cost of important losses in biodiversity.

Published on 05 April 2023

illustration What impact does promoting modern seed varieties among small farmers have on deforestation in Democratic Republic of Congo?
© Margaux Vinez

Increasing productivity and income for smallholder farmers is often seen as a central part of the fight against poverty and hunger. To this end, substantial investments have been made in international agricultural research and, in particular, the development, adaptation, and promotion of modern seed varieties in combination with chemical fertilizers. The Green Revolution resulted in substantial increases in yields and overall production between 1960 and 2000 in Asia and Latin America, but it did not bring the same benefits to Sub-Saharan Africa where the diffusion of modern seed varieties remains limited to date, and agricultural yields lag far behind those in other regions.

The Congo River Basin forest is the second largest tropical forest in the world after the Amazon forest and is one of the world’s main biodiversity reserves and carbon sinks. It is also one of the poorest regions in the world, where fragile farming constitutes the main livelihood. Sylvie Lambert and Karen Macours, INRAE economists at the Paris-Jourdan School of Economics and their colleagues Tanguy Bernard from the University of Bordeaux and Margaux Vinez from the Word Bank studied a large government program that provided subsidies for improved seed varieties to small farmers in the Democratic Republic of Congo.

Does intensifying agriculture help preserve the environment?

The positive effect of the diffusion of modern seed varieties on the economic well-being of populations is now proven and it is also often considered to contribute to forest conservation. This issue is of high policy relevance as land use change is the second most important human-induced source of greenhouse gas emissions globally, tropical forests support at least two-thirds of the world’s biodiversity, and agricultural expansion is the most important cause of tropical deforestation and loss of biodiversity. The impact of introducing yield-enhancing technologies on deforestation in a given area is, however, theoretically ambiguous, because under certain conditions of the fertilizer and labour markets, farmers can be pushed to cultivate the richest soils, which can lead to new land conversion and new deforestation.

To shed light on this issue, the researchers conducted a randomized control trial to study the causal impact of modern seed variety diffusion on deforestation of the Democratic Republic of Congo (DRC). The study was carried out in a remote area where the input and output markets were very low. No chemical fertilizers are available for the region’s smallholder farmers. The study was based on a programme of subsidies for improved seed varieties of rice (short cycle), maize (high-yielding), groundnuts (high yielding) and cassava (disease resistant).

What is a randomized control trial?

Along the lines of clinical trials which have been used in medicine since the end of the 1940s, randomized control trials are an impact evaluation method used in economics to assess the effectiveness of public policies. This method is based on a random draw to form similar groups, including one which will play the role of ‘control’ in order to be compared to the test group(s) receiving the treatment whose impact is to be measured1.

The use of modern seed varieties by small farmers does not aggravate global deforestation, but primary forest is more affected by clearing

One of the contributions of this study is to show the importance of distinguishing between the deforestation of primary forest and secondary forest. Following international definitions, we define a primary forest as a forest with no observable traces of cultivation and a secondary forest as a forest that is more recent regrowth on land which has been previously cultivated. The distinction between these two types of forest is relevant because the deforestation of primary forest has major consequences on carbon storage and biodiversity. This distinction is also relevant to farmers’ decision-making.  Farmers know that cereals have higher soil nutrient requirements. Thus, when there are no mineral or organic fertilizers or soil conservation practices, farmers may decide the best option is to cultivate more fertile soils and shift toward the cultivation of land cleared from primary forest where soils are richer in nitrogen. On the other hand, in villages where farmers can obtain legume seeds which can fix nitrogen from the air (essentially groundnuts), the deforestation of primary forests was more limited. Thus the risk of deforestation of primary forest is likely to be sensitive to the type of seeds used.

By using plot-level data on land conversion combined with remote sensing data, the researchers found that promotion of modern seed varieties did not lead to an increase in overall deforestation, but that it did not reduce the land used for agriculture. The results of this research also show that subsidizing modern seed varieties led to an increase in the deforestation of primary forest by beneficiary households. The authors concluded that if policies to promote modern seed varieties are adopted alone, they may come at the cost of important losses in biodiversity.

This work contributes to current debates on sustainable intensification practices which aim at reducing the trade-offs between productivity and environment, avoiding combining the use of improved varieties and mineral fertilizers, and rather adopting context-specific responses, including organic fertilizers and alternative soil fertility management practices. If public policy makers seek to reach the dual goal of increasing productivity and preserving primary forest, increased access to modern seed varieties must be combined with promoting sustainable technologies and practices to maintain soil fertility or else focus on crops which are less demanding in terms of soil nutrients.


1 Jatteau A., 2019, https://doi.org/10.4000/philosophiascientiae.1933 


Bernard, T., Lambert, S., Macours, K., & Vinez, M. (2023). Impact of small farmers' access to improved seeds and deforestation in DR Congo. Nature Communications, 14(1), 1603. 


Sylvie Lambert research directorPjSE

Karen Macours research directorPjSE



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