ROSA NL47 - Appendix 2: Achievements and limits of the green revolution

This article is an appendix of ROSA Zoom: "The Role of Agricultural Research for the Development of Sustainable Agriculture and Food Security in Sub-Saharan Africa" published in October 2013.

The most rapid advances in yields were obtained in the 1970s and 1980s thanks to the green revolution: international research centres (federated within the Consultative Group on International Agricultural Research – CGIAR) contributed extensively to disseminating agricultural techniques that made it possible to increase yields in many regions (by using improved varieties, chemical fertilizers, pesticides, irrigation and mechanization along with extension services).

The progress in average yields for the main food crops has been considerable (and constant) in Asia and Latin America in particular. However, this progress has been much less pronounced in sub-Saharan Africa. According to the World Bank’s 2008 World Development Report [1], average cereal yields rose by approximately 30% between 1960 and 2005 in sub-Saharan Africa while they increased by a factor of 2.5 in South Asia and Latin America and more than tripled in East Asia.

In addition, this increase in average yields hides differences within countries: it is above all farmers located in fertile areas with good rainfall (or efficient irrigation systems) that benefited from the green revolution. Even within these zones, we can see differences between farmers who initially had a large amount of capital allowing them to invest in inputs, and precarious farmers. The green revolution’s success has often been accompanied by land concentration and the eviction of the smallest farmers, also in conjunction with the spread of mechanization.

For African small holder farmers, it is difficult to adopt the green revolution’s classic improved production techniques based on significant cash investment in inputs (seed, fertilizer) because of farmers’ limited monetary capacities (even if a credit system were available) and above all because of the climate hazard that results in high risk of non-repayment in poor years.

In addition, this model of intensification based on the use of large quantities of synthetic chemical inputs (notably nitrogen and phosphate fertilizers) and intensive use of pesticides (insecticides, fungicides and more and more often herbicides) has negative consequences for the environment, surface water and even human health when pesticide residue on food exceeds certain thresholds. The excess fertilization results in the eutrophication of many coastal zones (such as the Gulf of Mexico) and lakes, and the pesticides are responsible for polluting water, sometimes with negative effects on biodiversity.

It also contributes to the increase in fossil energy consumption by agriculture and to the greenhouse effect. Ultimately, the agricultural production model based on fossil energy consumption and limited mineral reserves (notably phosphates) is doomed and will need to make the shift to a model that notably uses fewer inputs and less energy. This analysis comes up in the report of IAASTD, a collective expertise effort on the future of agronomic research worldwide (see Appendix 3).

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World Development Report 2008, World Bank Agriculture for Development