Moving toward a sustainable green revolution in sub-Saharan Africa
Written by: Keijiro Otsuka, T. S. Jayne, Yukichi Mano, Kazushi Takahashi
Sub-Saharan Africa struggles to achieve a sustainable green revolution, with cereal yields far behind other regions. This blog highlights the need for integrated soil fertility management, improved cultivation practices, and tailored strategies for maize and rice. It underscores the importance of investing in adaptive research and extension systems to boost productivity, ensure food security, and build resilience to climate challenges.
Much of the developing world has now benefited from a ‘green revolution’ with rapid growth in cereal yields. Yet sub-Saharan Africa (SSA) continues to lag behind. Cereal yields in SSA are far below all other regions of the world, and this yield gap is continually widening. Although cereal yields are not direct welfare indicators, they profoundly influence individual, household, and national welfare in agrarian societies.
International organisations supporting African development are in danger of losing sight of the primacy of sustainableagricultural productivity growthin transforming food systems in a way that achieves African governments’ key national development goals. Food systems cannot achieve food security or provide employment for a rapidly growing population unless the agricultural production base is productive and sustainable. To accomplish this, productivity-enhancing inputs and cultivation practices must be developed, adapted, and scaled up to meet Africa’s highly diverse agroecological and economic conditions. Improving productivity on existing farmland – rather than focusing on area expansion – is essential to food security and conserving the planet’s natural resources and diverse ecosystems.
Although the term ‘green revolution’ is strongly associated with increasing yields and productivity, the components of a sustainable green revolution have evolved over time. Sustainability and resilience are crucial, and climate change has further elevated their significance. And while fertiliser and improved seed varieties have always been associated with a green revolution, we argue that improved farm management will also be required in SSA to enable farmers to utilise these technologies profitably.
The challenges and key findings
A recent Viewpoint article in the journal Food Policy, written by the authors of this blog, synthesised evidence from a virtual special collection (VSC) of 25 Elsevier-published articles across agricultural economics, agronomy, and crop science, exploring the factors and challenges preventing a sustainable green revolution in SSA.
The article and VSC highlighted three major findings:
Achieving a sustainable green revolution in SSA requires consistent management practices
In 2020, maize and rice were SSA’s two most significant cereals in both production and consumption. Between 1980 and 2020, rice rose from fourth to second in terms of production value and from third to second in terms of consumption in SSA. While the importance of maize is widely understood, the extent to which rice has become a strategically important cereal remains underappreciated.
Different tactics are required to achieve a sustainable green revolution for each crop–and this necessity is also overlooked. Integrated soil fertility management (ISFM)–the use of both organic and inorganic fertilizers, improved fertilizer-responsive seeds, and other improved soil management practices–is integral to a sustainable green revolution in maize, while improved cultivation practices (such as bund construction and leveling of paddy fields) are needed for a sustainable green revolution in rice. Articles in the VSC demonstrate that adopting improved management practices in African settings enhances the effectiveness of inorganic fertilisers and improved seeds, increasing their benefits for farmers. As is shown in our Viewpoint paper, unsustainable production practices in SSA’s densely-populated areas are leading to yield-depressing soil degradation, further highlighting the importance of ISFM in maize production. Evidence also consistently shows that the adoption of improved cultivation practices increases rice yields appreciably. Yet, very few African farmers consistently use multiple ISFM and improved cultivation practices.
While the 2006 Abuja Declaration (signed by almost all African governments) resolved to increase fertiliser use on African farmers’ fields, subsequent implementation campaigns have done little to support greater ISFM use. In recent years, research has shown that farmers’ limited use of ISFM and improved cultivation practices has impeded their ability to achieve a sustainable green revolution. This evidence has arguably influenced the Africa Union’s current commitment to a continental African Fertilizer and Soil Health Initiative, which prioritises integrated soil fertility management and improved cultivation practices.
Increasing inorganic fertiliser use intensity in SSA is essential
Increasing the intensity of inorganic fertiliser use is crucial to achieve a sustainable green revolution in maize and rice. Nitrogen is the main limiting nutrient for cereal-crop performance across most areas in SSA. Indeed, inorganic fertiliser application is the primary approach of making nitrogen immediately available to plants. Nitrogen also enhances the production of biomass and other sources of organic matter that can augment soil quality. For this reason, raising the agronomic efficiency of nitrogen (AEN)–defined as the kilograms of additional grain harvested per kilogram of nitrogen applied to the field–is critical for achieving a sustainable green revolution.
Raising AEN can promote sustainable cereal productivity growth in several ways:
- Greater quantities of crops are produced per unit of nitrogen applied.
- Inorganic fertiliser becomes more profitable to use, thereby raising inorganic fertiliser demand among farmers.
- Enhanced farmer demand for fertilisers encourages greater private sector investment. ‘Last mile’ transaction costs in acquiring fertiliser can be high in SSA, so a denser spatial network of private fertiliser suppliers can reduce costs for farmers.
- Higher soil nitrogen levels from inorganic fertilizers make it more profitable for farmers to adopt soil fertility management practices, as the combined use of fertilizers and ISFM practices boosts yields more effectively than using either alone.
There is considerable evidence that low crop response to inorganic fertilisers has limited farmers’ commercial purchase of such fertilisers. A low yield response can occur due to factors such as insufficient levels of soil organic carbon, soil acidity, and untimely field operations. However, many causes of low AEN can be overcome by greater use of ISFM, which improves soil fertility.
Compared to maize, ISFM for rice poses fewer challenges because it is grown in submerged soil, which results in an increased supply of plant-available soil-nitrogen and phosphorous, and improved maintenance of soil organic matter. However, along with greater use of improved seeds and inorganic fertiliser, increased uptake of organic fertiliser is essential in achieving a sustainable green revolution, particularly for maize, in SSA.
Limitations in adaptive agricultural research, development, and extension systems thwart African farmers
The uptake of ISFM and improved cultivation practices and fertilisers in SSA is impeded by chronic low investment in on-the-ground adaptive agricultural research, development, and extension systems. Although international agricultural research organisations (notably CGIAR) have successfully generated agricultural technologies to improve livelihoods globally, it is widely recognised that local and national partners with detailed knowledge of local conditions are needed to adapt and scale-out technical innovations across Africa’s varied agro-ecological conditions. As such, strong national research, development, and extension partners on-the-ground are necessary.
The way forward
In light of these issues,how can SSA governments support their hundreds of millions of farmers in achieving a sustainable green revolution–especially in the face of climate change, soil degradation, and population growth?
While improved seeds and inorganic fertilisers are essential, they are insufficient on their own to sustainably enhance cereal crop productivity. Farmers also need consistent support to effectively adopt ISFM and improved cultivation practices.
Strengthen on-the-ground adaptive research, development, and extension services
Green revolution technology is management-intensive, and achieving more widespread and consistent use by smallholders requires much greater attention to overcoming management challenges. Best management practices, particularly for maize, will vary across agro-ecologies, elevations, soil type, market conditions, and household resources, as they are site-specific. Overcoming these challenges will require well-functioning, on-the-ground research, development, and extension programmes, which identify and disseminate new appropriate management practices. A recent Breakthrough Foundation study analyses opportunities for strengthening African national agricultural research and extension systems.
Differentiate priorities for maize and rice
The priorities and activities of research, development, and extension organisations differ between maize and rice. Articles in the VSC show that technologies and best IFSM practices for rice farming are well-established and similar, while there remains some debate about the best practices for maize.
Before large-scale extension is undertaken for maize, the priority is to conduct adaptive farming systems research in various ecosystem environments to establish best management practices. National agricultural research, development, and extension organisations will play a crucial role in identifying the appropriate location-specific maize farming systems, because the optimum mix of yield-enhancing technologies and improved cultivation practices can be highly site-specific.
Similar to maize farming, improved rice management practices are not widely adopted. However, the technologies needed to achieve a sustainable green revolution in rice farming are not site-specific, and the primary challenge involves disseminating information through strengthened extension programmes on improved cultivation practices to farmers in rice-producing areas of SSA. Research evidence shows that the application of improved cultivation practices, together with improved high-yielding varieties and inorganic fertilisers, can lead to rice yields in SSA comparable to the high levels seen in tropical Asia.
The current approach to maize among on-the-ground organisations in SSA is on research, development, and extension, while the focus on rice is primarily on extension. However, in the long-term, both crops will require continued attention in all three areas if they are to withstand continuous changes in environmental and economic conditions.
Photo: © Milu Muyanga