After decades of perseverance, the term “soil health” was finally on the agenda for discussions on food and climate security by leaders of Africa earlier this year. The African Fertilizer and Soil Health Summit, held in Nairobi, Kenya, May 7–9, 2024, was attended by about 4,000 participants from Africa and elsewhere. Participants included 15 Heads of State, 57 ministers of agriculture and foreign affairs, and many private sector representatives, researchers and academicians, civil society leaders, farmer organizations, media, and others (Africa Union 2024a). Plenary lectures, presented primarily by Heads of State and ministers of agriculture, environment, or foreign affairs, repeatedly focused on the poor state of soil health in Africa and emphasized an urgent need for its restoration and sustainable management.
The event was encouraging and served as a promise for improved agriculture practices to achieve better food and climate security. Yet, the Summit was merely a first step toward the ultimate goal of (1) developing a plan of action for achieving food self-sufficiency in Africa, (2) adopting an agenda for achieving a soil-centric Green Revolution in Africa, (3) adapting these action plans for site-specific situations in diverse agro-ecoregions, and (4) developing a budget and identifying sources of funds, including contributions by each country, to support these action plans. Nevertheless, the Summit was a critically important first step in the long journey ahead. This article summarizes the salient points of the Summit and deliberates on what needs to be done to translate these discussions into specific action plans and develop a road map for transforming agriculture in Africa to achieve food and climate security.
SOIL DEGRADATION
The term “soil degradation” was a focal point of numerous presentations by policymakers from Africa. The slogan of the Summit was aptly designated “Listen to the Land.” The widespread problem of soil degradation in Africa, the principal determinant of low soil water availability, is the primary cause of low crop and livestock productivity and poor farming livelihoods (Diop et al. 2022). The extent and severity of soil degradation is attributed to the interactive effects of processes, factors, and causes of soil degradation (figure 1) that are mutually reinforcing and aggravated by societal needs. The process is often set in motion by the depletion of soil organic matter (SOM) content, a decline in soil structure, and crusting and compaction, which lead to water runoff and erosion by hydric processes in humid and subhumid regions and by aeolian processes in semiarid and arid regions. The problem of soil degradation, triggered by land misuse and soil mismanagement, is aggravated by multipliers such as nutrient mining, elemental imbalance, salinization, acidification extractive farming, and accelerated soil erosion (figure 2). The “Law of Return,” which states that everything taken from soil should be returned to it (Howard 1943), is rarely followed in Africa’s agro-ecosystems, which has aggravated the problem of nutrient mining on a continental scale. Therefore, the severe problem of soil degradation is due to not entirely natural factors but also anthropogenic factors.
Interactive effects of processes, factors, and causes of soil degradation in Africa.
Soil processes, biophysical factors, and human activities that alter soil functions.
Some examples of land misuse include deforestation to convert land for agricultural purposes through the use of heavy machinery designed for construction, followed by the burning of biomass and plowing that involves soil turnover and exposes bare soil surfaces to harsh tropical environments. These inappropriate methods of land use and land use change, especially on steeper slopes and in regions of intense rainfall, aggravate the problem of soil erosion by water in humid and subhumid regions (Mens et al. 2023) and by wind in semiarid and arid regions (Zhang et al. 2024). Soil suffers from the drought-flood syndrome, experiencing floods during the rainy season and drought during the dry season, thereby losing rainwater from runoff and evaporation. Land pressure, caused by a rapid increase in population, is among the major causes of nutrient depletion in Sub-Saharan Africa (SSA; defined as the zone south of the West African Sahel, East African Highlands, and Southern Africa) (Drechsel and Penning de Vries 2002).
Rather than pursuing deforestation to create land for agricultural use—a so-called “horizontal expansion”—SSA needs vertical growth in productivity from existing land under agro-ecosystems. This is accomplished by adopting proven practices of soil, water, and crop management and upscaling them through policies that reward farmers for generating specific ecosystem services (e.g., carbon sequestration in land-based sinks). However, what was missing in most plenary presentations during the Summit were examples of concrete and site-specific action plans with detailed road maps and timetables for adopting innovative options. Alas, also missing from the Summit were presentations on science-based management of soil health in Africa with examples of upscaling and panel discussions between scientists and policymakers on how to translate science into action in diverse eco-regions of Africa.
MANAGING SOIL HEALTH IN AFRICA
Improving soil water storage and increasing the availability of plant nutrients while controlling soil erosion are important to enhancing agronomic productivity. In soils of SSA, which have been subject to negative nutrient budgets for decades, restoring soil fertility is a high priority (Mateete et al. 2010; Dimkpa et al. 2023; Dugué et al. 2024). There is research available on the use of site-specific technology for nutrient management in small-scale, land-holder systems that promote biological nitrogen fixation (BNF) through using native resources such as phosphate rock, recycling organic materials, and improving use efficiency of mineral fertilizers. An approach to managing soil nutrients, called integrated soil fertility management (ISFM) (Vanlauwe et al. 2015), builds upon traditional knowledge with modern technologies to increase availability of mineral fertilizers to small land-holder farmers in SSA. One strategy for restoring soil fertility involves a series of components (Stewart et al. 2020): (1) strengthening inorganic fertilizer-based systems, (2) increasing access to and use of quality organic inputs, (3) strengthening capacity-building along the entire knowledge transfer value chain from scientist to farmer, and (4) strengthening farming systems research and development across biophysical and socioeconomic factors. The goal of this strategy is to combine fertilizer use with the adoption of conservation agriculture (CA), agroforestry (AF), and systems of water harvesting and recycling at farm scale, which are important for restoring soil and ecosystem resilience (Diop et al. 2022). Combining CA with drip irrigation can alleviate drought in addition to improving plant nutrient supply (Assefa et al. 2020). These scientific results on the effectiveness of modern innovations in managing soil health and improving practices were the focus of several workshops and symposia, organized as side events during the Summit.
The side events related specifically to soil health and its management were organized by development organizations (e.g., Food and Agricultural Organization, The Rockefeller Foundation, US State Department), CGIAR centers (e.g., International Food Policy Research Institute, International Institute of Tropical Agriculture, Center for International Forestry Research and World Agroforestry, International Fertilizer Development Center), and other international organizations (e.g., CABI, AGRA, Africa Plant Nutrition Institute). They covered topics such as actions taken after previous Summits, advancements in soil health monitoring, building fertilizer data sets, empowering women farmers, case studies in nature-positive fertilizer production, strengthening national soil information systems, and more (see the list of events in Africa Union [2024a]). The scientific information presented at these events was useful to agriculture in SSA. However, the events were conducted somewhat in silos, neither integrated among themselves nor with the keynote lectures presented in the plenary sessions. There was no link between the plenary sessions involving policymakers and the side events involving the scientific community. This obvious lack of interconnectivity was indeed a missed opportunity for policymakers and scientists to work together to translate the known science of soil health and its management into an action plan for improving agriculture in Africa.
Whereas the focus of many of the side events was on improving the rate of fertilizer use in Africa from 20-22 kg ha−1 at present to 50-60 kg ha−1 by 2034 (in ten years), the basic problem of managing soil health should have been given more emphasis. The use efficiency of fertilizer, which is low, especially for nitrogenous amendments, depends on the judicious management of soil quality or functions. Key components of soil quality include physical (structure, temperature, water retention and transmission, soil strength or compaction), chemical (pH, CEC, soil fertility, nutrient/elemental balance), biological (soil organic matter content, activity and species diversity of soil biota [macro, meso, and microorganisms, soil enzyme activity, microbial biomass carbon]), and ecological properties (nutrient cycling; coupled cycling of carbon with that of water, nitrogen, phosphorous, and sulfur; erosion processes; nutrient imbalance). Judicious management of these components of soil quality is critical to improving soil functions and ecosystem services, including nutrient use efficiency, productivity and nutritional quality of food, and water quality and renewability, and to making agriculture part of the solution to climate change.
Whereas the rate of fertilizer use in Africa must be increased, other components of managing soil health in Africa cannot be ignored. The integrated management of soil health (i.e., physical, chemical, biological, and ecological) is essential to improving the use efficiency of inputs while increasing agronomic productivity, leading to improvement in adequacy, nutritional quality, and safety of the food produced.
THE NAIROBI DECLARATION
Following in the tradition of the Abuja Summit and other meetings, this meeting announced the Nairobi Declaration. The Nairobi Declaration included thirteen commitments. However, there was some duplication (bullet points 7 and 8, and 10 and 11), and the actual number is eleven. Important among these to be achieved by 2034 are the following (Africa Union 2024b):
Triple domestic production and distribution of certified quality organic and inorganic fertilizers to improve access and affordability for smallholder farmers
Make available to at least 70% of smallholder farmers on the continent targeted agronomic recommendations for specific crops, soils, and climatic conditions to ensure greater efficiency and sustainable use of fertilizers
Formulating and implementing policies and regulations to create a conducive environment for fertilizer and soil health interventions
Developing and promoting systemic national capacity building for locally relevant fertilizer and soil health management practices and technologies
Promoting African solidarity through knowledge sharing, training, development, and transfer programs for best practices in soil fertility and soil health
Ensuring that at least 70% of smallholder farmers have access to quality extension and advisory services on fertilizer and soil health both from public and private extension systems
AN EXAMPLE ACTION PLAN AND THE SOURCES OF FUNDS
While the Declaration is a great starting point, the need for concrete action plans at multiple local and regional levels cannot be overemphasized. Well-designed policies are needed to reverse the trend of nutrient mining in SSA, reward farmers who adopt conservation-effective measures, and promote sustainable management of soil and agriculture on a long-term basis (Henao and Baanante 2006). Road maps identifying a five-year action plan with specific deliverables and expected outputs should be developed at the farm, district/county, state, biome/watershed, country, eco-regional, and continental levels.
An example road map at the continental level, which may be adapted and developed for different countries, is outlined in table 1. It is recommended that funds come from the following sources: 50% from the country implementing it, 25% from the private sector (e.g., companies producing fertilizers, agricultural machinery, irrigation equipment, improved seed or varieties, food processing and storage), 15% from development organizations and NGOs, and 10% from consumers. The general public—the consumers—must play an active role and show commitment to bringing about this long-awaited and much-needed transformation.
Example road map for Sub-Saharan Africa on a continental scale.
MAKING AFRICA THE BREAD-BASKET OF THE WORLD
Africa is endowed with a broad range of soils, climates, and growing seasons suitable for cultivating diverse crops, raising livestock, establishing plantations of fruits, and producing industrial crops (e.g., coffee, tea, oil palms, olive, cocoa, rubber, and medicinal plants). There are also raw materials available for the production of fertilizers, soil amendments, and pest control options. What is needed to transform Africa’s agricultural practices is political willpower to translate science into action through policies that are pro-nature, pro-agriculture, and pro-farmers. CA in Africa must move from concept to performance, with measurable steps to achieve specific ecosystem services (Cordeau 2024), such as food and climate security. Policymakers must work closely with the private sector to promote science-based agriculture. By doing so, Africa, and SSA specifically, can become an example of agrarian revolution. There are already pockets of such transformation in the Accra Plains and East Africa. Yet, the Green Revolution in Africa must be soil-centric, eco-efficient, and science-driven, with recarbonization of the terrestrial biosphere (i.e., carbon storage in soil and trees) as the bedrock of its sustainable development, regenerative agriculture, and agroecology.
- Received September 3, 2024.
- © 2024 by the Soil and Water Conservation Society
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