2 Status of soil health practices for mitigating impacts of climate change in Africa
2.1 Soil health practices
Soil health practices are human actions aimed at improving or promoting soil health. They are essential for maintaining and improving the quality of soil, which in turn supports sustainable agriculture and helps mitigate the impacts of climate change. Figure 2.1 summarizes some of the key soil health practices for mitigating climate change, controlling soil degradation, improving soil quality, and providing support services.
Figure 2.1: Examples of soil health practices
Examples of soil health practices are (Al-Kaisi and Lowery 2017):
- Conservation Agriculture: This involves minimal soil disturbance, maintaining a permanent soil cover, and practicing crop rotations. These techniques help protect the soil from erosion, enhance water retention, and increase organic matter content.
- Organic Amendments: The incorporation of compost, green manure, and other organic materials helps replenish soil organic matter, improve soil biodiversity, and enhance soil structure.
- Agroforestry: Integrating trees and shrubs into agricultural landscapes helps improve soil fertility, reduce erosion, and increase carbon sequestration.
- Balanced Fertilization: Applying the right amounts of macro and micronutrients ensures that soils receive the necessary nutrients to maintain fertility and support crop productivity.
- Climate-Smart Agriculture: Techniques such as using drought-resistant crop varieties, efficient irrigation systems, and practices that enhance carbon sequestration contribute to both soil health and climate change mitigation.
- Cover Cropping: Growing cover crops during off-seasons helps prevent soil erosion, improve soil structure, and enhance nutrient cycling.
- Soil conservation: Protecting soil from different forms of degradation by employing structural, agronomic, vegetative, and any combination of these practices
2.1.1 Status of soil health practices in Africa
Soil health practices vary across Africa due to many factors including ecological, socio-political, economic, regional climates, soil types, and agricultural traditions. In the arid regions of Northern Africa, practices such as crop rotation and the use of organic compost are vital to maintaining soil fertility (Araya et al. 2024). Similarly, in the Sahelian zone, the focus has been more on the development of water-harvesting systems than conservation agriculture because crop residues are highly prized for animal fodder. In contrast, the tropical climates of Central Africa often utilize cover cropping and agroforestry to prevent soil erosion and maintain nutrient levels. The diverse landscapes and farming systems found across the continent necessitate a localized approach to soil health management, ensuring that each region can sustainably support its agricultural needs.
In terms of conservation agriculture (CA), Africa does not seem to have widely embraced the practice. CA in Africa is reportedly accounting for less than 1% of the global CA coverage. The global area under conservation agriculture (CA) is more than 200 million hectares, which is about 12% of the world’s cropland area (Kassam, Friedrich, and Derpsch 2022). Most conservation agriculture practices in Africa are found in East and Southern Africa regions. In West and Central Africa, CA is can also be found in Ghana and Cameroon (Nana et al. 2014). Climate-Smart Agriculture (CSA), like CA, is also not widely adopted in Africa. However, CSA has been steadly increasing in adoption over recent years. Through the combined action by researchers, international development partners, and the Food and Agriculture Organization (FAO), several African countries have recognized the vital importance of sustainable agricultural practices in combating the adverse effects of climate change. According to recent studies, approximately 30% of farming households in sub-Saharan Africa have adopted some form of climate-smart agriculture (CSA) practices (Ariom et al. 2022; Ogisi and Begho 2023). These practices include water conservation techniques, the use of drought-resistant crop varieties, and integrated pest management, among others.
Soil conservation is the only soil health practice with a long history and widespread application in Africa (Reij 1991). Today, soil conservation efforts in Africa are a mix of traditional practices and modern scientific approaches. Various governments, non-governmental organizations (NGOs), and international agencies are actively involved in promoting sustainable soil conservation practices. The World Overview of Conservation Approaches and Technologies (WOCAT, https://wocat.net/en/about-wocat/) has established a global database of soil conservation practices which show areas in Africa with different types of conservation typologies. However, the status of most conservation efforts as well as their impacts in improving soil health is not fully documented for many places in Africa.
In general, most soil health practices in Africa have poor documentation to support clear judgment of their impacts on soil health at the national, regional and continental levels. Efforts are needed to support ongoing soil health practices including appropriate documentation to benefit further actions and promotion on the continent.
2.1.2 Challenges with soil health practices for mitigating climate change in Africa
Despite the numerous benefits of soil health practices and promising adoption in Africa, numerous challenges still impede widespread adoption and effectiveness of soil health practices in mitigating climate change across the continent. Table 2.1 gives a summary of the main challenges affecting soil health practices for mitigating climate change in Africa.
| Main.group | Sub.category | Affected.Stakeholders |
|---|---|---|
| Socio-economic barriers | Poverty and resource limitations | Smallholder farmers |
| Knowledge and awareness | Smallholder farmers and policy makers | |
| Environmental and climatic challenges | Variability in climate conditions | All stakeholders |
| High rates of land degradation | Smallholder farmers | |
| Policy and institutional constraints | Weak policy frameworks | National governments and regional coordination units |
| Institutional support | National, regional, and continental leadership | |
| Technological and infrastructure limitations | Access to technology | Smallholder farmers, extension officers |
| Infrastructure development | All stakeholders | |
| Poor planning and prioritization | Poor planning | Smallholder farmers, national governments |
| Lack of prioritization | Smallholder farmers, national governments |
- Socio-economic barriers
Poverty and Resource Limitations: Many African farmers operate on small-scale subsistence farms with limited resources. Financial constraints hinder their ability to invest in soil health practices such as organic amendments, cover cropping, and advanced irrigation systems. The lack of access to credit and financial services further exacerbates this issue, making it difficult for farmers to adopt sustainable practices (Bwema Ombati Mogaka, Bett, and Ng’ang’a 2021).
Knowledge and Awareness: There is a significant knowledge gap among farmers regarding the benefits and implementation of soil health practices. Extension services, which play a crucial role in disseminating agricultural knowledge, are often underfunded and understaffed. Consequently, many farmers remain unaware of the techniques that could improve soil health and mitigate climate change (Eze et al. 2021).
- Environmental and climatic challenges
Variability in Climate Conditions: Africa’s diverse climatic zones present a challenge in implementing uniform soil health practices. Techniques that work in one region may not be suitable in another due to varying rainfall patterns, temperatures, and soil types (Atoloye 2024). This variability necessitates tailored solutions that require extensive research and adaptation.
High Rates of Land Degradation: Land degradation, driven by deforestation, overgrazing, and unsustainable agricultural practices, is a significant issue in Africa. Degraded soils have reduced fertility and water-holding capacity, making it challenging to restore soil health (Muchena et al. 2005; Tully et al. 2015). Efforts to rehabilitate degraded lands require substantial investment and long-term commitment, which are often lacking.
- Policy and institutional constraints
Weak Policy Frameworks: Many African countries lack robust policies that promote and support soil health practices. Existing agricultural policies may not prioritize soil conservation, and there is often a disconnect between policy formulation and implementation (Ginzky and Ruppel 2022). This gap hinders the scaling up of effective soil health interventions.
Institutional Support: Effective implementation of soil health practices requires strong institutional support, including research institutions, government agencies, and non-governmental organizations. However, institutional capacity is often limited in African countries, with insufficient funding and coordination among stakeholders. This lack of support undermines efforts to promote and sustain soil health initiatives.
- Technological and infrastructure limitations
Access to Technology: The adoption of soil health practices is closely linked to the availability and accessibility of appropriate technologies. In many parts of Africa, farmers lack access to modern agricultural tools, equipment, and inputs that are essential for implementing sustainable practices. Bridging the technology gap is crucial for enhancing soil health and mitigating climate change.
Infrastructure Development: Poor infrastructure, including inadequate transportation networks and storage facilities, poses a significant barrier to the adoption of soil health practices. Efficient supply chains are necessary for delivering inputs, accessing markets, and disseminating knowledge. Investing in infrastructure development is essential to support sustainable agricultural practices.
2.2 Impacts of climate change on soil health
2.2.1 Impacts of climate change on soil health
Climate change in the form of variability, rising temperatures and precipitation, and change of onset time for seasons have affected soil management programs, altered soil properties, and influenced land use types in ways that have introduced significant impacts on soil health (Table 2.2).
| Impact.area | Influence | Reference |
|---|---|---|
| Soil management | Changes in soil conservation to adjust to climate change | (Ling et al. 2024) |
| Climate change causes change in use of soil amendments | (Rubin et al. 2023) | |
| Changes in cropping calendar and land preparation | (Waha et al. 2013) | |
| Soil functions | Changes in soil properties | (Prasad and Pietrzykowski 2020) |
| Changes in soil functional capacities | ||
| Land use | Changes in land use types and diversification | (Winkler et al. 2021) |
| Intensification of land uses |
- Altered soil management programs
Climate change is touted as a main driver to changes in soil management programs worldwide. For example, changes in precipitation characteristics have been shown to influence the rate and amount of soil loss when all other factors remain constant (Adeyeri et al. 2024). Consequently, the soil conservation measures must be changed to deal with the new threat volume. In areas where climate change has caused a decrease in soil moisture, the soil conservation types seem to also change to focus more on soil moisture management. Similarly, increase in temperature due to climate change can occasion change in soil organic matter mineralization which forces the need for increase in use of organic amendments to sustain soil fertility (Rubin et al. 2023). Climate change in the form of changes in duration and arrival of seasons also influences the type and intensity of cropping interculture and investment decisions by majority of land users. The shift in arrival of seasons and change in duration of the seasons in cropland areas influence changes in cropping calendar and spiral effects on soil management programs that are needed to conform to the available window for land preparation.
- Altered soil properties
Rising temperatures, increased precipitation, and extreme events put pressure on the soil which may result in changes in soil properties such as organic matter content, fertility, salt accumulation, etc. The literature shows that climate change has caused some soils to become net sources of atmospheric carbon which indicate lowering of soil organic carbon (Brevik 2013). Similarly, there are also reports indicating increase in salinization due to climate change in some parts of the world (Hassani, Azapagic, and Shokri 2021), signifying changes in soil electrical conductivity, pH, and cation exchange characteristics.
- Influenced land use changes
There is a close association between land use/cover change and climate change (Bununu, Bello, and Ahmed 2023). However, from the perspective of response to climate change, the literature show that land use types have been changed to accommodate the reality brought about by climate change. For example, in the face of dwindling livestock pastures, some communities abandon free-range livestock management to feedlots, controlled grazing, zero-grazing, etc. Similarly, increased swamping due to climate change potentially increases opportunities for paddy rice production and vice versa for drying of swamps which trigger reclamation of the wetland for crop production (Khairullah et al. 2021). Climate change can also trigger mitigation responses that focus on intensification of land use types (Campbell et al. 2014).
2.2.2 Extent of impacts of climate change on soil health in Africa
Impacts of climate change on soil health in Africa have not been adequately studied at the continental level. However, information gleaned from global studies shows that soil health is likely to deteriorate in the near future in more than half of the continent (Figure 2.2) [Borrelli et al. (2020); hassani_global_2021].
Figure 2.2: Impacts of climate change on erosion (Borelli et al., 2020) and salinization (Hassani et al., 2021)
Areas projected with the most deteriorating soil health are found in West Africa, Sahel, East Africa, Southern Africa, and northern Mediterranean coastal areas (Figure 2.2). They are also expected to show declining soil fertility due to climate change (St.Clair and Lynch 2010). Coincidentally, these areas are the breadbasket areas of Africa, implying significant impacts on food security as well on the continent in the near future.
Figure 2.2 shows that more than half of Africa is likely to experience deteriorating soil health in the near future. The literature also depicts 65% of the continent as undergoing soil different forms of soil degradation. This implies that a vast majority of the continent will continue to experience poor soil health unless proper action is taken. AFSH-AP and SIA framework is likely the antidote for this soil health problem.