1 Introduction
1.1 Background
Soil and water conservation aims to control or prevent soil loss (erosion), loss of soil nutrients, and general deterioration of soil and water quality, which are the major global threats to soil health, agricultural productivity, and environmental quality. Planning for soil and water conservation is traditionally part of agricultural and environmental planning to protect and maintain the crucial media for plant growth, biodiversity sustenance, climate regulation, and environmental exchange (Hudson 1987; Morgan 2005). It is therefore not surprising to find soil and water conservation aspects included in the 2024 Africa Fertilizer and Soil Health Action Plan (AFSH-AP) and the Soil Initiative for Africa (SIA)a framework (AU-FARA 2024). Soil and water conservation also targets soil water, which is one of the major limiting factors for agriculture production, particularly in the drylands. Soil water management is especially important for Africa’s agriculture performance where close to half of the continent is dryland that supports over 75% of Africa’s agriculture (Cervigni and Morris 2016). Further, the collection and conservation of rainwater in the soil is also essential for maintaining and increasing water resources in general, which are in turn critical for both productive uses (like livestock production) and domestic uses (drinking, bathing and washing of household goods like clothing, etc.) Water resources are already in short supply in Africa and are predicted to decline further – thus this aspect of soil and water conservation has massive implications for human life and livelihoods well beyond plant growth. Lastly, it needs to be noted that soil and water conservation at the level of individual plots is essential, but not sufficient, to restore soil health and water resources across the continent. Soil and water conservation at the landscape level is also essential for fully capturing rainwater as it falls, and for the protection of the productivity of grazing areas, forest lands, wetland areas and other critical ecosystems. Thus, the SIA framework clearly calls for action on soil and water conservation at both the farm-level and the landscape level.
There are many options for soil and water management in the literature which can fit different scenarios in Africa (Diop et al. 2022; Namirembe, Nzyoka, and Gathenya 2015; Hudson 1987). A careful selection of appropriate and sustainable practices is needed, which will also promote soil health on the continent. Soil health and soil and water management are interrelated, and in fact in many instances it is necessary to manage soil to manage water. Soil and water management influences numerous physical, chemical and biological processes that shape soil health (Williams, Colombi, and Keller 2020). This inter-relationship can be used to guide the selection of appropriate soil and water management alternatives that optimize soil health to improve agricultural productivity and environmental quality. This document elaborates on the strategies for optimizing soil health and water management across agricultural sub-sectors and landscapes in Africa with a view to improving agricultural productivity and environmental quality on the continent. However, it should also be recognized that the selection of locally viable soil and water management strategies and technologies is highly location specific (influenced by culture, availability of farmer’s resources, topography, rainfall averages, etc.). It is therefore essential to involve local farmers in the final selection of technologies for soil and water conservation.
Technologies which have been developed for managing soil water and improving soil health primarily target reduced soil disturbance, increased organic carbon and fertility, reduced soil loss, increased availability of soil moisture, and reduced weed, pest and disease infestation (Altobelli et al. 2020; Blanco and Lal 2010; Hudson 1987). Globally, the trend of adopting of most technologies for soil and water management is shaped by the increasing impacts of climate change, population pressure on available land, competing demand for resources, socio-economic and legal challenges, and access to information and advancing technologies. In Africa, weak policy support and inadequate prioritization of soil and water management (at both farm and landscape levels) in most countries have compounded the challenges with the adoption of the technologies, thus contributing to negative consequences on overall soil health and declining water resources on the continent (Degfe et al. 2023; Diop et al. 2022; Rotich et al. 2024). The Soil Initiative for Africa (SIA) prioritized soil and water management to alleviate soil health, agricultural productivity, declining water resources and environmental quality in Africa (AU-FARA 2024). It is anticipated that its implementation will catalyze existing campaigns to promote improved soil and water management, soil health and agricultural productivity in Africa.
1.2 Progress with sustainable soil and water management in Africa
Sustainable soil management (SSM) is a set of practices and technologies that preserves or improves the long-term services provided by soil without significantly impairing the present or future soil functions (FAO 2017; Smith and Powlson 2004). SSM aims to limit misuse, neglect, and degradation of the soil resource while improving overall long-term soil health and productivity. The practices and technologies under SSM vary by ecoregions, landscapes, land use types, etc. This variation complicates the development of a complete spatial distribution of SSM practices and technologies at the global, continental or national levels, which would have been useful in tracking areas under SSM, impacts of SSM on multilevel soil degradation, etc. The World Overview of Conservation Approaches and Technologies (WOCAT), which is a global network on Sustainable Land Management (SLM), has attempted a global database of SSM practices and technologies (https://explorer.wocat.net/). Although the WOCAT database is not complete, it can serve as an indicator of existing SSM practices and the starting point for assessing the global progress with SSM (Haregeweyn et al. 2023).
In Africa, many SSM practices and technologies exist in different places although the majority of them have not been adequately published (Brempong et al. 2023; Critchley and Graham 1991; Diop et al. 2022; FAO 2017; Namirembe, Nzyoka, and Gathenya 2015; Reij 1991). There is no clear and complete documentation in the literature on the progress with implementation of SSM at the country, regional or continental levels. The WOCAT database of SSM, which shows data at the national level in more than half of the countries in Africa, does not represent a complete compendium of existing practices and technologies. In contrast, land degradation (FAO 2021), soil erosion (Borrelli et al. 2017), and even salinization (Omuto et al. 2024) are well documented at all levels in Africa. The CAADP pillars and SIA framework have identified the need for building an information platform in the form of a database which will be used in sensitizing, promoting, tracking, and optimizing soil and water management and soil health across agriculture sub-sectors and landscapes in Africa (NEPAD 2003; AU-FARA 2024). This chapter highlights the necessary steps to implement SIA and AFSH-AP strategies for promoting SSM and soil health in Africa.