Looking back and moving forward: 50 years of soil and soil fertility management research in sub-Saharan Africa

Low and declining soil fertility has been recognized for a long time as a major impediment to intensifying agriculture in sub-Saharan Africa (SSA). Consequently, from the inception of international agricultural research, centres operating in SSA have had a research programme focusing on soil and soil fertility management, including the International Institute of Tropical Agriculture (IITA). The scope, content, and approaches of soil and soil fertility management research have changed over the past decades in response to lessons learnt and internal and external drivers and this paper uses IITA as a case study to document and analyse the consequences of strategic decisions taken on technology development, validation, and ultimately uptake by smallholder farmers in SSA. After an initial section describing the external environment within which soil and soil fertility management research is operating, various dimensions of this research area are covered: (i) ‘strategic research’, ‘Research for Development’, partnerships, and balancing acts, (ii) changing role of characterization due to the expansion in geographical scope and shift from soils to farms and livelihoods, (iii) technology development: changes in vision, content, and scale of intervention, (iv) technology validation and delivery to farming communities, and (v) impact and feedback to the technology development and validation process. Each of the above sections follows a chronological approach, covering the last five decades (from the late 1960s till today). The paper ends with a number of lessons learnt which could be considered for future initiatives aiming at developing and delivering improved soil and soil fertility management practices to smallholder farming communities in SSA.     

Soyabeans and sustainable agriculture in southern Africa

Maize is the dominant staple crop across most of southern Africa—it is so dominant in some areas that more than 80 per cent of the smallholder land area is planted with maize. Soyabean was identified as the crop with a potential to address the need for diversifying the cropping systems, which could assist in overcoming the pervading soil fertility constraints and could provide smallholder farmers with an opportunity to earn income while also addressing the nutritional security of households. An initiative was launched in the 1996/97 cropping season in Zimbabwe, to test soyabean as a potential smallholder crop. From an initial 55 farmers in the first year, soyabean production expanded rapidly to an estimated 10,000 farmers three years later. Since then, soyabean has diffused spontaneously to most smallholder farming areas in the higher rainfall zones of Zimbabwe. Thus, the initiative has assisted a large number of smallholders to grow soyabean, and exploded a long-held belief in Zimbabwe that soyabean is not a suitable crop for smallholders.     

Sustainable crop production intensification in the Senegal and Niger River basins of francophone West Africa

This paper reports on how the farmer field school (FFS) approach has been used to successfully catalyse important changes among stakeholders in the savannah zones of West Africa. Improved agronomic practices, better decision-making skills and diversification of smallholder farms in developing countries are shown to provide farmers the opportunity to rebuild soil fertility, optimize input use and introduce new sources of food and nutrition and marketable products for local populations. This is a knowledge-intensive endeavour best addressed through community-based processes of education. By the end of 2010, approximately 116,000 rice, vegetable, cotton and other farmers would have been involved in season-long FFS in four West African countries, resulting in improved yields and incomes and ushering substantial progress in both reducing the use of chemical pesticides and improving the use of fertilizers and organic amendments. The programme is increasingly being successfully integrated into local, provincial and national structures. Experienced personnel are being employed to initiate similar programmes in nearby countries. The evolving network of experienced actors and committed countries provides a platform for collaboration by a growing set of partners and represents a large-scale, long-term programmatic approach to helping sustainably intensify and develop agriculture in Africa.     

Land fragmentation,climate change adaptation,and food security in the Gamo Highlands of Ethiopia

Household food security among smallholder farmers is sensitive to a variable and changing climate, requiring farmers in the Gamo Highlands of Ethiopia to adopt new land management practices to improve food security. Agricultural land in the Gamo Highlands is highly fragmented. The extent to which land fragmentation (LF) moderates the food security effects of sustainable land management (SLM) practices is unknown. This study used probit and Poisson models to explain this relationship. The study found that food insecurity was severe during the food shortfall season. LF provides more potential opportunities for improving food security than challenges. Furthermore, SLM practices had both positive and negative effects on food security and their effects were conditioned by the magnitude of LF. Reducing severe LF through the assembly of small parcels into larger heterogeneous plot clusters could enhance food security by exploiting synergies between adaptation practices and LF.     

Research and Development Towards Sustainable Agriculture by Resource-Poor Farmers in Sub-Saharan Africa: Some Strategic and Organisational Considerations in Linking Farmer Practical Needs with Policies and Scientific Theories

Sustainable agricultural development is presented as a diverse and dynamic process through which it copes with agro-ecological and socio-economic diversity at field level and with ever-changing needs and opportunities of (smallholder) farmers. In support, agricultural research—aimed at locally appropriate and environmentally friendly technologies—should contribute to bridging the currently increasing gaps between scientific theories and government agricultural policies as opposed to the practical field realities that farmers are facing.

These gaps are best illustrated by—what in the West is often presumed to be—a stagnant African agricultural (in reality it is not!) in spite of many ambitious policies and projects by national governments and international donors for several decades. Disappointing adoption rates by resource-poor smallholders of the proposed ‘modern’ agricultural technologies have often been blamed. However, the actual local systems are primarily based on ‘ecological’ and ‘organic’ concepts. Localised intensification through recycling of organic by-products is an integral part of such systems. Consequently, these systems are uniquely adapted to the diverse framer needs resulting from widespread variations in soil, climate and socio-economic conditions. By contrast most international R&D support for the African agricultural sector is aimed implicitly at creating a modern conventional system of farming based on external inputs and along a Western industrial model.

To cope with diverse and complex, location specific problems inherent in development, sustainability and poverty alleviation, requires strong national research and development (R&D) institutions that adopt comprehensive, people-centred approaches as opposed to the technocratic nature of most formal international development assistance. The development debate therefore should be turned around. The ‘existing’ smallholder farming systems and their needs should be a point of departure, while the various development initiatives and policies should be handled by including the related institutional aspects.     

Conditioning trends shaping the agricultural and rural landscape in Africa

African countries continue to face deepening food crises that have been accentuated by the global food, energy, and financial crises. This situation is part of a long‐term structural problem: decades of under‐investments in agricultural sector and poor policies of support for smallholder farmers who form the bulk of the farming population. The inability of these farmers to achieve a supply response when commodity prices were high and market access was less of a problem suggests that there are multiple sets of binding constraints that continue to limit the potential of agricultural growth to reduce food security and poverty on the continent. This article reviews some of the historical trends that have hampered the performance of the agriculture sector. In addition, it reviews the impacts of more positive trends that could stimulate agricultural growth in Africa that could change the African agricultural landscape. The article however warns that there are more recent global developments and some continental challenges that could prevent or slow agricultural growth. These include the global financial crisis, public sector investments, inequities in global agricultural development policies, rush for agricultural lands by foreign investors, domestic commercial financing markets, climate change, and emerging carbon markets. The article argues that while opportunities for accelerated growth exists for African agriculture, new sets of policy instruments will be needed to support smallholder farmers to access new agricultural technologies, finance, reduce impacts of climate change, and adopt sustainable land use practices that can allow them to benefit from emerging global carbon markets.     

Breeding for Africa's new smallholder maize paradigm

This paper describes the evolution of a newly emerging smallholder maize paradigm in southern Africa beginning in 1996. This new paradigm involves the breeding, extension, and adoption of a new generation of open-pollinated ‘flinty’ maize varieties that specifically address the needs of southern African smallholder farmers for seed varieties that can be replanted (recycled) and that resist drought and low fertility problems increasingly common in southern Africa. The described mechanism is the extension and breeding work of the Southern Africa Drought and Low Fertility programme (SADLF) of the Centro Internationale por la Mejoridad de Maize y Trigo (CIMMYT). This paper explains the devolution of southern African maize production in the past two decades from centralized large-scale producers to smallholder farms, signalling a shift in research and plant breeding needs. The research/extension approach described here had profound consequences beyond the technical benefits of screening maize varieties for tolerance to stress; it empowered small-scale farmers to become informed consumers of agricultural technology. The transformation of the smallholder from a passive consumer to one actively seeking the best opportunity and seed to produce food, create economic opportunities and address local social conditions is an important development in the history and sustainability of maize production in southern Africa, and one consistent with modern African history of economic liberalization in the global food economy.     

Socio-ecological niche: a conceptual framework for integration of legumes in smallholder farming systems

There are numerous examples of technologies with great potential that have not been accepted by smallholder farmers. Quite often, these technologies do not fit well into smallholder systems due to the inherent high level of heterogeneity of these systems. For example, despite their great potential, the adoption of legumes by smallholder farmers in many parts of sub-Saharan Africa has remained poor. A wide range of biophysical (e.g. climate, soil fertility, etc.) and socio-economic variables (e.g. preferences, prices, production objectives etc.) influence the use of legumes in smallholder systems. While some of these variables constrain the adoption of some legumes, others offer opportunities for beneficial use of other legumes in the same system. Therefore, widespread adoption of legumes in smallholder systems can only be achieved if all of the major biophysical and socio-economic constraints are simultaneously identified and addressed. The ‘socio-ecological niche’ concept proposed in this paper provides the framework through which this might be achieved. The socio-ecological niche, in any given region of agricultural activity, is created by the convergence of agro-ecological, socio-cultural, economic and ecological factors, to describe a multidimensional environment for which compatible technologies can be predicted. The socio-ecological niche concept can be applied in many different contexts in technology development. However, this paper discusses its use with respect to the development of legume technologies. Two case studies are presented to illustrate the concept and to demonstrate its practical significance. The concept is being used in on-going research on legumes in smallholder farming systems in western Kenya.     

Environmental discounting behaviour of smallholder farmers in Chibombo District,Central Zambia

This study utilised 158 semi structured interviews, three focus group discussions and two key informant interviews to achieve its aim of investigating environmental discounting by smallholder farmers in Chibombo, Zambia. Results suggest that most smallholder farmers were willing to continue using mineral fertilisers in the short to medium term even when they were told there could be potentially negative effects as a result. This result was attributed to the farmers’ experience with neutralising soil acidity through lime application and crop rotations. The proportions of smallholder farmers who would continue using pesticides increased with the period it takes for pesticide induced soil infertility to manifest. The respondents seemed more concerned about effects on the soil that would manifest in five years. Smallholder farmers preferred soil improving practices with short term benefits, and low risk. The proportions of smallholder farmers willing to plant fertiliser trees reduced from 68.5 % when the benefits accrue in five years to about 38 % when said benefits accrue to the next generation. Study recommends that agricultural development interventions should focus on low risk, locally available technologies with shorter term benefits and minimal future costs. Study recommends that agricultural development interventions include innovation of practices with shorter term benefits, minimal future costs and farmer sensitisation on the benefits of sustainable agriculture.     

Farmer perceptions of legumes and their functions in smallholder farming systems in east Africa

Legumes play an important role in sub-Saharan Africa (SSA) farming systems through the provision of food, feed, fuel, income and a range of biophysical benefits, such as soil fertility enhancement and erosion control. However, their full potential is not being realized. The purpose of this study was to assess farmers’ perceptions and knowledge towards legumes and the rationale of farmers for current legume production practices using a survey of 268 farmers in the Democratic Republic of Congo and Kenya. Most of the farmers had some knowledge of legumes and their characteristics. However, they had little knowledge of some key functions, including soil erosion control and soil fertility improvement. Most farmers relied on radio and other farmers for legume-related information. Farmers with relatively large livestock holdings ranked provision of livestock feed as an important legume function. We conclude that farmers put more value on short-term benefits of legumes including food and income than long-term benefits such as natural resource management and thus grain legumes are more readily identified by farmers than forage species. Also, we conclude that farmers require more than just information about legumes to increase uptake, they also require improved market access to procure inputs and sell products to realize other benefits that are associated with growing legumes.     

Research,development and scaling-up the adoption of fodder shrub innovations in East Africa

Smallholder farmers in developing countries face numerous limitations that hinder them from embracing improved agricultural practices and innovations with great potential for meaningful transformations of livelihoods. Consequently, farmers continue living in vicious cycles of poverty despite decades of government and donor expenditures on poverty alleviation. In the last two decades, research and development organizations collaborated in testing and validating selected fodder shrub species as reliable sources of less expensive and easily available protein feeds. With minimal interventions, the research findings have great potential to improve productivity for many smallholder farmers. Tested species include Calliandra calothyrsus, Leucaena spp., Chamaecytisus palmensis, Sesbania sesban, Morus alba and Gliricidia sepium. Dissemination and adoption surveys estimated that 205,000 smallholder farmers (40–50 per cent being women) had planted fodder shrubs by 2005. Currently, fodder shrubs contribute US$3.8 million annually to farmers' incomes and estimated potential annual income is US$81 million. Factors associated with success in fodder scaling-up include deliberate involvement of fodder technology champions, collective action in community mobilization and project implementation, pluralistic extension approaches, sustainable germplasm supply systems, broader partnerships and civil society campaigns. Constraints and challenges include: ineffective delivery of extension and research services, inhibitive policies, political interferences, frequent droughts and inadequate monitoring and evaluation systems.     

Do Plant Clinics Improve Household Food Security? Evidence from Rwanda

One of the main drivers of food insecurity is pests, which are estimated to cause around 40% of crop losses worldwide. We examine the food security effects of plant clinics, a novel agricultural extension model that aims to reduce crop losses due to pests through the provision of demand‐driven plant health diagnostic and advisory services to smallholder farmers. The study is based on survey data from maize‐growing households in Rwanda, where 66 plant clinics have been established. Using switching regression and matching techniques as well as various food security metrics, including the food insecurity experience scale, we find evidence that participation in plant clinics is significantly associated with a reduction in household food insecurity. For instance, among the participating households, plant clinics contribute to a decrease in the period of food shortage by one month and a reduction in the severity of food insecurity by 22 percentage points. We also show that these effects are more pronounced for female‐headed households. Overall, our findings suggest that plant clinics can play an important role in achieving the Sustainable Development Goal 2 of zero hunger.     

Soil Fertility Management and Compost Use in Senegal's Peanut Basin

The Jóór (Dior) soils of Senegal's Peanut Basin are inherently low in organic matter, limiting yields of millet and other crops and threatening the food security of smallholders. Focus groups and interviews were conducted in eight villages to characterise the site-specific fertility management by farmers in the Peanut Basin. Results of the qualitative survey revealed that farmers base management decisions on a series of fertility indicators that include type, colour, and texture of soil, presence of vegetation, and productivity in previous years. In an effort to equalise fertility across the field, farmers amend areas they classify as less fertile with decomposed manure and household waste from the family sëntaare (traditional pile) orwith compost from managed piles. On-site measurements of soil in areas of fields amended with compost or sëntaare material revealed significant increases in peanut and millet growth over unamended areas, but little difference between the effects of compost and manure. Similarly, chemical analysis revealed increased effective cation exchange capacity (ECEC) and nutrient concentrations (K, Mg and Al) in soils amended with compost or manure. Similarities in the chemical characteristics of compost and sëntaare material suggest that development workers could emphasise improved pile management rather than promoting more labour-intensive composting.     

Induced innovation and land degradation: Results from a bioeconomic model of a village in West Africa

This paper introduces a modeling method which simulates a village's response to population and market pressure. The method combines a recursive and dynamic linear programming model with a biophysical model of soil condition and plant growth that predicts yields and land degradation for different type of land, land use and cropping patterns. The linear programming model simulates farmers' plans aggregated at the village level under constraints of risk aversion, food consumption, land area, soil fertility, soil depth, labor and cash availability. Detailed agroecological factors determine Ihe main processes of land degradation. A large number of technological alternatives, representing different degrees of labor and/or land-saving techniques available in the study areas, are introduced, taking into account their respective constraints, costs and advantages. The method has been calibrated for a village located in the sub-humid region of Burkina Faso. Several simulations are carried out to the Year 2030. The results show that population pressure leads to intensification and investment in land conservation practices out not necessarily to better farm incomes. Increasing market opportunities can play a more positive role in boosting productivity, but for the next decades the best way to increase production per farmer is to let farmers migrate from the high-population-density areas to the low-population-density areas because, under the current economic conditions of most Sahelian countries, intensification per hectare is stil more expensive than the fallow system.     

‘Because of poverty,we had to come together’: collective action for improved food security in rural Kenya and Uganda

Agricultural productivity in East African smallholder systems is notoriously low and food production faces multiple challenges, including soil degradation, decreasing land availability, poor market integration, disease burdens and climate change impacts. However, recent evidence from an in-depth study from two sites in Kenya and Uganda shows signs of new social dynamics as a response to these multiple stressors. This paper focuses on the emergence of local social institutions for collective action, in which particularly women farmers organize themselves. Although previous research on collective action has largely focused on common-pool resource management, we argue that collective action is one potential pathway to livelihood and sustainability improvements also in a setting of private land ownership. Trust building, awareness raising and actions to improve livelihood security through risk sharing and pooling of labour and other limited assets have given people more time and resources available for diversification, preventative activities, experimentation and resource conservation. It thereby strengthens farmers’ capacity to cope with and adapt to change, as well as contributes to the agency at the local level.     

Tradeoffs and complementarities in the adoption of improved seeds,fertilizer, and natural resource management technologies in Kenya

There is widespread consensus that agricultural technology has an important role to play for poverty reduction and sustainable development. There is no consensus, however, about the types of technologies that are best suited for smallholder farmers in Africa. While some consider natural resource management (NRM) technologies as most appropriate, others propagate input intensification with a stronger role of the private sector. In the public debate, these two strategies are often perceived as incompatible. Environmental non‐governmental organizations in particular consider low‐external input strategies as the only sustainable form of agriculture, a view that has considerable influence on policymakers and the international donor community. Most existing research studies on smallholder innovation focus on the adoption of individual technologies, so that comparisons between different types of technologies in the same context are not easily possible. We use representative data from maize‐producing households in Kenya and a multivariate probit model to analyze the adoption of different types of technologies simultaneously. Results indicate that NRM technologies and strategies that build on external inputs are not incompatible. Interesting complementarities exist, which are not yet sufficiently exploited because many organizations promote either one type of technology or the other, but rarely a combination of both.     

Understanding the adoption of climate change adaptation strategies among smallholder farmers: Evidence from land reform beneficiaries in South Africa

Climatic change has a negative impact on people’s livelihoods, agriculture, freshwater supply and other natural resources that are important for human survival. Therefore, understanding how rural smallholder farmers perceive climate change, climate variability, and factors that influence their choices would facilitate a better understanding of how these farmers adapt to the negative impacts of climate change. A Zero-inflated double hurdle model was employed to estimate the factors influencing farmers’ adoption of adaptation strategies and intensity of adoption at the household level in South Africa. Different socioeconomic factors such as gender, age, and experience in crop farming, institutional factors like access to extension services, and access to climate change information significantly influenced the adoption of climate change adaptation strategies among beneficiaries of land reform in South Africa. Concerning intensity of adoption, age, educational level, farming experience, on-farm training, off-farm income, access to information through ICT and locational variables are the significant determinants of intensity of adaptation strategies. Thus, education attainment, non-farm employment, farming experience are significant incentives to enhance smallholder farmers' adaptive capacity through the adoption of many adaptation approaches. This study therefore concluded that farm-level policy efforts that aim to improve rural development should focus on farmers’ education, on-farm demonstration and non-farm employment opportunities that seek to engage the farmers, particularly during the off-cropping season. The income from non-farm employment can be plough-back into farm operations such as the adoption of soil and water conservation, use of improved planting varieties, insurance, among others to mitigate climate variability and subsequently increase productivity. Policies and investment strategies of the government should be geared towards supporting education, providing on-farm demonstration trainings, and disseminating information about climate change adaptation strategies, particularly for smallholder farmers in the country. Thus, the government, stakeholders, and donor agencies must provide capacity-building innovations around the agricultural extension system and education on climate change using information and communication technologies.     

Who is resilient in Africa’s Green Revolution? Sustainable intensification and Climate Smart Agriculture in Rwanda

Under the banner of a "New Green Revolution for Africa," agricultural intensification programs aim to make smallholder agriculture more productive as well as "climate smart". As with Green Revolutions in Asia and Mexico, agricultural innovations (hybrid seeds, agronomic engineering, market linkages,and increased use of fertilizer and pesticides) are promoted as essential catalysts of agriculture-led economic growth. Intensification programs are now frequently linked to Climate Smart Agriculture (CSA), which attempts to build resilience and reduce greenhouse gas emissions while increasing crop yields. This article considers who and what is resilient in Africa’s Green Revolution. We report on a multi-season study of smallholder food producers' experiences with Rwanda’s Crop Intensification Program (CIP) and related policies that aim to commercialize subsistence agriculture while implementing CSA. . We suggest that there are fundamental limits to the climate resilience afforded by CSA and development efforts rooted in Green Revolution thinking. Our findings illustrate that such efforts foreground technology and management adjustments in ways that have reduced smallholder resilience by inhibiting sovereignty over land use, decreasing livelihood flexibility, and constricting resource access. We put forth that rural development policies could better promote climate-resilient livelihoods through: 1) adaptive governance that enables smallholder land use decision-making; 2) support for smallholder food producers’ existing agro-ecological strategies of intensification; 3) participatory approaches to visualize and correct for inequalities in local processes of social-ecological resilence Such considerations are paramount for meeting the United Nations Sustainable Development Goals and building climate-resilient food systems.     

Can mobile phones improve nutrition among pastoral communities? Panel data evidence from Northern Kenya

The digital revolution and the ongoing dissemination of mobile phones carry several prospects for smallholder farmers in sub-Saharan Africa. Food insecurity and low dietary quality remain major issues among African smallholders. Mobile phones could potentially facilitate access to food markets and thus improve food security and nutrition, but research on such types of effects remains scarce. In this study, we analyze whether mobile phones improve dietary quality among pastoral communities in Northern Kenya. We use six rounds of household panel data covering the period between 2009 and 2015. During this period, mobile phone ownership in the sample increased from less than 30% to more than 70%. Regression models with household fixed effects allow robust estimation while reducing potential issues of unobserved heterogeneity. The estimates show that mobile phone adoption and use are positively and significantly associated with dietary diversity. The effects are particularly large for frequent mobile phone users. We also examine the underlying mechanisms. Mobile phone use improves dietary diversity mainly through better access to purchased foods. These results encourage the promotion of mobile phone technologies as a valuable tool for nutritional improvements, especially in remote rural settings with poor access to food markets.     

Targeting,bias, and expected impact of complex innovations on developing‐country agriculture: evidence from Malawi

Agronomic analyses of new technologies are often conducted under carefully controlled research station programs or trials managed by self‐selected farmers. Oftentimes, the technologies are then scaled up with minimal evaluation under real‐world conditions. Yet, the interim step between agronomic trials and large‐scale promotion is crucial to generate evidence on the social and economic impact of technologies that is both internally valid and generalizable. The article focuses on a participatory action research program in Malawi designed to test and identify scalable technology options to intensify the smallholder sector and contribute to poverty reduction and food and nutrition security. We examine the socioeconomic characteristics of farmers testing technologies and find evidence of systematic targeting of better‐endowed farmers. After controlling for observable differences using matching and a doubly robust estimator, we find evidence of early positive effects on maize yield and harvest value, although placebo tests suggest possible selection on unobservables. We note that attention should be given to program design and household characterization to better define and improve targeting criteria, technology selection, and external validity.