Farming Systems In sub-Saharan Africa Research Articles

Efficacy of Clausena anisata and Plectranthus glandulosus leaf powder against Prostephanus truncatus (Coleoptera: Bostrichidae) and two strains of Sitophilus zeamais (Coleoptera: Curculionidae) on maize

Powdered leaves of Clausena anisata and Plectranthus glandulosus were evaluated on Cameroonian and German strains of Sitophiluszeamais and Prostephanus truncatus for their insecticidal activities, the effects on progeny production, grain damage and population increase by admixing powders and maize grains. The two powders caused significant mortality of the three insects with P. glandulosus being far more effective than C. anisata. P. truncatus was less susceptible to P. glandulosus powder compared with the two strains of S. zeamais. The German strain (LD50 = 2.75 g/100 g grain) of S. zeamais was less susceptible to P. glandulosus powder than the Cameroonian strain (LD50 = 1.86 g/100 g grain). P. glandulosus unlike C. anisata powder, considerably reduced grain damage, progeny production and population increase. This study shows that there is a great potential for the powder of P. glandulosus as a promising grain protectant for integration within the subsistence farming systems of sub-saharan Africa.

Improving water productivity in mixed crop–livestock farming systems of sub-Saharan Africa

In sub-Saharan Africa problems associated with water scarcity are aggravated by increasing demands for food and water, climate change and environmental degradation. Livestock keeping, an important livelihood strategy for smallholder farmers in Africa, is a major consumer of water, and its water consumption is increasing with increasing demands for livestock products. At the same time, current low returns from livestock keeping limit its contribution to livelihoods, threaten environmental health and aggravate local conflicts. The objectives of this review are to: (1) synthesize available knowledge in the various components of the livestock and water sectors in sub-Saharan Africa, (2) analyze livestock–water interactions and (3) identify promising strategies and technological interventions for improved livestock water productivity (LWP) using a framework for mixed crop–livestock systems. The interventions are grouped in three categories related to feed, water, and animal management. Feed related strategies for improving LWP include choosing feed types carefully, improving feed quality, increasing feed water productivity, and implementing grazing management practices. Water management for higher LWP comprises water conservation, watering point management, and integration of livestock production in irrigation schemes. Animal management strategies include improving animal health and careful animal husbandry. Evidence indicates that successful uptake of interventions can be achieved if institutions, policies, and gender are considered. Critical research and development gaps are identified in terms of methodologies for quantifying water productivity at different scales and improving integration between agricultural sectors.

Identifying key entry-points for strategic management of smallholder farming systems in sub-Saharan Africa using the dynamic farm-scale simulation model NUANCES-FARMSIM

African smallholder farming systems are complex, dynamic systems with many interacting biophysical subcomponents. In these systems the major inputs and outputs are managed by human agency – the farmers. To analyse potential developmental pathways of smallholder farming systems in sub-Saharan Africa (SSA), we recognised the need for a tool that can capture the effects and consequences of decision-making on the use of resources. Here we describe and apply such a new modelling tool, developed within the NUANCES framework (Nutrient Use in ANimal and Cropping systems: Efficiencies and Scales), called NUANCES-FARMSIM (FARM SIMulator), an integrated crop – livestock model developed to analyse African smallholder farm systems. NUANCES-FARMSIM was used to analyse a representative case study farm in the highlands of Western Kenya, a site for which each of the components of FARMSIM has been thoroughly tested. We present the results of a sensitivity analysis which showed the model to be sufficiently robust to identify key management options that explain most of the variability in farm productivity, and the long-term consequences of these options for the case study farm. The analyses showed clearly that the most important decisions are those related to the interactions between the different components of the farm and therefore justify the need of integrating crop and livestock components within one modelling tool. The allocation of limited resources across the farm, and the way organic matter is recycled or redistributed within the farm determines the long-term production capacity of the system. The results of the sensitivity analyses further showed that for the case study farm in Western Kenya a strong focus on improving the reliability of the subsystem level or process descriptions will only result in minor improvement in simulating productivity at farm level.

Network analysis of N flows and food self-sufficiency—a comparative study of crop-livestock systems of the highlands of East and southern Africa

Smallholder farming systems in sub-Saharan Africa are often nutrient-limited, and therefore imports must be increased to compensate exports and losses. To explore whether the properties of nutrient cycling networks relate to the systems’ capability to sustain rural families, we investigated N flows within contrasting crop-livestock systems in Ethiopia, Kenya and Zimbabwe applying concepts from ecological network analysis. Farm households were conceptualised as networks, the compartments were the household and their farming activities which were connected by the N flows. Indicators assessing network size, activity and cycling, and the organisation and diversity of the N flows were compared with system productivity and food self-sufficiency. Results showed that organisation and diversity of N flows to, from and within the farm households differed more between farms of different resource endowments than across sites. The amount of N cycled per household was small and comparable across sites: less than 25 kg N year−1, and for the poor households less than 5 kg N year−1. Poor households with soil N stocks that were 50–60% smaller than wealthier households depended more on external inputs (e.g. a dependence of 65% vs. 45% in Zimbabwe). Productivity was positively related to network size, its organisation and N cycling, but utilisation efficiencies were different across sites in relation to soil N stock and the importance of livestock for N flows. Greater size of the N flow network and its organisation led to increased productivity and food self-sufficiency, reducing dependence, which may increase the adaptability and reliability of smallholder crop-livestock systems.

Manure and Soil Fertility Management in Sub-Humid and Semi-Arid Farming Systems of Sub-Saharan Africa: Experiences from Kenya

Manure and Soil Fertility Management in Sub-Humid and Semi-Arid Farming Systems of Sub-Saharan Africa: Experiences from Kenya

Coping better with current climatic variability in the rain-fed farming systems of sub-Saharan Africa: An essential first step in adapting to future climate change?

Rain-fed agriculture will remain the dominant source of staple food production and the livelihood foundation of the majority of the rural poor in sub-Saharan Africa (SSA). Greatly enhanced investment in agriculture by a broad range of stakeholders will be required if this sector is to meet the food security requirements of tomorrow's Africa. However, production uncertainty associated with between and within season rainfall variability remains a fundamental constraint to many investors who often over estimate the negative impacts of climate induced uncertainty. Climate change is likely to make matters worse with increases in rainfall variability being predicted. The ability of agricultural communities and agricultural stakeholders in SSA to cope better with the constraints and opportunities of current climate variability must first be enhanced for them to be able to adapt to climate change and the predicted future increase in climate variability. Tools and approaches are now available that allow for a better understanding, characterization and mapping of the agricultural implications of climate variability and the development of climate risk management strategies specifically tailored to stakeholders needs . Application of these tools allows the development and dissemination of targeted investment innovations that have a high probability of biophysical and economic success in the context of climate variability.

Le jeu croisé des dynamiques agraires et foncières en Afrique subsaharienne

Over the last decades different factors such as demographic growth, the opening of markets and alterations in rural policies have induced quick changes to farming systems in sub-Saharan Africa. Throughout the period, shifting cultivation with long fallows has been replaced by fixed cropping systems without fallow. This evolution has led to a progressive change in land tenure rules. The present communication aims at recalling the main steps of this dual evolution of farming systems and land tenure rules: several case studies make it possible to analyse the mutual relationships between agrarian and land tenure dynamics. More often than not, changes in farming systems have brought about an alteration in land tenure rules, although in some situations it is the land tenure rules which have made the adoption of new farming systems a success or a failure. Another purpose of this communication is to show that the occurrence of this farming system and land tenure mutual evolution is neither uniform nor synchronous whatever scale you consider: national, regional, local, village or production unit. The reasons for this space and time heterogeneity are analysed as well as its results on social links within rural communities and on the States of sub-Saharan Africa facing difficulties in drawing up and enforcing new regulations and laws to improve land tenure management.

Socio-economic Factors, Soil Fertility Management and Cropping Practices in Mixed Farming Systems of Sub-Saharan Africa: A Study in Kiambu, Central Highlands of Kenya

A study was carried out in Kiambu District, central highlands of Kenya to explore the effects of household socio-economic factors on farm nutrient balances and agro-economic performance and to determine nutrient depleting and conserving cropping practices in the crop-dairy (mixed) farming system. Data was collected from 30 smallholder farmers and processed using nutrient monitoring (NUTMON) tool. Family earnings (sum of net farm income and off-farm income) were low and off-farm income accounted for 61% of family earnings of the studied households. On-farm livestock density (TLU ha-1) was the main determinant of farm N, P and K nutrient stocks and balances. The mean farm (total) nutrient balances were -2.6 kg N ha-1 half year-1, 36.7 kg P ha-1 half year-1 and 16.9 kg K ha-1 half year-1. In the analysis, purchased livestock feeds (and fertilizers) were the major determinants of farm N, P and K nutrient balances. The major loss pathway for P and K was erosion, accounting for 35 and 66% of total P and K outflows respectively. For N, it was leaching. Farmers adopted preferential soil fertility management strategies for cropping practices resulting in nitrogen, phosphorus and potassium nutrient mining under Napier (monocrop) and coffee (intercrop) fields and nutrient conservation under maize (intercrop) fields.

Comparing the “Big Five”: A framework for the sustainable management of indigenous fruit trees in the drylands of East and Central Africa

Abstract There are many fruit trees that could be integrated into dryland farming systems in Sub-Saharan Africa to support income and nutritional security. Fruit contains almost all known vitamins and many essential minerals. Five important fruit species that are cross-regional include: Adansonia digitata, Tamarindus indica, Zizyphus mauritiana, Sclerocarya birrea, and Mangifera indica. While these species are well integrated in the Sahel region, besides mango, they are generally absent from smallholder farms in East and Central Africa. Fruits of the species in this region are mostly harvested unsustainably from the wild communal areas. Unlike the situation in the neighboring Southern Africa region, where S. birrea is utilized extensively in the wine industry, there is virtually no use for the tree in this region, largely because of limited knowledge. Z. mauritiana use is also limited because of low quality germplasm—the hard stone clings to the flesh. An analytical framework based on five factors (site requirements, genetic variability, propagation methods, nutritional properties and utilization, and commercial potential) is used to compare knowledge status and gaps on the species in the region. While this analysis reveals the existence of considerable knowledge between and within the species, lack of improved germplasm and markets emerge as two key constraints limiting their conservation through on-farm planting. Key research and development needs identified are: (a) fostering cross-collaboration and knowledge exchange with other regions where the species are fairly well utilized, and (b) developing criteria and indicators for monitoring impacts and increased investments on the “Big Five” on livelihood of dryland communities and on biodiversity conservation.

Boserup versus Malthus revisited: Evolution of farming systems in northern Côte d’Ivoire

In the literature on the evolution of farming systems in Sub-Saharan Africa, the theses of Malthus and Boserup seem to offer contrasting views on rural development. The purpose of the present study is to revisit these theses and empirically examine them through a case study of northern Côte d’Ivoire. We surveyed a sample of farms in four villages in the Dikodougou region during three agricultural seasons. The villages mainly differ regarding their population density and historical genesis. Comparative analysis of the villages and farm types identifies population pressure as a key factor of the evolution of farming systems in this region. Our empirical analysis shows that Boserupian and Malthusian processes coexist, rather than contrast. Through mechanisation and intensification, Boserupian innovation has been largely able to compensate for the Malthusian repercussions of increasing population pressure. However, in a first stage demographic pressure engenders migration, i.e. Malthusian population control, rather than Boserupian mechanisms of induced innovation, which seem to be unleashed after a critical population density is attained.

Biological Capital, User Costs and the Productivity of Insecticides in Cotton Farming Systems in Sub-Saharan Africa

This study presents a conceptual framework and then uses field data collected in cotton fields of Côte d'Ivoire to illustrate the dynamics of the interaction between insecticides use, natural biological capital and the productivity of insecticides over time. Results show that the divergence between insecticide productivity estimates on one hand and, public concern that insecticides are overused on the other hand may not be attributed exclusively to functional specification of estimation models. However, some insights into resolving the paradox can be gained through disaggregation of the estimates (e.g. by chemical use history) and interpreting them in the context of the inter-temporal changes that have occurred in the biological capital of production systems over time. A disaggregation of the marginal value products of insecticide by chemical use history shows that in the zones where insecticides have been used for a longer period and crop diversity is narrower, the marginal value products of insecticides are consistently higher due to lower biodiversity which raises the economic importance of the chemical in such zones. To ensure long term sustainability of cotton in the region, the study recommends the promotion of targeted insecticide management practices that takes cognisance of the differences in the amount of biological capital and the economic value of the potential crop yield that would be saved by the chemical application in the different production systems. It also recommends that panel data consisting of entomological and the state of the agro-ecosystem being studied should be collected concurrently with agro-economic data and integrated into models for estimating insecticides’ productivity.

Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: I. The plant component under semi-permanent cultivation

Organic matter (OM) is both a commodity and a means of production in low-input farming systems of sub-Saharan Africa. Since this resource is becoming increasingly scarce in West African savannas (WAS), there is a need to assess OM, carbon (C), nitrogen (N), and phosphorus (P) allocation in local ecosystems related to land management. Carbon, N and P storage under semi-permanent cultivation in savannas in southern Senegal was thus measured through a chronosequence including 25 groundnut ( Arachis hypogaea L.) crops and plots left to fallow for 1–26 years. The amounts of C, N and P in cropped plots were 5.5 t C, 106 kg N and 5.9 kg P ha −1, they increased to 17.7 t C, 231 kg N and 19.6 kg P ha −1 in fallow plots aged 1–9 years. A threshold was reached after 10 years of fallow. Beyond it biomass amounts remained steady. Older fallow plots stored 29 t C, 333 kg N and 33.8 kg P ha −1. Highest increases in woody components were found within the very first year following crop abandonment, and were achieved at the expense of the herbaceous layer. Carbon and nutrient allocation to woody below-ground biomass occurred only later. Massive nutrient losses were expected to occur at clearing due to both burning and wood exportation. Because storage in woody and herbaceous biomass remained steady in fallows aged more then 10 years, young fallows were found to have the highest productivity for wood and forage. However, plant productivity relied on the high resprouting capacity of local tree species, and thus on the maintenance of long breaks of fallow needed for the maintenance of perennial rooting systems. One of the aims of programs to improve the management of fallows, or to replace them with agroforestry techniques, should thus be to preserve perennial rooting systems by any means that are possible in the cropping systems of the WAS.

Implications of livestock feeding management on soil fertility in the smallholder farming systems of sub-Saharan Africa

The role of livestock in nitrogen cycling in mixed crop–livestock farming systems of sub-Saharan Africa was explored. Cattle were fed a range of diets to investigate the effects on partitioning of nitrogen between urine and faeces and on the chemical composition of the manures produced. The trade-offs in efficiency between using the feed resources as a direct soil amendment for crop production compared with feeding to livestock and use of the manure as a fertiliser are discussed. Increased dry matter (DM) and nitrogen intake of a poor quality basal diet (barley straw) was achieved by supplementation with 15 and 30% of DM offered as Calliandra calothyrsus, Macrotyloma axillare or poultry manure. Urinary-N excretion for the basal diet (0.5 mg kg −1 liveweight (W) per day) was similar to C. calothyrsus at 15 and 30% supplementation (1.3 and 0.8 mg kg −1 W per day, respectively) and M. axillare at 15 and 30% supplementation (0.4 and 0.6 mg kg −1 W per day, respectively). In contrast, feeding poultry manure, a supplement containing highly degradable N, resulted in larger excretions of excess rumen ammonia as N in the urine, 17.5 and 23.2 mg kg −1 W per day for 15 and 30% supplementation, respectively. Diets containing the largest rate of C. calothyrsus supplementation had the lowest digestibility of N in the acid detergent fibre (ADF) and neutral detergent fibre (NDF) fractions. This was reflected in faeces from cattle fed diets supplemented with C. calothyrsus, which had substantially greater amounts of N bound to fibre (ADF and NDF) fractions than faeces from the other diets. When incubated in leaching tubes prunings of C. calothyrsus showed net N mineralisation from week 2, whereas barley straw, M. axillare and poultry manure immobilised N for >28, 24 and >28 weeks, respectively. Faeces derived from supplementation with C. calothyrsus and M. axillare resulted in shorter nitrogen immobilisation in leaching tubes (16 weeks) than supplementation with poultry manure (24 weeks) when compared with faeces derived from animals fed straw only (28 weeks). Similarly, reduced N uptake from 10-week-old maize plants was observed in pots to which faeces had been added compared with the control treatment. A second crop of maize had increased N uptake. Feeding poor quality crop residues like barley straw to animals produces manures with a decreased capacity to immobilise mineral N in the soil. This was shown with faeces derived from feeding ruminants a diet of only barley straw, which had a faster N mineralisation rate than fresh barley straw, a shorter and smaller N immobilisation stage in leaching tubes and gave greater N uptake in maize grown in pots. These results indicate that N losses in urine from livestock may be less important than previously thought. Most of the N is excreted in the faeces, which must be conserved and managed to maximise nutrient cycling.

Soil fertility and crop yields under improved-fallow systems in southern Mali

Improved fallows involving short-rotation woody and/or other perennial species are increasingly being tried as a means of sustaining crop production in impoverished farming systems of sub-Saharan Africa. The soil-improving potential of two tree species [Gliricidia sepium (gliricidia) and Pteocarpus erinaceus (pterocarpus)] and a shrubby legume Stylosanthes hamata (stylosanthes) was investigated in a four-year study on farmer's field and in a research station in the Koutiala region in southern Mali (12.25° N, 5.42° W; 650 to 850 mm annual, unimodal rainfall; on a Typic Plinthustalf). Two strategies for soil improvement were tested: improved fallow sensu stricto and biomass transfer, the former ‘on-farm’ and the latter ‘on-station.’ In the on-farm experiment, maize (Zea mays) yielded best when it followed a two-year fallow of gliricidia alone or in association with stylosanthes. On the research station, maize dry matter production and grain yields during two seasons following the application of ex-situ grown biomass were similar and highest in the stylosanthes- and manure-applied treatments. The biomass decomposition rates of the three species were in the order: gliricidia > stylosanthes > pterocarpus. The treatments did not have any significant effects on the soil fertility parameters that were monitored, possibly because of the short-term nature of the study. The treatments effects on crop yields were, however, significant. Gliricidia + stylosanthes in combination appeared to be particularly promising as short-rotation-fallow species in the region.

The evolution of farming systems in Northern Côte d'Ivoire : Boserup versus Malthus and competition versus complementarity

A socio-economic analysis of a sample of farms in Northern Cote d'Ivoire revisits two debates about the evolution of farming systems in sub-Saharan Africa. Taking into account the diversity of farming systems, the debates Boserup vs. Malthus and competition vs. complementarity between cotton and food crops become better informed and less straightforward. (Resume d'auteur)

Evolution des systèmes agraires dans le nord de la Côte d'Ivoire : les débats "Boserup versus Malthus" et "Compétition versus complémentaire" revisités

Une analyse socio-economique sur les exploitations agricoles dans quatre villages de la region de Dikodougou (nord de la Cote d'Ivoire) permet de nuancer deux debats sur l'evolution des systemes agraires en Afrique subsaharienne. Premierement, les deux points de vue de la controverse «Boserup versus Malthus» se completent plus qu'elles s'opposent. Dans une premiere phase, l'accroissement demographique enclenche bien des mecanismes malthusiens (enherbement, degradation du milieu biophysique, de la fertilite globale et de la rentabilite du systeme de production traditionnel) creant ainsi des conditions propices a l'adoption de la traction animale. Dans une deuxieme phase, le changement du systeme de production illustre bien la reponse boserupienne a une situation ou le systeme traditionnel ne repond plus aux nouvelles conditions socioeconomiques. Deuxiemement, l'analyse economique propose a nuancer le debat «competition versus complementarite» entre le coton et les cultures vivrieres. La these de competition semble seulement valable pour les exploitations non mecanisees, ou le coton rentre en competition avec les cultures vivrieres quant a la force de travail. Cependant, la deuxieme phase de l'evolution des systemes de production (utilisation d'intrants, passage de la culture manuelle vers la culture attelee) est possible grâce aux conditions favorables (acces aux intrants, aux credits et au savoir-faire) creees par la CIDT (Compagnie Ivoirienne de Developpement des Textiles). (Resume d'auteur)

Development patterns under population pressure: Agricultural development and the cassava-livestock interaction in smallholder farming systems in Sub-Saharan Africa

This paper identifies the pathways along which smallholder farming systems evolve in a context of population pressure in the cassava producing zones of Sub-Saharan Africa. The analysis indicates the existence of the cassava-livestock interaction. Particularly the use of cassava roots by pigs is important. Generally, two alternative development paths can be observed. Land scarcity induced by population growth is the driving force behind them. For countries like Ivory Coast and Ghana, intensification of arable crop production including cassava is prevalent while in the East African countries, mixed crop (cassava)-livestock systems are emerging. The case of Nigeria is peculiar as farming systems evolve along both pathways. In the absence of population pressure and land scarcity extensive crop production systems evolve, as in Zaire. It is concluded that emphasis should be placed on institutional support and research that will encourage the productivity and sustainability of either systems. In Nigeria both policy strategies may have to be adopted.

Some animal-related factors influencing the cycling of nitrogen in mixed farming systems in sub-Saharan Africa

In sub-Saharan Africa the importance of nutrient cycling in mixed farming systems is poorly understood, and there is a paucity of information in the literature. The vital role played by livestock in regulating fluxes through nutrient cycles is often ignored in experimentation and crop modelling although, in farming practice, the animal is an integral part of the system. The aim of this review is to highlight animal-related factors which can influence the dynamics of nitrogen (N) cycling in mixed farming systems on the sub-continent. Marked changes in seasonal feed availability and nutritive value occur which affect both the quantity and quality of excreta. The partition of N excretion between urine and faeces can also fluctuate widely with changes in diet composition, and may be influenced by the degradability of the dietary protein in the rumen. The presence of tannins in feeds has been shown to be negatively correlated with protein degradability and digestibility. Different species and classes of livestock produce excreta with varying nutrient concentrations. By controlling animal movements, adjusting carrying capacity in a grazing situation, or storing and distributing excreta from animals kept in confinement, a farmer can influence the proportions of nutrients returned to the soil. Losses of nutrients in storage and on application can be appreciable. The management of the soil and the returned nutrients will determine the losses incurred after application and the quantity potentially available to the crop. The farmer will also decide on the crops to be grown and their management. Crops differ in their nutrient requirements and the efficiency of utilisation. The partition of nutrients between grain and the vegetative parts of the plant affect the nutritive value of the components. When residues are grazed in situ, consumption will depend on animal numbers and the length of time spent grazing. Animals select preferred plant parts, and appreciable losses due to trampling and soiling may occur. The many factors influencing nutrient cycling provide opportunities for decision-making by the farmer. This process can be helped by mathematical modelling where the effects of different management options can be simulated. In taking account of animal-related factors, more realistic simulation models can be developed for the study of crop production in mixed farming systems in sub-Saharan Africa.

Economics of the Family and Farming Systems in Sub-Saharan Africa: Development Perspectives

Economics of the Family and Farming Systems in Sub-Saharan Africa: Development Perspectives

Agricultural Mechanization and the Evolution of Farming Systems in Sub-Saharan Africa. Edited by Pingali Prabhu, Bigot Yves and Hans P. Binswanger. The Johns Hopkins University Press (1987), pp. 216, £22.95.

Agricultural Mechanization and the Evolution of Farming Systems in Sub-Saharan Africa. Edited by Pingali Prabhu, Bigot Yves and Hans P. Binswanger. The Johns Hopkins University Press (1987), pp. 216, £22.95. - Volume 25 Issue 4