Agroforestry's contribution to livelihoods and carbon sequestration in East Africa: A systematic review

Agroforestry is a powerful practice for sustainable and regenerative intensification because it promotes multifunctional landscapes that deliver ecological functions that contribute to livelihoods, land productivity, biodiversity conservation, and other ecosystem services. Despite a large body of literature on agroforestry in East Africa, a systematic understanding of its livelihood benefits and contribution to carbon sequestration is still lacking. A systematic review was used to provide a quantitative and qualitative synthesis of available evidence and knowledge gap from 185 publications that met the selection criteria regarding the contribution of agroforestry to livelihoods (n = 152) and carbon sequestration (n = 43) in East Africa. The main livelihood benefits include fodder, food, firewood and income, reported in over 70, 63, 56 and 40 publications, respectively. These and other benefits diversify livelihoods of rural communities and act as safety nets in times of climate shocks. Agroforestry systems in East Africa stock an average of 24.2 +/- 2.8 Mg C ha-1 in biomass and 98.8 +/- 12.2 Mg C ha-1 in the soil. Much of the aboveground carbon is held in homegardens (34.3 +/- 7.9 Mg C ha-1), perennial treecrop systems (29.9 +/- 12.7 Mg C ha-1) and trees on boundaries (26.7 +/- 14.1 Mg C ha-1). Empirical studies are needed for better understanding of belowground carbon in agroforestry and emission of greenhouse gases in different agroforestry practices. A smaller number of studies reported income from sale of carbon credits, suggesting a gap in the development of science regarding carbon rights, land tenure, tree tenure rights, and the potential impact of climate change on the growing niches of tree species in the region. The results show that agroforestry is a powerful climate adaptation and mitigation solution as it can increase household resilience and sequesters significant amounts of carbon dioxide from the atmosphere

Climate change awareness and adaptation strategies by smallholder farmers in semi-arid areas of Zimbabwe

Agricultural production, food, nutrition and income security of smallholder farmers in sub-Saharan Africa are threatened by extreme weather events, such as increased frequency of mid-season dry spells and increased temperatures. Their impacts are exacerbated by the prevalence of sandy soils, characterized by limited water and nutrient retention capacity leading to low crop productivity. In this study, we aimed at assessing farmers' awareness of extreme weather events, identify adaptation strategies and evaluate maize yield from different soil fertility and water management practices. A household survey including 245 smallholder farmers in Marange, Zimbabwe was carried out. The results revealed that farmers were aware of and had experienced extreme weather events. Among adaptation strategies used were soil water-harvesting, use of improved varieties, mulching and planting trees. Maize yield remains significantly low, averaging 0.62 t ha-1 among farmers using some forms of soil fertility and water management strategies. To further understand the reason for low maize yields and improve climate change related adaptation strategies, more research is needed to quantify and confirm management practices applied by farmers, such as fertilizer use and rates, water and nutrient management, use of improved varieties as well as socio-economic factors

Waste recovered by-products can increase growth of grass-clover mixtures in low fertility soils and alter botanical and mineral nutrient composition

The effectiveness of four by-products (biogas digestate, pot ale, rockdust and wood ash) as fertilisers of a perennial ryegrass (Lolium perenne)-red clover (Trifolium pratense) mixture in terms of biomass production, botanical composition and macro- and micronutrient concentrations was tested in an outdoor pot trial. This was carried out over two growing seasons using two inherently low-fertility soils used for forage production. Macro- and micronutrients (N, P, K, Ca, Mg, Co, Cu, Mn, Mo and Zn) relevant for crops and livestock were determined in soils and plants. All the by-products increased overall biomass production and affected nutrient concentrations of the individual plant species to varying degrees. In addition the competitive balance between grass and clover was altered leading to different botanical composition in the different treatments and consequently differences in the nutrient concentrations of the species mixture. Changes were due to the nutrients applied in the by-products per se and/or to changes in the soil chemistry caused by the by-products. The results suggest a potential to enhance agricultural productivity through improved production and quality of forage on less fertile land by matching of by-products and soil properties

Effect of short-term perennial leys on life cycle environmental performance of cropping systems: An assessment based on data from a long-term field experiment

Modern agriculture's dependence on the intensive use of inputs, such as chemical fertiliser and pesticides, leads to high environmental impacts and, possibly, vulnerability in food security, since most of these inputs are im-ported from other countries. This calls for more sustainable and resilient agricultural practices. Diversification of crop rotations, e.g. by including perennial leys, enhances provision of ecosystem services, leading to healthier crops and increased yields. Perennial crops also increase soil organic carbon (SOC) stocks, which is interesting from a global warming mitigation perspective. In addition, legume-rich leys can utilise atmospheric nitrogen (N) through symbiotic association with N2-fixing bacteria. However, few studies have evaluated the effects of short-term perennial leys in rotation on cropping system performance over long periods and under different conditions. In this study, we used data from three sites in a long-term experiment in Sweden (initiated in the 1960 s), in combination with Life Cycle Assessment methodology, to assess the environmental and yield effect of including ley in crop rotations. Two N fertiliser regimes (High, Low) in combination with three six-year crop rotations, consisting of either i) two-year mixed grass-legume ley, ii) two-year pure grass ley or iii) annual crops without ley, were compared. Environmental impacts (climate impact, energy resource depletion, eutrophication poten-tial) of the different combinations were quantified per kg harvested crop (expressed in cereal units, CU) and per hectare. The lowest environmental impact, at all sites, was found for the crop rotation with two-year mixed ley under the Low N regime. On average, this combination resulted in 329 g lower GHG emissions per kg CU than the crop rotation without ley and Low N, primarily due to lower input of chemical N fertiliser, which reduced the impact from fertiliser production and soil N2O emissions. Comparison of mean SOC change over the study period revealed reduced SOC stocks for all rotations and all sites, especially in the rotation without ley. Therefore, including short-term perennial leys, especially leys containing legume species, in crop rotations can be a useful tool in meeting policy targets on reducing the environmental impacts of agriculture, and in reducing the dependence on purchased agricultural commodities. However, despite the potential benefits of rotational leys, the market demand for the produced ley biomass may be insufficient. Hence, incentives to increase demand are necessary to promote large-scale adoption, for example, for use in bioenergy production and feed

Appraisal of world reference base for soil resources - from a nordic point of view

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Enclosures in West Pokot, Kenya: Transforming land, livestock and livelihoods in drylands

Dryland livestock production systems are changing in many parts of the world, as a result of growing human populations and associated pressure on water and land. Based on a combination of social and natural science methods, we studied a 30-year transformation process from pastoralism to a livestock-based agro-pastoral system in northwestern Kenya, with the overall aim to increase the understanding of the ongoing transition towards intensified agro-pastoralist production systems in dryland East Africa. Key to this transformation was the use of enclosures for land rehabilitation, fodder production, and land and livestock management. Enclosures have more soil carbon and a higher vegetation cover than adjacent areas with open grazing. The level of adoption of enclosures as a management tool has been very high, and their use has enabled agricultural diversification, e.g. increased crop agriculture, poultry production and the inclusion of improved livestock. Following the use of enclosures, livelihoods have become less dependent on livestock migration, are increasingly directed towards agribusinesses and present new opportunities and constraints for women. These livelihood changes are closely associated with, and depend on, an ongoing privatization of land under different tenure regimes. The results indicate that the observed transformation provides opportunities for a pathway towards a sustainable livestock-based agro-pastoral system that could be valid in many dryland areas in East Africa. However, we also show that emergent risks of conflicts and inequalities in relation to land, triggered by the weakening of collective property rights, pose a threat to the sustainability of this pathway