Cashew cultivation is a vital economic driver for smallholder farmers in northern Côte d’Ivoire, contributing to improved livelihoods. However, the widespread adoption of monoculture cropping has raised environmental concerns, particularly regarding ecosystem degradation, soil depletion, and the long-term sustainability of cashew production. To mitigate climate risks and ensure the resilience of cashew orchards, crop diversification presents a viable alternative to monoculture cultivation. This study aimed to develop evidence-based diversification strategies for cashew farming in northern Côte d’Ivoire. Findings indicate that cashew plantation ownership is predominantly male, with men representing 90.3% of the sector. Plantation ages range from 6.2 to 21.7 years. Some farmers incorporate annual crops—such as maize (Zea mays), groundnuts (Arachis hypogaea), and yams (Dioscorea alata)—within their cashew plantations. Additionally, tree species like Vitellaria paradoxa (Shea, 51.9%), Parkia biglobosa (Néré, 45.7%), and Mangifera indica (Mango, 34.1%) are retained in orchards for their socio-ecological benefits, including income generation, food security, and medicinal uses. Through farmer interviews and field studies, the research identified 40 plant species integrated into cashew orchards, with nine species preferred by farmers, particularly V. paradoxa and P. biglobosa. The study outlines key strategies for diversifying cashew cropping systems: (i) developing mixed cashew/food crop systems (e.g., maize and yam) using good agricultural practices, (ii) promoting parkland-based cashew agroforestry systems featuring V. paradoxa, P. biglobosa, and M. indica as intercrops, and (iii) creating a conducive environment to facilitate the agroecological transition within the cashew sector. These approaches aim to enhance sustainability while ensuring continued productivity and resilience in cashew farming.
Tag: monoculture
The utility of process-based models for simulating N2O emissions from soils: A case study based on Costa Rican coffee plantations
Soil moisture and gaseous N-flux (N2O, N-2) dynamics in Costa Rican coffee plantations were successively simulated using a mechanistic model (PASTIS) and two process-based models (NGAS and NOE). Two fertilized (250 kg N ha(-1) y(-1)) coffee plantations were considered, namely a monoculture and a system shaded by the N-2 fixing legume species Inga densiflora. In situ N2O fluxes were previously measured in these plantations. NGAS and NOE used specific microbial activities for the soils. To parameterize NGAS, we estimated N mineralization via in situ incubations and the contribution of heterotrophic soil respiration to total soil respiration. Potential denitrification rates and the proportion of denitrified N emitted as N2O were measured in the laboratory to define the values of NOE parameters, as well as nitrification rates and related N2O production rates for parameterizing both models. Soil moisture and both NGAS and NOE N2O fluxes were best modelled on an hourly time step. Soil moisture dynamics were satisfactorily simulated by PASTIS. Simulated N2O fluxes by both NGAS and NOE (3.2 and 2.1 kg N ha(-1) y(-1) for NGAS; 7.1 and 3.7 kg N ha(-1) y(-1) for NOE, for the monoculture and shaded plantations respectively) were within a factor of about 2 of the observed annual fluxes (4.3 and 5.8 kg N ha(-1) y(-1), for the monoculture and shaded plantations respectively). Statistical indicators of association and coincidence between simulated and measured values were satisfactory for both models. Nevertheless, the two models differed greatly in describing the nitrification and denitrification processes. Some of the algorithms in the model NGAS were apparently not applicable to these tropical acidic Andosols. Therefore, more detailed information about microbial processes in different agroecosystems would be needed, notably if process-oriented models were to be used for testing strategies for mitigating N2O emissions. (C) 2009 Elsevier Ltd. All rights reserved.
Pest outbreaks in tropical forest plantations: is there a greater risk for exotic tree species?
In the context of the ongoing expansion of forest plantations of exotic tree species in the tropics, a critical assessment was made of the risk of insect pest outbreaks in exotics. To date, there have been two opposing views: that plantations of exotic species are at greater risk compared to indigenous species and conversely, that exotics are at lesser risk. Both views rest on theoretical arguments. In this study, an empirical approach was used to address the issue. For nine most commonly planted species in the tropics, the pest problems in natural forest stands, in countries in which the species are indigenous (native plantations), and in exotic plantations were compared. The species chosen were Acacia mangium, Eucalyptus spp., Gmelina arborea, Hevea brasiliensis, Leucaena leucocephala, Paraserianthes falcataria, Pinus caribaea, Swietenia macrophylla and Tectona grandis. The results showed that: (1) monoculture itself caused an increase in the pest problems; and (2) the pest risk of exotics was variable, for some species similar to that of native plantations, while greater or lesser for others. The risk of pest outbreak is therefore not solely dependent on the exotic or indigenous status of a species. Empirical results also showed that pest outbreaks occurred in native plantations. The theory relating to insect population dynamics and causes of pest outbreaks is discussed and based on a mix of empirical evidence and theory. It is concluded that the following factors determine the risk of pest outbreak in exotic monoculture plantations: (1) presence or absence of plant species closely related to the exotic; (2) extent of area under the exotic species; (3) genetic base of the planted stock; (4) distance from the native habitat of the exotic; (5) existence of serious pests in the native habitat of the exotic; (6) time elapsed since introduction; (7) chemical profile of the exotic species; and (8) innate biological attributes of the insects associated with a tree species. The overall conclusion from this study is that while all monoculture plantations are at greater risk of pest outbreaks than natural forests, plantations of exotics are at no greater risk than plantations of indigenous species. It should be possible to develop a pest risk rating system for different tree species for different locations, based on these criteria.
Botryosphaeriaceae disease complex: a threat to baobab and marula in agroforestry systems in Kenya
Sesbania tree fallows on phosphorus-deficient sites: Maize yield and financial benefit
Rotation of Sesbania sesban (L.) Merr., a fast-growing N2-fixing tree, with maize (Zea mays L.) has potential for increasing fertility of tropical soils, where fertilizer use by resource-poor farmers is limited. At two sites in Kenya (Ochinga, with a Kandiudalfic Eutrudox soil, and Muange, with a Kandic Paleustalf), we compared maize yields and financial returns for (i) sesbania grown for three or four seasons followed by three maize crops (sesbania fallow), (ii) one maize crop followed by natural regrowth of vegetation for three seasons and then three maize crops (natural fallow), and (iii) maize monoculture for seven seasons. After the fallows, plots were split with and without added P. Maize responded to P at both sites. Cumulative grain yields for seven seasons of maize monoculture were 8.4 Mg ha1 at Ochinga and 5.6 Mg ha1 at Muange. They were comparable to cumulative maize yields for sesbania fallow (Ochinga, 10.6 Mg ha1 Muange, 4.5 Mg ha1) and natural fallow (Ochinga, 7.7 Mg ha1; Muange, 4.2 Mg ha1), even though maize was grown for only three or four seasons in the fallow treatments. Sesbania fallow was financially attractive at Ochinga (500 mm rain in each season) but not at Muange, where low rainfall (<300 mm in each posffallow season) limited maize yield. Phosphorus fertilization of maize at Ochinga increased (P < 0.2) net benefit for sesbania fallow. Improved fallows have potential to supply nutrients to crops, but they are unlikely to eliminate the need for P fertilizers on P-deficient soils.
Adopt and learn: modelling how decisions are made and the flow of information
Adopt and Learn is a simple model of an ‘adoption’ process. It explores how farmers learn of new technology or information and eventually make a decision to adopt or not. The model is useful for understanding factors influencing the success or failure of a technology-dissemination project, including the role of extension agents. The model works at community scale with a diversity of agents and their multiple learning styles
Harnessing the potential of agroforestry to boost yields and strengthen food security in Rwanda
Rwanda’s national agricultural policy seeks to promote the transformation of Rwanda’s agriculture from subsistence agriculture to market-based agriculture through highly intensified farming systems. However, low productivity of major staple crops on the country’s smallholder farms remains a key obstacle in achieving this goal. The country’s dense and rapidly growing population (currently at 416 people per km2 with an annual growth rate of 2.6 percent), puts pressure on existing land. Strategies to increase land productivity have become imperative.Agroforestry is a traditional farming practice that integrates trees into farming systems. The Government has been promoting agroforestry as an option for sustainable agricultural intensification in Rwanda. However, the adoption by farmers has been slow. By integrating trees with their crops, Rwandan farmers can obtain tree products e.g. fuelwood, timber, poles, stakes for climbing beans, fodder, fruits and services like improve the fertility of their soils, control soil erosion, protect biodiversity, diversify their incomes and reduce poverty.This policy brief is based on a review of Rwanda’s policy context with respect to agroforestry and identifies ways and means through which agroforestry adoption can be accelerated on a sustainable level.
Scattered shade trees improve low-input smallholder Arabica coffee productivity in the Northern Lake Kivu region of Rwanda
In suboptimal conditions for coffee growth, the use of shade tree is usually considered beneficial to production. This study aimed to evaluate this benefit in the poorly documented East African smallholder Arabica coffee systems in optimal climatic but suboptimal management conditions. In a 4 year observational trial in 50 coffee farms, the association of shade trees and coffee generated an average 55 % cherry production increase. Neither delay in berry maturation nor buffer in alternate bearing patterns were observed, probably due to the low productivity of unfertilized coffee plants. Quality wise, the presence of shade trees did not result in an increase of larger green beans, but it reduced the proportion of altered and lighter cherries in 2009, a low production year. A shade species effect was detected through the positive influence of two non-leguminous shade trees, Persea americana and Ficus thonningii on production. The effect was correlated to greater canopy openness and increase in K soil content. In general, soil mineral content was not influenced by the presence of trees, but the legume species Inga oerstediana appeared responsible for a slight increase of total C and N soil content. It is concluded that in the small holder context of the Northern Lake Kivu region, the association of mature trees is beneficial to coffee production and can contribute to the improvement of producer’s income.
Agroforestry for Livelihoods of Smallholder Farmers in Northwest Vietnam – Research in Development
In Northwest Vietnam, rain-fed crop cultivation is dominated by monoculture maize,upland rice and cassava on sloping lands. The loss of topsoil during the rainy season leadsto a depletion of soil fertility and plant nutrients leading to reduction in crop yield. Farmershave to invest heavily in chemical fertilisers for the maize to remain productive comparedto the past. Harsh weather conditions also reduce yields or even lead to crop loss and makesoil and water conservation more difficult.The project has introduced trees in mono-cropped landscapes through agroforestry toreduce dependence on annual crops, as well as increase and diversifies incomes from treeproducts, while also conserving the natural resource base. The research approach combineddifferent activities, which support each other to be possible bring valuable researchresults to apply to reality. The agroforestry systems were designed through participatorywhich the scientific knowledge and local knowledge are combined. These established trialsare evaluated to find out the suitable options. The add value for agroforestry adoptionalso involved research on propagation of priority agroforestry species, small-scale nurserydevelopment, research and transfer processing techniques, exploring value-adding opportunitiesby smallholders and facilitating links between producers and other market actors.The research findings were spread through farm cross-visits, farmer field days and trainingsessions held at the test sites, accompanied by regular impact assessments. In addition,these findings were used to inform the communication strategies, policy dialogues, extensionand expansion activities through workshops, media products, extension materials andtraining. To promote the agroforestry adoption, the project has been developed at threelevels: Participatory Farmer Trials, Farmer Demonstration Trials and Exemplar Landscapeswhere the scientific knowledge and local knowledge are combined and utilised. Thisapproach is primarily based on the classic extension and dissemination theories, but highlightsthe important elements of collective action and social capital development amongfarmers, and between extension workers, local governments and researchers. The resultshave been found useful in demonstrating farmer adoption of agroforestry practices anddeveloping value chains and market linkages in varying contexts, and they support thelocal governments to define strategy development through policy interventions.
Competition for light in heterogeneous canopies: Application of MAESTRA to a coffee (Coffea arabica L.) agroforestry system
In agroforestry systems (AFS), quantifying the competition for light is a prerequisite toward understanding the impact of shade trees on the productivity of the under-cropModels for homogeneous canopies and shade/full-sun approaches do not address the intra-plot heterogeneity, typical of AFS. For the first time, MAESTRA, a 3D light absorption model, was fully parameterized in a heterogeneous 2-canopy layers AFS. We quantified competition for photosynthetic photon flux density (Q) between shade trees (Erythrina poepiggiana) and coffee (Coffea arabica), with a spatial resolution from the plant to the plot (2.7 ha) and a temporal resolution from half-hour to one full year. The predicted transmittance through the 2-canopy layers was verified against field measurements. The goodness of fit (R2 > 0.75, RRMSE < 26%) was comparable to the predictions from 10 other studies using 3D light models and mostly verified in one-layered systems (mean R2 = 0.89 and mean RRMSE = 17%). Maps of absorbed Q showed that despite their low density in the plot (5.2 trees ha-1), the tall Erythrina trees reduced Q available for the coffee layer by 14% annually. Annual pruning of the oldest unproductive coffee resprouts maintained a large horizontal heterogeneity in coffee LAI, with direct impact on the Q absorption mapThis management practice had a strong impact on seasonal variations of absorbed Q by the coffee canopy. We proposed also a simple approach to estimate Q absorbed yearly by the coffee plants in AFS of variable tree density, requiring only few measurements in the field. An extrapolation indicated that the amount of Q absorbed by the coffee canopy would display a negative exponential relationship (k = -0.34) when increasing shade tree density (from nil to 29 trees ha-1). The estimated k was similar to the shade tree extinction coefficient of diffuse radiation measured with a plant canopy analyzer. We showed that the presence of shade trees tends to reverse the diurnal time course of the fraction of Qa when compared to a plantation in the open. Overall, MAESTRA proved to successfully unlock the question of intra-plot heterogeneity for light absorption and to provide defensible light budgets as a continuous and mapped covariable, a crucial step for many field experimentations.