Farmers’ Motivation and Biophysical Impact of using Cordia africana and Albizia coriaria on Coffee-Bean Intercrops in the Mt Elgon Region (Uganda)

Abstract

Farmers in developing countries are struggling to feed families due to low crop yields resulting from land degradation, land use pressures and unsustainable use of water resources. While deliberate integration of trees into farming systems (agroforestry) has been practiced traditionally in the Mt. Elgon region of Uganda since time immemorial, with modernisation of society and commercialisation of agriculture, many farmers are motivated to dismantle agroforestry systems in favour of monocultural farming systems. The science needed to improve agroforestry in the Mt Elgon region should focus on tree-crop water interactions because the competition for light and water is one of the main reasons that farmers remove trees in favour of annual crops. Additionally, long-term adoption of agroforestry has been negatively affected by an underlying culture of financial expectancy and highly subsidized extension by research and development programmes, leading to ‘pseudo adoption’. I contend that modernised agroforestry practices, informed by science generated in a participatory manner, have the promise of improving household food security, livelihoods and resilience. The study is aligned to a pragmatic interdisciplinary research approach to embrace the domains of both biophysical science (tree-water use and crop productivity studies) and social science (farmer motivations and perceptions). It generally demonstrates effective application‐oriented research and farmer decision-making, with a specific case of managing trees in a relevant agroforestry system. The study seeks to understand how farmers’ knowledge and attitudes towards agroforestry change in response to exposure to the generation of scientific information from biophysical experiments. The four central research questions for this research are: (i) what influences the intentions of smallholder farmers in Mt. Elgon region to plant and retain trees on their farms?; (ii) what factors influence farmers’ perceptions of the impact of trees on common bean and coffee productivity?; (iii) what are the impacts of trees and their management on crop productivity and water use across a range of farm contexts?, and; (iv) what is the impact of biophysical information on farmers’ perceptions about agroforestry tree management in coffee-bean systems? A conceptual framework integrating the biophysical and social components of the study has been developed to inform the key agricultural technology adoption pathways of smallholder farmers. The study had an initial phase of in-depth, semi-structured farmer interviews and generation of biophysical information on impact of tree canopy pruning on tree water use and crop productivity from two selected farms with Cordia africana and Albizia coriaria trees integrated with coffee and common beans. The information from the biophysical data (collected over a 20-month period) was then reported to farmers through a series of extension events that were followed by a second phase of farmer interviews. Lastly, all the data and information collected from the second phase of farmer interviews and the biophysical experiment were used to establish the potential impact of incorporating C. africana and A. coriaria on soil water resources and sustainable crops productivity that would result from farmer adoption of biophysical information. Results from the biophysical component of the study show that C. africana and A. coriaria exhibit contrasting patterns of seasonal tree water use across leaf shedding stages, characterised by episodes of reverse flow in A. coriaria at specific periods of the year. While tree canopy pruning altered the synchrony in the vegetative phenology of Albizia trees, the pruned Cordia and Albizia trees respectively used 22.8% and 50.1% less water than unpruned trees whose average daily water use was 76.5L day-1 and 133.7L day-1. Coffee trees growing under pruned Cordia and Albizia trees used more water than coffee growing under unpruned trees, which could have resulted from more transpiration pull in coffee resulting from increased radiation with reduced shading. Canopy pruning also reduced the water demand of the tree component and resulted in recharge in the crop-rooting zone. In terms of crop productivity, yields of parchment coffee were highest under pruned Albizia (949 kg/ha), followed by coffee under unpruned Albizia (792 kg/ha). Unshaded coffee produced the least yield at 402 kg/ha and 422 kg/ha in the Albizia and Cordia sites, respectively. The highest common beans yields (708 and 688 kg/ha) were obtained from common beans planted in open field sites, followed by those grown under unshaded coffee sites. The low yields from coffee and common beans under unpruned trees is attributed to below and above ground competition consistently outweighing the benefits of shade. The social component of the study applied a Structural Equation Modeling (SEM) technique to assess the psychological drivers of smallholder farmers’ intention and their motivation to integrate trees in their farming systems based on the Theory of Planned Behavior (TPB). The findings indicate that psychological factors are key drivers to the farmers’ internal decisionmaking process in agroforestry technology adoption and can be context specific. The adoption behaviour of smallholder farmers is mainly shaped by existing community social norms and beliefs that tend to promote knowledge exchange, as opposed to the conventional knowledge transfer extension approaches. While I provide evidence that attitude and perceived behavioural control are reliable predictors of farmer tree planting behaviour, farmer perceptions and knowledge of the impact of trees on farm and their management varies across the farmer categories studied, where the intended purpose of trees on farm is perceived differently. This study argues that bridging local and scientific knowledge through participatory research and extension is fundamental to enhance agricultural technology adoption among smallholder farmers. Therefore, the final phase of the study drew upon knowledge generated from biophysical component on impact of pruning on tree water use and crop productivity to assess farmers’ perceptions and willingness to adopt practices emanating from the study following exposure of 394 farmers to the research outputs. The extension events facilitated dialogue between the researcher and the farmers, and the results show that the information delivered through extension events was better understood by majority of the farmers directly interacting with the project. However, overall, only 184 farmers of the 394 participants (47%) were convinced that higher coffee yield could be obtained from shaded coffee. Therefore, over 50% of these farmers are still hesitant to change, as the majority of them prune their trees only when there is need for fuelwood and or poles. In the African context, agroforestry is strongly promoted via development projects, that provide incentives to farmers in form of free planting materials, tree nursery inputs and capacity building on planting and management of agroforestry components. There is always a likelihood that what appears as adoption is in fact trialling of the new practice, which masks actual longterm adoption. I therefore suggest that adoption information exchange through social networks and general community interactions may enhance long-term agroforestry adoption. These complex interaction processes should be applied at the early stages of technology adoption and would facilitate introduction of socially and biophysically appropriate agroforestry interventions into local realities. In conclusion, the results from the biophysical component of the study have demonstrated that agroforestry tree canopy pruning is an important on-farm management decision for controlling competition and subsequently increasing crop yields, while prolonging the period of intercropping in intensive farming systems. However, farmers may be hesitant to adopt such useful information due to an underlying culture of financial expectancy leading to ‘pseudo adoption’, underutilization of existing social networks during research and extension, limitations in the period of exposure to a technology, and constraints in measuring and predicting adoption. The study has generally demonstrated that adoption is not merely related to the technology, socio economic and behavioural factors, and the research and extension methods applied, but also a result of complex interactions between people, technologies and institutions. For effective extension, there needs to be a lot more visibility of the research itself and over a long period of time rather than the formal short-term interactions between farmers and extension agents. The impacts resulting from effective application-oriented research, understanding farmer decision making and successful adoption of biophysical information can be essential for informing policy decisions relating to agricultural technology adoption pathways of smallholder farmers and household food security.