Farmers’ Motivation and Biophysical Impact of using Cordia africana and Albizia coriaria on Coffee-Bean Intercrops in the Mt Elgon Region (Uganda)
Date
2021
Authors
Buyinza, Joel
Editors
Advisors
Nuberg, Ian
Denton, Matthew
Muthuri, Catherine
Denton, Matthew
Muthuri, Catherine
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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.
School/Discipline
School of Agriculture, Food and Wine
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2021
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