Infrastructural services including roads, electricity, telecommunications and irrigation,
are all considered to be of major importance in stimulating agricultural investment
and growth. However, their existence is still very limited in most rural areas of many
developing countries. Whilst there exist much information in the scientific and grey
literature on the issues relating to infrastructural impacts on agricultural development,
there is no recent, objective, and independent review of the available evidence. The
research question for this systematic review was therefore to assess “What is the
impact of infrastructural investments in roads, electricity and irrigation on agricultural
This systematic review summarises the research objectives, approaches and methods,
including the search criteria, data sources, search and extraction strategies, data
synthesis, analysis and interpretation. The systematic review principally focussed on
four main areas (i) road infrastructure (incorporating road networks and transport
vehicles) and its impact on farmer access to agricultural markets; (ii) rural electricity
supplies (consumption and expenditure) and its impact on agricultural productivity
(irrigation, storage, cooling/refrigeration), product price, labour wages and rural GDP;
(iii) telecommunications (telephones and internet) and its impact on crop prices,
response to market demands, feed and fertilizer supply and costs, and (iv) irrigation
infrastructure (incorporating water storage capacity per unit area, access to water and
expansion of irrigated areas) and its impact on crop diversity, crop productivity
(yield), crop prices, labour costs, rural consumption and returns of irrigation
investment to the rural community and poverty reduction.
Following definition of suitable search terms and study inclusion/exclusion criteria, a
detailed search of available evidence was completed using a range of scientific
bibliographic sources and internet websites. In total, 934 articles were identified, and
then screened by title and abstract to provide a final listing of 155 articles and reports.
These were imported into Refworks and analysed. Data were presented on the basis of
a narrative synthesis but supported by quantitative analysis, based on an aggregation
of reported observations and using simple impact assessment classification (positive
impact, neutral impact and negative impact). An attempt was made to undertake some
meta-analysis based on 307 observations, but this was not possible given the wide
range of units reported in the literature, even within a particular impact indicator, and
the impact of various ‘effect modifiers’.
A narrative synthesis by infrastructural impact was therefore completed first, with
evidence aggregated by country, where possible. Tables summarising the reported
effects on agricultural productivity were produced for a range of productivity/output
indicators. Next, a quantitative analysis using the 307 ‘observations’ was completed.
From the evidence, it was apparent that a wide range of indicators had been used to
assess the impact of investment in rural infrastructure on agricultural productivity.
These were categorised into 9 main classes (i) agricultural productivity (measures of
crop yield and output per unit area), (ii) consumption (measures of rural consumption
and expenditure), (iii) GDP (measures of changes in total or rural GDP), (iv) income
(measures of rural income, crop revenues and gross margins), (v) inputs (measures
prices, demand, use and supply of agricultural inputs including seeds, fertilisers, fuel,
labour and high yielding varieties (HYVs)), (vi) labour (measures of rural
employment and wages), (vii) poverty (measures of the number of people in poverty,
(viii) prices (measures of process of agricultural outputs) and (ix) production
(measures of the quantity of production of crops and livestock).
For road infrastructure, most evidence (37% observations) related to this investment,
with the majority of reported impacts on agricultural productivity being positive,
particularly in relation to GDP gains and poverty reduction. For electricity
infrastructure, there was limited evidence (16% observations) but again positive,
especially for poverty reduction. For telecommunication infrastructure, there was very
limited evidence (6% observations) but the majority were positive. The impacts for
this area are most likely to be mixed in with other forms of infrastructural investment.
Finally, for irrigation infrastructure, a third of all evidence related to this aspect, with
the majority of impacts on agricultural productivity being positive, especially in
relation to income and poverty reduction. The SR also identified some important gaps
in knowledge on the direct impacts of investment in electricity and
telecommunications infrastructure on agricultural productivity, and a number of
methodological limitations due to ‘effect modifiers’. This may not be surprising given
that these types of investment are difficult to examine in isolation. Finally, the review
has generated significant new aggregated data on infrastructural impacts on
agricultural productivity which should be of broad international relevance to those
engaged in assessments of agricultural and rural development.
rural; infrastructure; roads, transport; electricity; irrigation; agriculture; productivity; crop; yield
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