Growing rice under stressed water availability: an economic evaluation of irrigation technologies in Kilombero sub-basin
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Date
2024
Authors
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Publisher
Sokoine University of Agriculture
Abstract
Growing rice in Tanzania’s major basins is threatened by climate
change impacts. It is projected that rice yield will fall by 7.6% in
these major basins in aggregate. Climate change impacts in
Tanzania’s major basins including Kilombero sub-basin (KSB)
which is the biggest feeder of Rufiji basin is attributed to increasing
temperature which accelerates surface evaporation. There is also
increased water demand due expanding agriculture, influx of
livestock and water for hydropower generation. Climate change
impacts and increasing water demand in the sub-basin have called
for planned and sustainable use of water. One of the implemented
techniques is the new adaptive rice growing technologies. Irrigation
technologies like traditional flooding irrigation technology (TFIT) for
rice farming that exposes water to surface evaporation is no longer
a viable adaptation technology for growing rice under stressed
water availability from scientific point of view. Alternatively, the
system of rice intensification (SRI) irrigation has recently been
encouraged in KSB by the Ministry of Agriculture (MoA) to reduce
water loss through surface evaporation through controlled water
usage. However, 90% of rice irrigable land in KSB is still under
flooding irrigation which is inefficient in use of water.
From literature there is enough evidence in agronomic point of view
that SRI irrigation is more water use efficient than TFIT but
information on their economic efficiency at household level
especially in KSB is not readily available. This study was
conducted in Kilombero district to evaluate the profitability of TFIT
and SRI irrigation technologies and the determinants of profitability
of the two irrigation technologies and; factors that determine the
choice of rice irrigation technology in KSB. Data were collected
through Focus Group Discussions (FGDs), Key Informant Interview
(KIIs) and household survey that involved 100 households. The
study used farm budget method to evaluate profitability (Net
Revenue) of rice produced under SRI and TFIT. From Net Revenue (NR) obtained, profitability determinants were
evaluated using multiple linear regressions. This represented first
published paper on the economics of the irrigation technologies.
Furthermore, this study used the reduced household model to
evaluate factors that motivate farming households to decide on the
type of rice irrigation technology and allocation of production
resources between the two technologies in situ SRI and TFIT which
is the second published paper.
The findings from first published paper (on economics of SRI
irrigation and TFIT) have shown that on average rice production
costs per acre are TZS 471 572.5 and 248 939.9 for SRI and TFIT
respectively. Also, the study found that on average farming
households practicing SRI and TFIT produce 1268 and 608 Kgs of
threshed rice respectively per acre. Adding on that the average NR
per acre under TFIT and SRI were TZS 902 236 and 1 276 841
respectively, indicating that SRI irrigation was more profitable than
TFIT. Despite being more profitable, the findings have shown that
SRI is more labour intensive than TFIT; a farming household
practicing SRI needs to supply an average of 23 man-days per
acre per season while a household practicing TFIT has to supply
14 man-days per acre per season. On one hand, the study found
that farming experience, farm size, fertilizer application, agricultural
supporting services like capital assistance and high frequency of
extension visits positively and statistically influenced the profitability
of both SRI and TFIT but differed in magnitudes for example each
increment in extension visit caused a TZS 169 000 increase in SRI
compared to TZS 101 000 in TFIT ceteris paribus. One of the
notable recommendations from the findings is that the subsidization
to industrial fertilizers is the viable option by the MoA to benefit rice
farmers who irrigate using SRI principles and traditionally. Also
increasing extension officers is important especially in areas found
with inadequacy like Sululu.
Description
Disertation
Keywords
Sub-Basin, Irrigation Technologies, Kilombero and Farming Households, Growing rice, Climate change impacts