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Can metal silo technology offer solution to
grain storage and food security problem in
developing countries? An Impact
evaluation from Kenya
Zachary M. Gitonga, Hugo de Groote, Kassie
Menale and Tadele Tefera
28th
International Conference of Agricultural Economics
Foz do Iguacu, Brazil, 1824 August 2012.
Published as:
Gitonga, Z.M., Hugo De Groote, Kassie Menale and Tadele Tefera. 2013. Measuring
the impact of metal silos on household maize storage and food security in Kenya
using propensity score matching. Food Policy 43:44-55.
Introduction
Introduction
 Farmers suffer huge losses due to insect
damage and poor storage.
 sell shortly after harvest at low prices
 Buy later in the market at higher prices
 Food insecurity and poverty cycle
 Many using storage facilities that do not
protect against storage pest
 Hermetically sealed Metal silo can kill
pest through oxygen deprivation w/o
pesticides
 Has worked in Latin America (Postcosecha)
 Elsalvador, Guatemala,Honduras, Nicaragus
 Impact of metal silo at farm level not
studied in ESA
Objectives
 We therefore evaluated the impact of
metal silos on:
 maize storage loss due to pests,
 cost of storage,
 duration of storage
 food security.
 Hypotheses:
 Households that use metal silos:
 incur negligible losses due to pests
 spend less on storage chemicals
 delay selling their maize,
 are more food secure than non adopters
Methods:
Sampling:
 Multi stage random sampling for control
 Sub-locations from KNBS & grouped according to AEZ
 Proportionate to size random sampling used to select
120 sub-locations across the six AEZ.
 a sampling frame of all households in each sub-location
 1468 household interviewed
 Same questionnaire used for adopters and non
adopters of metal silos
Impact evaluation
 Assessing the impact of metal silos requires
making an inference about the outcomes that
would have been observed for adopters had they
not adopted.
 Impact evaluation is a problem of missing data
 it is impossible to measure outcomes for someone in
two states of nature at the same time
 Propensity score matching technique used to
match adopters and non adopters on observable
characteristics
 Propensity score or balancing test used to check
for selection bias
Impact evaluation
 Sensitivity analysis conducted to check hidden
bias
 Endogenous switching regression used to check
the robustness of PSM results
 The model simultaneously estimates adoption and
outcome equations
 the estimated coefficients of correlation (rho) between
the adoption equation and the outcome equations not
significantly different from zero.
 unobserved factors did not influence the decision to
adopt metal silos.
 Results:
 Benefit of maize storage
 Embu is a maize deficit area
 Prices low in during harvest
time & high before next harvest
Harvest in Rift valley around
August but green maize in July
Results: Maize sale after storage
 adopters & non-adopters
sell within the first month
of harvest
 Non adopters sell more
soon after harvest at low
prices
 Adopters sell very little
initially
 Adopters sell more in the
fifth month
 to take advantage of
improved prices
The propensity to adopt
Variable Coef. Std. Err. P>z
Moist transitional 2.63 0.78 0.00
Moist mid altitude 3.24 0.79 0.00
Household size 0.05 0.04 0.24
Gender of the household head 0.37 0.38 0.33
Age of the household head 0.02 0.01 0.20
Literacy of the household head 1.08 0.53 0.04
Having mobile phone account 1.33 0.56 0.02
Having bank account 0.79 0.27 0.00
Total cultivated land 0.04 0.02 0.08
Hosting big social events 0.21 0.24 0.39
Farming experience -0.02 0.01 0.09
Distance to a passable road (km) -0.07 0.03 0.03
Natural log shelled maize stored 0.09 0.09 0.32
Constant -8.64 1.32 0.00
Number of observations 892.00
LR chi2
(17) 178.01
Prob > chi2
0.00
Pseudo R2
0.25
Test for selection bias
Mean t-test
Variable Treated (124) Control (768) %bias t p-value
Moist transitional 0.5 0.4 19 1.5 0.127
Moist mid altitude 0.5 0.6 -20 -1.5 0.128
Decision maker, female15-64yr 0.3 0.2 14 1.2 0.242
Decision maker, male>64yr 0.1 0.2 -10 -0.7 0.492
Decision maker, female >64ys 0.0 0.1 -17 -1.3 0.198
Household size 6.9 6.8 1 0.1 0.951
Gender of the household head 1.1 1.2 -15 -1.2 0.233
Age of the household head 53.3 54.7 -10 -0.9 0.385
Literacy of the household head 1.0 1.0 0 0.0 1.000
Having mobile phone account 1.0 0.9 7 0.9 0.357
Having bank account 0.8 0.8 -4 -0.3 0.756
Experience 24.6 25.5 -6 -0.5 0.602
Hosting big social events 0.3 0.3 3 0.3 0.794
Distance to a passable road (km) 1.5 1.6 -2 -0.2 0.874
Land owned (ha) 9.2 6.6 18 1.4 0.158
Ln shelled maize before storage 1.8 1.8 2 0.1 0.886
Total cultivated land (ha) 8.3 8.5 -4 -0.2 0.828
Matching method Pseudo R2 LR chi2
p>chi2
Mean Bias Median Bias
Before matching 0.244 175.16 0.000 32.9 29.42
Neighbor matching 0.043 14.89 0.604 8.9 7.0
Radius matching 0.019 6.35 0.991 4.3 2.6
Kernel matching 0.015 5.01 0.998 4.1 2.9
Mean t-test
Variable Treated (124) Control (768) %bias t p-value
Moist transitional 0.5 0.4 19 1.5 0.127
Moist mid altitude 0.5 0.6 -20 -1.5 0.128
Decision maker, female15-64yr 0.3 0.2 14 1.2 0.242
Decision maker, male>64yr 0.1 0.2 -10 -0.7 0.492
Decision maker, female >64ys 0.0 0.1 -17 -1.3 0.198
Household size 6.9 6.8 1 0.1 0.951
Gender of the household head 1.1 1.2 -15 -1.2 0.233
Age of the household head 53.3 54.7 -10 -0.9 0.385
Literacy of the household head 1.0 1.0 0 0.0 1.000
Having mobile phone account 1.0 0.9 7 0.9 0.357
Having bank account 0.8 0.8 -4 -0.3 0.756
Experience 24.6 25.5 -6 -0.5 0.602
Hosting big social events 0.3 0.3 3 0.3 0.794
Distance to a passable road (km) 1.5 1.6 -2 -0.2 0.874
Land owned (ha) 9.2 6.6 18 1.4 0.158
Ln shelled maize before storage 1.8 1.8 2 0.1 0.886
Matching method Pseudo R2 LR chi2
p>chi2
Mean Bias Median Bias
Before matching 0.244 175.16 0.000 32.9 29.42
Neighbor matching 0.043 14.89 0.604 8.9 7.0
Radius matching 0.019 6.35 0.991 4.3 2.6
Kernel matching 0.015 5.01 0.998 4.1 2.9
Common support
 y-axis: frequency of the
propensity score
distribution
 propensity scores for the
adopters and non-
adopters after matching
greatly overlap
 there is a high chance of
getting good matches
Impact evaluation: Storage loss abatement
Loss abatement range
from US$ 95 to
US$135
adopters lost US$ 1.99
 adopters keep some
maize aside for regular
consumption
 The net effect of MS
adoption is a 98.54%
reduction in storage
losses of maize due to
pest.
Impact evaluation: Reduction in storage cost
Metal silo adopters saved
between US$10 & US$18 per
season.
Some adopters used pesticides
because:
adopters keep some maize in
bags for regular consumption
 they were told to do so during
the installation by the artisans
Maize damage is negligible in
metal silo with or without
pesticides (Kimenju and De
Groote, 2010).
Impact evaluation: Length of storage and food security
Metal silos
Adopters:
Store maize by
between 1.8 months
and 2months longer.
are food secure by >
a month more than
non-adopters.
Conclusion
Metal silo technology can
effectively help smallholder
farmers to:
 reduce storage cost and losses
due to storage pests
 earn better incomes by delaying
sale of their produce
 improve their household food
security situation.
 Reduce health risks
Recommendations
 Promotion and awareness
creation
 Address supply side issues
 Initial investment in metal silo is high for
smallholder farmers
 Collective action can address
 technical (handling and maintenance)
 financial constraints
 Provision of subsidized credit (Kilomo biashara)
 Lobbing for zero-rating of metal sheets
 Training more artisans near farmers localities:
 increase access to metal silos,
 reduce transport costs
 enable the artisans to offer aftersales service to the
farmers.
ObrigadoBueno, 臓gracias por escuchar
mi presentaci坦n! 臓El pastel
est叩 servido!

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  • 1. Can metal silo technology offer solution to grain storage and food security problem in developing countries? An Impact evaluation from Kenya Zachary M. Gitonga, Hugo de Groote, Kassie Menale and Tadele Tefera 28th International Conference of Agricultural Economics Foz do Iguacu, Brazil, 1824 August 2012. Published as: Gitonga, Z.M., Hugo De Groote, Kassie Menale and Tadele Tefera. 2013. Measuring the impact of metal silos on household maize storage and food security in Kenya using propensity score matching. Food Policy 43:44-55.
  • 3. Introduction Farmers suffer huge losses due to insect damage and poor storage. sell shortly after harvest at low prices Buy later in the market at higher prices Food insecurity and poverty cycle Many using storage facilities that do not protect against storage pest Hermetically sealed Metal silo can kill pest through oxygen deprivation w/o pesticides Has worked in Latin America (Postcosecha) Elsalvador, Guatemala,Honduras, Nicaragus Impact of metal silo at farm level not studied in ESA
  • 4. Objectives We therefore evaluated the impact of metal silos on: maize storage loss due to pests, cost of storage, duration of storage food security. Hypotheses: Households that use metal silos: incur negligible losses due to pests spend less on storage chemicals delay selling their maize, are more food secure than non adopters
  • 5. Methods: Sampling: Multi stage random sampling for control Sub-locations from KNBS & grouped according to AEZ Proportionate to size random sampling used to select 120 sub-locations across the six AEZ. a sampling frame of all households in each sub-location 1468 household interviewed Same questionnaire used for adopters and non adopters of metal silos
  • 6. Impact evaluation Assessing the impact of metal silos requires making an inference about the outcomes that would have been observed for adopters had they not adopted. Impact evaluation is a problem of missing data it is impossible to measure outcomes for someone in two states of nature at the same time Propensity score matching technique used to match adopters and non adopters on observable characteristics Propensity score or balancing test used to check for selection bias
  • 7. Impact evaluation Sensitivity analysis conducted to check hidden bias Endogenous switching regression used to check the robustness of PSM results The model simultaneously estimates adoption and outcome equations the estimated coefficients of correlation (rho) between the adoption equation and the outcome equations not significantly different from zero. unobserved factors did not influence the decision to adopt metal silos.
  • 8. Results: Benefit of maize storage Embu is a maize deficit area Prices low in during harvest time & high before next harvest Harvest in Rift valley around August but green maize in July
  • 9. Results: Maize sale after storage adopters & non-adopters sell within the first month of harvest Non adopters sell more soon after harvest at low prices Adopters sell very little initially Adopters sell more in the fifth month to take advantage of improved prices
  • 10. The propensity to adopt Variable Coef. Std. Err. P>z Moist transitional 2.63 0.78 0.00 Moist mid altitude 3.24 0.79 0.00 Household size 0.05 0.04 0.24 Gender of the household head 0.37 0.38 0.33 Age of the household head 0.02 0.01 0.20 Literacy of the household head 1.08 0.53 0.04 Having mobile phone account 1.33 0.56 0.02 Having bank account 0.79 0.27 0.00 Total cultivated land 0.04 0.02 0.08 Hosting big social events 0.21 0.24 0.39 Farming experience -0.02 0.01 0.09 Distance to a passable road (km) -0.07 0.03 0.03 Natural log shelled maize stored 0.09 0.09 0.32 Constant -8.64 1.32 0.00 Number of observations 892.00 LR chi2 (17) 178.01 Prob > chi2 0.00 Pseudo R2 0.25
  • 11. Test for selection bias Mean t-test Variable Treated (124) Control (768) %bias t p-value Moist transitional 0.5 0.4 19 1.5 0.127 Moist mid altitude 0.5 0.6 -20 -1.5 0.128 Decision maker, female15-64yr 0.3 0.2 14 1.2 0.242 Decision maker, male>64yr 0.1 0.2 -10 -0.7 0.492 Decision maker, female >64ys 0.0 0.1 -17 -1.3 0.198 Household size 6.9 6.8 1 0.1 0.951 Gender of the household head 1.1 1.2 -15 -1.2 0.233 Age of the household head 53.3 54.7 -10 -0.9 0.385 Literacy of the household head 1.0 1.0 0 0.0 1.000 Having mobile phone account 1.0 0.9 7 0.9 0.357 Having bank account 0.8 0.8 -4 -0.3 0.756 Experience 24.6 25.5 -6 -0.5 0.602 Hosting big social events 0.3 0.3 3 0.3 0.794 Distance to a passable road (km) 1.5 1.6 -2 -0.2 0.874 Land owned (ha) 9.2 6.6 18 1.4 0.158 Ln shelled maize before storage 1.8 1.8 2 0.1 0.886 Total cultivated land (ha) 8.3 8.5 -4 -0.2 0.828 Matching method Pseudo R2 LR chi2 p>chi2 Mean Bias Median Bias Before matching 0.244 175.16 0.000 32.9 29.42 Neighbor matching 0.043 14.89 0.604 8.9 7.0 Radius matching 0.019 6.35 0.991 4.3 2.6 Kernel matching 0.015 5.01 0.998 4.1 2.9 Mean t-test Variable Treated (124) Control (768) %bias t p-value Moist transitional 0.5 0.4 19 1.5 0.127 Moist mid altitude 0.5 0.6 -20 -1.5 0.128 Decision maker, female15-64yr 0.3 0.2 14 1.2 0.242 Decision maker, male>64yr 0.1 0.2 -10 -0.7 0.492 Decision maker, female >64ys 0.0 0.1 -17 -1.3 0.198 Household size 6.9 6.8 1 0.1 0.951 Gender of the household head 1.1 1.2 -15 -1.2 0.233 Age of the household head 53.3 54.7 -10 -0.9 0.385 Literacy of the household head 1.0 1.0 0 0.0 1.000 Having mobile phone account 1.0 0.9 7 0.9 0.357 Having bank account 0.8 0.8 -4 -0.3 0.756 Experience 24.6 25.5 -6 -0.5 0.602 Hosting big social events 0.3 0.3 3 0.3 0.794 Distance to a passable road (km) 1.5 1.6 -2 -0.2 0.874 Land owned (ha) 9.2 6.6 18 1.4 0.158 Ln shelled maize before storage 1.8 1.8 2 0.1 0.886 Matching method Pseudo R2 LR chi2 p>chi2 Mean Bias Median Bias Before matching 0.244 175.16 0.000 32.9 29.42 Neighbor matching 0.043 14.89 0.604 8.9 7.0 Radius matching 0.019 6.35 0.991 4.3 2.6 Kernel matching 0.015 5.01 0.998 4.1 2.9
  • 12. Common support y-axis: frequency of the propensity score distribution propensity scores for the adopters and non- adopters after matching greatly overlap there is a high chance of getting good matches
  • 13. Impact evaluation: Storage loss abatement Loss abatement range from US$ 95 to US$135 adopters lost US$ 1.99 adopters keep some maize aside for regular consumption The net effect of MS adoption is a 98.54% reduction in storage losses of maize due to pest.
  • 14. Impact evaluation: Reduction in storage cost Metal silo adopters saved between US$10 & US$18 per season. Some adopters used pesticides because: adopters keep some maize in bags for regular consumption they were told to do so during the installation by the artisans Maize damage is negligible in metal silo with or without pesticides (Kimenju and De Groote, 2010).
  • 15. Impact evaluation: Length of storage and food security Metal silos Adopters: Store maize by between 1.8 months and 2months longer. are food secure by > a month more than non-adopters.
  • 16. Conclusion Metal silo technology can effectively help smallholder farmers to: reduce storage cost and losses due to storage pests earn better incomes by delaying sale of their produce improve their household food security situation. Reduce health risks
  • 17. Recommendations Promotion and awareness creation Address supply side issues Initial investment in metal silo is high for smallholder farmers Collective action can address technical (handling and maintenance) financial constraints Provision of subsidized credit (Kilomo biashara) Lobbing for zero-rating of metal sheets Training more artisans near farmers localities: increase access to metal silos, reduce transport costs enable the artisans to offer aftersales service to the farmers.
  • 18. ObrigadoBueno, 臓gracias por escuchar mi presentaci坦n! 臓El pastel est叩 servido!