Can we profitably double maize
yields in southern Tanzania?
Environment and Production Technology Division, International Food Policy Research
Institute
December 7, 2016
Context
• Slower than desired growth in crop yields coupled with
rising populations present an ongoing challenge to the food
security of some African countries
• Some countries like Tanzania have signed the Malabo
declaration, which aims to double food productivity by 2025
• This study examined the productivity and economic effects
of different seed and fertilizer practices in Mbeya, Tanzania
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Research questions
• For maize in the Mbeya district of southern Tanzania:
– How does seed and fertilizer management affect the yield
and profit of maize?
– What are the marginal value-cost ratios of fertilizer use for
different seed practices?
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Methods
• Simulated how fertilizer and seed practices effect maize
grain yields
• computed economic and risk indicators of alternative
practices
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Methods
• Crop management factorial simulated:
– 10 or 30 kg N ha-1
– Traditional or improved maize cultivars
– Traditional or improved sowing dates
– No manure, 80% crop residues removed from field
– Used DSSAT from 2009 to 2009 in six maize-growing districts
of Mbeya
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Methods
• Profit: value of grain production minus the cost of
production. District-level prices used
• Agronomic efficiency: change in yield divided by change
in quantity of fertilizer applied
• Marginal value-cost ratio: agronomic efficiency
multiplied by ratio of grain to fertilizer price
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Results: historical and extrapolated grain yield
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Results: simulated yields and profits
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Results: agronomic efficiency and price ratios
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Results: value-cost ratio
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Results: probability of the marginal value-cost ratio (MVCR)
associated with using more fertilizer exceeding different thresholds
Practices
Traditional seed and
planting date
Traditional seed and
sowing with a lower AE or
higher fertilizer price
Traditional seed and
improved planting date
Improved seed and
improved planting date
Probability MVCR >1 (%) Probability MVCR >2 (%)
80
59
73
43
100
100
100
100
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Conclusion
• Changes in seed and fertilizer application can help
double yields and increase profits
• Heterogeneity exists in profitability of fertilizer
application
• Questions remain if it is more cost effective to lower
fertilizer prices or increase agronomic efficiency by an
equivalent percentage
• Questions remain why farmers don’t use more fertilizer
given the MVCR we calculated
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