1. Can we profitably double maize yields in southern Tanzania?
Environment and Production Technology Division, International Food Policy Research Institute
December 7, 2016

2. 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

3. 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?

4. Methods
Simulated how fertilizer and seed practices effect maize grain yields
computed economic and risk indicators of alternative practices

5. 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

6. 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

7. Results: historical and extrapolated grain yield

8. Results: simulated yields and profits

9. Results: agronomic efficiency and price ratios

10. Results: value-cost ratio

11. Results: probability of the marginal value-cost ratio (MVCR) associated with using more fertilizer exceeding different thresholds
Practices
Probability MVCR >1 (%)
Probability MVCR >2 (%)
Traditional seed and planting date 80 59
Traditional seed and sowing with a lower AE or higher fertilizer price 73 43
Traditional seed and improved planting date
100
Improved seed and improved planting date

12. 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