Macro Trends and Determinates of Fertilizer Use in Sub-Saharan Africa

Reviews the the dynamics of fertilizer use in Africa, specifically with regards to the trends in fertilizer consumption at the continental, regional and country level and the factors associated with changes in fertilizer use.

Finds that:

On trends in fertilizer use

• Aggregate figures for fertilizer consumption in SSA show a steady increase, measured in terms of both absolute levels (metric tons of fertilizer consumed) and dosage (kilograms per hectare of arable land).
• Consumption of fertilizer in 1970 was 425 million metric tons and has increased at a rate of almost 36 thousand MT per year
• Fertilizer dosage (per cultivated area) rose from 3.3 kg/ha in 1970 to 9.9 kg/ha in 1995.
• Notwithstanding the above figures, fertilizer use has been highly variable and concentrated among a few countries
• For the period 1991-1995, consumption varied from a low of 1.95 thousand MT for the Central African Region to a high of 16.55 thousand MT for Southern Africa
• For the same period, the four countries (Ethiopia, Kenya, Nigeria, and Zimbabwe) used 60% of all fertilizer in SSA, with Nigeria having accounted for the largest share.

On key determinants affecting fertilizer use:

• The correlation analysis conducted in this paper found that fertilizer use per hectare was positively correlated with
  • the amount of rainfall per year. This finding underscores the need to find seed/fertilizer technologies that are more responsive in the type of low moisturesituation that characterizes much of SSA
  • the density of road infrastructure. However the size and significance of the road density co-efficient has been declining over time, especially since the early 1980s
  • the number of children in school (both primary and secondary). This suggests that investments in schooling may have indirect effects on stimulating fertilizer use (e.g., by improving human capital at the farm level and among those providing services to farmers).
  • the percentage of cultivated area devoted to cotton. Cotton production schemes have been used to introduce fertilizer to small farmers in a variety of SSA settings where the use has subsequently been expanded to other crops, particularly coarse grains. The lesson to be learned from this variable is not so much that cotton per se is the best way of getting fertilizer into the farming system, but that some type of cash crop scheme that provides farmers with reliable input, credit, extension, and output marketing services can play a significant role in promoting fertilizer adoption.
• A number of factors that we expected to be highly correlated with fertilizer use per hectare did not exhibit statistically significant coefficients in the broad analysis using data from more than 30 countries. Among the most surprising were:
  • Share of area cultivated in maize. This result is surprising as maize is generally considered the most significant user of fertilizer in SSA (accounting for about 25% of total use), and it is a crop that Desai and Gandhi (1988) found to be highly correlated with fertilizer use between 1979 and 1983. We believe the link between fertilizer use and maize production warrants careful monitoring in the future because maize is one of the most fertilizer responsive crops grown in SSA and it has been the crop of choice for introducing fertilizer to farmers in a number of recent extension efforts (e.g., the Sasakawa/Global 2000 programs).
  • Share of cultivated area benefitting from irrigation. The lack of correlation between fertilizer use and percent of area irrigated is also a bit of an anomaly as the irrigated production schemes we are familiar with in SSA (e.g., Mali’s Office du Niger and the Senegal River Basin) use large quantities of fertilizer per hectare. It is possible that the total amount of irrigated area in SSA is so small that it is not possible to show a statistically significant relationship with the aggregated data covering so many diverse countries.

Although our analyses provide some important insights into recent fertilizer use trends and determinants at an aggregated level, there are still many unknowns. A critical first step in developing a better understanding of factors that are driving fertilizer use at both the country and the regional level is improving the fertilizer data base in each country. Among the key improvements needed are better dis-aggregations by agroecological zone, crop, and type of fertilizer used. Data series on fertilizer prices by location and type of fertilizer would also be helpful. When these types of data become available at the country-level, both national and regional policy analysis will improve. [author]