Home > Ecological economics, International agricultural research > Is a fertilizer revolution the right recipe for African agriculture?

Is a fertilizer revolution the right recipe for African agriculture?

It is often argued that to increase its farm yields and close its yield gap, Africa needs a new Green Revolution, based on the expanded use of fertilizer. An intriguing analysis by Pablo Tittonell of Wageningen University, however, tells a somewhat different story (find it on p.17ff. in Tittonell’s inaugural lecture at WUR.

In an on-farm research program carried out in Western Kenya, Tittonell and others compared maize yields on the fields of 60 households under different management regimes. A part of the plots was managed by the farmers themselves, with or without use of fertilizers. Another part was managed by researchers without the use of fertilizers, only taking care of the right planting time and plant spacing, frequent weeding, and using certified local cultivars. A third part of the plots was managed by the researchers with the use of N-P-K fertilizers.


Source: Taken from Tittonell (2013).

The figure shows the striking result that the plots managed by researchers even without fertilizers had higher yields than the plots managed by the farmers, thus illustrating the potential of proper agronomic management. In particular with rising distance from the homestead this potential is high.

On the other hand, the figure also shows that N-P-K fertilization has an even higher potential for increasing yields. However, the researchers also argue that, given the current quality of the road network, bringing the amounts of fertilizers required to obtain significant yield increases at scale to the rural communities would not be feasible .

The analysis raises a number of interesting questions. The overarching question is – taking optimized agronomic management and the use of higher amounts of N-P-K fertilizers as alternatives – what is the better alternative?

From this question, one can ask for the better alternative in the short run and in the long run.

In the short run, considerations about the feasibility and the associated costs of both alternatives play a role. Optimizing agronomic management is a largely knowledge-based undertaking and getting farmers to adopt improved management practices would most certainly require substantial extension efforts. The associated costs may be high and it may be difficult to achieve impacts at scale.

On the other hand, since supplying farmers with the necessary amounts of fertilizers may be restricted by the lack of market and road infrastructure, complementary investments may be required. However, even if those investment costs are high, it may still be easier to reach a larger amount of farmers in a relatively short time. Also, once available on local markets, the use of fertilizers may spread more quickly than improved agronomic practices might be adopted. Moreover, improvements in infrastructure may contribute to better connecting farmers to markets and therefore may have a positive development impact that goes beyond the mere increases in crop productivity from higher fertilizer use.

In the long run, however, the use of synthetic fertilizers may not prove sustainable. Some of the reasons include that there are negative environmental externalities associated with the use of chemical inputs, such as soil fertility problems, water pollution or air pollution (see a report by Maredia and Pingali for details). Further, there are concerns about the long- term availability and long-term cost of synthetic fertilizers. As Tittonell points out in his lecture, future expansion of the use of energy intensive farm inputs may become constrained by the availability and cost of the energy inputs required to produce them.

Improved management practices, in contrast, may not have that kind of implications in the long run. In addition, once enshrined in farmers’ practices, it will unfold long lasting impacts on crop productivity without the recurrent cost of fertilizer purchases.

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