Georgina Smith/CIAT

On the fertilizer-starved continent of Africa, the discourses about soil fertility revolve around the availability of inorganic fertilizers, and how policy – subsidies, tariffs, markets – can be made to support their use.

Supporters say that poor farmers are not able to make investments in restoring degraded soils because it takes too long to see yield increases or benefit from soil improvement measures.  Poor farmers simply can’t wait that long to see results - they say.

But in degraded, low-input and low-output systems so prevalent across the continent, agro-ecological approaches, including principles of organic farming - if properly managed - can increase yields immediately and restore soils to support productive farming.

Communities dig terraces to stop soil erosion in Lushoto, Tanzania.
Communities dig terraces to stop soil erosion in Lushoto, Tanzania.
Georgina Smith/CIAT

In celebration of the International Year of Soils, we asked a number of experts:

Is investing in inorganic fertilizers really a better option than restoring soils over the long-term using an agro-ecological approach?

Join the debate in the comments section below.

For more information, see below.


Can Organic Farming Feed Us All? World Watch Magazine, May/June 2006, Volume 19, No. 3

Pretty J, Noble A D, Bossio D, Dixon J, Hine R E, Penning de Vries F W T and Morison J I L. 2006. Resource-conserving agriculture increases yields in developing countries. Environmental Science & Technology 40 (4), 1114 -1119.

Ponisio LC, M’Gonigle LK, Mace KC, Palomino J, de Valpine P, Kremen C. 2015 Diversification practices reduce organic to conventional yield gap. Proc. R. Soc. B 282: 20141396.

Badgley, C., J. Moghtader*, E. Quintero*, E. Zakem*, J. M. Chappell*, K. Aviles-Vázquez*, A. Samulon*, and I. Perfecto. 2007. Organic agriculture and the global food supply. Renewable Agriculture and Food Systems 22 (2): 86-108. Or blog here.

Pretty J, Toulmin C and Williams S. 2011. Sustainable intensification in African agriculture. International Journal of Agricultural Sustainability 9.1, pp 1-241

Pretty J and Bharucha, Z P. 2014. Sustainable intensification in agricultural systems. Annals of Botany. doi:10.1093/aob/mcu205, 1-26

Pannerselvam, P.; Hermansen, J.E. & Halberg, N. 2011. Food security of small farmers: comparing organic and conventional systems in India. Journal of Sustainable Agriculture, 35: 48-68.

Panneerselvam, P.; Hermansen, J.E.; Halberg, N. & Arthanari, P.M. 2013a. Impact of large-scale orgnaic conversion on food production and food security in two Indian states, Tamil Nadu and Mahya Pradesh. Renewable Agriculture and Food Systems, Cambridge University Press. 1-11.

Panneerselvam, P.; Halberg, N & Lockie, S. 2013b. Consequences of organic agriculture for smallholder farmers' livelihood and food security. In: Niels Halberg and Adrian Müller (Eds.). Organic Agriculture for Sustainable Livelihoods. Routledge, London and New York. Chapter 2: 21-44.


What good are inorganic fertilizers when soil water is limiting?

In addition to yield gaps attributed to suboptimal soil fertility and land degradation, large regions of Africa have been facing increased climate variability and growing frequency and intensity of drought events. Smallholder farmers regularly experience additional and simultaneously occurring environmental stresses and these challenges to stable food production should not be left out of the discussion.

Restoring soils provides an entry-point to build resilience to multiple abiotic stresses through maintenance of critical ecosystem services under sub-optimal conditions. Although soil degradation is widely recognized as reducing agricultural potential, few studies have explicitly measured its effects on system vulnerability. Enhancing soils capacity to perform agronomic and environmental functions have been shown to increase yield stability and help mitigate hot and dry weather in the Midwest US rainfed systems (eg. PLoS ONE 10(2): e0113261). Additional studies are needed to investigate the impact of better soil quality and health on soil water conservation and its functional significance on African soil; however, agro-ecological approaches toward system improvement will likely show greater promise to reduce risk of crop failure in a context of greater yield variability than inorganic fertilizers.

If we do not change,the change will change us,Inorganic fertilizes did well in the 1940 and 1970 but now when you compare the harm it did,it is almost irreversible,this can be compared to the pre-industrialization period and to day when every where there is an industry,climate change and pollution is becoming too much,now every humanity is paying for the sin committed by those who become billionaires at that time,the resources accumulated by then is getting ruined but the difference is only one that we are all paying, the poor and the rich,therefore ecological agriculture is the best way to go,slow but sure.

YES, Africa has great potential to serve its soils.

Through the promotion of integrated farming that makes effective use of products from crops, livestock fish and trees and also practicing climate smart agriculture system. Scaling these practices/system will require great investment in technology generation and dissemination. It is time that African Government and the Development Partners prioritize investments in management of the soils.

In reading the discussion document, I am concerned about lack of understanding regarding comparison of organic vs conventional yields. For example, the meta-analysis paper cited from Michigan State faculty (2007) has a number of major flaws. One is that these kinds of studies compare crop yields per se without regard to the time dimension, and in most organic systems there is need for rotation with non-food crops (e.g. legume cover crops), or with food crops that produce lower yields of protein and calories, than in the "conventional" systems being compared.

Another major concern is that a large proportion of the studies cited are from grey literature that is not based on field studies with proper experimental design or use comparisons that typically involve finely tuned organic production systems implemented by people motivated to make organic production successful versus "off-the-shelf" conventional practices that are not fine-tuned for the field in which the experiment is conducted (which is what a reasonable farmer would do).

Hence, findings regarding performance of organic versus conventional systems are biased and unreliable in such meta-analyses because of so many of the studies included in the analysis are of such poor quality (Cassman, 2007).

Cassman K.G. 2007. Can organic agriculture feed the world—science to the rescue? Renewable Agric. Food Sys. 22:83-83.

How can they afford to not implement soil improvement practices? There is so much technology available today that effect improvements in soil productivity that practical for small plots as well as the largest farms. A hungry people would be foolish to ignore them long term.

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