Can Africa afford to save its soils?

It has long been thought that small farmers will not invest in improving the natural capital (particularly in the context of soils) of their farm systems, either because they cannot afford to do so, or because they lack the land security to reap the benefits in the future.

But evidence from a large number of agroecosystems and countries shows that poor farmers can and do invest in improvements that lead to increased food outputs if they have access to three things: i) the human capital in terms of knowledge and convincing evidence; ii) the social capital (so that collective actions can transform whole landscapes), and iii) the available technologies and practices. This implies the intensification of production systems so that existing lands become more productive.

Sustainable systems exhibit a number of key attributes at the production end of food systems. They seek to:

1. Utilise crop varieties and livestock breeds with a high ratio of productivity to use of externally- and internally-derived inputs;
2. Avoid the unnecessary use of external inputs;
3. Harness agroecological processes such as nutrient cycling, biological nitrogen fixation, allelopathy, predation and parasitism;
4. Minimise use of technologies or practices that have adverse impacts on the environment and human health;
5. Make productive use of human capital in the form of knowledge and capacity to adapt and innovate and social capital to resolve common landscape-scale or system-wide problems (such as water, pest or soil management);
6. Minimise the impacts of system management on externalities such as greenhouse gas emissions, clean water, carbon sequestration, biodiversity, and dispersal of pests, pathogens and weeds.

This leaves some critical questions: can the sustainable intensification of agricultural systems work? Can it produce more food, fibre and other valued products whilst improving natural capital? Is it possible to produce more whilst not trading off harm to key renewable capital assets? The evidence suggests yes, and that it works for small as well as large farmers.

The UK Government Office of Science Foresight programme commissioned reviews and analyses from 40 projects in 20 countries of Africa where sustainable intensification had been developed or practiced in the 2000s. The cases comprised crop improvements, agroforestry and soil conservation, conservation agriculture, integrated pest management, horticultural intensification, livestock and fodder crops integration, aquaculture, and novel policies and partnerships.

By early 2010, these projects had documented benefits for 10.4 million farmers and their families and improvements on approximately 12.75 million hectares. Across the projects, yields of crops rose on average by a factor of 2.13 (i.e. slightly more than doubled). The timescale for these improvements varied from 3-10 years. It was estimated that this resulted in an increase in aggregate food production of 5.79 million tonnes per year, equivalent to 557 kg per farming household (in all the projects).