Dirt & Development

I have a paper with a former Ph.D. student on the difficulties of agricultural production in tropical sub-Saharan Africa.  It has been an interest of mine ever since I first read Jared Diamond’s Guns, Germs, and Steel and later Jeffrey Sachs’ papers on the development difficulties of tropical climates.  So I was intrigued when I saw that the European Union’s Institute for Environment & Sustainability has just published a Soil Atlas of Africa and it is available online. It uses computer mapping techniques to create stunning illustrations of the the type of soil problems that Africa suffers from.  Below is a picture from the cover of the atlas:


While the maps are incredible, the message is pretty sobering.  Among other things, the atlas finds that:

1. “While Africa has some of the most fertile land on the planet, the soils over much of the continent are fragile, often lacking in essential nutrients and organic matter.”

2. “Aridity and desertification affects around half the continent while more than half of the remaining land is characterised by old, highly weathered, acidic soils with high levels of iron and aluminium oxides (hence the characteristics colour of many tropical soils) that require careful management if used for agriculture.”

3. “Soils under tropical rainforests are not naturally fertile but depend instead on the high and constant supply of organic matter from natural vegetation and its rapid decomposition in a hot and humid climate. Breaking this cycle (i.e. through deforestation) quickly reduces the productivity of the soil and leaves the land vulnerable to degradation”

4. “In many parts of Africa, soils are losing nutrients at a very high rate, much greater than the levels of fertiliser inputs. As a result of rural poverty, farmers are unable to apply sufficient nutrients due to the high costs of inorganic fertilisers or from a lack of farm machinery (Africa has the lowest use of industrial fertilisers in the world). Traditional practices, such as long fallow periods that improve nutrient budgets and restore soil fertility, are difficult to implement due to the increased pressures on land and changes in land tenure that restrict traditional nomadic lifestyles.”

Yikes, sobering indeed.