Making land from bare rock

Photo credit: © Paul Harrison

In the drylands of Eastern Mali (in West Africa), Matias Djiguiba, a Dogon farmer, is growing an impressive array of crops on virtually bare rock.

Using traditional methods of irrigation, Dogon agriculture is probably the most intensive and productive in Africa. Every square centimetre of usable soil is planted, every gramme of plant or animal waste is recycled to achieve yields that for some crops rival those of any Western market gardener. Indeed, with onions, the Dogon achieve extraordinary yields of 42 tonnes a hectare - equal to the US yields, which are the third highest in the world.

In Matias' village of Kamba-Sareme, 95 per cent of the village lands is bare rock or boulders. On the bare baking rock ledges, crevices only 20cm wide, as long as they have a little soil, are planted with carefully selected crops such as millet and beans.

The Dogon are extremely skilled irrigators and have developed an impressive array of water and soil conservation techniques by themselves. Most remarkable is the creation of new land by making soil terraces on bare rock. The farmers break the rocks and, with the leftover rock pieces, create an enclosure wall. They then fill the patch with soil dug out of crevices and dried up seasonal ponds, and homemade compost. Once the terrace is filled, extra stones are placed to create a patchwork of one-metre squares. These act as micro basins, and retain water and soil.

But the struggle for subsistence and sustainability is never ending. Drought plus rapid population growth have taken their toll on the land. Every year the Dogon area sees natural population growth of well over 3 per cent a year, while the average rainfall has plummeted from 620mm a year in the late 1960s to an average of 450mm today.

It is a problem facing all parts of Africa's arid, semi-arid and dry sub-humid zones, which make up a fifth of the land surface, where a quarter of the continent's population lives. And in many cases it is being met with locally-tailored farming systems, drawing on farmers' own knowledge and skills.

Source: Sustaining the Soil: People & the Planet Vol 7, No 4 .

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