Grain

• And what is true for the universe is even truer in the Sahel, the name given to the vast, arid belt that skirts the Sahara and stretches across Africa from east to west.
• Overlooked for many years, the secrets of the Sahelian landscape are starting to pique the interest of researchers and decision-makers.

The art of catching rain

• They are now a desolate crust where torrential rains are simply swept away as run-off before they have a chance to seep through.
• In a barren field in the village of Gourga, Yacouba and his family are hard at work perforating the crusted soil in preparation for the first rain.
• Each wielding a daba (which is a traditional tool similar to an adze), they dig down into the red laterite earth.
• Into each one, they drop a handful of compost, a few grains of sorghum and a dusting of light soil.

• But this expertise, known as zaï, has been honed by the peoples of the Yatenga for centuries.
• By virtue of this revolutionary farming technique, they have mastered the art of catching rain.
• And so it was that Yacouba, nicknamed “the man who stopped the desert,” restored hope to his whole village.

Ingenious, but costly

• Well, while it may seem simple, zaï is actually based on a number of complex ecological mechanisms.
• The technique involves concentrating water and manure at one spot, thereby favouring crop growth in a context of scarce, unpredictable rainfall.
• Then, when the rain comes, the enriched pocket fills with water and releases nutrients that attract termites of the genus Trinervitermes.
• With the promise both of bountiful harvests and of benefits for the ecosystem, zaï is a genuine one-stop solution.

• When digging with a daba for four hours each day, it takes one farmer three months to sow a single hectare.
• Not only that, three tons of manure must be accumulated or purchased in order to enrich each pocket.

The widespread, manifold forms of zaï

• In the 1980s, there were concerted efforts from development aid to tackle desertification in Sahelian regions weakened by heavy drought.
• What followed was a whole spectrum of projects and programmes to test, promote and improve zaï in sub-Saharan Africa.

• The aim here is to improve sorghum yields while surmounting the major barrier of costly organic matter.
• Agronomists are also working on ways to combine cereals inside one seed pocket, for example planting sorghum with legumes such as cowpea.
• Lastly, they are testing out zaï on new crops, from maize to cotton, watermelons and horticultural species like aubergines.

An “alternative” way of adapting

• From dams to mega-basins to irrigated perimeters, the over-riding policy across the board is to expand watered surfaces by any means necessary.
• But although this option fulfils a certain short-term need, it carries with it a serious risk of maladaptation.
• Indeed, the hidden trade-off of these large-scale farm water projects is depleting water resources, social injustice and geopolitical tensions.

The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.