Preventing the spread of deserts: good for both crops and the climate

The Ethiopian smallholder Meseret Teshome looks out upon his field and sees lush greenery and life. Once again. He remembers: ‘We used to be able to live off our land, but then the soil deteriorated and turned to desert. In the end, there was nothing left to harvest.’ The Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH gave him the training he needed to make his soil fertile again. Instead of relying exclusively on mineral fertilisers, now he cultivates his field using sustainable farming methods. He was soon convinced by their effectiveness: ‘We saw how our land suddenly became productive again.’

Yet healthy soil and bountiful harvests are growing harder to come by throughout the world. Every year, an area of fertile soil one third of the size of Germany vanishes. When farmers are overly reliant on mineral fertilisers or farm their fields too intensively without returning sufficient organic matter to the earth, the amount of organic matter in the soil – the humus – declines further and further. But humus is especially important for soil health. Climate change exacerbates the effect: long droughts, short but intense periods of rain and dust storms all degrade soil and render it infertile. Juliane Wiesenhütter, soil expert at GIZ, explains: ‘When this happens, we call it desertification.’

New shoots

Drylands now cover around 40 per cent of global lands and are home to almost a third of the world’s population. The consequences of water scarcity are evident in this summer’s events in Europe, where the likelihood of droughts increased twentyfold between 1900 and 2020. Climate change and unsustainable land use are turning drylands into deserts: globally, an area larger than half the United States was affected by such desertification between the 1980s and 2015.

For this reason, GIZ is working on behalf of the Federal Ministry for Economic Cooperation and Development (BMZ) to preserve or regenerate soil in several countries, including Ethiopia, Benin and India. Since 2014, over 1.1 million hectares of soil in seven countries have successfully been preserved or restored. This is an area approximately the size of Cyprus. The Ethiopian smallholder Meseret Teshome is one of 3 million people who are benefitting from this. After all, healthy soil yields significantly greater harvests. On average, farmers are able to harvest 43 per cent more than before. 

Farmers learn how to increase the amount of organic matter in the soil and how to enrich it with nutrients such as nitrogen, potassium and phosphorus. This is achieved, for example, by using special seeds, lime and organic fertiliser, as in Teshome’s case – or through skilful use of crop rotation as in the case of Madinatou Garba, a maize farmer from Benin. GIZ trained her in how and when to plant the legume mucuna in her field so as to increase the size of her maize harvests. ‘As recommended in the training, I planted mucuna on my plot and then the maize. By doing this, I harvested 50 sacks of maize instead of only twelve as before,’ she said, reporting on her success. Approximately 840,000 smallholders have taken part in training programmes like this or similar ones.

‘Protecting soil also means protecting the climate’

Yet soil is more than just the basis for our food supply – it is also the world’s second biggest carbon sink after the oceans, and therefore plays a particularly important role in the fight against climate change. Soil stores more carbon than all of the world’s forests and the Earth’s atmosphere combined. Only healthy soil can achieve this, however. Each hectare of soil which turns to desert is therefore a loss on two counts.

With this in mind, GIZ is investigating practices which combine soil protection and climate action. One such option involves using charcoal. It may sound contradictory at first: charcoal as a climate action measure? What is really meant here is biochar, which is made from plant residues, for example. In Burkina Faso, GIZ is teaching farmers how to carbonise plant residues under low oxygen conditions. The resulting biochar contains the carbon previously extracted from the air by the plants. When the farmers introduce the biochar to the soil, this not only improves soil health, it also stores carbon in the soil for the long term – a win-win situation. This is why GIZ is also working on expanding the use of biochar into other regions too.

It offers great potential: using soil more sustainably could offset up to 20 per cent of anthropogenic greenhouse gas emissions. Juliane Wiesenhütter sums it up in a nutshell: ‘Protecting soil also means protecting the climate!’