[LUM#15] Research Major Soils
In Africa, 45% of the land is considered “degraded.” A process of desertification, resulting human pressure and exacerbated by climate change, is undermining the future of the continent and threatens the food security of its populations.
“Desertification is not at all about the desert encroaching,” insists Jean-Luc Chotte, a soil specialist at the Eco&Sols* laboratory. “It is a general process of soil degradation that leads to a loss of soil productivity, as well as a loss of biodiversity and ecosystem services.” ” While degraded land can be found everywhere, we only speak of desertification when this phenomenon affects arid, semi-arid, or dry sub-humid areas. It is estimated that 25% of the planet’s land is degraded. That figure rises to 45% in Africa.
From Soil to Climate
How can we explain why Africa is so severely affected? “Generally, this results from overexploitation or misuse of the soil,” explains the researcher, who is also chair of the French Scientific Committee on Desertification. This overexploitation is not measured in quintals of production but in the ratio between production and the soil’s natural potential. Indeed, when land is cultivated, some of its chemical components (nitrogen, potassium, etc.) are extracted from the soil by plants, leading to a decline in fertility that is all the more severe the more fragile the soil is. Another harmful effect of this poor land use is the release of carbon stored in the soil “which ends up in the atmosphere, thereby contributing to global warming,” emphasizes Jean-Luc Chotte.
150 million people affected in the Sahel
In the Sahel alone, 150 million people are affected by desertification, “and we know that the population will grow, and with it, food needs.” This immense challenge prompted the United Nations, as early as 1994, to launch the Convention to Combat Desertification (UNCCD). Seven years later, in 2001, the Great Green Wall project was launched with the goal of restoring, by 2030, more than 100 million hectares of degraded land between Dakar and Djibouti (watch the Global Days conference). “This wall should be seen as a vast mosaic of landscapes in which practices are adapted to the different environmental, climatic, and socio-economic conditions of Burkina, Niger, or Chad.”
For an integrated approach
In northern Senegal, significant efforts have been made to combine annual crops with tree plantations suited to local drought conditions. Pastoralism is also encouraged there for its beneficial effects on the soil. “The idea is to find a tree that, by producing gum arabic for example, will provide farmers with additional income while helping to restore degraded land, ” continues Jean-Luc Chotte. Documenting best agroecological practices while also mapping ecosystem health to prioritize areas “where intervention will have the greatest impact on people and biodiversity, since we cannot act on all degraded lands.” Given the immensity of the task, this is a way to keep our feet… on the ground.
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*Eco & Soils (IRD – CIRAD – INRAE – Institut Agro)