Soil degradation

Two billion people affected by land degradation

Since the beginning of December, the United Nations has been conducting an intense campaign s pollution and land degradation alert system (#StopSoilPollution). It makes a worrying observation that may put a large part of humanity at risk. Indeed, degraded soils become irrecoverable in less than a generation. Pollution causes chain reactions that impact all biodiversity while new pollutants such as pharmaceuticals and heavy metals seep into the earth. It is estimated that two billion people are already affected by a scourge that affects a third of the planet's surface and affects a hundred countries on all continents.
Parge degradation is a process leading to a permanent loss of the biological and economic productivity of ecosystems; it is caused by wind and water erosion, loss of the capacity of soils to store water, loss of soil fertility, and the absence of vegetation. Desertification represents its ultimate stage.

In the countries concerned, three quarters of the pastureland and half of the cultivated areas are thus threatened, inevitably leading to the deterioration of the living conditions of the populations and an increase in poverty.

It is now known that the degradation of climatic conditions increases the risks of land degradation, including increased desertification: prolonged droughts and unsuitable ways of exploiting natural resources lead to their overexploitation, exacerbate their fragility and cause situations of irreversibility. The soil becomes uncultivable, there is no more vegetation, we can no longer live in these conditions.

The last two IPCC reports predict an increase in droughts and floods, a decrease in the flow of major rivers and an increase in desertification.

Degraded soil in the Western High Atlas in Morocco. Vincent Simonneaux/IRD

A vicious circle

Affected countries, particularly in the Sahel, generally derive their income from the exploitation of renewable natural resources. If these diminish, they will see their GDP fall, the poverty of their population increase and they will enter "poverty traps": without other sources of income, farmers and herders will increase the area under cultivation.

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If they do not change their practices, this will lead to further land degradation and desertification, resulting in further decline in income, weakening of social ties and forced migration.

Added to this is the issue of demographic pressure: a third party of the world's population already lives in the world's dry regions and will therefore be exposed to climate change and land degradation. In Africa, for example, it will be necessary to feed twice as many in the next 20 years.

If agricultural productivity cannot be increased sufficiently to feed these future populations, migration within countries (rural and urban migration), regional migration and South-North migration will increase.

Fighting degradation

In affected countries, farmers have implemented ad hoc control methods that allow for successful adaptations to drought situations; and sometimes, with the support of scientists, farmers have implemented more integrated methods such as stone bunds, water infiltration aids, tree planting, theagro-ecology

But it is also essential to compensate for the lack of nutrients in the soil. (phosphorus and nitrogen). Global statistics show that the mean intake annual fertilizer output per hectare is, in Africa, around 10 kg, while in Asia it is around 60 kg and in Europe more than 200 kg. It may be considered too much in Europe, but too little in Africa... but nutrient deficiencies must be overcome if we want to double or even triple yields with agro-ecological practices.

Physical and biological restoration work is yielding positive results in West Africa, India and China. Analyses have shown that the investment required to rehabilitate environments, with a minimum input of fertilizers, amounts to about $300 to $400 per hectare per year for three or four years and that it allows for a doubling of yields and economic rates of return of up to 20 % to 30 %. On the occasion of its twentieth anniversary, the French Scientific Committee on Desertification (CFSD) devoted a seminar to these questions and proposes on its website many resources on this subject.

Insufficient agricultural investments

Studies to assess the overall cost of land degradation give estimates ranging from 1 to 9 % of agricultural GDP for each country concerned. A global assessment, carried out in 1992 and partially revaluedThe report, which is based on the data from the World Bank, indicates annual losses of $42 billion per year; adjusted today, this amounts to more than $80 billion.

But for more than 30 years, agricultural investments from official development assistance (ODA) have been declining. In Africa, in 1981, they amounted to $1.9 billion, or 22 % of ODA; in 2001, they amounted to $0.99 billion, or only 6 % of ODA.

A December 2006 study shows that the financial contribution to reducing degradation would thus be less than the costs of degradation; it suggests that ODA should increase its contribution to sustainable land management from 10 to 15 % over 10 years, thus releasing US$ 10-12 billion per year, which would be sufficient to reverse the process of land degradation and provide income for the poorest.

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Revegetation to slow the advance of the desert in Inner Mongolia. Thibaut Vergoz/IRD

Tracks to explore

Farmers and pastoralists in the affected countries are among the poorest and cannot invest. It seems essential to consider other sources, such as money from the return of migrants for example, which could be used as collateral for private loans. Good conditions must also be guaranteed for these investments to be economically, socially and environmentally profitable: stable public policies guaranteeing access to resources (land, water), stable agricultural prices (inputs, crops), training for farmers and herders, the existence of professional groups and a civil society capable of dialogue with the State.

Another imperative concerns the modalities of the aid to ensure that it reaches the farmers. Finally, it is important to prioritize investments: restoration and rehabilitation of degraded environments, restoration of soil fertility; adoption of sustainable cropping systems meeting the dual objectives of production and protection; investment in human and societal capital; promotion of export channels; promotion of activities other than agricultural activities.

As long as States and official development assistance do not increase their financial efforts, farmers will become poorer and desertification will worsen.

Marc Bied-CharretonProfessor Emeritus, agro-economist and geographer, member of the French Scientific Committee on Desertification (CFSD), University of Versailles Saint-Quentin en Yvelines - University Paris-Saclay and Robin DuponnoisResearch Director, Microbiologist, President of the French Scientific Committee on Desertification (CFSD), Institute of Research for Development (IRD)

The original text of this article was published on The ConversationUP' Magazine's editorial partner.

To go further :
 – GreenFacts Synthesis, November 2018

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