Soil and water

The march of salt and plastic on the world’s soils – Global issues

  • by Baher Kamal (Madrid)
  • Inter Press Service

In fact, it is currently estimated that there are over 833 million hectares of saline soils in the world (8.7% of the planet). This involves the loss of the soil’s ability to produce food and also increasing impacts on water and the ability to filter pollution.

Soil salinization and sodification are major soil degradation processes threatening ecosystems and are recognized as some of the most important global issues for agricultural production, food security and sustainability in arid and semi-arid regions. arid, said the UN on the occasion of World Day 2021. Soil Day.

Not only: Soils affected by salt have serious consequences on soil functions, such as decreased agricultural productivity, water quality, soil biodiversity and soil erosion and have reduced capacity to act as a buffer and filter against pollutants.

Soils affected by salt reduce both the ability of crops to absorb water and the availability of micronutrients, and they also concentrate ions that are toxic to plants and can degrade soil structure.

A threat to the global pantry

Soil salinity is a natural occurrence in arid environments, such as deserts, where intense evaporation and a chronic lack of water often make the land too saline. Soils like these are less fertile because salt hinders the natural ability of plants to absorb water from the soil, says the Food and Agriculture Organization of the United Nations (FAO).

“But unsustainable human activities exacerbate soil salinity. Excessive tillage, overuse of fertilizers, inappropriate irrigation methods and use of poor quality water, deforestation or overuse of groundwater are the main drivers of salinization of the original soils. anthropogenic.

World Soil Day 2021 and its “Stop Soil Salinization, Increase Soil Productivity” campaign aimed to raise awareness of the importance of maintaining healthy ecosystems and human well-being by addressing the growing challenges of soil management. soils, by combating soil salinization, by increasing soil awareness and encouraging societies to improve soil health.

According to the FAO, these are, among others, the impacts of saline soils:

Soils affected by salt have severe impacts on some of the ecosystem services typically provided by soils, which are essential to support human life and biodiversity, leading to a range of consequences, including:

  • decrease in agricultural productivity, water quality, soil biodiversity and increased soil erosion;
  • decreased ability to act as a buffer and filter against contaminants;
  • degraded soil structure;
  • decreased functions of ecological systems such as hydrological and nutrient cycles;
  • reduced capacity of crops to absorb water
  • reduced soil fertility and micronutrient availability.

Half of Uzbekistan’s soil covered with salt

The Central Asian country is doubly landlocked – meaning it is surrounded by countries that are themselves landlocked – and more than half of Uzbekistan’s soils are affected by salt, making it very difficult to l productive agriculture, reports the Food and Agriculture Organization (FAO). for example.

Not just salt … also plastic

A new FAO report from December 2021 suggests that the land humans use to grow food is contaminated with “much greater amounts of plastic pollution,” posing an even greater threat to food security, the human health and the environment.

The report – “Assessing Agricultural Plastics and Their Sustainability: A Call to Action” – is FAO’s first global report of its kind and contains startling figures.

According to data collected by experts from the UN agency:

– Agricultural value chains use 12.5 million tonnes of plastic products annually.

– 37.3 million additional tonnes are used in food packaging. The crop production and livestock sectors were found to be the largest users, accounting for 10.2 million tonnes per year collectively, followed by fisheries and aquaculture with 2.1 million tonnes, and forestry with 0.2 million tonnes.

– Asia is estimated to be the largest user of plastics in agricultural production, accounting for almost half of global use. In the absence of viable alternatives, the demand for plastic in agriculture will only increase.

– According to industry experts, for example, global demand for greenhouse films, mulch and silage will increase by 50%, from 6.1 million tonnes in 2018 to 9.5 million tonnes in 2030.

– Such trends make it essential to balance the costs and benefits of plastic. Microplastics, which have the potential to harm human health, are of growing concern. Although there are data gaps, they should not be used as an excuse not to act, FAO warned.

“This report is a strong call for coordinated and decisive action to facilitate good management practices and curb the disastrous use of plastics in agricultural sectors,” FAO Deputy Director-General Maria Helena Semedo said in the report. Foreword to the report.

The report was presented today at a virtual event on the occasion of World Soil Day, which is celebrated annually on December 5.


“Plastics have become ubiquitous since their widespread introduction in the 1950s, and it’s hard to imagine life without them today.

In agriculture, plastic products greatly contribute to productivity, according to the report.

“Mulch films, for example, are used to cover the soil to reduce weed growth, the need for pesticides, fertilizer and irrigation; Films and nets for tunnels and greenhouses protect and stimulate plant growth, extend growing seasons and increase yields.

This is also the case with “coatings on fertilizers, pesticides and seeds control the rate of release of chemicals or improve germination; Tree guards protect young plants and saplings from animal damage and provide a microclimate that improves growth.

Meanwhile, plastic products help reduce food loss and waste and maintain their nutritional qualities across a myriad of value chains, thereby improving food security and reducing greenhouse gas emissions, the report says. .

Billions of tons of poorly disposed of plastic

Of the 6.3 billion tonnes of plastics produced up to 2015, nearly 80% have not been disposed of properly, according to the FAO.

Once in the natural environment, plastics can cause damage in several ways. The effects of large plastic objects on marine life have been well documented.

However, as these plastics begin to decay and degrade, their impacts begin to exert at the cellular level, affecting not only individual organisms but also, potentially, entire ecosystems.

Microplastics (plastics smaller than 5mm) are considered to present specific risks to animal health, but recent studies have detected traces of microplastic particles in human stool and placentas. There is also evidence for mother-to-fetus transmission of much smaller nanoplastics in rats.

While most scientific research on plastic pollution has been directed to aquatic ecosystems, especially the oceans, FAO experts have found that agricultural soils receive much greater amounts of microplastics.

Given that 93% of the world’s agricultural activities take place on land, it is evident that further investigation is needed in this area, the report concludes.

Need to know more ?

Very little of the plastic we throw away every day is recycled or incinerated in waste-to-energy facilities. Much of it ends up in landfills, where decomposition can take up to 1,000 years, leaching potentially toxic substances into the soil and water, according to the United Nations Environment Program (UNEP), which warns that ‘one third of all plastic waste ends up in soil or freshwater.

In addition: more than 400 million tonnes of plastic are produced worldwide each year. An estimated one-third of all plastic waste ends up in soil or freshwater, according to researchers at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB).

More than marine pollution

Most of this plastic decays into particles smaller than five millimeters, called microplastics, and further decomposes into nanoparticles, smaller than 0.1 micrometers.

“In fact, terrestrial microplastic pollution is much higher than marine microplastic pollution – an estimate of four to 23 times higher, depending on the environment. Wastewater, for example, is an important factor in the distribution of microplastics.

Also that “80 to 90% of particles in wastewater, such as fibers from clothing, persist in sludge. Sewage sludge is then often applied to fields as fertilizer, which means that several thousand tonnes of microplastics end up in our soils each year.

© Inter Press Service (2022) – All rights reservedOriginal source: Inter Press Service