The extent of the world's land affected by excess salt is rapidly expanding, with potentially devastating effects on food production, a study has found.
Approximately 1.4 billion hectares (3.4 billion acres), or 10% of the world's land, are affected by salinity, with a further 1 billion hectares classified as 'at risk'. Report from the Food and Agriculture Organization of the United Nations I found it.
This is already having a severe impact on agriculture, with around a tenth of irrigated farmland and a similar proportion of rain-fed farmland around the world suffering from excessive salinity. In some cases, as much as 70% of crop yields can be lost.
Some of the world's largest and most populous countries have been particularly hard hit, including China, the United States, Russia, Australia, and Argentina. The Central Asia region is also a hotspot, with Afghanistan, Kazakhstan and Uzbekistan being severely affected, with Iran and Sudan also ranking among the worst affected countries. These 10 countries account for 70% of the world's saline soils.
In the first major assessment of the problem in 50 years, FAO scientists found that climate change and poor agricultural practices are to blame. As temperatures rise, the extent of saline soils could increase from a quarter to a third of all land by the end of this century if current trends do not stop.
Crops need some salt, but too much salt reduces soil fertility. Too much salt will absorb water, reducing the amount that plants can absorb. Salt also changes the physical structure of the soil, causing it to aggregate and become more susceptible to erosion.
Water scarcity, poor drainage, and overexploitation of the soil are the main causes of increased salinity. Sea level rise will exacerbate this by intruding salt water into coastal areas.
Pressure to increase short-term yields often drives farmers to poor practices, which creates long-term problems. According to the report, global water use has increased six-fold in the past century, and this overexploitation of irrigation aquifers is causing groundwater salinization. Farmers also irrigate crops with low-quality or salty water, pump too much water to feed crops, and use too much chemical fertilizer. Removing deep-rooted vegetation such as trees can increase soil salinity.
In parallel with tackling the climate crisis, FAO says the best way to restore soil fertility is through traditional techniques such as mulching, layering the soil with loose materials and improved crop rotation, as well as: We have discovered that combining innovative technologies such as Development of salt-tolerant cropsthe use of bacteria, fungi, and plants to remove or sequester salts.
Regenerative agriculture practices that focus on natural soil fertility may also play a role. More government support is needed, said Anand Ethirajar, project director at Cauvery Calling, which is helping more than 250,000 farmers adopt agroecological practices. “If we don’t financially support farmers to restore soil, [declining fertility] “It will affect all of us, everyone who depends on food to survive,” he said.
The report was released on Wednesday at the International Soil and Water Forum in Bangkok. The plight of the world's soils has also been in the spotlight this week in Saudi Arabia, where two weeks of talks under the United Nations Convention to Combat Desertification are scheduled to conclude on Friday.
Rising global temperatures and increased pressure on agriculture are causing land to become drier around the world. Experts warn that these factors, along with rising salinity and declining soil fertility, are combining to pose an unprecedented threat to food production.
Pravina Sridhar, Chief Technology Officer of the Save Soil Movement, said: “Global hunger is no longer a distant threat. The soil crisis is invisible to many, but unless policymakers act, its effects will reach every corner of the world.”
