11 March 2024

Researchers in China propose a new solution for saline-alkaline soils


For more than a decade, a group of researchers in China has been developing a restoration method based on planting crop stems that prevent salt from rising to the surface, writes the South China Morning Post

by Matteo Cavallito


Turning salt-rich soils in China into fertile soils: that is the goal of scientists working in Wuyuan County, Inner Mongolia. The initiative, reported by the South China Morning Post, involves a group of scientists led by Li Yuyi, a researcher at the Chinese Academy of Agricultural Sciences.

Saline-alkaline land contains an excess of both soluble salts and exchangeable sodium, making it more difficult to farm,” the Hong Kong newspaper writes. “Farmers in Wuyuan overirrigate their farmland with water from the nearby Yellow River throughout the year, causing the water table to rise and salts in the soil to migrate upwards.”

The test in China

Researchers spent more than a decade in developing and testing a new restoration method in Shandong and Heilongjiang provinces in northern China. The method used involves planting crop stems between 5 and 15 centimeters in length at a depth of 30 to 40 centimeters. In this way, the stems prevented the salt from rising to the surface.

The scientists also covered the soil with a layer of plastic with the aim of retaining moisture. And the results were not long in coming. After this treatment, the paper still writes, citing Science and Technology Daily, “the salt content of the soil was reduced by 36 per cent on average and crop yields increased by 30.5 per cent.”

Between salinization and desertification

China has been facing the problem of saline-alkaline soils for decades, which, to date, would occupy an area of about 100 million hectares. A figure that makes the country the third most affected nation on the Planet in terms of the overall extent of the phenomenon. Most of these barren lands are located in the arid and semi-arid regions of the west-central area that includes Qinghai Province, Inner Mongolia and the Xinjiang Uygur Autonomous Region.

The problem of salinization, in short, comes alongside the issue of desertification, which is an obstacle to food security and agricultural development especially in Central Asia. Here, some experts say, desertification is advancing at an increasing rate, aided by the effects of climate change. Threatening, according to some estimates, the security of half a billion inhabitants.

Excess salt is a global problem

The problem of excess salt in the soil, FAO estimates, affect 20 to 50 percent of all agricultural soils on the Planet, forcing more than 1.5 billion people to face significant difficulties in food production due to soil degradation. In detail, deeply affected soils cover 833 million hectares. At global level there are also 424 million hectares where the phenomenon occurs only or even at the surface level.

The FAO looked at so-called Salt-affected soils (SAS), that is, saline and sodic soils (sodic category also includes alkaline soils, that is, those in which the pH exceeds 8.5).

Saline soils are definitely more prevalent, accounting for 85 percent of salt-affected surface soils and 62 percent of those affected at the subsurface level. A minority share of the salt-affected soils (5 percent at the surface, 14 percent below 30 centimeters deep) suffer simultaneously from salinization and sodification. The most affected areas are in Asia, Africa, and Latin America, especially in deserts and steppes.

La distribuzione dei suoli affetti da salinizzazione. FONTE: FAO.

The distribution of soils affected by salinization. SOURCE: FAO