Frozen saline water may improve barren soil

BEIJING－Chinese researchers have discovered that saline land may be reclaimed by freezing saline water over the soil in winter. In addition, they found that the desalination depth of saline ice meltwater in saline-alkali soil was greater than that of salt-free ice, according to a recent study published in the European Journal of Soil Science.

China has about 100 million hectares of saline-alkali land that lacks adequate freshwater resources. This type of land restricts agricultural production and plant growth. Scientists have been trying to figure out how to turn barren, salty soil into arable land.

Researchers from the Chinese Academy of Sciences' Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology evaluated infiltration and soil desalination after saline ice melted into saline soil. They found that saline ice meltwater went deeper into the saline soil than fresh ice meltwater.

Previously, the researchers developed a saltwater irrigation method to improve cotton yields in saline soils, based on the separation of saline and freshwater by melting saline ice. They used salty water with a concentration of less than 15 grams per liter to irrigate the salinealkali land in winter. The saline water was frozen on the top of the soil. When spring came, the saline ice melted and gradually infiltrated into the saline soil.

The continuous infiltration of the meltwater with higher salinity was followed by meltwater with lower salinity. The following rainwater washed the soil salt further, allowing the crop roots to avoid the influence of the salt.

A great desalination effect was observed in coastal saline soil with soil salt content reduced to less than 0.3 percent during the entire season, and the cotton yield reaching 200 kilogram per 667 square meters.