BEIJING, June 20 (Xinhua) -- Researchers from the Institute of Geology and Geophysics under the Chinese Academy of Sciences (CAS) have discovered that the soil particles of black soil in Northeast China were initially transported by wind.
Their findings were published in the international academic journal Catena.
Black soil, renowned as "the giant panda among arable land," is recognized as one of the most fertile soils in the world, and Northeast China's black soil region is a significant grain production base. However, the black soil is under severe threat due to intensified human activity.
"Clarifying the origin and depositional setting of Northeast China's black soil will help targeted erosion control endeavors in the region," said Yang Shiling, researcher at the CAS institute and corresponding author of the paper.
Researchers conducted grain size analysis and optically stimulated luminescence (OSL) dating tests on collected samples of Northeast China's chernozems and underlying sediments to explore their genesis and depositional background.
The results of the grain size distribution revealed that the chernozems in the western part of Northeast China resemble the sandy loess on the northern Loess Plateau, displaying typical characteristics of wind deposition. In contrast, the chernozems in the eastern part resemble the secondary loess on the alluvial plains, indicating signs of subsequent hydraulic modification.
Additionally, the average median grain size and sand content of the chernozems revealed that the particle size gradually decreased from west to east, a trend that aligned perfectly with the direction of the wind during the dust storm season in the region.
"We believe that although the eastern chernozems underwent localized hydraulic modification, the spatial distribution pattern of the grain size has not changed on a larger scale, and the chernozemic matter was originally transported by wind," said Zhang Shihao, the first author of the paper and a doctoral student at the Institute of Geology and Geophysics, Chinese Academy of Sciences.
Chronological studies indicate that the Northeast China chernozems primarily formed during the Holocene, about 10,000 years ago, while the underlying sediments mainly originated from the Last Glacial Period and have a relatively wide age range (12,000 to 65,000 years ago).
"This result suggests that during the Last Glacial Period, the landforms in the chernozem region were not stable, subject to various degrees of erosion, possibly due to enhanced wind erosion during the glacial period and water erosion caused by meltwater from surrounding mountain glaciers. During the Holocene, warmer and wetter climates led to vegetation growth, enabling the deposition of windblown dust and the formation of chernozems rich in organic matter," Zhang explained.
Yang Shilong pointed out that this study holds great significance for chernozem protection in Northeast China. Considering the crucial role of vegetation in the accumulation of windblown dust and soil development, proper revegetation efforts will contribute to the sustainable development of chernozem resources.
(Image provided by the Institute of Geology and Geophysics, Chinese Academy of Sciences)
