Popular Science: The mysterious history of chernozems
The distribution of chernozems is related to the long-term duration of the continental climate of the temperate zone, so it is possible to speak of “zonal” soil. The annual precipitation is around 250-600 mm, while it is slightly lower than the evaporation, which ensures minimal nutrient elution. The typical vegetation covering the chernozems are steppes with dominating grassland, the mother rocks are carbonate bedrock, usually loess. One of the main characteristics of the chernozems is a deep organic horizon with an active edaphon and a natural high supply of nutrients, thanks to which they are the most fertile soils of the temperate zone.
Due to the high fertility, chernozem regions were considered to be the breadbasket of the world and were used intensively as arable land. Only small isolated islands of chernozems in the landscape are currently left to their natural development with grassland cover. However, these are currently under pressure because of the extension of agricultural land, the invasion of trees and bushes and the decrease in bot
Although chernozems are always mainly associated with the steppes, there are no environmental conditions in Central Europe to allow the development of steppes. In various sources, the occurrence of chernozems is also documented under the woodlands of thermophile oaks or oak-hornbeams. The paleoenvironmental studies have not yet revealed what vegetation has occurred in Central Europe during their development, so a team of experts focused on this issue to pull back the veil of secrets of these unique and fertile soils.
In total, they investigated 23 sites of chernozems, especially those not currently used as arable land. Samples come mainly from Central Europe, though Ukrainian and Russian chernozem were also examined. Near infrared spectroscopy (NIRS) was used for their analysis. This makes it possible to assess the qualitative and quantitative characteristics, in the case of this study, of the origin of soil organic matter. The principle is to compare the results of the analyzed sample with an unknown origin of humus with a set of known samples from the spectral reference library with well-known vegetation (in this case forest and grasses).
The spectral reference library and the use of NIRS have yielded results in the research of the origin of chernozems and the characteristics of their genesis and evolution. The study found that although grassland is necessary for the primary development of chernozem, the chernozem can remain even thousands of years under woodland or forest-steppe cover without changing to another soil type. This may happen when ambient conditions have changed as, for example, has currently happened in southern Moravia, where erosion is not only changing the soil's creditworthiness, but is also changing the soil type. Thus, new findings have shown that the occurrence of chernozem cannot be directly linked only to the presence of grassland, as they could be also covered by forest vegetation for a limited period.
The research of chernozem and its development conditions are very important as it is one of the most fertile soils and must be protected. The results proving the vegetation history of chernozem are also applicable in archaeological research to create a model of settlement in the past.
The distribution of chernozems with the identification of individual areas of research. Source: Authors of the original article.
Strouhalová, B., Ertlen, D., Šefrna, L., Novák, T.J., Virágh, K., Schwartz, D. (2019): Assessing the vegetation history of European chernozems through qualitative near infrared spectroscopy. Quaternaire 30 (3), s. 227-241.