Changes in the Carbonate Status of Chernozems of Azov Region upon Their Conversion from Cropland to Long-Term Fallow
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ADATION, REHABILITATION, AND CONSERVATION OF SOILS
Changes in the Carbonate Status of Chernozems of Azov Region upon Their Conversion from Cropland to Long-Term Fallow A. M. Bulyshevaa, *, O. S. Khokhlovab, N. O. Bakunovichb, V. A. Rusakova, T. N. Myakshinab, and A. G. Ryumina aSt.
Petersburg State University, Institute of Earth Sciences, St. Petersburg, 199178 Russia
bInstitute of Physicochemical and Biological Problems of Soil Science, Russian Academy of Sciences, Pushchino, 142290 Russia
*e-mail: [email protected] Received November 20, 2019; revised February 26, 2020; accepted February 27, 2020
Abstract—Properties of chernozems of different-aged abandoned plots are compared with their analogues within cropland in the Rostov oblast (Russia). The main attention is focused on the carbonate status of chernozems. The field data on the morphology of soil profiles, results of meso- and micromorphological examination, and physicochemical properties of soils are analyzed; the carbonates were dated by radiocarbon method both in the carbonate-accumulative horizon and in the horizons transitional to the parent rock. Decompaction of the former plowed and lower horizons to a depth of 50 cm is observed in the abandoned plots. The organic carbon is accumulated; carbonates are partially leached; and pH values decrease. When the cropland is conversed to an abandoned plot, hard carbonate nodules in the lower part of the profile dissolve and disappear, whereas carbonate migrational forms appear in the upper part (ABca and BCAnc horizons; 40–80 cm). The carbonates in chernozems under the plots abandoned about 30 years ago acquire a new quasi-stable state different from that in the cropland. Vegetation that develops on abandoned plots also has a considerable effect on the transformation of the carbonate status of the studied chernozems. Keywords: abandoned land, tillage, pedogenic carbonates, radiocarbon dating, chernozem DOI: 10.1134/S1064229320080025
INTRODUCTION Sustainable environment management requires an insight into the consequences of human activities during the interaction with natural systems, in particular, soils. The theory of anthropogenic soil evolution considers the mechanisms of changes in soils, in particular, chernozems, caused by human activities; however, this theory is far from being complete [13]. Agricultural use alters the soil regimes and influences the set of integral soil characteristics. The current concepts of the changes in chernozems caused by agricultural impact comprises the following issues: (i) the soil climate is changed by tillage and the natural plant communities are substituted causing the replacement of more northern chernozem subtypes by more southern ones [1, 7, 19, 25]; (ii) the initial natural chernozem subtypes diverge during a long-term farming followed by agrogenic convergence into a unified agrochernozem subtype [27, 29]; and (iii) analysis of the changes in chernozems over 100 years demonstrates deterioration in their hydrophysical properties and structural condition, as w
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