Carbon and nitrogen compounds and emission of greenhouse gases in ancient and modern soils of the Arkaim Reserve in the Steppe Trans-Ural Region.

Carbon and nitrogen compounds and the emission of CO, CH, and NO were studied in the ancient buried and modern background soils developed from different parent materials in the Arkaim Reserve of Chelyabinsk oblast. The studies were performed after an 18-year-long period of absence of anthropogenic loads on the local ecosystems. Element contents in the humus horizons of the chernozems of the former plowland and pastures and of the forest soil reach 28-45.6 g/kg for C, 2.5-4.5 g/kg for N, 140-423 mg/kg for labile carbon (C), 32-73 mg/kg for labile nitrogen (N), 350-952 mg/kg for carbon of microbial biomass (C), and 38-85 mg/kg for nitrogen of microbial biomass (N). The contents of different forms of C and N depend on the soil type and texture and on the type of land use, including that before reservation of the territory. The emission of greenhouse gases was examined in this area for the first time. The production of CO by the soil buried about 4000 years ago is an order of magnitude lower than that by the modern soil. The emission and sink of NO are small in both modern and ancient soils. The behavior of methane is clearly different in the automorphic and hydromorphic soils: the former serve as methane sinks, whereas the latter act as methane sources. The rate of the CO emission from the soils is controlled by many factors, including the soil type, texture, degree of hydromorphism, composition of parent materials, and type of land use. [ABSTRACT FROM AUTHOR]