Assessment of the Influence of Pyrogenic Factors on the Biological Properties of Chernozems
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BIOLOGY
Assessment of the Influence of Pyrogenic Factors on the Biological Properties of Chernozems K. Sh. Kazeeva, *, M. Yu. Odabashiana, A. V. Trushkova, and S. I. Kolesnikova aSouthern
Federal University, Stachki prosp., 194/1, Rostov-on-Don, 344006 Russia *e-mail: [email protected]
Received August 7, 2019; revised November 19, 2019; accepted April 24, 2020
Abstract—Changes in the biological properties of chernozems caused by several pyrogenic agents have been studied in simulation experiments with the low-temperature plasma, infrared irradiation, straw burning, and fume of burning products. It has been shown that the pyrogenic effect has a complex nature, so that worsening of biological parameters depends on temperature, duration of fire episode, intensity of fume, ash impact, and soil moisture. Such integrated effect induced a decrease in microbial biomass by 39%, population of nitrogenfixating bacteria by 29% versus the control values. The inhibition of dehydrogenase and catalase (oxidoreductase class) was 44–53%; the activity of hydrolase (phosphatase and invertase) was lower (by 16–18%). A maximal effect was recorded for the uppermost soil layer (0–1 сm) as compared to the lower 4–5 сm layer. Microbiological indices went down by 52–56% after placing the sample in the flame of a gas burner for 3 minutes, while soil enzyme activity decreased by 25–26%. For the latter, the duration of flame effect was of special importance; the correlation coefficient for dehydrogenase activity was –0.81; for invertase activity, –0.86; for catalase activity, –0.78; and for phosphatase activity, –0.85 (р < 0.01). Increasing IR irradiation also resulted in growing inhibition of biological indices. Even a minimal impact of fume of straw burning products (3 minutes at temperature 52°С) reliably decreased soil microbiological and biochemical parameters (by 4–19%, р < 0.05). Higher level of impact suppresses the biological activity by 20–30%. Keywords: fire, burn, biological indicators, enzyme activity DOI: 10.1134/S106422932011006X
INTRODUCTION Pyrogenic effect is possible under natural conditions and it is an important factor significantly changing natural ecosystems [38]. However, human activity caused significant increase of frequency as well as intensity of fires. The influence of fires on ecosystems and soils is of interest for many researchers all over the world [20, 44, 46, 48, 54]. This is due not only to pyrogenic changes of territories in the result of fires, but also to the fact that the restoration of the burned territories takes long time and depends on the intensity of pyrogenic impact [15, 21–23, 25, 36, 39]. Pyrogenic impact on soil differs depending on fire type (crown, creeping, underground), fire intensity (weak, medium, strong), duration (from several minutes to several hours), and frequencies. Physicochemical, hydrothermal, and biological properties can change directly in the result of influence of high temperatures, fume, and ashes and indirectly via complete burning of native flora and further replacem
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