Influence of Spring Burns on the Properties of Humus Horizon of Chernozem in the Southeast of Western Siberia

Influence of spring grass fires on the properties of the upper humus horizon of migrational–mycellary chernozem (Haplic Chernozem) has been studied by the example of soils at the Basic Experimental Complex, Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences (Tomsk). A total of 56 samples (5–14 replicates) were collected at the plots burned two months ago, 1, 2, 3, and 11 years ago. A considerably high stability of the controlled soil properties (cation–anion composition of water extract, content of grain-size fractions and mobile compounds of a wide range of elements, total C and N, organic carbon, pH value, basicity of \({\text{HCO}}_{3}^{ - }\) ) under pyrogenic impact of spring grass fires has been found. The content of mobile Ca, Mg and Sr, as well as water-soluble Mg²⁺ and basicity of \({\text{HCO}}_{3}^{ - }\) appear to be informative parameters reflecting a significant pyrogenic impact over the past 11 years. Their content is higher in the soils at recently (0–3 years ago) burnt plots as compared to old-burnt (11 years ago) and unburnt plots. Among the studied parameters, the pH value, the content of mobile Ba and Sr, and the content of grain-size fractions 1–5, 5–10, and 10–50 µm show a low variation coefficient (mainly <20% in all studied subsets of samples); whereas the content of water-soluble ammonium and mobile Li and Zn manifest a high variation coefficient (>70%).