Articles

The degree of spatial variation of agrochemically important properties of plowing horizon (pH KCl, hydrolytic acidity, absorption capacity, the degree of saturation of bases, humus content, mobile phosphorus and exchange potassium) is estimated. It is shown that the partition of the set into subsets corresponding to classification units significantly reduces the degree of variation of humus and physico-chemical properties, practically without changing the variability of pH, the content of mobile phosphorus and exchange potassium. Discriminant analysis shows that the arable horizons of sod-medium podzolic, gray forest and dark gray forest soils are satisfactorily classified for a given set of properties. Poorly classified bog-podzolic and gray forest gleyed soils. Light gray forest soils occupy an intermediate position, gravitating toward gray forest soils.

The concentrations of potassium were measured in 1 М NH₄OAc, 2 M HCl, and hot 10% HCl extracts from samples of the rhizosphere of Norway maple ( Acer platanoides ) and of bulk soil taken in five replicates from the (AO)EL horizon of a podzolic soil. The rhizosphere soil was found to contain reliably more exchangeable potassium due to higher content of OM and more potassium compounds extractable with hot 10% HCl. According to the existing guidelines on growing the leaf-bearing trees the rhizosphere soil and the bulk soil can be referred to highly and moderately provided with available potassium respectively. The higher content of potassium soluble in hot 10% HCl in the rhizosphere soil can be explained by the dissolution of the finest poorly crystallized illite particles. These particles can be accumulated in the rhizosphere soil due to intensification of two processes: illitization and physical disintegration of illite particles enhanced by growing roots.

The joint development of sod-podzolic and lightgray forest soils is investigated on the land released from agricultural use situated within the southern slope of Gorokhovetsky spur of the North-East of the Vladimir region. Morphological and physico-chemical properties of light gray forest and sod-podzolic soils influenced by both natural and anthropogenic factors are analyzed.

Forest litter of some coniferous and deciduous plantations within the Botanical Garden of the Moscow State University is studied. It is established that in the conditions of the deciduous plantations, forest litters of destructive types develop, whereas in the coniferous plantations - fermentative and humified ones. The total reserves of forest litters range from 500-800 g/m² in deciduous plantations, up to 1000-5000 g/m² in coniferous ones. It is shown that small-leaved plantations are characterized by high rates of cycling, with a significant decrease in the coniferous ecosystems. It was shown for the first time that with an increase in the proportion of leaves in the litter, the overall decomposition rate of terrestrial litter increases substantially, which is confirmed by the theory of “hot points” proposed in the scientific literature.

The effects of the crane-fly larvae (Diptera, Tipulidae) on the functional diversity of soil microbial communities, as well as the activity of the processes of transformation of nitrogen and carbon in the soil, were studied. It has been established that the rate of nitrogen fixation, denitrification and methanogenesis significantly increases as a result of the life activity of larvae in the soil, the indices of functional diversity (the number of consumed substrates, the metabolic work) and the stability of the microbial complex increase.

This research based on both direct and seeding methods revealed high bacteria concentration on bogs plants: Carex nigra, Eriophorum vaginatum, Drosera rotundifolia, Ledum palustre. There was identified a correlation between bacteria number and investigated plants’ organs. Proteobacteria dominated in phyllosphere, bacilli and actinomycetes - in rizoplane and rhizospheric soil. Representatives of the genus Pseudomonas and Erwinia dominated in phyllosphere. Nitrogenase activity of bacterial populations in rhizosphere soil was high and reached the maximum in Drosera rhizospheric soil.

The action and aftereffect of the construction main pipeline on the characteristics of humus and the features of its distribution over particle-size fractions of soddy-podzolic soil were studied; features of humus technogenic degradation and the degree of their expression in comparison with the control soil in different periods of observations in relation to the specificity of ecological situation were characterized.

Environmental toxicity assessment of roadside soils across Leningradskoe highway in Moscow region was carried out by rapid laboratory phytotest using two test cultures. The toxicity of soils was determined based on growth parameters inhibition of Lepidium sativum L. (cress) and Hordeum vulgare L. (rye). Topsoils (0-3 cm depth) were examined at the distance up to 300 m from the road pavement. Soil toxicity was determined on the most part of the studied territory and was characterized with bimodal distribution: it was maximal at the distance of several meters from the highway (highly toxic soils), sharply decreased at a distance of 7 m from it and gradually increased again towards the end of the studied zone (moderately toxic soils). The degree of phytotoxicity differentiated depending on the test culture variant: H. vulgare was characterized by a lower sensitivity to pollutants and did not reveal toxicity in the area of 7-25 m from the Leningradskoe highway, while L. sativum revealed the toxicity of soils all over the investigated territory. Among test parameters analyzed, the root length and length of the seedlings showed the greatest sensitivity to pollutants, while seed germination was not informative.

The analysis of experimental methods for assessing the cellulosolytic activity of soils and methods for calculating the results of its measurement are discussed basing on publications and authors' experiments. A brief overview of factors and dynamics of this phenomenon in soil profiles, including its seasonal changes, is presented, as well as information on its the geographic variability. The materials presented may be helpful for research in this area by emphasizing various details responsible for obtaining reliable results for interpretation.

The paper presents the results of the study of fatty acid profiles of typical chernozems with different management practice. The study showed that degradation of soil organic matter in typical chernozems is accompanied by depletion of fatty acids, while its accumulation resulted in an increase in their diversity. In this regard, the composition of fatty acid soil profiles allows classifying the soil successfully according to the prevailing processes of transformation of organic matter. An uneven distribution of fatty acids was discovered in soil aggregates of different sizes for the untillage chernozems, whereas arable chernozems possessed regular distribution of fatty acids among aggregates of different size. Eicosapentaenoic acid which is a moiety of microalgae, and dihomo-gamma-linolenic acid which is synthesized by fungi Mortierella can be considered as biomarkers of the withdrawal of typical chernozem from agricultural use to a fallow land.