Tatyana Alexandrovna Gracheva

The paper presents the results of assessing the eff ect of the degree of soil erodibility on the abundance and diversity of cultivated fungi and actinomycetes in diff erent seasons of the annual cycle. The objects of the study are sod—podzolic soils (Umbric Retisols (Abruptic)) of diff erent degrees of washout, located on the slope of the southeastern exposure (Moscow region, Solnechnogorsk district), used for a long time for the cultivation of agricultural crops. The indicators of microbial abundance were determined by the cup method, identifi cation was carried out on the basis of phenotypic characters. It is shown that the decline in physical and agrochemical parameters of the soil, which is a result of erosion processes, leads to a change in microbiological parameters. A decrease in the abundance and species diversity of fungi and actinomycetes was found with an increase in the degree of soil erosion. Significant diff erences were found in the taxonomic composition of microbial communities of non-eroded and washed away soils (the Sorensen species similarity coeffi cient does not exceed 0.42 for fungi and 0.30 for actinomycetes). Taxonomic units of mycelial microorganisms have been identifi ed. Among the fungi are representatives of the species Aspergillus, Cladosporium and Scopulariopsis, among the actinomycetes are Streptomyces malachitospinus, S. candidus and Micromonospora aurantiaca.

The paper presents the results of grouping the lands of the Educational and Experimental Soil and Ecological Center of Lomonosov Moscow State University "Chashnikovo" territory according to the degree of erosion and the need for anti-erosion measures. The work uses an express method of mapping the studied territory using a 1:5,000 scale topographic base, a soil map and an on-farm land management plan. The grouping of the lands of the territory was carried out for the territories of field crop rotations № 1 and 2. It has been established that the lands of the second (46.3%) and third (38.1%) categories of erosion hazard predominate in the territory of crop rotation № 1 (total area 75.6 hectares). An analysis of the land distribution of field crop rotation № 2 (area 67.2 ha) showed that the land categories were distributed as follows: the first — 37.5%, the second — 26.5% and the third — 29.3%. The main recommendations for the rational use of crop rotation areas are given, taking into account the application of anti-erosion measures on lands of 4 categories. No special anti-erosion measures are required in the territories assigned to the first category of Class "A" lands. On lands of the second category, preventive measures are needed to reduce surface runoff and soil drainage (carrying out basic and auxiliary soil treatments across the slope or close to the horizontal). Lands of the third category — it is necessary to carry out a complex of anti-erosion measures aimed at reducing surface runoff and soil washout (contour plowing, soil deepening, formation of artificial microrelief). On lands of the fourth category of erosion hazard, the introduction of a soil-protective crop rotation is required, in which row crops are excluded. The share of perennial grasses (2/3 of the area) and grain crops (1/3 of the area) is increasing. Increased doses of fertilizers are required on lands of the third and fourth categories. The doses are increased for lands of the 3rd category by 15%, 4 — by 30% compared to the doses for the 2nd category.

The paper evaluates the effect of erosion processes on the agrochemical and microbiological properties of the soil in different seasons of the annual cycle. The objects of the study are agro-gray soil of varying degrees of water erosion (uneroded, slightly and moderately eroded) and gray soil under woody forest plantations (south of the Moscow region). It was found that the content of alkaline hydrolyzable nitrogen, exchangeable potassium and mobile forms of phosphorus in the soil depended both on the degree of soil erosion and on seasonal fluctuations. Analysis of the chemical composition of soil organic matter showed that in the summer there was an increase in carboxylic, carbonyl and aromatic components, and in other periods – carbohydrate fractions. In the agro-gray soil, bacterial biomass stocks ranged from 27 to 96 kgha‒1, fungal biomass – from 10 to 357 kgha‒1, their dynamics were determined to a greater extent by the degree of washout and to a lesser extent by the season. With an increase in the degree of washing, both fungal and bacterial biomass decreased in the series unwashed>slightly washed>medium washed. Washed-away soils lost an average of 50% of bacterial and 59% of fungal biomass relative to non-washed soils. In the gray soil, bacterial biomass stocks varied seasonally from 43 to 107 kgha‒1, and fungal biomass from 171 to 621 kgha‒1. The gray soil under forest was superior in microbial pool to all variants of agro-gray soil, and was also characterized by a high content of mycelium, both actinomycete and fungal. In the studied soils, the level of potential respiration (SIR) exceeded the level of actual respiration (BR) by 2‒33 times. Microbial biomass reacted most actively to the introduction of glucose in the average washed soil in the spring and summer periods.