The influence of various tree species of forest plantations on the soil properties of the “Kamenno-Stepnoye Experimental Forestry” (Talovsky District, Voronezh Region, Russia) is considered. The aim of the study is to reveal the degree of transformation of the properties of chernozems under various perennial plantations, since forest reclamation is the most important measure to optimize the agroecological state of soils. The researchers note that different tree species have different effects on soil properties. However, this issue is still insufficiently studied and relevant. The research results showed the positive role of tree species on the structural and aggregate state of soils and their water-physical properties. It was found that tree species contribute to the optimization of soil density, humus and moisture reserves. It was revealed that the influence of different tree species on the agroecological state of chernozems is not the same. Thus, under larch (Larix siberica Ldb.) And maple (Acer platanoides L.), the maximum increase in the level of soil humus was observed, as well as a significant improvement in the physical and water-physical properties of soils. What makes this breed the most promising for use in soil protection of the steppe zone.

The long-term dynamics of the humus content and reserves in the forest-steppe and steppe chernozems of the center of the Russian Plain was studied in a series: virgin land - perennial arable land. To the greatest extent, the transformation of the humus profile of chernozems as a result of plowing is manifested in its upper part. The depth of transformation spread reaches approximately 80-90 cm. In the series of subtypes: podzolic - leached - typical - ordinary chernozems, there are differences in the amount of humus lost. Long-term plowing of these soils leads to the humus content decrease. Therefore, real (t/ha) and apparent (%) humus losses in soils during their long- term plowing can differ significantly. The greatest losses of humus were recorded in leached chernozems – 15 t/ha. In podzolic and ordinary chernozems, the loss of humus reserves was approximately the same and amounted to 13 and 14 t/ha, respectively. Typical arable soils, as a rule, contain 15 t/ha fewer humus reserves than virgin soil. The humus level of chernozems varies significantly in the first years of use, then it stabilizes at a fairly high level according to the new regime of matter and energy circulation in agrocenoses. An objective assessment of changes in the main indicators of the humus state of chernozems during their long-term agricultural use should be carried out not by the percentage of humus but by its reserves, taking into account the corresponding values of the equilibrium addition density.

One of the ways to maintain soil fertility is to use organic fertilizers. One of them can be straw of cereal crops (winter wheat and barley). However, the process of its decomposition can be delayed for several years. It is possible to accelerate the transformation process by using the native strain of cellulosolytic micromycete (Humicola fuscoatra VNIISS 016). Its introduction together with straw before plowing stabilizes agrophytocenosis. The experiments were carried out in laboratory under simulated conditions close to field ones. Scheme of the experiment: 1. Straw; 2. Straw + N (40 mg/4 g, which corresponds to 40 kg/ha); 3. Straw + N + H. fuscoatra + PC (nutritional supplement – molasses) (Kolesnikova M.V., 2014). As a result of the studies, it was established that winter wheat straw without additional components lost 0.86 g in weight (from the initial 4 g), 1.03 g when adding nitrogen fertilizer to the straw, and 1.49 g when using H. fuscoatra. We found that the addition of nitrogen to the straw stimulate the process of its transformation. Straw with nitrogen decompose faster than straw without any additives (by 41.5%). However, the addition of the native strain of micromycete accelerate the process by 48.3%. Barley straw lost 0.82 g in weight, straw with nitrogen fertilizer lost 1.06 g, straw and H. fuscoatra – 1.13 g. Further, the decomposition rate increased in the following row: straw → straw + N, where the speed was 26.7% higher → straw + N + H. fuscoatra, the decomposition rate is – 85.3% higher.

A large role in the creation of soil fertility and water-resistant structure, in the processes of humus synthesis and mineralization, as well as in the provision of agricultural plants with elements of mineral nutrition, belongs to soil microorganisms. For leached chernozem, the influence of field crops on the main groups of microorganisms, which are involved in the formation of effective and potential soil fertility, and associated enzymes was established. The purpose of the work is to study the effect of agricultural plants on the structure of the microbial community of the soil and the activity of enzymes involved in the formation of effective and potential soil fertility. Soil samples were taken from the 0-25 cm layer. They differed in anthropogenic load: virgin soil and soil where crops were cultivated. To count the number of soil microorganisms in the crops and their rhizospheres, we used the method of culturing successive dilutions of the soil suspension on selective nutrient media. The catalase activity of the soil was determined by the gasometric method. It is based on measuring the decay rate of hydrogen peroxide when it is interconnected with the soil in terms of the amount of oxygen released. The method for determining phosphatase activity is based on the quantitative calculation of inorganic phosphorus, which is formed by the breakdown of organic phosphorus compounds under the action of phosphatases.

Рассмотрены особенности динамики валового содержания гумуса и трансформации его активного пула при разных системах основной обработки чернозема выщелоченного в зернопаросвекловичном севообороте. Выявлена наиболее оптимальная система основной обработки почвы, способствующая относительной стабилизации гумусового состояния почвы The features of dynamics of gross content of humus and transformation of its active pool at different systems of main tillage of leached black soil in grainbeet crop rotation are considered. The most optimal system of main tillage is revealed, which contributes to the relative stabilization of humus state of the soil.

Changes in the fertility of a leached chernozem under different tillage technologies (moldboard, non-inversive, and combined tillage) were studied in a multifactor stationary field experiment established in 1985 in Voronezh oblast on a low-humus medium-deep light clayey leached chernozem. The nine-field rotation of cereals and sugar beet was practiced. It was found that the major parameters of soil fertility—the content and qualitative composition of humus and the physicochemical and physical properties of the chernozem—remained relatively stable independently from the applied primary tillage technologies. However, taking into account economic characteristics (crop yields, production costs, energy expenses, etc.), the combined tillage system proved to be most efficient. It can be recommended for cereals–sugar beet rotation systems in the central chernozemic region, as it ensures the highest efficiency of crop growing and preserves the fertility of leached chernozems.

The effect of different fertilizing systems on the main humus status parameters and the physical, physicochemical, and agrochemical properties of leached chernozems has been considered. The most economically and energetically effective fertilizer rates for sugar beet favoring the conservation and expanded reproduction of fertility of the studied chernozems in the forest-steppe of the Central Chernozemic Zone have been revealed.

It has been demonstrated that continuous use of various kinds of basic tillage treatments and fertilizers is accompanied by decrease in the humus content and the activity of enzymes participating in the cycle of major biogenic elements, such as carbon, nitrogen, and phosphorus. Protease and urease activities appeared to be the most sensitive to the mechanical tillage and fertilizer load. It was concluded that the necessary condition in agrotechnology, such as the usage of organic fertilizers, can promote keeping the content of humus at the level of average values and regulate the activity of enzymes in nitrogen exchange.

The physical properties of ordinary chernozems and meadow-chernozemic soils under different land management practices (maple, larch, birch, and pine sections of the shelterbelts; continuous (since 1959) fallow; and arable field (since 1952)) were studied in the Kamennaya Steppe. The soils had favorable physicochemical properties, light clayey texture, and high microaggregation independently from the type of land management. The long-term impact of the shelterbelts improved the soil structure in the upper part of the humus horizon: the content of agronomically valuable aggregates increased, the content of coarse aggregates (>10 mm) decreased, the aggregation coefficient increased by 3.7–4.3 times, and the water stability of the aggregates became by 8–12% higher. The soils under the shelterbelts were characterized by minimum values of the bulk density and solid phase density and by maximum values of the total, active, and air porosities. At the same time, no considerable differences between water reserves in the studied range of soils were detected. The ratio of the optimum productive water range to the active (productive) water range (OPWR/AWR) within the upper soil meter varied from 0.42–0.44 to 0.45–0.54. This points to changes in the character of perched water: the content of intra-aggregate capillary-perched water decreases, and content of film perched water increases down the soil profile.

The effect of various fertilization and tillage systems on active compoients in humus of chernozem is examined. The role of active components of humus in the formation of the humus stock is shown. A new method is proposed for assessing the transformation capacity of humus of arable chernozems.

The effect of long application of fertilizers in crop rotation on the physicochemical properties of leached chernozem and dynamics of the humus content in it is established.