PHYSIC-CHEMICAL PROPERTIES OF TYPICAL CHERNOZEMS OF PRYDNISTERSK PODILLYA

This article analyzes the physic-chemical properties of typical chernozems. According to the methods, a laboratory study was performed. Physic-chemical parameters that are typodiagnostic for subfacial classification division of typical chernozems of the Prydnistersk Podillya are determined. Typical chernozems of the Prydnistersk Podillya are low-humus (2.78–3.98%). With depth, the humus content decreases by an average of 0.2% for every 10 cm, which indicates a uniformly accumulative type of distribution of organic matter in the profile of chernozems. In the same direction, humus reserves are declining. There is a spatial correlation between the humus content and the amount of physical clay in the fine soil. Humic acids predominate in the humus to a depth of 90–100 cm (Sgk: Sfk is 1.12–1.78). The general tendency of relative “fulvatization” of the arable layer as a result of its agrotechnical depletion is noticed. In relation to SGC to total organic C, chernozems of the study area are characterized by a high and very high degree of humification of organic matter. It is highest (62–70%) in the soils of the key section “Humentsi”, decreasing to 52–62% and 43–63% in the western direction. The humic acids of typical chernozems are dominated by calcium humates (GK-2). The largest number of them (29–35%) is concentrated on the contact boundary of humus and carbonate profiles. The convex nature of the distribution curves of the fraction of 2 humic acids and a sharp decrease in its content deeper than 100 cm, indicates their high migration capacity and the possibility of significant deposition of only a significant excess of calcium carbonates. The intensity of migration processes of the GK-2 fraction decreases in the direction of increasing the stiffness of hydrothermal conditions, due to the pulling of carboxylic acid salts closer to the soil surface, supersaturation of the solution with calcium bicarbonate, and as a consequence, increasing the total alkalinity in the humus horizon. The capacity of cation exchange (ECO) of typical chernozems is quite high (29–32 mmol-eq / 100 g of soil) with the dominance of calcium and magnesium cations in the composition of the soil-absorbing complex (GVC). There is a general tendency to increase these indicators in chernozems with low values ​​of SCC of the territory. The pH of the aqueous extract of typical chernozems of the Prydnistersk Podillya increases with depth from weakly acidic in the arable horizon to weakly and medium-alkaline within the carbonate profile. The reasons for such changes in the increase with the depth of the concentration of Ca2 + bicarbonates, which in their dissociation leads to an increase in the amount of hydroxyl ion and increase the alkalinity of the soil. The carbonate profile of typical chernozems is dominated by migratory forms of carbonate neoplasms - mold, carbonate plaque, veins. The vertical curve of carbonate content has an eluvial-illuvial type of profile structure. The content and reserves of carbonates in the 1.5-meter layer of typical chernozems increase from the west (434–714 t / ha) to the east (979–1847 t / ha). Key words: physic-chemical properties, typical chernozems, humic horizon, humic acids, carbonate profile.

DYNAMICS OF FERTILITY OF AGRICULTURAL CHERNOZEMS OF FOREST-STEPPE ZONE OF THE CENTRAL CHERNOZEM REGIONS OF RUSSIA

The research was carried out to study the dynamics of fertility of arable soils in the southwestern part of the forest-steppe zone of the Central Chernozem region. The work was carried out according to the results of an agrochemical soil survey on the territory of Yakovlevsky district of Belgorod region. The soil cover was represented mainly by typical chernozems (57.7%) and leached (28.2%). Under these conditions, an increase in the average dose of organic fertilizers in the region from 6.5 t/ha in 2010–2014 up to 14.6 t/ha in 2015-2018 while maintaining the use of mineral fertilizers at the level of 82.9 kg a.i./ha, it became one of the main factors in the growth of the weighted average content of mobile forms of phosphorus in the soil from 101 to 167 mg/kg, potassium - from 120 to 183, sulfur - from 2.5 to 4.7, manganese - from 11.0 to 13.1, zinc - from 0.4 to 0.7 mg/kg. Bringing liming volumes in the region for 2015–2018 to 32.7 thousand hectares contributed to a decrease in the share of acidic soils from 84.7 in 2009 to 52.9% in 2018.Along with the improvement of the agrochemical parameters of arable soils, there was a significant increase in the yield of the main agricultural crops: winter wheat - from 3.38 to 4.55 t/ha, corn for grain - from 4.84 to 7.60 t/ha, sugar beet - from 36.8 to 56.4 t/ha

Technical and technological improvement of sunflower cultivation in the dry regions of the Volga federal district

The article presents the results of studies of the effectiveness of liquid mineral nitrogen and nitrogen-sulfur-containing fertilizers based on urea-ammonia mixture-UAN in comparison with solid-ammonium nitrate when growing sunflower in arid, typical for the zone of "risky farming" - the Volga region, years (2018-2020) with the use of modern high-performance equipment manufactured in Russia (Samara) at JSC "Eurotechnika" of the German company AMAZONEN-Werke. Conducted three-year studies on typical chernozems of the Samara region on the experimental fields of the Samara State Agrarian University, showed a significant advantage of liquid fertilizers with an increase in sunflower yield on average for three years according to experimental options up to a maximum of 6centners / ha or by13 %.

METHOD OF FORECASTING THE YIELD OF APPLE TREES DEPENDING ON THE SOIL CONDITIONS OF THE NORTH OF THE CENTRAL CHERNOZEM REGION

The following soil indices that determine the level of apple tree yield have been determined: agrochemical indi-ces: pHKCl, hydrolytic acidity, total exchangeable bases, alkali-hydrolyzable nitrogen, easily-hydrolyzable nitrogen, mobile phosphorus, exchangeable potassium, humus con-tent, and ground water mineralization; morphological indi-ces: humus horizon thickness (A + B1), root layer thick-ness, carbonate depth, gleying depth, ground water depth, water-soluble salt depth; physical indices: soil density, mesoaggregate content (0.25-10 mm), physical clay con-tent (< 0.01 mm); water-physical indices: hydroscopic mois-ture, maximum hygroscopic content, capillary moisture capacity, minimum water capacity, available moisture, wa-ter stability coefficient; orographic indices: slope steepness and slope exposure. A method for predicting apple tree yield for soil types in the northern part of the Central Cher-nozem Region has been developed; the method is based on the agrochemical, morphological, water-physical, and orographic soil indices and takes into account the rootstock vigor. The method shows the range of the expected aver-age annual yield of apple trees during the period of full fruiting without fertilizer application. According to the devel-oped software, the highest yield of apple trees on semi-dwarf rootstock (using the example of 62-396) will be ex-pected on typical chernozems; on medium-sized rootstock (54-118) -on leached chernozems, podzolized and dark gray forestsoils; on strong-growing rootstock (pomaceous) -on podzolized chernozems and dark gray forest soils.

The yield values of densimetric fractions from typical chernozems of different land use types

One of the most justified and applied approaches to isolating pools of soil organic matter is fractionation in heavy liquids. The main problem with this approach is rather large losses in the separation of fractions at the stage of washing fractions from heavy liquids. The paper presents a densimetric fractionation protocol that can significantly reduce these losses. It is suggested to use 0.001 M HCl for washing. This approach, in comparison with distilled water, allows reducing losses of weight from 15 to 5% and of carbon from 7.5 to 2.5%. The paper provides a detailed protocol, used by the Laboratory of Soil Biochemistry of V.V. Dokuchaev Soil Science Institute, to isolate four densimetric fractions using sodium polytungstate solutions: free and occluded SOM with a density of <1.6 g/cm3, occluded SOM – of 1.6–2.0 g/cm3, and a mineral residue with a density >2.0 g/cm3. In the work we used samples of typical chernozems of different land use types. It was shown that the processes of soil restoration and degradation significantly affect the content of light occluded soil organic matter.