№ 9 (2024)

In long-term experiments, the content of humus in natural and agroecosystems on meadow-chernozem soils depended on the species diversity of plants, the state of the vegetation cover, the cultivation of the arable horizon and its erosion. During the 10-year observation period, the humus content in arable soil decreased by 4.5% relative to the initial state, while under meadow grasses, on the contrary, it increased by 22%. Then, during the 20-year accounting period, the processes of humus accumulation in the cultivated soil changed little. Among natural ecosystems, humus accumulation processes were most active in the humus-accumulative (A) and transitional horizons (AB) under the aspen forest. The reserves of humus and nutrients in eroded soils decreased dramatically, causing a decrease in the productivity of meadow grasses. It has been established that for a significant accumulation of humus (up to 8%) in the non-eroded soil of the 100-year period of ecosystem functioning, it is necessary to combine incoming carbon in the form of forest litter and roots with the biomass of perennial meadow grasses.

In 2021–2023, in the experimental field of the All-Russian Corn Research Institute in the zone of sufficient moisture in the Stavropol Krai the effectiveness of pre-sowing application of ammonium nitrate (N30) and nitroammophoska (N30P30K30) to the soil was studied in comparison with non-root fertilization of maze plants in the 8-leaf phase with Batr Zinc fertilizer (1.0 l/ha). On average, over the period of 3 years, the height of Mashuk 220 MV hybrid plants increased from ammonium nitrate by 12, nitroammophoska by 17, from fertilizing with Batr Zinc fertilizer by 16 cm, Mashuk 355 MV hybrid – by 19, 23 and 23 cm, respectively. From the listed fertilizers, green mass yield increases were obtained: on average for 3 years, for the Mashuk 220 MV hybrid they amounted to 5.0, 6.7, 6.0 t/ha, respectively, and for the Mashuk 355 MV hybrid – 4.1, 7.0, 6.8 t/ha. Fertilizers increased grain yields annually. The average grain yield increase of Mashuk 220 MV hybrid from ammonium nitrate was 0.64, from nitroammophoska – 0.40, from Batr Zinc fertilizer – 0.63 t/ha. The grain yield of Mashuk 355 MV hybrid from fertilizers increased by 0.71, 0.81 and 0.74 t/ha, respectively. The cost of using ammonium nitrate as a fertilizer amounted to 2566.96, nitroammophoska – 8001.87 rub./ha. The cost of carrying out foliar fertilization of corn plants with Batr Zinc fertilizer amounted to 1030.69 rub./ha. The cost of using nitroammophoska did not pay off with an increase in grain yield. Fertilizing plants of Mashuk 220 MV hybrid with Batr Zinc fertilizer for every 1 rub. of costs gave an income of 6.33 rub., Mashuk 355 MV hybrid – 7.62 rub., which was 3.2–3.3 times more than the introduction of ammonium nitrate into the soil.

In a long-term precision microfield experiment, the effect of liming acidic sod-podzolic light loamy soil with dolorous flour (DF, dose range 0–2.0 H_a, 9th year of the aftereffect) on the soil reaction, the content of mobile compounds Zn, Cu, Mn, Fe, Cd, Pb in the soil, and the trace element composition of barley plants (Hordeum L.) was studied. It was revealed that the most sensitive to changes in the acid-base properties of the soil were Zn and Mn, the content of which in the organs of barley plants significantly decreased linearly in the dose range of DF 0–2.0 H_a. The consequence was significant even at the minimum dose of DF (0.2 H_a). There was a tendency to a decrease in the Fe content in straw and ear of plants (r = –0.572 and –0.570, respectively) in the indicated dose range. The data obtained confirmed that precipitation can lead to an increase in the Cd content in grain crops: in the dose range of DF 0.8–2.0 H_a, the increase in the element content in the ears of plants relative to the control variant of the experiment reached 1.6–2.0 times, and in straw increased linearly in the dose range of DM 0–1.0 H_a (r = 0.945), the content of Cu and Pb in barley plants was weakly dependent on the dose of liming agent.

The effectiveness of the use of traditional and intensive technologies for the aerobic processing of compost mixtures based on sewage sludge (SS), peat and activators of biothermal processes was studied. It was found that the recycling of waste in clamps using traditional technology did not provide high-temperature sanitation of compost mixtures. Intensive aerobic processing in fermentation chambers activated biothermal processes, ensured reliable disinfection of the compost mixture, which included bird droppings, soil, peat. The production of biocompost met the requirements of GOST R 55570, GOST R 54651, EU Regulation No. 2019/1009, the National standard of Canada CAN/BNQ 0413-200. In comparison with processing in clamps, intensive aeration carried out in an extremely short time was accompanied by lower losses in compost mixtures of organic matter, nitrogen (by an average of 10%), an increase in the content of mobile potassium, selective accumulation of mobile forms of heavy metals (copper, zinc, lead), which did not affect phytotoxicity of biocompost.

The increased interest nowadays in quantitative assessment of soil respiration is largely due to studies of the role of various terrestrial ecosystems in changing the concentration of the most important greenhouse gas, CO₂, in the atmosphere. The review considers methodological aspects of determining the actual CO₂ emission from soils using chamber and absorption methods, as well as the use of the obtained data to assess the carbon balance in soils. Successful development of this topic will allow to promptly get an answer to the main question of this pressing environmental issue: what is the soil of this or that ecosystem for atmospheric CO₂ – a net source or a net sink? The article analyzes the results of works devoted to comparative determination of CO₂ emission from soils by these methods. It is shown that the widespread opinion about obtaining underreported data by absorption method is often based on studies in which the basic principles of the method were violated. It is concluded that it is necessary to carry out in-depth comparative studies on determination of average daily indicators of CO₂ emission from soil by chamber and absorption methods. It is recognized that, regardless of the method, the main problem in using CO₂ production data to estimate soil C balance is the adequate partitioning of total respiration into heterotrophic and autotrophic components, the ratio between which varies widely depending on soil and vegetation conditions. Due to imperfection and labor intensity of existing methods, this division can cause significant errors in determining the annual mineralization of soil organic matter. To reduce them, the approach to determination of mineralization losses of CO₂ in bare fallow soils is considered. It is natural for soils of agrocenoses, but as a methodological technique can probably be used in natural grass ecosystems as well. Reduction of errors can be ensured due to the fact that differences in actual mineralization of organic matter in bare fallow and plant-occupied soils are several times less than changes in the ratio between heterotrophic and autotrophic components of soil respiration in different biogeocenoses.