Agrohimiâ

In vegetable crop rotation with different fertilization systems of vegetable crops, the dynamics of the content of mineral elements of plant nutrition was determined, effective soil fertility was evaluated in comparison with potential under experimental conditions, and the most effective fertilizer system was identified not only to obtain the highest yields, but also to preserve and reproduce the potential fertility of alluvial meadow soil. The study was conducted in 2015–2019 in the Ramensky district of the Moscow region on the alluvial meadow medium loamy soil of the central floodplain of the Moscow River. The seasonal dynamics of the content of 3 elements of plant mineral nutrition (nitrate nitrogen, mobile phosphorus and potassium) in the carrot – beet – cabbage crop rotation was studied, using 3 main fertilization systems for vegetable crops (mineral, organic, organo-mineral). It was found that the maximum content of nitrate nitrogen (on average in crop rotation 47.4 mg/kg) and mobile potassium (on average 156 mg/kg) occurred in the third decade of June. The content of mobile phosphorus in the soil was high (>200 mg/kg) at all accounting periods. A close correlation was determined between the yield of root crops and cabbage with the average content of nitrate nitrogen in the soil during the growing season (r = 0.735–0.934), mobile phosphorus (r = 0.539–0.972) and potassium (r = 0.532–0.976). The effective soil fertility of the site under 3 crops per crop rotation had the following characteristics: when using a mineral fertilizer system, the content of nitrate nitrogen was 21.3, organic – 10.1, organo-mineral – 22.1 mg/kg, the content of mobile phosphorus when using a mineral system – 40.4, organic – 34.1, organo-mineral – 47.9 mg/kg, the content of mobile potassium is 44.4, 20.6, 50.8 mg/kg, respectively. It was found that under crops of carrots and beets, the potential fertility of the soil during crop rotation was reproduced with the use of mineral (recommended dose of NPK) and organo-mineral fertilization systems of these crops, and the yield of carrots (67–69 t/ha) and beets (67–68 t/ ha) under these systems was high, more than expected estimated 60 t/ha. Under cabbage, late soil depletion also did not occur when using the recommended mineral and organo-mineral fertilizer systems, yields of 78 and 81 t/ha were close to the expected estimated yield of 80 t/ha. At the same time, the organo-mineral system had an advantage: during crop rotation, it retained 13% more nitrate nitrogen in the soil, 8% more mobile phosphorus and 40% more mobile potassium than the mineral one. One and a half and double doses of mineral fertilizers for late cabbage led to a significant increase in its yield (85–90 t/ha), but at the same time a significant part of nitrogen (on average for the season 33–41 mg/kg) was irretrievably lost in the soil.

In long-term field experience on sod-podzolic heavy loamy soil, a significant return was revealed from the use of zinc, copper, magnesium fertilizers, the microbial preparation Bisolbifit together with phosphorus fertilizers in connection with liming in winter wheat crops. The beneficial effect of the studied techniques on grain quality, payback of fertilizers, consumption and utilization rate of phosphorus by plants was noted. On highly acidic, untreated soil with a high content of mobile aluminum (about 130 mg/kg), caused by the systematic introduction of physiologically acidic potassium chloride and ammonium nitrate, phosphorus fertilizers (on average for all the years of the study from 2017 to 2023) provided an increase in winter wheat yield by 69% at a dose of 11.5 tons of lime/ha of medium acid in the soil by 2.2 times, on slightly acidic (19.0 tons of lime/ha) – by 2.7 times, together with the use of trace elements and Bisolbifit – by 2.4 and 2.9 times from the average background level of nitrogen-potassium fertilizers (2.38 t/ha). At the same time, the payback of phosphorus fertilizers with winter wheat grain on slightly acidic soil from the introduction of micro fertilizers and Bisolbifit increased 2.7 times (up to 15.7 kg/kg), the protein content in the grain increased by 1.3%, phosphorus removal by 3.8 times (up to 70.7 kg/ha), the use of phosphorus by winter wheat plants by 2.7 times.

The biochemical processes mediating the positive effect of bacteria on plants experiencing herbicidal stress were investigated. For this purpose the effect of the Pseudomonas protegens DA1.2 bacterial strain, low molecular weight (<5 kDa) and high molecular weight (>5 kDa) fractions of its culture fluid (CF) on the activity of acetolactate synthase (ALS) and the antioxidant status of rapeseed (Brassica napus L.) of the Kupol variety grown under artificial lighting in methsulfuron-methyl contaminated soil was evaluated. Strain P. protegens DA1.2 and its metabolites contributed to an increase in the mass of rapeseed shoots by 21–68%, reduced the inhibition of the ALS enzyme by 11–24% and mitigated the manifestations of oxidative stress. The protective effect of the treatments decreased in a row: CF with living bacterial cells-low molecular weight fraction of CF-high molecular weight fraction of CF. An increase in the activity of superoxide dismutase by 51–94% and glutathione reductase by 17–20% in plants treated with bacteria or their metabolites indicated the possible participation of these antioxidant enzymes in reducing the phytotoxicity of metsulfuron-methyl soil residues for rapeseed plants.

In order to confirm the theoretical calculations of the validity of the use of natural pyrethrins together with the components of vegetable oils, biologically active compositions of insecticides isolated from Dalmatian chamomile (Pyrethrum cinerariaefolium) and synergistic substances obtained from sesame, kanang and anise oils have been developed. It was found that insecticidal compositions showed their effectiveness against model insect pests (greenhouse whitefly – Trialeurodes vaporariorum). It is shown that the developed compositions can be used as a promising basis for the creation of new means of protecting agricultural plants from insect pests.

In the Baikal region, the continuous cryolithozone occupies ≈15, the transitional intermittent zone with Talikov islands – 30, the transitional island zone – 45, taliki with a continuous area – 10%. Attention is drawn to the dominance of the transition band, which is characterized by unstable thermodynamic equilibrium. High-temperature permafrost is easily degraded by technoconversion of external heat exchange conditions: removal of ground covers (organogenic layer and snow cover), deforestation, plowing, fires, etc. These circumstances increase the natural hazards and risks in the region. In this regard, the territory of Transbaikalia is of great interest, being in the permafrost zone and near its southern border, on the one hand, and with increased warming rates in recent decades, on the other. The continentality and severity of the climate in Buryatia are much more pronounced than in neighboring single-latitude regions of Russia. The southern boundary of the cryolithozone stretches almost throughout the entire territory of the republic, within which a whole range of landscapes is distinguished – from automorphic forest ecosystems to widespread, due to the high proportion of lakes and swamps, hydromorphic landscapes formed under the active influence of permafrost, as well as dry-steppe. The implementation of the Kyoto Protocol on Stabilization of Greenhouse Gas (GHG) Concentrations in the Atmosphere requires a quantitative assessment of spatiotemporal changes in terrestrial carbon sinks. Identifying areas with high potential and strategies for managing sequestration of atmospheric carbon dioxide by ecosystems is an important task and there is great uncertainty about the actual estimates of carbon reservoirs and how they may be affected by climate change. In the current conditions, we consider the study of the patterns of functioning of the soil and plant carbon reservoir in Transbaikalia to be timely and relevant.

The influence of abscisic acid (ABA)-metabolizing bacterial strains of the genera Pseudomonas and Arthrobacter on the hormone content in the shoots and roots of wheat plants, as well as in a sandy substrate during dense planting, has been studied. The ability of bacteria to reduce the ABA content in the growing environments and in plants, albeit to varying degrees, was discovered already 10 days after inoculation. At the same time, most of the studied strains were characterized by decrease of ABA in shoots, and suppression of ABA in the roots was observed less frequently. The simultaneous decrease in the hormone in the shoots and in the sandy substrate, which manifested itself under the influence of strains P. plecoglossicida 2.4-D, P. frederiksbergensis IB Ta10m, P. veronii IB K11-1, was accompanied by a maximum increase of wheat weight plants as compared to non-inoculated plants. The studied bacteria to varying degrees stimulated the accumulation of shoot and root mass, as well as leaf area, which could probably be associated with their different ability to synthesize other hormones, such as IAA, and/or influence the hormonal system of the plant itself. The prospects of using ABA-destructor bacteria for the development of agricultural biological products that can mitigate the negative effects of thickened crops and increase resistance to other abiotic factors are discussed.

In the laboratory experiment, the effect of oil pollution on the short-term dynamics of the activity of urease, phosphatase, catalase, peroxidase and polyphenol oxidase of the chernozem soil of the south of the Far East was studied. It was found that when soil was contaminated with oil and petroleum products, urease activity decreased by 20–44% at the end of incubation, peroxidase activity increased by 39–49% in the middle and end of incubation, polyphenol oxidase activity increased 1.6–2.0 times in the middle of incubation. The activity of phosphatase and catalase was stable at different levels of contamination throughout the experiment. Examining the effect of the incubation period, it was found that the maximum activity of urease was on the 10th day, phosphatase – on the 20^th, peroxidase – on the 20^th and 30^th, polyphenol oxidase – on the 30^th day of the experiment. Catalase activity was stable throughout all incubation periods. It was shown that in the case of contamination of chernozem-like soil with oil and diesel fuel in doses up to 5000 mg/kg, inhibition of enzymatic activity did not occur in the early stages.

The results of research in long-term field experiments on the effectiveness of phosphorus fertilizers are presented. All experiments were based on the classical scheme and included, in addition to the control variant (without fertilizers), a nitrogen-potassium background, on which the effectiveness of phosphorus fertilizers was studied. At the same time, regional specifics were taken into account in each experiment: liming at the Experimental Station of the All-Russian Research Institute of Agrochemistry (Russia), the effectiveness of phosphorus fertilizers at increasing doses of nitrogen N100–300 at the Rothamsted Experimental Station (Great Britain), a combination of phosphorus fertilizers with manure at the Chinese National Soil Fertility Monitoring Base. In long-term experiments, the dynamics of changes in the content of mobile phosphorus, as well as individual fractions, taking into account the emerging balance of P₂O₅, are presented. It is shown that the redistribution of phosphorus between different soil fractions is reversible, and the direction of the processes depends on the emerging balance of P₂O₅. Phosphorus accumulated in more firmly held forms can subsequently be released and absorbed by cultivated crops. In all field experiments an increase in the yield gap between NK and NK + P variants was observed over time. On the one hand, this is due to a significant decrease in the phosphorus content in the background NK variant (in acidic soils – also an increase in Al mobility), in which phosphorus removal significantly exceeds control (without fertilizers), on the other – a significant increase in the content of P₂O₅ in the soil with a positive balance. In a long-term experiment at the Experimental Station of the Institute of Agrochemistry, the difference coefficient of phosphorus utilization from fertilizers was 25–27, at the Rothamsted station – 25–41, at the Chinese National Soil Fertility Monitoring Base – 45%. Attention is drawn to the high payback of phosphorus fertilizers in experiments at the Rothamsted experimental station (Great Britain) – 22–39 kg of grain/kg of P₂O₅ (when cultivating winter wheat in crop rotation). The main method of increasing payback in this case was the use of high doses of nitrogen – up to 200 kg N/ha. Studies have shown that liming acidic soils to a slightly acidic reaction, the use of zinc micronutrients, as well as phosphate-mobilizing microorganisms, are essential methods to increase the effectiveness of phosphorus fertilizers.