At present time, in the current economic and environmental conditions in Russia, with limited use of mineral fertilizers in agricultural production, the use of biological cropping techniques is relevant. One of the directions is application of microbial preparations safe for the person and environment, as an element of resource-saving technologies as their production is less power-intensive, than mineral fertilizers, and application is economically favorable. Purpose of research: with the help of microbiological indicators sensitive to agrogenic loads to evaluate and compare the effect of various biological products on the number of microorganisms and the intensity of the transformation processes of organic compounds in the potato rhizosphere, the formation of crops and the development of potato diseases. In the field experiments of 2013-2018, agents Rizoagrin, Azorizin, Mizorin and agents with fungicidal, insecticidal and stimulating properties-Mival-agro, potassium humate, Prestige were used. The quantity of microorganisms in the rhizosphere of potatoes was the highest in the variant with the treatment of tubers with the Mival-agro agent (126% to control). All groups of determined microorganisms in this variant reacted positively to the treatment. The Rizoagrin and Mizorin agents stimulated the microbial abundance by 61 and 17%, respectively, the agent showed fungicidal properties by 38.6% in comparison with the control variant. The coefficients of mineralization, immobilization of nitrogen and transformation of organic matter in potato rhizosphere were calculated from the ratio of groups of microorganisms. The predominance of immobilization processes in the soil was established. Nitrogen of non-symbiotic fixation, the amount of which increases as a result of the action of microorganisms of biological products, remains in the rhizosphere of the crop. Agents of complex action, including microbial, increased potato yield by 1.3-7.9 t/ha, reduced disease damage: rhizoctonoise (Rhizoctonia solani), scab (Streptomyces scabies), late blight (Phytophthora infestans). An average positive correlation was established between the total number of microorganisms in the rhizosphere, the number of saprophyte bacteria on meat-and-peptone agar and yield.
The researchers conduct the field stationary experiment with the use of mineral fertilizers and straw in the grain and steam crop rotation with the withdrawal field of alfalfa and study the number of microflora in the rhizosphere of winter wheat of the new variety Priirtyshskaya after treatment of seeds with biospecimen of complex effect - risoagrine. The highest number of useful crop groups of microorganisms was observed in the variant with inoculation of crop seeds by risoagrine on the basis of applying mineral fertilizers, as well as in combination of inoculation techniques, application of mineral fertilizers and straw (N15P23 + straw + inoculation), respectively, 444 and 355 million UU/yr with 217 million UU/yr in the control group. In the variant with inoculation of winter wheat seeds by mineral fertilizers (N15P23 + inoculation), the number ofoligonitrophils and bacteria, mineralizing mineral phosphates, increased by 2.2 times, nitrifiers - by 60%, microorganisms that utilize organic nitrogen compounds on MPA - by 39, consuming mineral nitrogen on CAA - by 73% compared to the control group. The celluloseolytic soil activity under winter wheat sowing in variants N15P23 + inoculation and N15P23 + straw + inoculation increased to 66.5-67.0%, exceeded the control group by 1.7 times. The highest increase in the crop’s grains was observed in the combination of mineral, organic (straw) and bacterial (rizoagrine) fertilizers - 40.3% in comparison with the control group. Additional nitrogen removal by winter wheat crop due to the activity of associative diazotrophs varied from 6 to 16.5 kg/ha. Correlative relations of high (r=0.84-0.91) and average (r=0.62-0.72) degree of microorganisms in the rhizosphere were observed among the indicators of crop yield and number of microorganisms. The closest correlation took place between the value of winter wheat grain yield and the number of bacteria growing on MPA, including ammonifiers, and the yield and number of nitrifying bacteria.
We studied the cellulolytic activity of the winter wheat rhizosphere soil in a stationary field experiment with the application of mineral nitrogen-phosphorus fertilizers (N15P23 per hectare of crop rotation area), straw, and seed inoculation. We estimated the crop yield depending on the intensity of cellulose decomposition in the soil. We established that the intensity of cellulose decomposition in the rhizosphere of winter wheat was most affected by the application of mineral fertilizers, as well as the combination of the application of mineral fertilizers, straw, and seed inoculation with the biopreparation rhizoagrin before sowing.
The research was carried out on an irrigated stationary crop rotation of the Federal State Budgetary Scientific Institution “Omsk Agrarian Research Center” in the southern forest-steppe of Western Siberia. The aim of the research was to establish the direction and intensity of mobilization biological processes in case of long-term irrigation, their quantitative characteristics, as well as possible adverse changes of biological (ecological) properties of meadow – black soil. The microbial community performs the function of maintaining soil homeostasis, therefore it quickly responds to habitat changes. The intensity of soil mineralization and humus formation processes was determined by a combination of fertilization and irrigation factors. It was found that immobilization processes prevailed in the soil under crops. The highest coefficient of organic matter transformation, i.e. transformation increase of plant residues into organic matter, was noted when introducing nitrogen-phosphorus fertilizers for barley crops. Application of mineral fertilizers promoted an increase of the number of the defined microorganisms, enhanced cellulose decomposition in the soil, potential capacity of soils to accumulate nitrate and enzyme activity, which ultimately increased the yield of cultivated crops. The yield of perennial grasses on a fertilized background was at the control level due to loss of legumes (goat’s rue) and predominance of bluegrass species (awnless brome). A strong correlation was obtained between the intensity of cellulose decomposition in the soil, nitrification capacity and crop yields (r = 0.67 ± 0.28 and 0.91 ± 0.16, respectively). Long-term irrigation of meadow-black soil did not have a negative impact on its ecological state, and usage of intensive cultivation technology of crops in crop rotation stimulated an increase of soil microorganisms and their activity.
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