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Promising essential oil plants from the Lamiaceae family, the raw materials of which are a source of valuable essential oil for pharmaceutical, perfume, cosmetic and food industries, pertain to the Monarda L genus. The Monarda didyma L. and Monarda fistulosa L. species were first imported to Ukraine from Europe and America in the middle of the twentieth century, and today they are successfully cultivated as decorative, spicy-aromatic and medicinal plants. The purpose of this study was to determine the morphobiological features, valuable economic and selective traits of Monarda didyma, Monarda fistulosa and Monarda × hybrida hort., developed for the arid conditions of the southern steppe of Ukraine at the Institute of Rice of the NAAS. The experimental part of the study was performed in 2016-2018 on southern sandy and medium loam black soils (chernozem) in the state enterprise (SE) "Research farm "Novokakhovske". The experiment was conducted using field, laboratory, mathematical and statistical methods in accordance with the generally accepted methods and guidelines in Ukraine. The plants of developed varieties undergo a full cycle of development under arid conditions of the southern steppe of Ukraine and are characterised by an increased decorativeness, goodeconomic value, high drought and winter tolerance as well as the resistance to pest damage. Yield, mass fraction and content of essential oil in the aboveground mass of plants were determined. Maximal plant height (120 cm), yield of aboveground mass (18 t/ha), concentration of essential oil (0.8% of crude mass) and thymol content (78.3%) are typical of the variety of Monarda fistulosa, Premiera. The variety of Monarda fistulosa, Fortuna, and variety of Monarda × hybrida hort., Tonya, were inferior to Premiera in all of the above-mentioned indicators but demonstrated increased decorativeness and greater resistance to the fungi causing powdery mildew (Erysiphe monardae, Golovinomyces biocellatus). Therefore, they can be recommended for region-wide cultivation in the agricultural enterprises of the southern steppe of Ukraine as promising essential oil, spice-aromatic and decorative crops. The yield of essential oil from raw materials of Monarda didyma variety, Nizhnist, was lower by 32.9% and 26.8%, while its concentration was lower by 37.5% and 28.6%, compared to the Monarda fistulosa varieties Premiera and Fortuna, respectively.

The use of biodestructors in agricultural technologies for efficient decomposition of crop residues affects the number and species composition of soil fungi, especially pathogenic species, and as a consequence, plant productivity. However, to date, this issue has not been extensively studied. The purpose of this experiment was to develop an effective method of destruction of post-harvest residues using biological products to realize the productive potential of soybeans in rice crop rotation. The work was conducted on the experimental plots of the Institute of Rice NAAS (Skadovsk district, Kherson region, Ukraine) during 2016-2018. In the experiment, the treatment of post-harvest rice residues with a biodestructor Biocomplex-BTU "Ecostern" (1 l/ha) in combination with concentrated amide water-soluble fertilizer, carbamide (30 kg/ha) was carried out in autumn. Application of carbamide alone (30 kg/ha) was used as a control. "Ecostern" is a concentrated agent, which comprises antagonists of pathogenic microorganisms as well as fungi and bacteria that accelerate decomposition of plant residues. The application of biodestructor Biocomplex-BTU "Ecostern" (1 l/ha) in combination with carbamide increased the total number of pathogenic and saprotrophic fungi in the soil from 65.5 to 80.5 thousand /g of soil or by 22.9%. However, the content of pathogenic microflora under this condition was 21.8% lower compared to the control (30 kg/ha carbamide), and the number of saprotrophs increased 3.3-fold. Following the combined use of biodestructor "Ecostern" and carbamide, the number of antagonist fungi has doubled, while the number of toxin-forming fungi decreased by 9.4%. The yield of soybeans also increased by 0.6 t/ha or by 17.9% compared to the control. The increase in yield was observed due to the higher standing density of plants and the number of beans per plant. Before the harvest, the standing density of soybean plants was 45 pcs/m 2 , which is 9.7% higher than the control (41 pcs/m 2 ), due to the high level of field germination of seeds. The number of beans was 24 and 28 pieces per plant, exceeding the control by 16.7%, and the weight of 1000 grains was 156.2 g and 157.5 g, which is 0.8% than the control.

For the implementation of productive potential of soybeans, it was presented an effective method of post-harvest residue destruction with the biologics in rice crop rotation. The research was conducted at the Institute of Rice of NAAS during 2016–2018. In autumn, post-harvest rice residues were treated with the Biocomplex-BTU Ecostern biodestructor (1l/ha) in combination with carbamide (concentrated amide water-soluble fertilizer) (30 kg/ha). The variant with the carbamide application (30 kg/ha) in autumn was a control. The application of the Biocomplex-BTU Ecostern biodestructor (1 l/ha) in combination with car-bamide increased the total number of pathogenic and saprotrophic fungi in the soil from 65.5 to 80.5 thou-sand/g of soil, or 22.9 %. Thus, the pathogenic microflora content in the studied variant was lower than in the control (carbamide application at rate of 30 kg/ha) by 21.8 %, and the number of saprotrophs increased 3.3 times. When Ecostern biodestructor and carbamide were combined for application, the number of antagonistic fungi doubled, while the number of toxin-forming fungi reduced by 9.4 %. Soybean yield at the combined application of Ecostern biodestructor and carbamide increased by 0.6 t/ha, or 17.9 % compared to the control (carbamide – 30 kg/ha). In addition, in this variant, the content of post-harvest rice residues in the soil at the soybean sowing was lower by 1.25 g/kg of soil, or 20.3 % compared to the control, which created favorable conditions for seed germination. It was observed that the yield increased due to the higher plant density and the number of beans per plant. Before harvesting, the soybean plant density due to the high field germination of seeds in the studied variant was 45 pcs/m2, which is 9.7 % more than the control (41 pcs/m2). The number of beans was 24 and 28 pcs/plant, and exceeded the control by 16.7 %; the thousand grain weight was 156.2 and 157.5 g which is more than the control by 0.8 %. Key words: post-harvest residues, microorganisms, fertilizers, soil, rice, soybeans, grain yield, thou-sand grains weight.