Soil organic matter can be divided into stable and labile, with the latter directly supporting plant growth and development during the growing season. To restore soil fertility and ensure high productivity of agrocenoses, a certain ratio between the labile and stable parts of humus must be maintained. The purpose of this study was to determine the content of labile organic matter under different tillage and fertilisation options and to establish the optimal ratio between their content and the content of total carbon, based on which to develop measures to restore and improve the fertility of chernozem soils. In stationary experiments, the study investigated the impact of the intensity of chernozem use, its cultivation and fertilisation systems on the humus state of the amount of labile organic matter and its ratio to humus carbon. Field research, laboratory method of soil sample analysis, systematisation, analysis, and generalisation were used in the study. The soil samples were analysed for humus content according to DSTU 4289:2004 and labile organic matter content according to DSTU 4732:2007. When chernozems are ploughed up, labile organic matter is mineralised the most and their share in humus decreases, while when arable land is converted to fallow land, it is restored the fastest. Minimising tillage systems and applying organic and mineral fertilisers increases the amount of labile organic matter in the humus of chernozems. The use of no-till for sixteen years resulted in a 0.13% increase in humus content, and a 0.53% increase over forty-two years compared to ploughing. The application of organo-mineral fertiliser increased the ratio of labile organic matter carbon content to total carbon content compared to the unfertilised variants. A strong correlation was found between the content of labile organic matter in chernozems and the yield of winter wheat and maize. The practical significance of the research results is to minimise the fertiliser rate and the C:N ratio to ensure gross crop yields and restore soil fertility

The article presents the results of research on the effectiveness of the use of crops of Silphium Perfoliatum L. for phytoremediation of soils in oil-contaminated areas. Silphium Perfoliatum L. is characterized by unique opportunities for productivity and longevity, can be cultivated in one place for many years. The aim of our work was investigating the rate of accumulation of heavy metals in the aboveground and root mass of Silphium Perfoliatum L. during the introduction of sewage sludge in oil-contaminated areas. The research was conducted in the Precarpathians of Ukraine in Ivano-Frankivsk region. The experimental field is slightly sod-podzolic sandy, there are several remnants of oil spills, the so-called oil slicks. The experiment included 8 options of fertilizing Silphium Perfoliatum L. In soils of contaminated areas determined content of total and mobile forms of metals and their content in the green mass and plant roots by methods according to ISO 4770.3 – GOST 4770.9, atomic adsorption methods in the lab of Ivano-Frankivsk State Institution branch “Soil Protection”. The metal translocation coefficient in the system «soil-vegetative mass» and in the system «soil-root» increases in a number: Cd → Ni→ Cot → Pb. That is, the lowest translocation coefficient is in the lead. However, the difference is that in the system «soil-root» the coefficient of translocation is higher by 2–3%, from the translocation of metals in the system «soil – vegetative mass». The coefficient of biological accumulation of heavy metals by perforated sylph increase in a number of elements: Pb → Co → Ni → Cd.

Summary Heterogeneity of soil need be studied when developing crop fertilization systems, especially in precision farming technologies. One of the main elements of plant nutrition is potassium, the content of which depends on the mineralogical, particle size distribution of soils and parent materials, features of geomorphological and hydrological conditions of the territory. The aim of the present study was to investigate the spatial heterogeneity of exchangeable potassium in chernozem depending on the granulometric content of the territory. The research was conducted on a stationary experiment in Kyiv region of Ukraine. In the soil samples were determined the texture and particle size distribution of the soil, the content of exchangeable potassium. The average dependence of the exchangeable potassium content on the particle size distribution of the soil was established. The content of exchangeable potassium ranged from 58 to 175 ppm, the largest number of events was content of 175 ppm in samples. The content of particles less than 0.01 mm varied from 20 to 53%, i.e. according to the classification of N.A. Kaczynski texture varied from light loam to heavy loam, in 54.4% of the samples the medium loamy texture was determined.

The influence of systematic application of mineral fertilizers, on the background (BG) of the after-effect of 30 t on ha of manure, on the content of nutrients in spring wheat plants of “Myronivska Yara” regional variety and winter wheat plants of “Myronivska 61” variety, and on nutrients removal by plants, during cultivation on Meadow-Chernozemic Carbonate Soil, was studied. The results indicate a close relationship between external conditions and internal metabolic processes in winter and spring wheat plants. Thus, a balanced ratio of nitrogen, phosphorus and potassium provides a more intensive supply of these elements from the soil, what increases their content in plants. The highest content of total nitrogen, phosphorus and potassium in winter wheat plants was observed in the variant, where 1.5 rate of mineral fertilizers was applied with the background of 30 t on ha of manure, in the tillering phase and was 4.86; 2.17; 3.48 %, respectively, what is almost 2 times higher, than the control. During the growing season, the nutrients content in all variants decreased. The same pattern was observed in plants of spring wheat. The maximum nutrients content was recorded in all variants in the phase of spring tillering, and also was recorded significant reduction in their adsorption from the soil and using by plants during the growing season. The content of total nitrogen in spring wheat plants in the tillering phase fluctuated in fertilized variants in the range of 2.21-2.51 %, compared with the control – 2.10 %; phosphorus – in the range of 1.20-1.47 %, compared with the content on the control – 1.04 %; potassium – 1.88-3.08 %, in the control, respectively – 1.68 %. The results of research indicate, that long-term application of fertilizers in crop rotation affects, as a result, also on the removal of nutrients with the crop. Thus, the removal of basic nutrients by plants of winter and spring wheat was the highest in the variant “BG + N110P120K120”. Under winter wheat it was 210 kg on ha N, 122 P2O5, 157 kg on ha K2O, compared with the control variant – 86.3 N, 48.2 P2O5, 57.8 kg on ha K2O. Under the spring wheat it was 119 N, 66.4 P2O5, 85.4 kg on ha K2O, and in control variant, respectively, – 46.6 N, 26.5 P2O5, 32.8 kg on ha K2O.