The study of changes in the structure of the phosphate fund of retisol after two rotations of a 4-field field crop rotation under the influence of the introduction of dolomite (CaMg(CO 3 ) 2 ) and limestone (CaCO 3 ) flour in different doses before the start of the first rotation was carried out in the stationary experiment of the Institute of Agriculture of the Western Polissia of Ukraine. The dose of limestone materials is calculated on the basis of hydrolytic acidity (Hh) 2.80-2.97 mol/kg: for dolomite flour 0.5 Hh -2.2 t/ha; 1.0 Hh -4.7; 1.5 Hh -6.7 t/ha; for limestone flour 1.0 Hh -4.9 t/ha. The saturation of crop rotation with mineral fertilizers was N 112 Р 87 К 105 . The general background of the experiment was the annual application of the non-marketable part of the crop at a dose of 6.0 t/ha of biomass. The purpose of the work is to investigate the directionality of the transformation of the forms and different fractions of retisol phosphorus under the influence of liming against the background of systematic fertilization after the completion of the second crop rotation rotation. Research has established that under the influence of the introduction of meliorants, the share of mineral phosphorus compounds (P inorganic) fluctuated widely according to the experiment options (47.0 -67.4% of P total), and organic -in the range of 28.5-37.5% P total. Liming against the background of fertilizer application also caused certain changes in the proportions between different forms of phosphorus. The main part (55.5-70.7%) of inorganic P is aluminum phosphates (Al-P) and iron phosphates (Fe-P). Liming with increasing doses of meliorants significantly (р = 0.05) affected the reduction of the total share of Al-P and Fe-P compared to the control and application of only mineral fertilizers, and also contributed to a significant increase in the share of Ca-P calcium phosphates (р = 0.01). At рН KCl 4.0-6.0, the content of P inorganic fractions was distributed in the order from maximum to minimum indicators: Al-P > Fe-P > Р soluble > Са-Р. Neutralization of the acidity of the soil solution also contributed to a significant increase in the content of the soluble fraction of phosphorus (P soluble) to 4.9-5.4% of total P (р = 0.05), and the level of availability of labile phosphorus compounds of the studied soil increased and was noted as high. The established features of the transformation of the phosphate pool in retisol under the influence of the introduction of chemical ameliorants indicate an increase in the share of bioavailable phosphorus compounds, significant changes in the conditions of phosphorus nutrition of crop rotation crops and a change in the functional stability of the agroecosystem in general.

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Topicality. Today, the search for ways to accumulate organic carbon and restore soil fertility, as well as increase crop yield, is a topical issue for the sod-podzolic soils of Western Polissia. Purpose. To determine the intensity of CO2 emission and the organic carbon balance on sod-podzolic soil at different fertilizer rates in the maize-soybean link against the background of chemical amelioration with incorporation of by-products. Methods. We used such methods as a stationary field trial, comparative and calculation method to determine the accumulated and emitted CO2 by plants, analytical and calculation methods to determine the organic carbon balance. Results. The CO2 emissions from organic matter mineralization amounted to 5.01–5.45 t/ha by the recommended fertilizer rate and calculated by the normative method on the background of dolomite and limestone powder, which was 23.4–34.2 % higher than the control (without fertilizers). The CO2 emission into the atmosphere through plant mass mineralization, depending on fertilization and chemical amelioration, was in the range of 18.6–24.7 t/ha and exceeded the control (without fertilizers) and the background of 1.0 Hh (hydrolytic acidity) CaMg(CO3)2 by 1.2–2.0 times, which is associated with improved soil conditions, higher by-products mass and CO2 accumulation by plants. The highest amount of CO2 was accumulated by maize (64.8–65.0 t/ha) and soybean (15.0–15.8 t/ha) at combination of the fertilizer rate calculated by the normative method with microfertilizers on the background of dolomite flour. The application of calculated fertilizer rates on the background of 1.0 Hh CaMg(CO3)2 provided an advantage in the formation of organic carbon in the soil, which formed a positive balance of 0.12 and 0.15 t/ha. In the variant without fertilizers and chemical amelioration, the ratio of total CO2 emissions into the atmosphere per 1 t of grain yield in the maize-soybean link was 4.65 and 4.62 units, while the application of the fertilizer rate calculated by the normative method against the background of 1.0 Hh CaMg(CO3)2 decreased to 3.78 and 3.89 units, respectively. Conclusions. For increasing the maize and soybean productivity on sod-podzolic loamy sandy soil, incorporation of plant mass into the soil with applying the fertiliser rates calculated by the standard method against the background of 1.0 Nh CaMg(CO3)2 is an effective method to control soil degradation that ensures the inclusion of additional organic carbon into the cycle, which is aimed at its fixation by forming a deficit-free balance of 0.12 and 0.15 t/ha. Key words: emission, organic carbon, productivity, fertilization, land amelioration, plant mass

The influence of cultures in short-rotation crop rotation of Western Polissia on the ecological component of sod-podzolic cohesive-sandy soil by the analyzing the balances of nutrients and humus is shown and an economic assessment of their cultivation is given. The most accessibly and fairly objective a complex assessment of certain crops impact on the ecological state of the soil can be carried out by their contribution to the formation of balances of humus and nutrients. In article used the results of researches obtained in a field stationary experiment with winter wheat, maize for grand, spring barley and winter rape for 2012–2020 years. To assess the impact of cultures on the balances formation was chosen variant with the recommended rate of mineral fertilizers on the background of 1.0 Ha (hydrolytic acidity) dose of CaMg(CO3)2 (dolomite flour). It has studied that the supply of nutrients with plant biomass is a powerful source of their recycling. In particular, the highest content of nitrogen (3.56 and 2.75%) and phosphorus (0.95–0.99%) was obtained in rapeseed and winter wheat, while by-products showed the accumulation of potassium (1.52 and 1.39%) respectively. Taking into account the obtained results, the influence of growing crops on the formation of nutrient and humus balances was determined. It was established that by liming and fertilization with the return to the soil of by-products biomass of the studied crops was formed a positive balance of nitrogen in the range of 29.6–43.4 kg/ha, phosphorus 23.0–54.9 kg/ha, potassium 71.6–99.8 kg/ha. Only with the application of N120 under maize for grain was obtained nitrogen deficiency of –47.5 kg/ha. Due to crop residues and by-products of the studied crops, a positive balance of humus was determined: winter wheat 0.73 t/ha, corn for grain 2.17, spring barley 0.40 and winter rape 0.11 t/ha. The economic component of the technology of studied crops growing showed that the largest net profit was achieved for marginal crops: maize for grain (19.8 thousand UAH/ha) and winter oilseed rape (14.4 thousand UAH/ha). Due to the restrictive effect of other factors, primarily moisture supply, the system of fertilizing winter wheat and spring barley did not create conditions for the realization of the planned yield, which led to low profitability of their production.

Topicality. With climate change, agricultural production accounts for about 15 % of green-house gas emissions. Disbalance of organic carbon decreases the environmental sustainability and productivity of agroecosystems and soil fertility. With soil management, the intensity of carbon monoxide emission from the soil can reduce to optimize its organic matter. Issues. There is a crucial need to study and analyze comprehensively the effects of different rates of chemical meliorants and mineral fertilizers for crops in the Western Polissia crop rotation on the volume of CO2 emissions from sod-podzolic soil. Aim. To study the characteristic features of carbon dioxide emissions from sod-podzolic soil during winter wheat and spring barley cultivation with different rates of meliorants and fertilizers. Materials and Methods. Field experiment, agrochemical and statistical methods. Results. On the background of mineral fertilization, land reclamation with limestone materials at 0.5 and 1.0 rates determined by the hydrolytic acidity of the soil generally decreases CO2 emissions into the air. During the growing season, depending on the development stage of spring barley, the level of carbon dioxide emission in the variant with N90P90K90 was 89.8–68.3–63.5 mg CO2/kg soil, and in combination with 1.0 rate of dolomite powder – 83.1–59.8–63.6 mg CO2/kg soil. It is noted that the intensity of CO2 accumulation in the surface layer depended on rates of ameliorant, soil moisture and temperature. Thus, the carbon dioxide emission in a winter wheat field was the highest when 1.5 rates of dolomite powder were applied on the background of N120P60K90 , and in the stem elongation stage at air temperature 13.2 ℃ was 77.7 mg CO2/kg of soil. When air temperature increased to 22.0 ℃ in the heading stage, this indicator increased by 1.2 times and at air temperature of 20.4 ℃ in the full maturity stage, it decreased by 1.3 times. When 1.0 rate of dolomite powder was applied, CO2 emission decreased to 18.2 mg CO2/kg of soil compared with 1.5 rates in the full maturity stage of wheat due to the intensity of redox processes in the soil when different rates of limestone materials was applied. Conclusions. In the short-term crop rotation, lime application had a positive effect on the for-mation of deficit-free balance of organic carbon in sod-podzolic soil with intensive application of mineral fertilizers for crops. When we applied 1.0 and 1.5 rates of dolomite powder on the background of N120P60K90 in winter wheat crops, the organic carbon balance was 0.35–0.28 t/ha, in spring barley crops on the background of N90P90K90 – 0.10–0.16 t/ha. Key words: winter wheat, spring barley, land reclamation, fertilizers, carbon dioxide, balance.