The complex of measures to improve the fertility and protect agricultural lands from soil degradation in the Republic of Belarus for 2021-2025 includes measures to optimize the acidity of soils of arable and meadow lands, determine the amount of liming of acidic soils and the need for lime ameliorants to maintain an optimal soil reaction. Measures are given to increase the reserves of organic matter in soils, such as optimizing the ratio of row crops and perennial grasses, determining the need for organic fertilizers to ensure a deficit-free balance of humus in soils. The balance of nitrogen, phosphorus, potassium, sulfur was assessed and the need for mineral fertilizers for 2021-2025 was determined. The system of application of micronutrient fertilizers in the technologies of cultivation of agricultural crops is described and the need for micronutrient fertilizers for foliar feeding of agricultural crops is calculated. The system of measures to protect soil from degradation includes the recommended use of land and the structure of crops on lands with varying degrees of soil erosion, soil treatment, depending on the degree of their erosion and the particular application of fertilizers on eroded soils. The assessment of the effectiveness of measures to improve soil fertility and protect them from degradation has been carried out.

The article gives a characteristic and analysis of the current state of arable land in Belarus by administrative districts, including their area, fertility assessment and productivity (yield of grain and leguminous crops and gross grain harvests).

The effectiveness of the use of arable land for these crops per 100 score-hectares is established. Areas with maximum and minimum values for each of the analyzed indicators are given.

The article briefly describes the methodology for cadastral valuation of agricultural land in Belarus, gives a description of the main indicators of assessment: soil fertility score, standard net income, differential income, total land cadastral valuation score. Actual data on these indicators for the regions and for the whole country are given. The main directions of using the results of the assessment in the field of agricultural production and land relations are indicated.

The article analyzes the change in the basic physical properties of soils formed on limnoglacial loams, depending on the nature of their use. The value of indicators of the physical state of forest soils are in the ranges of optimal values, meadow - in the ranges of optimal and permissible, arable - within permissible.

Analysis of conjugated soil samples made it possible to establish a strong statistical relationship between the density and content of agronomical valuable aggregates on the humus content in the soil on forest lands (R² = 0,5034 and 0,6875, respectively), moderate statistical relationship between the density with humus content in meadow lands (R² = 0,1698) and virtually no dependence on arable land.

The article discusses the features of the application of the micro-area method in studying the role of humic substances in the formation of soil fertility and the effectiveness of agrotechnical methods on soils with different humus content. Based on specific data, an example of statistical processing of research results using a Microsoft Excel spreadsheet is shown.

There are presented in the article scientific and practical approaches to the planning and operational management of crop irrigation regimes using information technology in southern Ukraine. Parameters modeling of production processes of the studied crops for planning and operational management of irrigation regimes were carried out using the UN FAO computer program CROPWAT 8.0.

An analysis of meteorological conditions during the years of research indicates significant fluctuations in daily average temperatures and relative humidity - from minus 8,5° in January 2016 to 25,4-25,5 °C in August 2017 and 2018. The indicators of relative humidity and sunshine had a clear relationship with the temperature regime. Evapotranspiration was also closely related to meteorological indicators. The average monthly rainfall fluctuated significantly - from 0,2 mm in January 2016 up to 93 mm in June 2019. The modeling carried out allowed us to establish the conditional dates of the growing season for each crop, which is of paramount importance from the point of view of forming the water demand of crops and calculating their irrigation regimes. It has been proved that taking into account the soil water balance elements, current weather and agrotechnical conditions in the CROPWAT program makes it possible to accurately plan the irrigation regime for each crop and reduce irrigation water consumption for: winter wheat - by 17,1 %; corn - 21,3; soybeans - 20,8; sorghum - by 13,6 %.

Analysis of weather conditions for the period 2016-2019 it indicates a high level of aridization of the Southern Steppe of Ukraine, and violation of the natural moisture supply cycles and justifies the need for irrigation. By calculations it was determined that the maximum supply of irrigation water requires crop rotation - corn and soy, to a lesser extent - winter wheat and sorghum. The models obtained using the CROPWAT toolkit allow us to clearly establish the water shortage and the corresponding irrigation and irrigation norms, plan and promptly adjust irrigation regimes, reduce the consumption of water and other resources, which is of important agroeconomic and ecological reclamation value.

The data on changes in the photosynthetic activity of spring wheat plants under various fertilization systems are presented. A close relationship has been established between the crop yield and the indicators of photosynthetic activity. The optimal parameters of these indicators at the early stages of development of spring wheat plants have been determined, which make it possible to obtain a crop yield at the level of 60-65 c/ha.

Regular dose loads of poultry manure, liquid manure of cattle and pig effluents when applied no later than 3-4 months before sampling, increased the content of K⁺ in soils by 34-252 %, So₄^2- - by 7-268 %, Cl^- - by 6-148 %, РО₄^3- - by 33-255 %, water-soluble sodium - by 12-156 %, NH₄⁺ - by 18-70 %; exchangeable sodium - by 3-117 %, No_3- - by 1,5-11,1 times. Higher indicators (+7-669 %) with an increase in nitrates and phosphates by 3,7-27,3 times were obtained where pig effluents and poultry manure were introduced two weeks before sampling. No excess of maximum permissible concentration (MPC) of sulfates was found in soils near livestock complexes and poultry farms, the content of nitrates above the permissible level (1,4-1,7 MPC) was found where pig effluents and poultry manure were introduced two weeks before sampling. Low degree of soil degradation by chlorides and water-soluble sodium it was detected at the load of pig effluents from 350-450 to 500-600 t/ha, as well as in fields that were fertilized for a long time with very high doses of liquid cattle manure (900-1000 t/ha).

The constant introduction of liquid animal waste for 26 years has increased the content of mobile humic substances throughout the profile of sod-podzolic soils under maintaining the main trends characteristic of soils without loads. Their greatest accumulation was observed in the Ap and A₁ horizons with more intensive accumulation of C_HAmob: the content of C_mob increased by 28-90 %, C_HAmob - by 35-112 %, C_FAmob - by 24-73 %; from a depth of about 40 cm, the increase in C_mob reached 29138 %, C_HAmob - 8-88 %, C_FAmob - 33-146 % with a greater accumulation of C_FAmob.

In the field experiments conducted on sod-podzolic loamy sand soil (Podzoluvisol) dose negative correlations have been found between exchange calcium contents in the soil and ⁹⁰Sr accumulation by plants. The efficiency of soil saturation by calcium in discrimination of ⁹⁰Sr is much higher on soils with low Ca status. The minimum of bioavailability of ⁹⁰Sr was observed at the content of exchange calcium for grain crops at 1300-1400 ppm of soil, rapeseed - 1195, corn - 1236, timothy grass - 980, clover - 1229, alfalfa - 1502 and potato - 1260 ppm of soil.

A significant relationship (r = 0,50-0,66) was established between the content of N_min in the soil in the early spring period and after the first mowing and the activity of ¹³⁷Cs in the hay of perennial grasses of the first and second mowing. With an increase in the content of mineral nitrogen compounds in the soil, an increase in the specific activity of radionuclide in plants is observed. Strong correlations were found between the content of mineral nitrogen in the soil in the early spring period and after the first mowing of grasses and the hay yield of the first and second mowing. The correlation coefficients (r) were 0,83 and 0,73, respectively. With an increase of N_min reserves in the soil, a significant increase in productivity was observed.

Testing of monoinoculants (A. brasilense, B. circulans) and binary inoculant (A. brasilense + B. circulans) in field experiment on eroded sod-podzolic soils for grain crops growing (winter wheat, spring barley, winter rye and winter triticale) revealed some regularities of their action. It was found that sow treatment is effective technique of rhizobacteria application for spring and winter grain crops. Mono- and binary inoculation provided effective biological control of plant’s root infections and resulted in the increase of grain yields and grain’s quality. As a rule the inoculation efficiency on eroded soils exceeded that on watershed. Binary inoculation was more effective technique compared application of rhizobacteria monoinoculants.

The article provides data on the study of the effect of different forms of standard and new liquid mineral fertilizers (NS, NK, PK, NPK (chlorine-free) without additives and with the addition of trace elements and plant growth regulators) on the yield, content and collection of oil, its fatty acid composition, when cultivation of oil flax on sod-podzolic light loamy soil. It was found that when cultivating oil flax on sod-podzolic light loamy soil, the most effective fertilization system turned out to be the use of a full dose of mineral fertilizers in the main application to the soil with additional foliar dressing with various forms of liquid complex fertilizers (NPK - chlorine-free and mainly with additives of trace elements and growth regulators plants - Epin and Ecosil) and potassium monophosphate (without additives and with additives of microelements).

The article presents the results of studies on the accumulation and removal of microelements by winter wheat plants when cultivated on sod-podzolic highly cultivated light-loamy soil. It has been established that foliar feeding of winter wheat with micronutrient fertilizers ADOB promotes the accumulation of copper, manganese and zinc in the main and by-products. Trace elements carried out with the harvest of winter wheat are arranged in the following decreasing order: Mn > Zn > Cu.

The importance of greenhouse production of vegetable products for the Republic of Belarus is presented. Trends in the development of protected soil, the feature and significance of hydroponics are shown. The importance of developing an optimal system of vegetable crops nutrition is noted.

The feature of application of drip irrigation system, vegetable crops feeding modes is described. The requirements for the composition of nutrient solutions for growing plants on artificial substrates, requirements and technology for the use of water-soluble chemical fertilizers are considered in detail. The dependence of tomato nutrition on the climatic period is indicated. The importance of applying complex diagnostic methods, including visual, morpho-biometric and chemical instrumental methods for obtaining high productivity and quality of tomato fruit, which allows economical use of expensive chemical fertilizers, selectively apply quantitative diagnostic methods and promptly put in practice measures to eliminate detected violations in nutrition is noted. The economic efficiency of tomato nutrition system optimization is shown.

Based on the results of many years of research, the article presents indicators on the content of food elements in vegetable products. The total removal of nutrients by the crop of vegetable crops is influenced not only by the amount of formed biomass, but also by their content in a unit of production, which is largely determined by the level of fertilization. With the introduction of nitrogen, phosphorus and potassium fertilizers, the content of nitrogen, phosphorus and potassium in all parts of the plants increases, respectively, the removal per unit of production increases.

The effectiveness of the use of complex, macro-, micronutrient fertilizers and growth regulator Ekosil in the cultivation of carrots on sod-podzolic light loamy soil.

The article presents the results of studies on the use of complex fertilizer with boron and copper for the main application, complex fertilizer with Lifdrip microelements, MicroStim micronutrient fertilizers for foliar dressing and Ekosil growth regulator when cultivating carrots on sod-podzolic light loamy soil. The effect of fertilizers on the yield of root crops and such quality indicators as marketability, dry matter content, sugars, carotene and nitrates was studied. It was found that, according to a set of indicators, the best was the use of a complex fertilizer with microelements Lifdrip. over the years of research, the yield of root crops in this variant of the experiment was 58,6 t/ha with a payback of 1 kg NPK 124 kg of root crops, marketability - 86,1 %. The dry matter content in root crops was 11,8 %, carotene - 14,7 mg/%, sugars - 8,1 %.

The article presents the results of a study of the features of accumulation of ¹³⁷Cs in tall blueberries of the Bluecrop variety on sod-podzolic sandy loam soil. It was revealed that, according to the specific activity of ¹³⁷Cs, the organs of blueberry plants in the stage of fruit ripeness are ranked in the following order: roots > stems > leaves > berries. The transfer coefficient (Kp, Bq/kg : kBq/m²) of ¹³⁷Cs from soil to crop fruits is characterized by a high degree of dependence on soil acidity (R² = 0,70) and a noticeable degree of dependence on the content of in it K₂O (R² = 0,43). With an increase in pH_KCI values and the content of mobile forms of potassium, the intake of radionuclide into blueberry plants decreases. The introduction of mineral fertilizers reduces the intake of radiocaesium in blueberry fruits. The maximum input of ¹³⁷Cs from soil into plants occurred in the control variant without the use of fertilizers (Kp, 0,199 Bq/kg : kBq/m²). The application of phosphorus-potassium fertilizers reduced Kp by 29, 5%. The use of a complete mineral fertilizer does not contribute to a further decrease in the ¹³⁷Cs intake in blueberry fruits -the decrease in Kp relative to the control is 18,0-24,5 %, depending on the variant of the experiment. The limiting density of soil contamination that ensures the production of fruit crops corresponding to RdU-99 in terms of ¹³⁷Cs content, depending on the option of applying mineral fertilizers, varies from 8,4 Ci/km² to 11,4 Ci/km².