Analysis of changes in hydrothermal conditions of growing crops in the forest steppe zone of Ukraine over a period of 2004–2016 showed that by the average monthly air temperature more than a half of the years under study and by rainfall nearly a third of the researched period differed significantly from the average long-term value and were close to extreme weather. Statistical analysis of long-term indicators of the air temperature regime is evidence of a steady trend towards an increase in average annual air temperature with significant fluctuations in indices in separate periods from 7.9 ± 2.9 to 10.0 ± 2.5oС and a decrease in the amount and instability of natural moisture entry. The influence of weather conditions on the formation of productivity of spiked cereals (winter and spring wheat, spring barley) and maize was assessed at the current agrometeorological risks in the forest steppe of Ukraine. Based on the correlation-regression analysis, mathematical models were created that reproduce the dependence of grain yields upon the complex weather conditions of the growing season, the impact of which reached 60–70%. The conditions of eight years (2006–2008, 2011–2014 and 2016), when the hydrothermal index for the vegetation period was 1.13–1.76, turned out to be optimal by hydrothermal indicators to harvest maize yield at 5.83–9.47 t/ha. However, the years of 2005, 2009–2010 and 2015 were unfavorable as they received precipitation by 120 mm lower than a norm or 36% of the norm. The rainfall by 37–61% lower than a norm in June–July and grain yield 3.12–6.51 t/ha were also characteristic of the years mentioned above.
Corn is a highly productive crop of universal purpose, which is grown for food – 20–25 %, forage – 60–65 and technical purposes – 15–20 %. Increasing its yield is possible due to the improvement of the elements of the technology of cultivation taking into account biological characteristics. The growth and development of corn, the production of high yields, as well as the improvement of the quality of the main products are determined by factors of anthropogenic origin and weather conditions. Hydrothermal conditions of Ukraine have already begun to change significantly during the last decades, which resulted in a shift in the climatic seasons, changes in the vegetation period duration (depending on the zone and the biological features of the crops it can either decrease or expand), the decrease in the duration of a stable snow cover, changes in water resources of local drainage. The period 2005–2016 was analyzed for the reliable estimation of the typicality of weather conditions and their influence on the corn productivity under the following basic cultivation methods: ploughing at the depth of 28–30 cm (control), flat-cut tilling at the depth of 28–30 сm, chisel ploughing at the depth of 43–45 cm and disking at the depth of 10–12 cm. The dynamics of precipitation in the northern part of the Right Bank Forest Steppe during the corn vegetation period for the last 2005–2016 testifies to the noticeable tendency of increasing the amount of precipitation in May-June and their sharp decrease in July-August. It was determined that the conditions for eight years – 2006–2008, 2011–2014 and 2016 were optimal for their hydrothermal indices for the production of corn yields at the level of 5.83–9.47 t/ha. The hydrothermal coefficient for vegetation was 1.13–1.76. Weather conditions were unfavorable in 2005, 2009–2010, and 2015 with the amount of precipitation for vegetation of 120–288 mm, which is below the long-term amount by 120 mm, or 36 %. The peculiarity of these years was 37–61 % lower precipitation level in June–July with the grain yield of 3.12–6.51 t/ha. The mathematical-statistical analysis allows to characterize features and typicality of weather conditions of 2005–2016 and to estimate the influence of hydrothermal years and separate months on corn crops productivity. It has been established that there is the following correlation between weather conditions in July and the yield of corn: high correlation for disk soil cultivation (r=0.75–0.86), the average – for ploughing and chyzel loosening (r=0.49–0.53). Thus, the formation of a deep layer of soil with the best water–physical characteristics and fertility in these cultivation modes reduced the dependence of the elements of yield formation from the adverse weather conditions and provided a higher yield of corn by 6.0–8.0 %. Key words: hydrothermal conditions, hydrothermal coefficient (HTC), vegetation period, corn yield.
The aim of the research is to establish the peculiarities of the formation of the nutrient regime of gray forest soil with different systems of basic cultivation, fertilization and sealing of by-products of crops in short-rotation 4-field grain crop rotation – winter wheat–corn for grain–barley–soybean. Evaluate the quantitative inflow of biomass, participation in the formation of the nutrient regime of gray forest soil, especially the differentiation of 0–40 cm of soil layer depending on the distribution of nutrients in different tillage soil systems. The studies were carried out in a long-term stationary experiment of the department of soil cultivation and weed control of the NSC «Institute of Agriculture of the NAAS», founded in 1969. The fertilization system consisted of the application of mineral fertilizers N65Р58К68 kg acting things per 1 ha of crop rotation area. As an organic fertilizer, we used by-products of crop rotation, where during 2009–2013 received an average of 5,17–5,50 t/ha, and 2014–2017 – 6,65–7,76 t/ha of crop rotation. The existing yield of the main product significantly influenced the volume of the non-commodity part, with the growth of the main product, the growth of by-products also took place in direct proportion. Nitrogen removal averaged 105 kg/ha, and with biomass it returned on average 55,4 kg/ ha, nitrogen with a full mineralization cycle, in general, this corresponds to 45–47 % of the share of costs. In general, the return of phosphorus from by-products for the rotation of 5 received an average of 12,0–16,7 kg/ha and 4-field crop 26 rotation 19,5–22,0 kg/ha, which was 35–40 % of the total removal harvest. The soil received many times more potassium from the biomass of agricultural crops than part of the cost of the main product, due to the attraction of the maize leaf mass, from which an average of 177–253 kg/ha enters the soil, and for crop rotation – 61,4–95,4 kg/ha per hectare of sown area. Key words: gray forest soil, soil nutrient regime, recycling of nutrients, main and by-products of crops.
Goal. Investigate and identify the features of the formation of physico-chemical degradation of gray forest soil under different anthropogenic load in grain crop rotation. Methods. Field, laboratory, computational, mathematical and statistical. Results. Against the background of a decrease in the aftereffects of radical chemical reclamation by 10-13 years, the application of an annual dose of alkaline earth elements taking into account the physiological characteristics of the crop (average 11,4 kg/ha and 4,6 kg/ha of calcium and magnesium, respectively), provides for 10-12 years close to neutral, and for 13 years of action weakly acid reaction of soil solution. In addition, there is a slight increase in the content of metabolic Ca and Mg in soil absorption complex, their content increases to 6,71-7,00 mg-eq/100 g of soil.The results of research on the impact of different agrochemical loads on gray forest soil with increasing doses of fertilizers, both in combination with and without radical chemical reclamation measures, obtained during 2016-2019, are presented. It is established that the use of intensive fertilizer systems without radical chemical reclamation leads to the deterioration of the physicochemical properties of gray forest soil. Conclusions. The use of a dose of mineral fertilizers on gray forest soil, calculated according to the species genotypic ratio of the content of elements in the biomass of the crop against the background of lime application, provides: optimization of crop nutrition, reduction of phosphorus and potassium, optimization of physicochemical, soil toxicity and soil properties Н + and Al 3+ . The optimal combination of N, P, K, Ca and Mg (216 k/ha in the ratio 1:0,4:0,5:0,3:0,1) in combination with seed inoculation with nitrogen-fixing and phosphorus-mobilizing bacteria, provides an increase in the level of productivity of the grain crop rotation to 5,45 t/ha of grain units and the payback of 1 kg of active substance of fertilizers to 15,6 kg of grain units. Physico-chemical degradation on acid soils with the application of high doses of nitrogen fertilizers can be partially prevented by saturating the soil absorption complex with exchange cations of alkaline earth metals, supplementing the fertilization system by applying small doses of Ca and Mg calculated on the basis of species content based on the recommended dose of nitrogen, an element that is limited to acidic soils.
The paper aimed to establish features of formation and regularities of structural and aggregate content change in the cultivated layer of low-humus typical chernozem under constant application of various systems of fertilizing and the basic cultivation of soil in short-rotation 4-feld crop rotations with 75 % saturation with grain (winter wheat, barley or spring barley) and 25 % oilseeds (sunflower, spring rape). The research was carried out in a long stationary experiment of the Department of Agrosoil Science and Soil Microbiology of the NSC «Institute of Agriculture of NAAS» and the laboratory of agriculture of the Panfly Research Station of the National Scientifc Center «Institute of Agriculture of the National Academy of Agrarian Sciences of Ukraine». The research results reveal the efciency of different fertilizing systems (fertilizers with crop by-products) combined with tillage tools that differ in their intensity and principle of action. The fertilizing system affected the biomass formation and the tools effect involved layer-by-layer distribution of new crop biomass and formation of soil aggregates of certain shape and size, their share in the formation of structural properties formation which testifes the impact of various anthropogenic stress. The study defnes the direction of soil processes, features of structure formation for long-term implementation of different depth and methods of basic tillage with preservation and anti-erosion and intensive use of 0–30 cm tillage layer (plowing 25–27 cm – control) and long-term use of no–till technology for growing crops that vary on the principle of localization of the crops root system. Key words: structural and aggregate composition, typical chernozem, method of basic tillage, differentiation.
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