The content of exchangeable potassium in the soil depending on the method of tillage and meteorological factors

The article is a continuation of a series of publications on the results of the study of nutrient elements in the soil-plant system against the background of global and regional climate change, given the possibility of minimizing tillage. In the conditions of stationary field experiment on ordinary chernozem (Calcic Chernozem) in the Donetsk region for five years (1994-1998) it was monitored the content of exchangeable potassium in the arable layer of the soil under the row crop corn within the grain-growing crop rotation on the options of plowing and subsurface non-turning tillage under the same mineral fertilizer system. At the same time, the dynamics of precipitation and air and soil temperature were recorded. According to the results of research, it is a steady effect of meteorological factors on the level of potassium nutrition of plants and a general tendency to decrease the average level of exchangeable potassium contents in the soil under vegetative plants of maize within the arable layer, mainly due to layers of 10-20 cm and 20-30 cm. It is shown that for plowing the optimum of humidity of the previous year is characterized by hydrothermal coefficient of Selianinov (HTC) 1.0, and for subsurface non-turning tillage - 1.25. With a very dry (HTC 1.5), subsurface non-turning tillage may be more favorable for potassium mobility. But within the HTC 0.5-1.5 is more acceptable plowing. It is determined that the refusal to plowing leads to a decrease in the dependence of potassium mobility in the soil layer 0-30 cm on temperature, protecting from temperature fixation of potassium, and enhances the influence of the humidification regime in May. But dry and cool autumn is a likely cause of reduced potassium mobility without plowing. All conclusions are confirmed by the results of correlation, regression and variance (ANOVA) analysis.

Nutrients use efficiency by modern hybrids of maize under arid conditions of the Forest-Steppe

The nutrient use efficiency of maize hybrids from the soil or through fertilizers is considered. Cultivation of modern hybrids requires determining the necessary rate of fertilizer to get the planned yield, taking into account their potential productivity and weather conditions. In the absence of data of nutrient uptake for new hybrids, it is proposed to use an indicator of their level of intensity, which is calculated by the ratio of the actual yield and its normative (calculated) value. Studies were conducted in 2018 and 2019 in the fields of the Institute of Agriculture of the Northeast of the National Academy of Agrarian Sciences of Ukraine. Soil – chernozem typical leached (Endocalcis Chernozem). Three maize (Zea mays L.) hybrids of Ukrainian selection were used: Zoryany (FAO 190), Leleka (FAO 260) and Donor (FAO 310). The vegetation seasons 2018-2019 were characterized as very arid (hydrothermal coefficient of Selianinov (HTC) 0.45-0.46). The calculated rate intensity of hybrids on average of two years was 1.07 at sites without fertilizers, and 1.36 at sites with fertilizers (N100 P45 K45). The efficiency of soils N,P,K use increases by application of mineral fertilizers. The nutrients output from the soil: nitrogen ‒ 53.8-71.4 %, phosphorus ‒ 20.0-26.6 % and potassium ‒ 65.4-86.8 %. The relative effect of fertilizers on the yield decreases, therefore, rate of natural fertility in the growth of the crop on fertilized soil increases. Due to the natural fertility of soils, the yield of all hybrids increased by an average of 1.33-1.46 t/ha with N100 P45 K45 applying. The dependence of yield of all maize hybrids on hydrothermal conditions in June was obtained. It was found that, all other things being equal, the yield is directly correlated with the FAO index of the hybrid. The payback of mineral fertilizers is estimated as 0.86-1.14 t / c

Differentiation of the content of chlorophyll, nitrogen and phosphorus in soybean leaves of different tiers

The article presents the results of determining the content of chlorophyll, nitrogen and phosphorus in the leaves of different tiers in soybean plants. The results of testing the working hypothesis about the relationship between chlorophyll content and nutrients are shown and data on the dynamics of their content in soybean leaves in the phases of bean formation, grain filling and the beginning of physiological maturity are demonstrated. The study performed during 2016 and 2017 in the field small-scale experiment of the Department of Agrochemistry of Kharkiv National Agrarian University named after V.V. Dokuchaev in the Kharkiv region of Ukraine. The soil is typical medium loam chernozem (Haplic Chernozem) with a humus content of 5.5–6.1 %, easily hydrolyzed nitrogen – 5 mg / 100 g, mobile phosphorus – 7 mg / 100 g of soil. Soybean seeds treated with the bacterial preparation rhizohumin before sowing. The content of chlorophyll in the leaves of plants determined by colorimetric method after extraction with ethyl alcohol; the total content of nitrogen and phosphorus in the plant samples is also colorimetric after burning the sample in sulfuric acid by the method of wet ashing. The results showed that during all the controlled phases of ontogenesis, the young leaves of the upper tier contained the most chlorophyll, nitrogen and phosphorus, and the leaves of the lower tier contained the least. The highest content of chlorophyll, nitrogen and phosphorus recorded in the leaves of the upper tier in the phase of bean formation, the lowest - in the leaves of the lower tier at the beginning of physiological maturity. No significant difference found between the control variant and the variants with the use of fertilizers. The method of applying the same dose of mineral fertilizers also did not significantly affect the studied indicators. This stated the presence of a characteristic feature of the accumulation and reutilization of nutrients in the leaves of different ages, located on different parts of soybean stems. A close direct correlation was found between the content of chlorophyll in soybean leaves and the content of nitrogen (r = 0.85) and phosphorus (r = 0.76). There is also a direct relationship between the content of nitrogen in the leaves of all tiers and the phosphorus content (r = 0.80).

Rock magnetism and soil magnetic susceptibility

Information support of modern agriculture and ecology forms a demand for ever higher requirements for efficiency and density of the sampling network. This fact determines the spread of high-performance methods of soil research, among which are magnetometric ones. However, these methods have a number of limitations associated with the existence in soils of ferromagnets of non-pedogenic nature. The purpose of the study is to show the patterns of spatial and profile distribution of soils with high values of magnetic characteristics, inherited from parent rocks as a result of pedogenesis. The research used: determination of specific magnetic susceptibility using kappabridge KLY-2, determination of volumetric magnetic susceptibility with kappameter KT-5 and induction of magnetic field by proton magnetometer MP 203. The study was conducted at two objects located in the central part of the Ukrainian shield region. Studies have shown that soils developed on the weathering crust are characterized by certain features of their magnetic properties. First of all, it depends on the petromagnetic parameters of the source rocks. On magnetic rocks, the MS of soils is determined primarily by inherited magnetic minerals. The magnetic susceptibility of such soils has two maxima. The first is in the upper part of the profile, where it is determined by the sum of pedogenic and terrigenous magnets. The second is located in the lower part of the profile, which consists almost entirely of weathering products.

Agrogenic changes in the properties of dark chestnut virgin and arable soil with different use and irrigation

In the article, it was provided a comparative analysis of the ecosystem significance of soil characteristics transformed as a result of changes in the use conditions. At the three monitoring stationary sites in the Chaplinka district of the Kherson region, we studied the properties of dark chestnut soil (Haplic Kastanozem) on virgin lands (a biosphere reserve "Askania-Nova") and with more than a hundred years of use in agricultural production without irrigation and with a 50-year irrigation with water from the Kakhovsky trunk canal. Changes in the salt regime of the soil and the composition of exchangeable cations were established. In irrigation the total content of water-soluble salts up to 0.14-0.21% (toxic salts ‒ up to 0.06-0.15 %) was increased. The composition of salts was changed, their migration and accumulation in the lower soil layers. Under the influence of fresh water irrigation the process of dealkalinization in the dark chestnut soil took place. The involvement of virgin soil in agricultural use led to a decrease in the total content of humus and the transformation of its group composition. The content of humic acids (HA) was decreased. The content of fulvic acids (FA) was increased. The HA/FA ratio in the 0-10 cm layer changed from 2.6 (in virgin soil) to 1.6 in irrigated soil. The plowing and agricultural use of the dark chestnut soil led to a change in the state of the microbial cenosis. The number of microorganisms assimilating mineral and organic nitrogen, actinomycetes, oligotrophs, and eutrophs were increased. With irrigation the degree of transformation of the microbial cenosis increases. The indicator of biological degradation of irrigated dark chestnut soil was 4 %. This corresponds to a low level of degradation. A set of 10 indicators of the quality of the studied soil was proposed for calculating the level of its provision of ecosystem services (supplying and supporting). The algorithm and calculation results are presented. The soil of all monitoring sites of Markeev station is characterized by a high level of provision of ecosystem services. In virgin soil it was 8.3 points; in arable soil without irrigation it was 7.2, and with irrigation it was 7.5 points.

Impact of the depth of fertilizer localization on the nutrient regime of Luvic Chernic Phaozem and yield of spring barley

The purpose of the research is to determine the impact of the depth of local application of mineral fertilizers on the nutrient content in the arable layer of soil and the yield of spring barley. The studies were carried out during 2018 - 2020 in a temporary small-plot experiment. Soil – chernozem podzolized loamy (Luvic Chernic Phaeozem). The application of N60P60K60 in the form of nitroammophoska or a mixture of ammophos, ammonium nitrate and potassium chloride was compared to a depth of 10-12 cm and 20-22 cm from the soil surface. The row spacing of barley crops was 15 cm; the fertilizer tape was placed at a distance of 4-5 cm away from the row. Mixed soil samples were taken from fertilizer tapes twice during the growing season of barley (in the first half of the growing season and after harvesting). The weather conditions were quite contrasting: in 2018 it was dry at the beginning of the growing season and during grain ripening, in 2019 was dry only during the formation of grain, and in 2020 - rather humid and relatively cool during almost the entire growing season. At the beginning of the growing season of barley in 2018, the highest content of mineral nitrogen in the soil was found with a shallow location of the fertilizers, but in 2019-2020 - in case fertilizer tapes at 20-22 cm from the surface. Location of fertilizer at a depth of 20-22 cm also provided a higher level of mobile phosphorus and potassium in the soil than applying at a depth of 10-12 cm. After the barley harvest, the highest accumulation of mineral nitrogen in the soil in 2018 was found with shallow application and in 2019-2020 - with deeper application. A tendency of more accumulation of chlorophyll in plants was observed with an increase in the depth of fertilization. Local application of fertilizers gave a reliable increase in yield in all variants of the experiment. However, the increase was twice as high when placing the fertilizer tape was at a depth of 20-22 cm as at a depth of 10-12 cm. Application of nitroammophoska to a depth of 20-22 cm was more effective than mixtures of simple and complex fertilizers. It was concluded that the hydrothermal conditions of the growing season and the depth of the location of fertilizers mutually affect the nutrient regime of the soil. The advantage of deep fertilization is more significant under insufficient moisture.

Impact of energy crops on the quality of ecosystem services of Luvic Chernic Phaozem

The article presents the results of research on the impact of energy crops on the quality of such ecosystem services of Luvic Chernic Phaozem as providing, regulating and supporting. The observation was conducted during 2019-2020 in the SE "Experimental Farm "Grakivske", Novyi Korotych village in Kharkiv region of Ukraine. Energy perennial crops grown in the experiment: Miscanthus giganteus (plantings 2016 (I) and 2019 (II) years); Sida hermophrodita (2018); Silphium perfoliatum L. (2018). Control variables: determination of soil organic carbon content; pH level; number of microarthropods in the soil; plant stem length. An increase in organic carbon content was found in the upper soil layers beneath energy crop plants, especially in the root zone of Sylphium. Due to the root excretions of the crops a slight decrease in pH is also observed in all the variants compared to the control. A positive effect of the plants is also observed on the numbers of soil invertebrates – microarthropods, namely columbines and oribatids. The increase in their numbers indicates the formation of favorable conditions for these living creatures, in the root zone of all energy crops. For example, in May 2019 compared to the control (2706 ex. / m2) under four-year-old Miscanthus almost tripled (6126 ex. / m2), under annual Miscanthus – 4860 ex. / m2, under Sylphium – 5040 ex. / m2, and under Sida – 4320 ex. / m2. Positive changes in soil structure under the influence of Miscanthus giganteus cultivation, especially in the upper layer, were also noted. The coefficient of structure on the variants increased from 1.39 on the control, to 2.26 in layer 0-20 under Miscanthus. Measurements of stem height, showed that all of the selected crops were able to function normally despite reduced rainfall and increased temperatures in recent years. The plants are not depressed under drought conditions and only increase their biomass over time. Thus, the results indicate an overall improvement in the quality of soil ecosystem services in energy crop plantations. In particular, provisioning services – obtaining energy raw materials; regulating services – improving soil quality; and ecosystem services – depositing organic carbon, are improved.

Influence of mineral fertilizers on the quality of winter wheat grain on typical chernozem in the Left-Bank Forest-Steppe

The goal was to study the effect of certain types of mineral fertilizers (N, P, K) and their paired compounds (NP, NK, PK) on the protein and gluten content in the grain of winter wheat on chernozem typical (Haplic Chernozem (Profundihumic)). The research was carried out in the conditions of a field stationary experiment which was laid down in the experimental farm of the NSC "Institute for Soil Science and Agrochemistry Research named after O. N. Sokolovsky" in the Kharkiv region. Eight variants with the following norms of fertilizers were studied for winter wheat: 1 – without fertilizers (control); 2 – N60; 3 – P120; 4 – K90; 5 – N60P120; 6 – N60K90; 7 – P120K90; 8 – N60P120K90. The effectiveness of fertilizers was reseached on two agrophones - natural and aftereffect of fertilizers (240 t/ha for crop rotation). The content of protein and gluten in wheat grain was determined on the Spectran-119M. On typical chernozem of the Forest-Steppe of the left-bank high application of nitrogen and phosphorus fertilizers in norm N60P120 provides the content of protein in grain of winter wheat at the level of 12,9 – 14,7 % that corresponds to the 1st and 2nd classes of quality of grain according to the National standard (DSTU 3768 : 2010). The gluten content ranges from 23.6 to 25.0 %, which corresponds to the 2nd class of grain quality of winter wheat.

Removal of basic nutrients from the soil by field crop rotations with different fertilizers

The effect of application of different doses and combinations of mineral fertilizers in field crop rotation on the content of basic nutrients in plants, economic and relative removal of winter wheat, corn, spring barley and soybeans was studied. Soil - Luvic Chernic Phaeozem. The scheme of the experiment includes 11 variants of combinations and separate application of mineral fertilizers and, including the variant without fertilizer. It was found that the level of nitrogen content of easily hydrolyzed compounds in the soil significantly affects its content in the grain of spring barley, corn, soybeans (R2 = 0,92–0,93), less - winter wheat (R2 = 0,63). The content of mobile phosphates in the soil has almost the same effect on its content in the main and non-commodity part of the crop, regardless of the crop (R2 = 0,39–0,70). The smallest relationship between the content of mobile compounds in the soil and in the crop was in potassium, but in soybean seeds and straw of spring barley and soybeans it was clearly traced (R2 = 0,53–0,68). Nitrogen (64,4–149,9 kg / ha) has the largest share in the economic extraction of nutrients with grain and seed yield, followed by phosphorus – 21,1–51,4 kg P2O5/ ha, depending on the crop. On the formation of the crop unit of marketable and the corresponding amount of non-marketable crop products absorb nutrients in the following ratio N : P2O5 : K2O: winter wheat – 1 : 0,4: 0,7; corn – 1 : 0,3 : 0,8; spring barley – 1 : 0,4 : 0,7 and soy – 1 : 0,4 : 0,4. With the non-commodity part of the crop, nitrogen with corn stalks returns to the soil from economic removal – 28–36 %, phosphorus with soybean straw (47–54 %) and potassium with winter wheat straw and corn stalks – 74–80 %, depending on the experiment variant.