Forms Of Potassium Research Articles

Releasing Patterns of Potassium and its Relationship with Different Forms of Potassium in Acid Alfisols Soils of Ranchi, Jharkhand, India

A study was conducted during 2017-2018 at the Experimental Farm of Birsa Agricultural University, Kanke, Ranchi, Jharkhand, India to assess the releasing patterns of potassium and its relationship with different forms of potassium in surface (0-15 cm) and sub-surface (16-30 cm) soils of acid alfisols from the selected 9 treatments under long-term nutrient management practices in maize-wheat cropping system. The releasing power of soil potassium is an index of the availability of the nutrient to the crops over a longer duration and in general, it indicates the sum of water-soluble K, exchangeable K, and a fraction of non-exchangeable K which is not immediately available to the growing plants, but will be slowly available over a longer period. Repeated extraction with boiling 1N HNO3 has been suggested as one of the methods to assess the potassium-releasing capacity of soils. In this context, cumulative K, constant rate K, and step K as a part of non-exchangeable potassium proposed by Haylock (1956) measure the potassium-releasing capacity of soils more effectively under intensive crop cultivation. The amount of K release in successive extraction with boiling 1N HNO3 decreased consistently and reached a plateau at the 8th and 9th extraction steps in both depths of soils. Cumulative K is highest in INM (T6) while constant rate K and step K are highest in Lime, FYM, P2O5, and K2O treated plots (T8). The lowest contribution of potassium release patterns is generally observed in the control plot (T1). Also, the K release was found to be maximum in surface soils than in sub-surface soils concerning various selected treatments. Cumulative K, Constant- rate K, and Step K had highly significant and positive correlations with different forms of potassium (Water soluble K, Exchangeable K, Non-Exchangeable K, Total K, and Lattice K) in both depths. The potassium-releasing patterns evaluated through cumulative K, constant rate K, and step K could be meaningful for making fertilizer recommendation programmes, especially in intensively cultivated areas. Hence, the importance of study in terms of the possible contribution to plant available pool of soil K through potassium release patterns in two depths of given soil has been pointed out.

Reaction of winter rye on top-dressing to nitrogen fertilization at different level of mobile phosphorus and potassium in the soil

The article presents the results of assessing the effectiveness of methods for fertilizing winter rye with nitrogen, grown on soils with different levels of mobile forms of phosphorus and potassium. The studies were carried out in field experiments located on sod-podzolic heavy loamy soil. It has been established that with an increase in the content of available phosphorus in the soil to a level of more than 250 mg/kg, it leads to a mathematically proven increase in the productivity of winter rye by 1.0 c/ha (tfact.(10.0) > tcrit.(2.0)) (C - here and below 1 center (c) = 100 kg center). An increase in the amount of mobile potassium in the soil (> 120 mg/kg) contributes to a significant decrease in grain yield by 18.1 c/ha (tfact.(19.9) > tcrit.(2.0)). The fertilizing carried out contributed to a mathematically proven increase in the productivity of winter rye by 1.0-2.3 c/ha (tfact.(10.7-13.1) > tcrit.(2.0)). On average, the local method of fertilizing, compared to the spreading method, provided a greater increase in grain yield relative to the control (2.3 c/ha).

The edaphic niche of ploidy-different grasses in the light of the coarse-grained data modeling and direct soil sampling

In the framework of polyploidization, a widely discussed issue is the possibility of niche shift. Numerous studies have investigated niche differentiation among cytotypes, with some confirming distinct differences, while others finding them to be similar. Within this research project, we focus on the case of the cytotypes (2x and 4x) of Festuca amethystina L. and the closely related F. tatrae (Czakó) Degen (2x). We hypothesize that a significant change in the edaphic niche of tetraploids could be a factor that enabled them to occupy new lowland areas inaccessible to diploids which are characteristic of mountain habitats.The edaphic niche differentiation between Festuca amethystina cytotypes was determined by studying the niches’ breadths using PCA-based modeling and separate analyses of particular soil features. The modeling was based on SoilGridsTMdata, and the conclusions were compared with the results of the direct soil studies. Such a research model makes it possible to determine to what extent the data coming from the mentioned database allows for the indication of niche differentiation.Coarse-grained modeling based on SoilGridsTM data indicated a significant change in the edaphic requirements of the tetraploids, as well as pointed to the niche shift towards a higher content of sand, lower carbon and nitrogen content, and lower pH. The direct soil sampling and laboratory tests confirmed these trends and provided a more detailed understanding of the cytotypes requirements. However, no statistically significant differences were observed between cytotypes concerning soil pH, the majority of base cations, available forms of phosphorus and potassium, and the results of CHN elemental analysis. While the direct soil sampling did not reveal significant differences, the analyses based on the niche modeling, considering a wide background area in Central Europe (using SoilGrids data), captured significant variations. This comprehensive approach allowed us to uncover a highly logical pattern of niche shift, which indicates that tetraploids are predisposed to extend their geographical range to post-glacial lowland areas.Additionally, Festuca amethystina tetraploids display a wider edaphic niche breadth than their closely related and hypothetical ancestor Festuca tatrae. The decision to include the latter reduced the probability that the obtained result of the significant increase of the tetraploid edaphic niche was a simple result of hybridization.

Современное состояние почв лесных питомников таежной зоны Европейской части России

When producing planting material in the taiga zone, it is extremely important to assess problematic sites in forest nurseries. Attention should be paid to poor soil quality, which can significantly affect the growth rate of seedlings and the yield of standard planting material. The article considers a comprehensive assessment of soil conditions in forest nurseries of the taiga zone of the European part of Russia. The research was conducted in six forest nurseries. Agrochemical and physical properties of soils were determined. The content of organic matter in the soils of forest nurseries is low, mobile forms of phosphorus, exchangeable potassium and alkaline hydrolyzable nitrogen are insufficient for optimal growth and development of coniferous seedlings. The level of acidity in the soils of nurseries in the taiga zone of the European part of Russia turned out to be favorable. Half of the studied forest nurseries have increased density of soil composition, which can lead to the formation of soils with low pore volume, limiting air intake and moisture retention in the soil. A decrease in the intensity of seedling growth and yield of standard seedlings may occur due to the lack of technological measures such as weed control, lack of irrigation, etc., but one of the most important reasons is the insufficient supply of soils with mineral and organic substances. Equalization of soil fertility parameters in forest nurseries can be achieved by application of necessary fertilizers and by means of cultivation. The results of the presented work will make it possible to draw the attention of specialists engaged in the cultivation of planting material in the taiga zone of the European part of Russia to the problem of low soil fertility.

ДОСЛІДЖЕННЯ ЕФЕКТИВНОСТІ ВНЕСЕННЯ КАРБАМІД-АМІАЧНОЇ СУМІШІ АПЛІКАТОРОМ «DRAGON» ПРИ ВИРОЩУВАННІ ПШЕНИЦІ ОЗИМОЇ

The purpose of this research is determination of the effect of various methods of application of KAS by the DRAGON applicator from “ROPA-Ukraine” on the agrophysical and agrochemical parameters of the soil under crops during the growing season of winter wheat, the formation of biometric indicators and indicators of the yield structure and productivity of agrophytocenosis plants. Materials and Methods. Field studies on the application of KAS by the DRAGON applicator were conducted in the fields of the «Ploskivske» STOV farm, village Ploske, Bilotserkiv district, Kyiv region, on winter wheat crops and were accompanied by laboratory analyses and field observations. Statistical processing of accounting data was carried out by the method of variance analysis. The scheme of the experiment provided for the introduction of liquid KAS mineral fertilizers with the DRAGON applicator on the surface of the soil (plants) and into the soil with the help of injectors. Observations analyses and accounts accompanied experiments. To determine the structure of the crop, sample sheaves were selected. Conclusions regarding the effectiveness of applying a specific agrotechnical method were based on the results of comparing the values of the evaluation criteria obtained in the experiment with the values of the control variant. Results showed that application of fertilizers affects the supply of plants with available nutrients and is an effective means of increasing the productivity of field crops, including winter wheat. According to the results of the analysis of soil samples throughout the growing season of winter wheat, the content of mobile forms of phosphorus and potassium in the soil was high and very high in all variants of the experiment. Before the onset of winter, the compaction density, depending on the variant of the experiments and the soil layer, was from 0.94 to 1.30 g/cm2. At the time of vegetation recovery, the density of the 0-40 cm soil layer was within 0.82-1.36 g/cm3. The maximum compaction density – 1.36 g/cm3 – was in the version of feeding by injection. At the same time, its indicators did not go beyond the optimal parameters. The difference between the number of plants per unit area, before reaching the phase of full ripeness on variants with different methods of KAS, was 9.5%: with injection application of fertilizers, the density of standing plants was 4.949 million pcs./ha, for surface – 5.420 million units/ha. The biological yield of winter wheat grain on the control option, where fertilization was not applied, was 75.7 c/ha. Fertilization of KAS crops contributed to an increase in yield by 6.7-13.6 t/ha. Conclusions. The use of the DRAGON - 6000 applicator manufactured by ROPA Ukraine LLC when applying KAS contributes to the retention of productive moisture, loosening of the soil, the rate of accumulation of above-ground mass, graininess of ears, the formation of better agrochemical and biometric indicators of the soil under crops during the growing season of winter wheat, the formation of better biometric indicators and indicators of the yield structure and productivity of agrophytocenosis plants. Keywords: Applicator, injector, fertilizers, fertilizer application method, urea-ammonia mixture, productive moisture, soil compaction, biological yield, yield structure.

Experimental exploration of potassium compounds in the vicinity of a burning biomass pellet: From near-surface to downstream

The concentrations of gas-phase potassium hydroxide (KOH), potassium chloride (KCl) and atomic potassium (K(g)) were quantitatively measured from the near-surface to downstream area of burning pinewood pellets by a newly developed photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) technique to reveal the original form of the released potassium. The novel arrangement of the PF-TDLAS system enabled a spatial resolution of ∼1 mm3, which made it possible to obtain temporal release profiles of K(g)/KOH/KCl at different heights above the burning pellet surface. Surface temperature and mass loss of the wood pellet as well as the gas temperature at measurement points were measured simultaneously. During the devolatilization stage, the release of all three potassium species was observed, with each of them accounting for ∼1/3; while in char oxidation stage, the release of KOH was dominant, but the release intensity was strongly influenced by the local oxygen content. The results from different measurement heights showed there was a notable difference in potassium release profiles of different potassium species over the near-surface area, where the detected potassium forms were the best representative of the originally released forms of potassium. For a period of time during the devolatilization stage, only K(g) was detected in the near-surface area, and the concentration was significantly lower than the downstream area where KOH and KCl coexisted. This suggested that a large amount of potassium might leave the pellet as organic-K, which cannot be detected by the PF-TDLAS method. During char oxidation stage, the total potassium concentration at the near-surface area was also lower than the downstream area, but it was due to the lack of oxygen at the measurement position. A potassium release mechanism during the devolatilization stage of biomass combustion was proposed based on the experimental measurements, and the results also indicated the importance of spatially resolved measurement.

STATE OF SOD-PODZOLIC SOIL FERTILITY LOAMY SOIL DURING LONG -TERM HAYMAKING WHEN USING IT

Morphological changes of sod-podzolic loamy soil during its haymaking use for 85 years are traced. The description of soilоfillets under different methods of using grass stands and their influence on plantcover, as well as morphological changes in the sod-humus horizon, is carried out. It was found that the presence of a sufficient amount of biomass or crop residues with the con-stant use of mineral fertilizers (N120P60K90) contributed to an increase in the sod-illuvial horizon and a decrease in the podzolic one, but the presence or lack of it did not significantly affect the acidic background of the soil of the experimental site. The content of humic substances in the soil, mobile forms of phosphorus and potassium in natural conditions (reserved) largely depended on the volume of biomass, but the highest value of these indicators in the experiment was obtained in the variant with the use of mineral fertilizers. Migration of nitrogen, calcium, and magnesium was observed. The maximum content of mobile forms of phosphorus and potassium was found in the humus horizon up to 30 cm. A common feature of mineral elements is the presence of two horizons with the maximum content: in the sodм and transitionalм to the soil-forming rock.

SOIL CHARACTERISTICS UNDER SPONTANEOUS BIOCOVER OF PHALARIS ARUNDINACEA L. IN SERBIA

To investigate the quality of soils suitable for the growth of reed canarygrass (Phalaris arundinacea) L., soil samples and plant material were taken from six different sites in Serbia where the plant grows spontaneously. The basic fertility of the soil was analysed to determine the soil type on which the reed canary grass grows and the content of essential nutrients in the plant material. The soil samples from sites where reed canary grass grows had different pH values, ranging from strongly acidic to almost neutral. The soils differed in humus content, ranging from slightly humic to very humic. The nitrogen content and the available forms of phosphorus in the soil samples were low, while the content of available forms of potassium was medium to well supplied. The lowest nitrogen content and the highest content of potassium and phosphorus were measured in the stalks of reed canary grass.

Оценка на зеолит и диатомит за оптимизиране на хранителния режим при два типа почви

The research investigates the effectiveness of natural zeolites, diatomaceous earth and compost mixture as self-effects and their combinations on the NPK potential of two soil types. In both soils, the following variants were investigated: soil-compost (SC), soil-zeolite (SZ) and soil-diatomite (SD); as well as combined variants such as soil-compost-zeolite (SCZ) and soil-compost-diatomite (SCD). These components are composted over 60 days under controlled conditions. To achieve this goal, basic physicochemical parameters such as pH and electrical conductivity, cation exchange capacity (CEC), and agrochemical indicators – humus and mineral forms of nitrogen, phosphorus and potassium – before and after composting were traced. The study shows that combining natural zeolites and diatomaceous earth sludge with compost contributes to increasing potassium and phosphorus levels in the soil while maintaining the stability of soil organic matter, highlighting the most effective impact on phosphorus under certain pH conditions.

Dynamics of the Agroecological State of the Soils of the Central Chernozem Region during Long-Term Agricultural Us (on the Example of the Belgorod Region)

The paper analyzes the results of eleven survey cycles of arable soils conducted from 1964 to 2022 in the southwestern part of the Central Chernozem region in the Belgorod region. In the steppe zone of the region, ordinary chernozems predominate, in the forest-steppe zone – typical and leached chernozems. During the eleventh survey cycle (2019–2022), the average level of application of mineral fertilizers was 114.4 kg a.i./ha, organic – 9.6 t/ha, liming of acidic soils – 43.8 thousand hectares per year. As a result, the average yield of winter wheat increased to 5.09, sugar beet – up to 45.6, corn for grain – up to 7.15 t/ha. At the same time, the maximum value of the weighted average content of organic matter (5.3%) was recorded in the soils of arable land for the entire observation period. The proportion of acidic soils decreased to 28.6%, including moderately acidic soils, to 3.0%. The value of hydrolytic acidity decreased to 2.7 cmolc/kg. The weighted average content of mobile forms of phosphorus (139 mg/kg) and potassium (161 mg/kg) is the highest in the Central Black Earth region. 85.7% of the surveyed soils belong to the category of low content of mobile forms of sulfur, zinc – 97.2, copper – 92.5, cobalt – 98.8, manganese – 40.1, molybdenum – 21.3%. In terms of the content of mobile forms of boron, 98.2% of the soils are classified as highly rich.

Применение удобрений на клещевине (результаты исследований во ВНИИМК) (обзор)

The researches conducted in the V.S. Pustovoit All-Russian Research Institute of Oil Crops showed that castor plant yield increased by 0.08–0.20 t/hа after fertilizers application on leached chernozem. The more effective dose of a primary fertilizer under castor is N40P60, which applied in autumn separately under the plowing. Higher doses of the fertilizers are less effective. Application of potassium fertilizers jointly with nitrogen-phosphorus ones in both typical (K40–45) and increased (K80–120) doses did not caused the yield increase of castor plant. Under application of the different doses of the nitrogen-phosphorous or full mineral fertilizers, oil content in castor seeds did not change significantly comparing with unfertilized control, and oil yield was determined by seed yield and increased by 0.06–0.09 t/hа. The local application of N20P30 during castor plant sowing proved the same level of yield comparing with the dose N40P60 – 1.73–1.74 t/hа. The local application of fertilizers during sowing is the most effective when placing the fertilizers strips in a distance of 2 cm sideways of the seeds. Against the backfilling into the soil of 6.2–6.6 t/hа of winter wheat residues, the application of mineral fertilizers under castor plant caused the increase of seed yield by 0.21–0.29 t/hа, oil yield – by 0.11–0.14 t/hа. The dependence of castor plant yield on nitrate nitrogen, mobile forms of phosphorous, and exchangeable potassium contents the in leached chernozem in spring was revealed. It is determined the castor plant does not react positively on the addi-tional fertilizer application when contents of mobile forms of phosphates and exchangeable potassium in a soil layer of 0–20 cm are equal to 26–28 mg/100 g (in the hood by Chirikov F.V.) and 31–32 mg/100 g (in the hood by Maslova А.L.), respectively, and content of nitrate nitrogen in a soil layer of 0–60 cm is more 17–18 mg/kg (by Grandval-Lyazhu).

Studies on Potassium Fractions in Central and Southern Dry Zones of Coconut Growing Areas of Hassan District of Karnataka, India

The experiment was conducted in an order to get an insight about the potassium (K) fractions in Central and Southern dry zone of coconut growing areas of Hassan district, Karnataka during 2022-23. The soil samples from surface (0-30 cm) and sub-surface (30-60 cm) were collected from the soils of selected coconut gardens of Central and Southern dry zones of Hassan district for the study. Results revealed that the average water soluble K, hot water soluble K, exchangeable K, non-exchangeable K, lattice K and total K in surface soils of coconut gardens of Central dry zone of Hassan district registered was 2.76, 9.25, 54.65, 555.35, 5896.00 and 6509.00 mg kg-1, respectively. Whereas the above potassium fractions in sub-surface soil recorded were 2.67, 7.70, 47.36, 699.66, 7282.00 and 8032.00 mg kg-1, respectively. The various forms of potassium in surface soils of Southern dry zone revealed that water soluble K, hot water-soluble K, exchangeable K, non-exchangeable K, lattice K and total K was 2.87, 8.85, 53.51, 546.61, 5603.00 and 6206.00 mg kg-1, respectively. Whereas the above potassium fractions in sub-surface soil recorded were 2.21, 7.20, 45.21, 709.20, 7431.00 and 8188.00 mg kg-1, respectively. The trend of decrease in water soluble K and exchangeable K from surface to sub-surface layers was noticed in soils of Central and Southern dry zone whereas non-exchangeable K, lattice K and total K exhibited an increasing trend with depth. The contribution of each form of potassium to total potassium was in the order of water soluble < hot water-soluble K< exchangeable < non-exchangeable < lattice K. Knowledge of different forms of potassium in soil together with their distribution has greater relevance in assessing the long-term K supplying power of soil to coconut palm and is important in formulating a sound fertilizer program for a given set of soil.

Soil Properties of Fallow Land Invaded by Black Cherry (Padus serotina (Ehrh.) Borkh.)

The extensive spread of the invasive black cherry, Padus serotina, has been observed on abandoned agricultural land in Central and Eastern Europe. However, the impact of this species on invaded agroecosystems is still unknown, including the possibility of returning these ecosystems to agricultural production. In order to evaluate the selected soil properties of fallows invaded by P. serotina, their texture, field water capacity, reaction, and content of organic carbon, total nitrogen, and available forms of potassium and phosphorus were determined for 100 study plots. Taking into account the influence of soil conditions on floristic composition, the area covered by individual plant species in the study plots was also included in the analysis. A relationship was found between the presence of all the developmental stages of P. serotina and an increase in the phosphorus content in the soil. With the growth of a black cherry shrub layer, the content of soil nitrogen and potassium increased. An increasing proportion of P. serotina in the herb layer contributed to soil acidification and reduced the water content available for plants in the arable layer at 20–40 cm. The possible impact of P. serotina on soil properties may be an additional premise when considering the possibilities and benefits of the recultivation of fallow land invaded by this species.

Potassium Spraying Preharvest and Nanocoating Postharvest Improve the Quality and Extend the Storage Period for Acid Lime (Citrus aurantifolia Swingle) Fruits.

Citrus fruits are one of the most abundant crops globally in more than 140 countries throughout the world. Acid lime (Citrus aurantifolia swingle) is one of the citrus fruits which popularly has rich nutritional and therapeutic features. The storage period is the important factor that affects the economic and quality properties of this fruit. This study aims to demonstrate the enhancing effect of preharvest spraying with potassium, in addition to the postharvest dipping of fruits in some edible coatings, on the quality and storability of acid lime fruits. Preharvest spraying with organic and mineral forms of potassium, namely, potassium thiosulfate 1.75 g/L (S) and potassium tartrate 2 g/L (T), were carried out at three different times, in May, June, and July. On the other hand, postharvest treatments were carried out via dipping fruits in different types of biopolymers (carboxymethyl cellulose (E2) and gum arabic (E3)) and carboxymethyl cellulose/gum arabic composite (E4) as well as nanocoating formulation based on both biopolymers and doped zinc oxide nanoparticles (ZnONPs) (E1), which were prepared via acid lime peel waste extract. Herein, the physiochemical and morphological characterizations confirmed that the nanocoating was prepared at the nanoscale and doped with green synthesis ZnONPs, with recorded sizes of around 80 and 20 nm, respectively. Preharvest spraying with potassium tartrate enhanced fruit traits (Spraying with potassium tartrate at pre-harvest and nanocoating dipping at post-harvest (TE1), spraying with potassium tartrate at pre-harvest and carboxy methyl cellulose dipping at post-harvest (TE2), spraying with potassium tartrate at pre-harvest and gum arabic dipping at post-harvest (TE3) and spraying with potassium tartrate at pre-harvest and carboxymethyl cellulose/gum arabic composite dipping at post-harvest (TE4)), followed by potassium thiosulfate (spraying with potassium thiosulfate at pre-harvest and nanocoating dipping at post-harvest (SE1), spraying with potassium thiosulfate at pre-harvest and carboxy methyl cellulose dipping at post-harvest (SE2), spraying with potassium thiosulfate at pre-harvest and gum arabic dipping at post-harvest (SE3) and spraying with potassium thiosulfate at pre-harvest and carboxymethyl cellulose/gum arabic dipping at post-harvest (SE4)), compared to control. For postharvest treatments, E1 improved fruit quality, followed by E2, E4, and E3, respectively. The integration between pre- and postharvest treatments showed a clear superiority of TE2, followed by TE4, SE1, and SE2, respectively.

Study of the Different Forms of Soil Potassium in Ujjain Tehsil of Ujjain District of Madhya Pradesh, India

The current research was carried out in the Ujjain tehsil (Ujjain) district of Madhya Pradesh state, India, with the aim of estimation the different forms of soil potassium and different characteristics of the Soil. Throughout the research region, 150 surface soil samples with a depth of 0 to 15 cm were collected. Collected soil samples were analyzed for physico-chemical properties namely texture, pH, Electrical conductivity, organic carbon and different forms of potassium (K) i.e. Water Soluble Potassium, Exchangeable Potassium, Available Potassium, Non-exchangeable Potassium, Lattice Potassium and Total Potassium. To observe that the soil texture of Ujjain district is varied from silty clay to clay, soil pH ranged from 7.01 to 8.15, electrical conductivity was varied from 0.10 dSm-1 to 0.79 dSm-1, organic carbon is varied between 0.30 to 0.60 % and The research region's ranges for different forms of potassium i.e. Water Soluble Potassium, Exchangeable Potassium, Available Potassium, Non-exchangeable Potassium, Lattice Potassium and total K were 3.10-24.00 mgkg-1, 118.38-196.12 mgkg-1,129.95-206.70 mgkg-1,200.0-410.0 mgkg-1 ,7943.75-17515.71 mgkg-1 and 8500-18000.0 mgkg-1, in that order. The mean value of Water Soluble Potassium, Exchangeable Potassium, Available Potassium, Non-exchangeable Potassium, Lattice Potassium and Total Potassium was 11.47 mg kg-1, 148.67 mg kg-1, 160.11 mg kg-1, 330.16 mg kg-1, 12478.11 mg kg-1 and 12968.96 mg kg-1, respectively.

Simulated warming decreases acidity of forest topsoil under Norway spruce (Picea abies (L.) H.Karst.) stands in the Western Carpathians

Global warming is affecting the montane forests of the temperate zone, causing a number of changes in all elements of the ecosystem, including the soil. Norway spruce forests, weakened by ongoing decay over several decades, are likely particularly sensitive to climate-induced changes. The response of soil cation exchange capacity components of spruce stands to warming is not well understood. We have assumed that warming will cause significant changes in pH, disrupting ion-exchange relationships in the soil. To the best of our knowledge, the present study is the first devoted to examining the mechanisms of soil pH change in temperate forest under the influence of warming. The forest in-situ experiment, simulating the soil warming for 578 days, was performed. Laboratory analyses included measurements of pH, and concentrations of carbon and exchangeable forms of calcium, potassium, magnesium, sodium, and aluminum. Shortly after the beginning of simulated warming (84 days), we observed a significant increase in the pH of the topsoil horizons. On average, in the warmed organic (O) horizon, the pH increased by 0.21, and in the mineral (A) horizon by 0.29 pH units. Based on previous studies, the pH increase was most likely triggered by an increase in ammonium-nitrogen content in the warmed soil. Using the Henderson–Hasselbalch equation to model the pH revealed that, in the O horizon, the pH increase is a result of the presence of weaker organic acids, less able to release hydrogen ions during dissociation. In the A horizon, the increase in pH was explained by an increase in abundance of aluminum ions, probably migrating upward from deeper soil layers. We consider that the ion-exchange mechanisms described here will contribute to an improved understanding of the complex processes of spruce forest dieback in the context of climate warming.

Potash State of the Soil and Crop Productivity when Applying Mineral Fertilizers and Plant Residues

In micro-field experiments conducted on gray forest soil, changes in the forms of potassium under the influence of mineral fertilizers and plant residues were studied. It is shown that the soil potassium contained in a water-soluble and easily exchangeable form varied widely. In the conditions of 2012, when applying K60 on the background of nitrogen and phosphorus, the content of water–soluble potassium increased by about 2 times compared with the control, and the content of light-exchange potassium increased by 4 times. In the case of embedding plant residues in the soil, the potassium content in the water–soluble form increased by 2 times, light-exchange – by 2.5 times, respectively. The content of exchangeable potassium changed little in the variants, the changes affected the non-exchangeable form to a greater extent. In particular, the content of non-exchangeable potassium in 2018 decreased by 1.5–2.0 times compared to 2012, which required the creation of a more reliable basis for obtaining objective information about the state of the potash fund of the soils of the forest-steppe zone. Under the influence of K-fertilizers in combination with plant residues, plant productivity stabilized, and at the same time a positive balance of potassium in the soil was formed.

Changes in the Microbiological and Physico-Chemical Properties of Soils after Fires in Pine and Birch Forests of Central Regions of the Zabaikal Krai

The microbiological and some physico-chemical properties of illuvial-ferruginous soddy-podburs (Entic Rustic Podzols) soils in Scots pine forests and gray-humic typical light loamy soils (Umbrisols) in secondary birch forests of the central regions of the Zabaikal krai have been studied. Fires in soddy-podburs pine forests resulted in decrease in the total exchangeable basis, total nitrogen, mobile forms of potassium and phosphorus, and in increase in the proportion of C : N; while in birch forests, on the contrary, an increase of the mentioned indicators and a narrowing of the C : N proportion in the gray-humic typical soils were observed. The content of humus in the upper soil horizon decreases only in recently burned Scots pine forests after a high-severity fire, while in other sites it increases. A decrease in the soil acidity was observed at all burned sites. High-severity fires lead to a significant decrease in the content of microbial biomass and the intensity of basal respiration, as well as to a change in the structure of ecological and trophic groups of microorganisms in the soils up to a depth of 10 cm of the mineral horizon, while low-severity fires mainly affect the duff. The qCO2 coefficient increased 2–5 times after fires in the duff and 1.5–2 times in the humus horizon only after high-severity fires. In recently burned Scots pine forests, the storage of microbial biomass and microbial production of carbon dioxide significantly decreased up to a depth of 10 cm of the mineral soil layer. In the steppe site formed after the impact of fires in the pine forest, and in the birch forest after a high-severity fire, in the humus horizon the carbon storage of microbial biomass decreased by 15–20%, and the microbial production of CO2 increased by 10–20%, predetermining the predominance of mineralization processes. The considered post-fire transformation of the structural and functional parameters of soil microbiocenosis, as well as a 20–40% decrease in the total carbon storage of microbial biomass in the soils of all sites demonstrate a long recovery period of soils after fires in light coniferous and deciduous forests of the central regions of the Zabaikal krai.

Changes in crop rotation productivity and stability of agrocenoses with prolonged use of fertilizers

The article considers the results of many years of field experiment (1968-2018) conducted in the Central part of the Non-Chernozem zone of Russia (Vladimir region). The research was carried out during eleven rotations of the four-field grain crop rotation. The study shows the effect of use of organic and mineral fertilizers applied in various doses and combinations on crop rotation yield, fertility of sod-podzolic sandy loam soil. It was found that the organomineral fertilizer system (manure 10 t/ha + N50P25K60) provided stable crop rotation productivity (on average for eleven rotations) at the level of 39.9 c. e./ha, or 79.7 % higher than the control without fertilizers. The mineral fertilizer system at medium doses of fertilizers (N50P25K60) was at the level of the organomineral system. The organic system was inferior in efficiency to the mineral system, both at medium doses (manure 10 t/ha) and at elevated doses (manure 20 t/ha). At the same time, the long-term use of organic fertilizers provided an increase in the humus content, depending on the dose of litter manure, by 16-36 % compared to the initial values. The use of organic fertilizers led to the stabilization of the content of available forms of potassium in the soil at an average and elevated level, respectively. Stabilization of the content of mobile phosphorus in the soil at the level of average supply was noted in mineral, organomineral and organic fertilizer systems, respectively, with low and medium doses. When using increased doses of fertilizers, there is a further increase in the content of nutrients in the soil. Growing crops in crop rotation without the use of organic and mineral fertilizers gradually led to a decrease in yield. The use of fertilizers provided greater stability of crop yields over the years of the study compared to the variant without fertilizers. The soil in the variants with organic (manure 20 t/ha) and organomineral (manure 10 t/ha + N50P25K60) fertilizer systems was characterized by high values of the main physiological groups of microorganisms. The ratio of the number of amylolytic and proteolytic microorganisms was 1.1-1.2, that indicated a balance in the processes of mineralization of organic matter in the soil and its humification.

Variation and dynamics of soil properties of ordinary chernozem in the Saratov region

Based on data from an agrochemical survey using GIS technologies at test site No. 2 in 2009-2016 within the framework of the general scheme of soil-ecological monitoring of the Saratov region, an assessment was made of the dynamics and spatial variation of soil properties of ordinary chernozem, depending on the steepness and exposure of the slope. Soil and agrochemical characteristics in conditions of a pronounced relief demonstrate a certain dependence on the location and are very variable over time. Soil sampling on an area of more than 2000 hectares using navigation equipment made it possible to obtain agrochemical cartograms in GIS and analyze them using zonal statistics, taking into account a digital elevation model. The spatial variability of soil properties is often lower in leveled areas or short transition sections of the slope, while the maximum variability is noted on steeper slopes. The highest values of indicators are typical for flat watershed surfaces, which are the most fertile, however, the closest relationship between humus and other agrochemical indicators was noted just on steeper slopes. The variability of fertility indicators on differently directed slopes was within 28–36 % for P2O5, 20 % for K2O, and 4–6 % for pH. The greatest differences in the variability of the polar slopes along the survey tours are noted for the content of humus in the soil. In 2009, the coefficient of variation was 19 and 30 %, and in 2016, 11 and 24 % on the slope of the northern and southern exposure, respectively. A retrospective analysis showed that the highest rates of decline were noted for the content of humus in the soil and the reaction of the environment on gently sloping slopes (by 2 and 1.5 times, respectively) relative to the average change in the massif. For mobile forms of phosphorus and potassium, the maximum decrease was noted on gentle slopes.