Potassium Reserves Research Articles

The Influence of Slope Exposure, Profile Depth and Erosion Processes on Changes in the Content of Potassium, Phosphorus and Humus in Brown Soils of Mountain Pastures of Uzbekistan

Humus, potassium, and phosphorus are key components of soil that play crucial roles in ecosystem productivity, plant growth, and development. They control a wide range of processes, including greenhouse gas fluxes, nutrient cycling, infiltration, and water retention. This article presents the results of evaluating humus, potassium (K), and phosphorus (P) content in the profile of brown soils in mountain pastures of Uzbekistan, as well as their distribution within these soils. The brown soils studied in the mountain pastures of Uzbekistan have a loamy granulometric composition, with the clay fraction not exceeding 20%. The carbonate content is low (2.5-9%), with the maximum amount found in the carbonate horizon. The soils exhibit weak leaching. The total humus content in the upper horizon varies from 1 to 6.6%. It was observed that the soils on the more moistened northern and western slopes contain more humus than those on the southern and eastern slopes, indicating a dependence of high humus content on slope exposition. For the first time, the article allocates phosphorus and potassium of near, labile, and potential reserves (as a percentage of the total content) to estimate the change in the nature of brown soils under economic use. It was found that the potential reserve of phosphorus and potassium (35.5-90%) prevails in soils. Further study of the features of humus, potassium, and phosphorus, their accumulation, and restoration in brown soils is essential for developing recommendations for the rational use, anti-erosion protection, and increased productivity of mountain pastures in Uzbekistan.

A Portable Determination Method for the Soil Rapid Available Potassium via Enhanced NaBPh4 Turbidimetry

ABSTRACT Monitoring soil rapidly available potassium (RAK) reserves is extremely significant for developing precise fertilizer recommendations. The sodium tetraphenylborate (NaBPh4)-spectrophotometer method is applied to the detection of soil RAK content as a speedy, efficient and portable approach. However, the detection accuracy of this method is inferior to the ammonium acetate (NH4OAc)-flame photometer method. Here, the detection processes of the NaBPh4 turbidimetry were optimized to find the correlation with the NH4OAc method, further discussed the reasons for the different results by the two methods. The maximum relative error is 13% after conversion through the calibration curve. In addition, the accuracy of the calibration curve was verified by selecting non-fitting soil samples from two experimental sites. Therefore, our work proposes that the NaBPh4 turbidimetry, more convenient and rapid, can accurately detect the soil RAK content in the field. It provides an experimental guidance for the detection method of soil RAK content based on ultraviolet detection and on-site rapid detection devices.

Analisis Status dan Kemampuan Kesuburan Tanah pada Beberapa Lahan Tebu di Kecamatan Japah Kabupaten Blora

Sugarcane commodity is one of the important commodities in Indonesia. The relationship with the advanced industry of sugarcane is also very close, about 20% in the form of liquid sugar produced from this plant. This study was led to analyze the status and classification of soil fertility capabilities on sugarcane fields in the Japah Area. This study used a survey method with sugarcane fields selected from 9 selected villages and soil sampling depths of 0-20 and 20-40. The fertility status in sugarcane fields in Japah District is included in the Very Low (SR) and Low (R) criteria with C-Organic limiting factors, Potassium reserves, P reserves and low Base Saturation. The fertility ability classification is (T1) Ngiyono K is low, acidic and P is low, (T2) Sumberjo availability K and P are low, acidic, (T3) Wotbakah P is low, (T4) Bogem availability K and P is low, (T5) Gaplokan K and P are low, (T6) Kalinanas K and P are low, (T7) Tlogowungu availability K and low P, (T8) Dologan K and low P, (T9) Ngapus K and low P.Keywords : status, fertility capability, sugarcane land

Hydroxyl-Decorated Carbon Cloth with High Potassium Affinity Enables Stable Potassium Metal Anodes.

Highly anticipated potassium metal batteries possess abundant potassium reserves and high theoretical capacity but currently suffer from poor cycling stability as a result of dendritic growth and volume expansion. Here, carbon cloths modified with different functional groups treated with ethylene glycol, ethanolamine, and ethylenediamine are designed as 3D hosts, exhibiting different wettability to molten potassium. Among them, the hydroxyl-decorated carbon cloth with a high affinity for potassium can achieve molten potassium perfusion (K@EG-CC) within 3s. By efficiently inducing the uniform deposition of metal potassium, buffing its volume expansion, and lowering local current density, the developed K@EG-CC anode alleviates the dendrite growth issue. The K@EG-CC||K@EG-CC symmetric battery can be cycled stably for 2100h and has only a small voltage hysteresis of ≈93 mV at 0.5 mAcm-2 . Moreover, the high-voltage plateau, high energy density, and long cycle life of K metal full batteries can be realized with a low-cost KFeSO4 F@carbon nanotube cathode. This study provides a simple strategy to promote the commercial applications of potassium metal batteries.

SnS2 nanoparticles embedded in sulfurized polyacrylonitrile composite fibers for high‐performance potassium‐ion batteries

AbstractPotassium‐ion batteries (PIBs) have garnered significant attention as a promising alternative to commercial lithium‐ion batteries (LIBs) due to abundant and cost‐efficient potassium reserves. However, the large size of potassium ions and the resulting sluggish reaction kinetics present major obstacles to the widespread use of PIBs. Herein, we present a simple method to ingeniously encapsulate SnS2 nanoparticles within sulfurized polyacrylonitrile (SPAN) fibers (SnS2@SPAN) for serving as a high‐performance PIB anode. The large interlayer spacing of SnS2 provides a fast transport channel for potassium ions during charge–discharge cycles, while the one‐dimensional SPAN skeleton offers massive binding sites and shortens the diffusion path for potassium ions, facilitating faster reaction kinetics. Additionally, the excellent ductility of SPAN can effectively accommodate the large volume changes that occur in SnS2 upon potassium‐ion insertion, thereby enhancing the cyclic stability of SnS2. Benefiting from the above advantages, the SnS2@SPAN composites exhibit impressive cyclability over 500 cycles at 4 A g−1, with a capacity retention rate close to 100%. This study provides an effective approach for stabilizing high‐capacity PIB anode materials with large volume variations.

Hierarchically Structured Potassium-Vanadium-Phosphate/C Composites As Possible High-Voltage Cathodic Materials for Potassium-Ion-Batteries

Potassium-ion-batteries (PIBs) share technological similarities with Lithium- and Sodium-ion batteries (LIBs/SIBs) and are based on the inter- and deintercalation of K ions between two host materials.[1] The higher atomic weight and larger ionic radius of potassium ions results in lower gravimetric and volumetric capacities compared to LIBs.[2] But they offer similar advantages as SIBs (i.e. use of aluminium as current collector on both sides, evenly distributed potassium reserves) as well as graphite could be used as anode.[2,3] Also, they are expected to offer higher cell voltages due to the low standard potential of K/K+ vs. SHE of -2.93V.[3] To unlock the full potential of PIBs, cathode materials with high average potentials above 4 V need to be developed, which would significantly improve the energy density.[4] Polyanionic compounds, especially different Vanadium-Phosphates, are prepared and investigated for this purpose. Their thermal stability and diverse structural chemistry are advantageous for high energy PIBs. [2,5] One of the often-used synthesis methods for polyanionic compounds is the solid-state reaction. [4] In my work this well-known synthesis was coupled with a spray-drying process and a subsequently sintering process for K3V2(PO4)3/C composites. This created spherical secondary particles with a size in the micrometer range and an open micro-porosity. (see attached image)Through the addition of different amounts of organic sugars as a carbon source during the synthesis or sintering step an additional carbon coating of the primary and secondary particles was achieved, as well as the morphology of the secondary particles could be influenced. The influences of the different carbon contents during synthesis and sintering were investigated by thoroughly characterizing the morphology and crystal structure of the secondary particle with the help of SEM, BET, particle size distribution, XRD and porosity measurements. First electrochemical evaluation of the synthesized material was done by galvanostatic cycling the KVP/C composites against potassium.

Potassium in brown soils of mountain pastures of Uzbekistan

The studied mountain brown soils are characterized by loamy granulometric composition, nutty-cloddy structure, slightly acidic or slightly alkaline reaction. The total potassium content in the upper horizon varies from 1.240 to 1.685 %. Exchangeable potassium ranges from 265 to 1028 mg/kg of soil. The share of clay fraction varies from 2.9 to 18.3 %. In silty fractions, the con- tent of potassium is 2-3 times higher than in the soil as a whole and ranges from 1.26 to 3.02 %. Potassium reserves were identified - near, immediate and potential. Fluctuations in the content of potassium reserves in the humus horizon of the total content were: immediate from 1.5 to 8.31 %, near ө from 5.40 to 32.85 %, potential, dominant in the total content 65.12 to 93.0 %. It has been established that the distribution of potassium and its reserves in the pasture mountain brown soils of Uzbekistan is uneven and depends on many natural factors. It was revealed that potassium of a potential reserve is presented in a sufficiently large amount, and in a slightly smaller amount - near and immediate. Losses of near and immediate reserves of potassium lead to a decrease in the content of total potassium in general.

The Features of Potassium Dynamics in 'Soil-Plant' System of Sour Cherry Orchard.

This research aimed to study interannual and seasonal dynamics of different potassium compounds in orchard soil and the potassium status of sour cherry trees affected by the application of nitrogen and potash fertilizers. Afield experiment was started in 2017 at an orchard located in the forest-steppe zone of the Central Russian upland. Urea and potassium sulfate were applied to the soil once a year in early spring with rates from N30K40 to N120K160 kg/ha. The content of exchangeable and water-soluble potassium compounds was determined in soil samples five times throughout the growing season from May to September 2018-2020. The content of non-exchangeable potassium was determined twice, in 2017 and 2020. The interannual and seasonal dynamics of plant-available potash in unfertilized soil depended on the weather patterns and the uptake of potassium by trees. In the unfertilized plots, the first signs of potassium nutrition insufficiency appeared, such as low leaf and fruit potassium status and a decrease in the non-exchangeable potassium reserves in the20-40 cm soil layer. The annual fertilization led to the gradual accumulation of exchangeable potassium in the root zone. The accumulation was accelerated with increasing rates. When the exchangeable potassium level in the topsoil reached 200 mg/kg, the intensification of both the seasonal fluctuations in potash content and the potash leaching into the depths of the soil occurred in all treatments. In the conditions of our experiment, one-time treatments with superfluous potassium rates (over 80 kg/ha) did not provide an enlarged stock of plant-available potash in the soil but caused unreasonable losses of it due to leaching. An increase in fertilizer rates was not essential for normal metabolic processes and did not manifest itself as an increase in potassium content in leaves and fruits or as an increase in yield.

Effect of Potassium Application Rates on Sugarcane Yield in Soils with Different Non-Exchangeable Potassium Reserves and Fixation Capacity

Reliable fertilizer recommendations should account for factors influencing nutrient supply, including non-exchangeable potassium (K) reserves and fixation capacity, to ensure optimum crop yields. The combined effects of non-exchangeable K reserves and fixation capacity of soils on crop response to K application has not been evaluated. This study evaluated the response of sugarcane yields to K application on two soils with contrasting combinations of non-exchangeable K reserves and fixation capacity. Potassium was applied at 0, 120, and 240 kg K ha−1 at the commencement of the field trials and after each harvest on an umbric Acrisol, which had low non-exchangeable K reserves and medium K fixation capacity, and a cutanic Acrisol, which had ‘very high’ non-exchangeable K reserves and fixation capacity. Sugarcane stalk and sucrose yield, leaf, and exchangeable K were measured for each season. In the umbric Acrisol, a lower sucrose yield was measured in the 240 kg K ha−1 treatment compared to the control for the plant crop, but this application rate had higher yields for the second ratoon. In contrast, there was no yield response to K application in cutanic Acrisol. This study indicated the importance of non-exchangeable K reserves and fixation capacity when calculating K requirements and conducting field calibration studies.

The Influence of Logging Equipment on the Content, Stock and Stratification Coefficient of Elements of the Mineral Nutrition of Plants in the Soils of the Taiga Zone of Karelia

This study was carried out in the territories of Northern Europe, in the middle taiga subzone of Karelia. The paper presents the results of a study of an experiment on logging to study the impact of controlled logging using supervised logging with controlling cutting (SLCC) and conventional logging (CL) on the properties of soils (horizons O, E and BF) in a spruce forest 15 years after logging. Virgin forest (VF) was used as a control. The volume weight of soils, the contents of carbon, nitrogen and potassium in different soil layers (layers O, E and BF), as well as reserves of C, N and K and their stratification coefficients SRs (SR1 [O:E], SR2 [O:BF] and SR3 [E:BF]) were studied. The results showed a tendency to increase the volume weight of soils of anthropogenically disturbed (CL and SLCC) areas can be measured. The obtained data demonstrated that there was no sharp change in the contents or stocks of the studied elements between the anthropogenically disturbed (CL and SLCC) and undisturbed areas (VF). The largest reserves of carbon, nitrogen and potassium were noted in the upper horizons of the soils of all sites, averaging 35.6, 1.27 and 0.073 t/ha, respectively. In the lower horizons of the studied soils, the values were lower. The values of the stratification coefficients in the studied soils were arranged in decreasing order as SR2 > SR1 > SR3. At the same time, the general trend of unidirectional changes in the SR values for carbon and potassium in soils was noted; the data for nitrogen were somewhat different. The results showed a marked decrease in SOC concentration with an increase in soil depth. Higher rates of cellulose decomposition were observed in anthropogenically disturbed areas (CL—69.0 ± 3.6%; SLCC—57.4 ± 3.5%) compared with virgin forest (VF) (53.7 ± 3.1%), which is consistent with the results of other studies in the taiga zone. The data obtained indicate the importance of a more accurate assessment of the contents and stocks of elements, as well as the need to use tests for soil biological activity.

Reserves of Calcium, Copper, Iron, Potassium, Magnesium, Manganese, Sodium, Phosphorus, Strontium and Zinc in Goose Egg Yolk during Embryo Development.

This study evaluated the changes in calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), strontium (Sr) and zinc (Zn) values in goose egg yolk during the incubation period. This study was conducted on a completely random selection using 200 fertile eggs from a local flock of geese. A selection of 30 fertile eggs were randomly sampled on days 0, 9.5, 19.5, 25 and 30 of incubation (total: 150 eggs), and the yolks of 5 eggs in each replicate were mixed together and considered as one replicate (six replicates in each incubation period). The mineral content of the yolks was measured using the inductively coupled plasma (ICP) spectroscopy method. The results of this study show that, during the incubation of goose eggs from 0 to 30 days of embryo growth, except for Ca, the yolk content (absolute weight) of all the measured minerals, including Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn, on day 30 of incubation were statistically significantly lower than on day 0 of incubation. Additionally, the yolk concentrations of Fe, K, Mg, Na, P and Zn declined, the yolk concentrations of Ca and Sr increased, and the yolk concentrations of Cu and Mn were unchanged on day 30 compared to the first day of incubation. The results of the current study demonstrate that goose egg yolks' mineral concentrations change in absolute value during the incubation period, which could be the basis for further studies on chick feeding during the embryonic and post-embryonic phases.

The influence of nitrogen nutrition on the formation of the balance of nutrients in the agrocenosis of winter wheat

Аim. To study the influence of doses and methods of applying nitrogen fertilizers on the peculiarities of the use and balance of nutrients in the agrocenosis of winter wheat and to form a paradigm of an ecologically balanced fertilization system on leached chernozem. Меthods. Short-term field and analytical. Results. For the first time, under the conditions of sufficient moisture in the Forest Steppe of Ukraine, for the cultivation of winter wheat on leached chernozem, a fertilization system that forms a balanced balance of nutrients in the soil and ensures a grain yield of more than 6.5 t/ha has been substantiated. It was established that with a biological harvest, winter wheat takes the most nitrogen from the soil at the ratio N:P:K = 2.7:1:1.9. It was found that the formation of a balanced nitrogen balance in the soil depended mainly on the doses of nitrogen fertilizers and did not depend on the methods of their application. The potassium balance significantly depended on the removal of straw from the field and the doses of potash fertilizers, the phosphorus balance – on the doses of phosphorus fertilizers. Conclusions. Nitrogen was removed by plants mainly as part of grain yield, potassium – as part of by-products. In the control without fertilizers, removal of nitrogen by grain (4.77 t/ha) was 94 kg/ha, phosphorus – 33, potassium – 25, straw (5.35 t / ha) – 26, 10 and 57 kg/ha, respectively. The most ecologically stable fertilization system was that anticipated leaving winter wheat straw on the field and applying mineral fertilizers in a dose of N110Р60K60, where 60 kg / ha of nitrogen as ammonium sulfate was applied on the frozen soil surface, 30 kg/ha as ammonium nitrate on the soil surface or as urea foliarly in the phase of emergence into the tube (IVth stage of organogenesis) and 20 kg/ha as urea foliarly in the phase of milk-wax maturity (VIIIth stage of organogenesis) on the background of P60K60 applied under deep plowing. Under such conditions, an almost balanced balance of nutrients was achieved in the soil with nitrogen deficiency – 20–22 kg/ha and the accumulation of phosphorus and potassium reserves in the amount of 14–15 and 24 kg/ha, respectively. Obtaining a grain yield of more than 6.5 t/ha based on sustainability requires the application of mineral fertilizers in the dose of N130Р50K40 and under the condition that winter wheat straw remains on the field. In the case of removal of straw from the field, a deficiency of nitrogen and potassium was formed in the soil in the amount of 62–64 and 63 kg/ha with a balanced phosphorus balance, which is evidence of an ecologically unstable fertilization system.

Agrochemical Indicators, Content and Reserves of Mobile and Nonexchangeable Potassium Forms in the Profile of Arable Soddy-Podzolic Soil of a Long-Term Experiment with Introduction of Increasing NPK Doses

Agrochemical Indicators, Content and Reserves of Mobile and Nonexchangeable Potassium Forms in the Profile of Arable Soddy-Podzolic Soil of a Long-Term Experiment with Introduction of Increasing NPK Doses

Dynamic potassium flows analysis in China for 2010–2019

China is the largest potassic fertilizer user, but with very limited potassium reserve. This study aims to present an accurate and dynamic potassium inventory from a life cycle perspective. The spatiotemporal features of the main anthropogenic potassium flows and stocks are uncovered by applying substance flow analysis (SFA). Results show that China's potassium demand had doubled and domestic extraction of potassium resources had increased by 44%, from 2.89 Mt in 2010 to 4.15 Mt in 2019, due to the increasing population and rapid agricultural development. In terms of potassium usage, regional disparity existed and the overall usage efficiency was low. A total of 63.18 megatons (Mt) potassium was discharged into local environment as wastes, and a surplus of 24.89 Mt potassium was kept in soil as stock during the study period. Scenarios analysis results show that the total potassium demand will reach 9.56 Mt, 10.34 Mt, 11.32 Mt, 9.09 Mt, and 9.80 Mt under SSP1, SSP2, SSP3, SSP4 and SSP5 scenarios, respectively. Such findings indicate that China's potassium reserve will be quickly depleted. Based upon these findings, several policy recommendations are raised, including sustainable potassium resource supply, the recycling of potassium resources, and advanced technologies to further improve potassium resource efficiency.

Interconnected MnCO3 nanostructures anchored on carbon fibers with enhanced potassium storage performance

Potassium-ion batteries (PIBs) have gained considerable attention in the past decade because of the rich potassium reserves in our planet. However, the development of anode materials is still a major challenge because of the hard reaction kinetics and poor cycling stability in the insertion/extraction process. Herein, we report interconnected MnCO3 nanostructures anchored on carbon fibers (MnCO3/CF) composites as anode for PIBs. The MnCO3/CF can be directly used as anode on PIBs, avoiding the addition of polyvinylidene fluoride (PVDF) binders and the complicated slurry coating onto copper process. The nanosized MnCO3 nanostructures are interconnected with each other, which can provide short ions diffusion length during the charge/discharge process. The MnCO3 nanostructures are firmly anchored on the surface of CF through C–Mn bonds, ensuring cycling stability. Also, the CF with good electronic conductivity guarantees fast electrons transportation in MnCO3/CF system. Benefiting from the advantageous features mentioned earlier, the MnCO3/CF anode behaves enhanced potassium storage performance compared with that of pure MnCO3 anode. The MnCO3/CF anode delivers a high capacity of 462 mAh/g at 50 mA/g after 100 cycles, whereas the capacity of pure MnCO3 anode is only 134 mAh/g at 50 mA/g after 80 cycles. This work demonstrates the prospect of metal carbonate as anode materials for PIBs and provides a useful strategy to design advanced anode materials for PIBs.

Effect of Long-Term Fertilization on Aggregate Size Distribution and Nutrient Accumulation in Aeolian Sandy Soil.

Soil aggregates are the material basis of soil structure and important carriers of nutrients. Long-term application of organic and inorganic fertilizers can affect the composition of soil aggregates to varying degrees, which in turn affects the distribution and storage of soil nutrients. We report the results of a 15-year long-term field-based test of aeolian sandy soil and used the wet sieve method to analyze the stability of water-stable aggregates, as well as the distribution characteristics of nutrients in different particle size aggregates. Our results show that long-term application of organic fertilizer (M3) and combined organic–inorganic treatments (NPK1-M1, NPK1-M2, and NPK1-M3) help to increase the amount of organic carbon, inorganic carbon, and cation exchange in the macro-aggregates, and the improvement rates are 92–103%, 8–28%, and 74–85%, respectively. The organic content of the fertilizers also promotes the formation of macro-aggregates, and the stability of aggregates increase from 0.24 to 0.45. In contrast, the application of inorganic fertilizers (NPK1, NPK2, and NPK3) has no marked effect on the formation and stability of macro-aggregates; the application of inorganic fertilizers can merely maintain the organic carbon content of the soil. Correlation analysis shows that the application of organic fertilizers and chemical (inorganic) fertilizers containing phosphorus and potassium can markedly increase the content and reserves of available phosphorus and potassium across all aggregate sizes, and there is a significant positive correlation between these parameters and the amount of applied fertilizer (p < 0.05). Aggregates of various sizes in aeolian sandy soils in arid areas have the potential for greater nutrient storage. Therefore, organic fertilizers can be used in the agricultural production process to improve soil structure and fertility.

Cheese-like porous SnP2O7 composite as a long-life and high-rate anode material for potassium-ion batteries

The abundant reserve, low price, and low redox potential (-2.94 V vs. SHE) of potassium render potassium-ion batteries (PIBs) a potential for commercialization. However, developing suitable anode materials for PIBs remains an elusive challenge, and the low charge storage capacity of inserted anode materials also is not conducive to the realization of high energy density PIBs. In this work, a porous SnP2O7 filled with rGO (P-SPO/rGO) composite material with both conversion and alloying reactions was prepared by solvothermal and calcination methods. Compared with bulk SnP2O7 (B-SPO), P-SPO/rGO, used for the first time as an anode material for PIBs, delivers a high reversible capacity of 351.5 mAh g−1, long cycling life and excellent rate performance due to the porous structure which can alleviate the large volume change of the material during the cycling processes. Ex-situ transmission electron microscope and in-situ X-ray diffraction were carried out to characterize the intermediate chemical reaction process during discharging/charging. All these findings not only suggest that P-SPO/rGO is a promising anode material for PIBs, but also point out a new direction for the development of anode materials for PIBs.

Changes of the agrochemical soil characteristics in the stone fruit orchard with the permanent application of nitrogen and potash fertilizers

The purpose of the research was to evaluate the changes in the agrochemical properties of the sour cherry orchard soil after the permanent soil fertilization with urea and potassium sulfate. The field experiment was conducted during 2017-2021 in the soil and climatic conditions of the Central Russian Upland (Oryol region). ‘Turgenevka’ sour cherry trees grafted on the rootstock V-2-180 were planted in 2015 at a distance of 5x3 m. The soil of the orchard is loamy Haplic Luvisol with the following parameters: pHKCl - 5.8, organic matter content - 2.8%, available phosphorus - 383 mg/kg, exchange potassium -120 mg/kg, alkali-hydrolysable nitrogen - 108 mg/kg. Experimental scheme: 1. Control (no fertilizers); 2. N30К40; 3. N60К80; 4. N90K120; 5. N120K160. Fertilizers were applied once a year in early spring. The annual use of fertilizers in N90K120 dose or more contributed to an increase in the reserves of mobile phosphorus, exchange potassium, and alkali-hydrolysable nitrogen in the orchard soil, but did not have a stable effect on the tree productivity. At the same time, there was an increase of soil acidity and loss of exchange calcium under the influence of fertilizers, which indicates the beginning of degradation processes.

Potassium dynamics in orchard soil and potassium status of sour cherry trees affected by soil nutritional conditions

The influence of mineral fertilizers on the seasonal dynamics of exchangeable potassium in the soil, potash status and productivity of trees was studied in field experiment with sour cherry trees cv. ‘Turgenevka’ in soil-climatic condition of Central Russian upland in 2018-2019. The urea and potassium sulfate were applied annually in early spring at doses of N30K40, N60K80, N90K120, and N120K160 kg/ha. The potassium level in soil-plant system depended on weather conditions, the doses of fertilizers and uptake of the element by trees. The reserves of exchangeable potassium in loamy Haplic Luvisol at the level of 100-200 mg/kg were sufficient to ensure the sour cherry yield in the start of fruiting. Fertilization by doses of N60K80 and higher increased the content of exchangeable potassium in root zone (more than 200 mg/kg), but the features of potassium seasonal dynamics were similar to unfertilized plots. With increase in the average fruit load from 4.6 (2018) to 8.3 (2019) kg/tree, the uptake of potassium by young trees increased, which led to a significant decrease in the concentration of potassium in the soil and leaves during the fruit development period (June and July). Fertilization reduced this effect but did not significantly influence on the productivity of trees and fruit potassium status.

Relação quantidade-intensidade de potássio em solos gipsíferos no Iraque

ABSTRACT In gypsiferous soils, potassium (K) undergoes leaching, precipitation and other reactions that reduce its availability. This study aimed to evaluate the physicochemical behavior of K in gypsiferous soils of the Salahaddin province (Iraq), in twelve locations chosen according to the variation in their soil physical and chemical properties. The K adsorption phenomenon was described by using thermodynamic parameters according to the quantity-intensity ratio (Q/I), with the following results: equilibrium activity ratio of 16 to 48 x 10−5 (mol L−1 )1/2, total labile K of 19 to 80 x 10−3 cmolc kg−1, potential buffering capacity of 22 to 42 cmolc kg−1 (mol L−1)−1/2, free energy of exchange of -1.237 to -1.086 kJ mol−1 and Gapon selectivity coefficient of 3.86 to 5.45 (L mol−1)1/2. All the investigated soils are characterized by good potassium reserves, but low in release.