Potash Research Articles

Efficacy of potassium schoenite as indigenous source of potassic fertilizer for potato crop grown in Western India

To attain the optimal production and quality, potato (Solanum tuberosum L.) farming requires a large amount of potassium fertilizers. Due to a lack of K mineral reserves, several nations, including India, import potassic fertilizers, which place additional financial strain on the country’s economy. Thus, potassium schoenite produced from sea bittern may present an attractive substitute for potassium nutrition in crop production. The current study examined the relative effect of indigenously produced potassium schoenite (PS) on potato crop. The findings demonstrated that potassium schoenite considerably increased potato growth, yield characteristics, yield, and quality of tuber. With 100% RDK (220 kg/ha K2O) through potassium schoenite + 1% foliar spray of potassium schoenite @ 30 and 45 DAP, the greatest yield attributes, total tuber yield and starch output were achieved which remained at par with 75% RDK (165 kg/ha K2O) through potassium schoenite + 1% foliar spray of potassium schoenite @ 30 and 45 DAP. Furthermore, potassium schoenite saves 25% K2O in potato production as compared to potassium sulfate and muriate of potash. Thus, indigenous potassium sources have been found to be far more effective than imported potassium sulfate and muriate of potash in enhancing potato productivity.

Synergistic conservation approaches for nurturing soil, food security and human health towards sustainable development goals

Using chemical fertilizers extensively in small farms has helped increase crop yields, supporting food security and economic growth. However, recent studies show that these fertilizers are often used inefficiently and inconsistently. This leads to environmental harm, unbalanced soil nutrients, and lower-quality food production. These issues threaten food security, which is vital for human survival and may lead to the abandonment of arable land. This situation calls for a significant shift in soil conservation research to better connect scientific findings with practical conservation methods, ensuring that agricultural progress goes hand in hand with environmental sustainability. Effective use of nitrogen (N), phosphorus (P), and potassium (K) fertilizers is vital for both environmental sustainability and food security. Correcting nutritional imbalances, especially the disrupted N/P ratio caused by faulty fertilization practices, is key to ensuring a balanced nutrient supply. These imbalances have a substantial effect on aquatic and terrestrial ecosystems, altering their functionality, biodiversity and human nutrition Therefore, adopting balanced fertilization techniques is essential to combine environmental sustainability with global food security and achieve the Sustainable Development Goals (SDGs).To optimize nutrient consumption and production efficiency, regulations should be enacted to enforce the 4R principle, which involves applying the right nutrient source at the appropriate rate, time, method and location. This article emphasizes the connections between current agricultural practices, land use, fertilizer application, soil degradation, and future challenges. It promotes environmentally friendly farming methods that recognize the vital links between soil quality, food security, human health, and environmental sustainability.

The Effect of Potassium Dosage and Branch-Pruning on the Growth and Yield of Butternut Squash (Cucurbita moschata Durch)

Butternut squash (C. moschata) is a honey squash plant (Cucurbita moschata Durch) which is an introduced plant from the lowlands of South America and has adapted to Indonesia. The research was carried out in the planting area of Kampung Labu Madu, Toyoresmi Village, Ngasem District, Kediri Regency from January to June 2021. Potassium is among major nutrients needed by plants in their growth and development. Potassium fertilization can help plants improve the regulation of photosynthetic mechanisms, carbohydrate translocation, protein synthesis This research was a two-factor factorial experiment prepared using a Split Plot Design. The first factor (main plot) was the branch pruning (P) treatment which consisted of 2 levels and the second factor (subplot) was the dose of KCl (K) fertilizer which consisted of 4 levels. The results of the research showed that there was a real influence in the treatment without pruning on the parameters of the number of male flowers and on the parameter of fruit weight with the best treatment being pruning, whereas for the treatment the dose of KCl fertilizer had a real effect on the parameters.

HONEY PUMPKIN STEM BORER, Apomecyna saltator FABRICIUS (COLEOPTERA: CERAMBYCIDAE) CAN BE CONTROLLED WITH PHOSPHORUS AND POTASSIUM FERTILIZER

Apomecyna saltator, a notorious pest of honey pumpkin plants, poses a significant threat to both vegetative and generative phases, leading to considerable production losses. Despite its agricultural impact, there are limited studies on effective management strategies for this pest. This research investigates the effect of combined phosphorus and potassium fertilization on controlling A. saltator infestations in honey pumpkin plants. The study was conducted at the Teaching and Research Farm of the Faculty of Agriculture, Jambi University. A randomized block design with five treatments and five replications was used, testing different combinations of SP-36 phosphorus and potassium chloride (KCl) fertilizers: no fertilization (p0), SP-36 0.67 g/plant + KCl 1.25 g/plant (p1), SP-36 1.00 g/plant + KCl 1.88 g/plant (p2), SP-36 1.34 g/plant + KCl 2.51 g/plant (p3), and SP-36 1.67 g/plant + KCl 3.13 g/plant (p4). The variables observed included stem diameter, larval population, percentage of plant damage, number of attacked plant segments, fruit weight, and overall production. Data were analyzed using ANOVA and Duncan's Multiple Range Test (DMRT). The results indicated that combining phosphorus and potassium fertilizers significantly increased stem diameter, fruit weight, and yield while reducing larval populations, plant damage, and affected segments. The study demonstrates that phosphorus and potassium strengthen honey pumpkin plants and negatively impact A. saltator infestations. This research highlights a novel approach to pest control, showing that targeted fertilization promotes plant health and suppresses the honey pumpkin stem borer (A. saltator). This dual benefit of nutrient application provides a sustainable and efficient pest management strategy, offering a fresh perspective on integrated crop protection.

NaCl-induced effects on photosynthesis, ion relations, and growth of Chloris gayana Kunth in the presence of two levels of KCl

Soil salinization is a widespread environmental problem that impacts agriculture. Potassium fertilization is often associated with stress mitigation. Aiming to identify the ability of Rhodes grass (Chloris gayana Kunth) to cope with high salt as well as to investigate the potential of K+ fertilization to alleviate stress symptoms, we investigated the combined effects of NaCl and KCl on photosynthesis, ion distribution, and growth of two Rhodes grass cultivars, Callide and Reclaimer. Plants were grown under different regimes (0, 200, 400, and 600 mM NaCl + 1 or 10 mM KCl). For Reclaimer, 10 mM KCl induced positive effects in photochemistry under 0 and 200 mM NaCl, as illustrated by fluorescence transients OJIP-bands and JIP-test parameters. However, such improvements did not lead to superior biomass accumulation nor net photosynthesis compared to the corresponding treatments under 1 mM KCl, which may not justify KCl application. In Callide 10 mM KCl induced deleterious effects on photochemistry of plants under low NaCl levels. High salinity (600 mM) induced stress-triggered biomass reduction of up to 70% in both cultivars, but all plants remained photosynthetically active. Exposure of both cultivars to NaCl concentrations equal to or higher than 200 mM triggered response mechanisms such as the ability to accumulate inorganic solutes accounting to osmotic potential, stomata closure, and excretion (up to 70%) of the retained Na+ onto the leaf surface irrespective of KCl. Our data reinforce that Rhodes grass is an auspicious forage crop for saline environments and, therefore, in revegetation programs for saline soils pasture in subtropical regions.

Combustion-explosion suppression and environmental protection of typical sulfur-containing hazardous chemicals.

Sulfur, as a crucial chemical raw, poses increased combustion-explosion risks when mixed with other hazardous substances due to its dual nature as both an oxidant and a reducing agent. Additionally, sulfur-induced combustion and explosions can result in environmental pollution. Combustion-explosion suppression technology plays a crucial role in industrial production by effectively preventing hazardous chemical explosion incidents. This research investigates the combustion-explosion suppression of black powder, a common hazardous chemical containing sulfur, by utilizing two solid-based blast suppressants, NH4H2PO4 and NaHCO3. On this basis, examining changes in the oxidation states of sulfur and explaining the mechanisms of combustion-explosion suppression through the examination of combustion-explosion products. Additionally, numerical calculations are employed to analyze the evolution patterns of gaseous and solid-phase products throughout the entire combustion-explosion process. Research indicates that NaHCO3 exhibits a more effective combustion-explosion suppression effect on black powder compared to NH4H2PO4, which attributed to the valence state transformation of sulfur and the reduction of carbon oxidation. Furthermore, with the enhancement of combustion-explosion suppression effect, K2S, which a pollutes the environment, is gradually transform converted into potassium fertilizer K2SO4, which benefits plants. These results offer new insights into the research of combustion-explosion suppression of sulfur-containing substances and environmental protection strategies.

Application of hydrogel polymers and fertilizers for increasing winter wheat grain yield in conditions of rain-fed agriculture

This study aims to address the critical issue of water scarcity, which is being intensified by climate change and presents significant challenges to rain-fed agriculture, especially in arid regions. The research focuses on enhancing winter wheat grain yield productivity under rain-fed conditions through the utilization of locally produced, environmentally friendly hydrogel polymers. The methodology involved a field experiment conducted in the Spitak community, Armenia, from 2022 to 2023, covering an area of 630 m². Along with control groups, the study had 21 experimental treatments that used Aquasource and Van polymers in different ways, with and without nitrogen, phosphorus, and potassium (NPK) fertilizer. The findings indicated that the application of Aquasource and Van polymers at doses of 50-100 kg ha⁻¹ and 750-1000 kg ha⁻¹, respectively, without fertilizers significantly increased soil moisture absorption during the tillering and heading stages by 11.5-12.5% and 5.5-7.5%, compared to the controls. On the other hand, using these polymers with NPK fertilizer (N50P50K50 and N100P100K100) together made it harder for plants to absorb water, especially when more polymers were used. Soil moisture levels had a substantial impact on winter wheat grain yield metrics during these growth stages, demonstrating a strong correlation (R = 0.71-0.91). Enhanced moisture absorption resulting from polymer application led to a 22-24% increase in winter wheat grain yield. The practical implications of this study lie in its identification of key factors that influence winter wheat yield in rain-fed agriculture, particularly regarding locally sourced polymer dosage and application methods, both independently and in conjunction with fertilizers.

Potassium fertilization and defoliation intensity effects on forage characteristics of “BRS Zuri” guineagrass

Potassium fertilization and defoliation intensity effects on forage characteristics of “BRS Zuri” guineagrass

Impact of Potassium Fertilization on Growth and Yield of Small Millets

Aims: To evaluate the impact of varying potassium application levels on the growth and yield of small millets and to assess the economic viability of potassium fertilization in small millet farming. Methodology: A split plot design experiment was carried out, featuring four crops as the main treatments: C1 - Proso millet, C2 - Barnyard millet, C3 - Kodo millet, and C4 - Browntop millet. Potassium fertilizer was applied at four different rates (0, 10, 20, and 30 kg/ha) as sub-treatments. Throughout the cropping period, various morpho-physiological traits were monitored, including plant height (cm), tiller count per plant, and yield-related metrics such as the number of panicles per plant, 1000-grain weight (g), and biomass production per plant (g). At harvest, yield data and yield attributes were recorded, followed by an economic analysis. Results: The results indicated that, Proso millet showed a plant height increase from 75.85 to 94.37 cm, number of productive tillers (4.73) with high potassium doses, while Barnyard millet reached a maximum height of 119.13 cm, grain yield significantly increased from 1547 kg/ha without potassium to 2055 kg/ha with the highest potassium dose. Barnyard millet (achieving the highest gross return of Rs 61650/ha and a B: C ratio of 2.20 with the highest potassium dose. Conclusion: Application of potassium 20 kg/ha, along with the recommended dose of nitrogen and phosphorus, recorded 31.8% higher yield, greater tolerance to lodging, reduced pest and disease incidence and remunerative economics in millet cultivation.

Optimized nitrogen and potassium fertilizers application increases stem lodging resistance and grain yield of oil flax by enhancing lignin biosynthesis

The lodging issue is a significant factor that hinders the enhancement of oil flax production efficiency in northern China. Crop lodging or not, and lignin content in the stems are closely related, and how nitrogen fertilizer and potassium fertilization interaction regulate lignin biosynthesis in the stems of oil flax requires further in-depth study. Therefore, the research aims to enhance the lodging resistance and facilitate an increased yield of oil flax. We are examined the interaction of different nitrogen fertilizers (75, 150, and 225 kg N ha-1) and potassium fertilizers (60 and 90 kg K2O ha-1) on oil flax lignin metabolism, lodging resistance, and grain yield in 2022 and 2023 growing seasons. The results indicated that nitrogen and potassium fertilizer levels and their interaction treatments are facilitated lignin accumulation, achievement of lodging resistance and high yield. Compared to CK, the 75-150 kg N ha-1 in combination with 60 kg K2O ha-1 treatments significantly enhanced the enzyme activities (TAL, PAL, POD, and CAD) and the gene expressions (4CL1 and F5H3) for lignin syntheses, lignin content dramatically increased 29.63-43.30%, improved stem bending strength and lodging resistance index, and grain yield increased 23.27-32.34%. Correlation analysis indicated that nitrogen and potassium fertilizer positively regulated the relative enzyme activities and genes expression for lignin to facilitated lignin biosynthesis and accumulation, and enhanced stem bending strength and lodging resistance index. Positive correlations were found among the relative enzyme activities and gene expressions for lignin, lodging resistance and grain yield. To summarize, 75-150 kg N ha-1 in conjunction with 60 kg K2O ha-1 treatment was promoted to lignin biosynthesis and accumulation, enhanced the lodging resistance and grain yield of oil flax in the dryland farming region of central Gansu. Furthermore, it served as a technical guide for cultivating stress tolerance and high-yield oil flax in the dryland farming region.

Effect of Adding Potassium and Organic Fertilizers on the Soil NPK Content and the Productivity of maize (Zea mays L.)

Effect of Adding Potassium and Organic Fertilizers on the Soil NPK Content and the Productivity of maize (Zea mays L.)

Estimation of Electrical Conductivity (EC) of Arpa River Based Soil of Bilaspur Chhattisgarh

Abstract: This research explores the investigation and significance of electrical conductivity in the quality of agricultural soil. Soil electrical conductivity is an indirect measurement that is associated with several physical and chemical characteristics of soils. The electrical conductivity (EC) of the soil is directly correlated with the concentration of nutrients and inversely correlated with the soil depth. The soil electrical conductivity (EC) values are indicative of the salinity level in the soil. greater EC values correspond to greater salt concentrations in the soil, whereas lower EC values indicate lower salt concentrations. A total of six soil samples were collected from various points along the Arpa River and sent to the soil test laboratory for examination. All samples were analysed using conventional techniques. For this investigation, one of the crucial soil parameters that was taken into consideration is electrical conductivity (EC). The objective of this study is to assess agricultural land using electrical conductivity. The measured electrical conductivity ranges from 0.4 to 0.7 dS/m. The anticipated value is between 0 and 2 decisiemens per metre (dS/m). All soil samples exhibit a standard level of electrical conductivity. Soil electrical conductivity (EC) measurements and total dissolved solids (TDS) may be used to determine the necessary quantity of NPK (nitrogen, phosphorus, potassium) fertilisers

Optimizing Sweet Cherry Attributes through Magnesium and Potassium Fertilization

Plant nutrition through fertilizer application plays a crucial role in enhancing crop quality and yield, necessitating a balanced fertilization approach. Sweet cherry, esteemed as one of the most prized crops worldwide, was the focus of this three-year study spanning from 2019 to 2021, involving the sweet cherry cultivar Burlat. This study investigated the foliar application of magnesium (Mg) and potassium (K) to enhance fruit quality parameters. Different doses of Mg (250 g hL−1 and 125 g hL−1) and K (100 g hL−1 and 50 g hL−1) and a control treatment were administered to sweet cherry trees to assess their impact on fruit quality. At the commercial ripening stage, fruits from each treatment were harvested for comprehensive evaluation, including biometric and chromatic parameters, fruit firmness, routine parameters, sensory profile, and nutrient content analysis. Results from the study revealed notable enhancements in fruit weight and dimensions, particularly in the control treatment in 2020. Furthermore, Mg125 and Mg250 treatments exhibited improved color development and accelerated maturity by increasing the total soluble solids content while decreasing titratable acidity. Sensorial profiling indicated that Mg125 and Mg250 treatments intensified color intensity and sweet taste while mitigating sour taste perceptions. Conversely, potassium fertilization, especially the K50 treatment, led to increased fruit firmness and nutrient content. These findings offer valuable insights into optimizing sweet cherry production practices globally.

Updating soil organic carbon for wheat production with high yield and grain protein

Soil organic carbon (SOC) is crucial for mitigating global warming and significantly impacts crop production. While the relationship between SOC and wheat yield is well-documented, its effect on wheat grain protein content, which is essential for food security and human health, remains unclear. This study gathered management data from wheat farmers and collected plant and soil samples in the Huang-Huai winter wheat region, China’s primary wheat-growing area, from 2015 to 2022. Boundary line analysis was used to quantify the responses of wheat yield and protein content to variations in SOC. Our findings reveal that increases in SOC significantly enhance wheat yield and protein content. The highest yields, reaching up to 10,848 kg ha–1, and a maximum protein content of 17.3 % were observed in soils with SOC ranging from 7.8–18.1 g kg–1, and high-yielding, high-protein wheat exhibited higher spike numbers and grain weights and more efficient nutrient accumulation from soil or fertilizer to shoots. Optimizing SOC levels to produce high-yielding, high-protein wheat could substantially reduce nitrogen (N), phosphorus (P), and potassium (K) fertilizer use by 9.42×104, 0.70×104, and 3.66×104 Mg per year, decrease greenhouse gas emissions by 3.36 Mt CO2 eq and generate an economic benefit of 2.77 billion USD. In conclusion, our study expands the understanding of SOC’s role in crop production beyond crop yield, providing valuable insights for producing high-yielding, high-protein wheat.

Postponed Application of Phosphorus and Potassium Fertilizers Mitigates the Damage of Late Spring Coldness by Improving Winter Wheat Root Physiology.

Late spring coldness (LSC) is the main limiting factor threatening wheat yield and quality stability. Optimal nutrient management is beneficial in mitigating the harms of LSC by improving wheat root physiology. This study proposed a nutrient management strategy that postponed the application of phosphorus (P) and potassium (K), effectively strengthening wheat's defense against LSC. This experiment used the winter cultivar "Yannong19" (YN 19) as plant material for two consecutive years (2021-2022 and 2022-2023). Two fertilizer treatments were used: traditional P and K fertilizers application (R1: base fertilizer: jointing fertilizer = 10:0) and postponed P and K fertilizers application (R2: base fertilizer: jointing fertilizer = 5:5); wheat plants at the anther connective formation stage shifted to temperature-controlled phytotrons for normal (T0, 11 °C/4 h) and low temperatures (T1, 4 °C/4 h; T2, -4 °C/4 h) as treatments of LSC. The results showed that under low temperature (LT) treatment, compared with R1, the R2 treatment increased the concentrations of osmotic adjustment substances (soluble sugars and soluble protein contents by 6.2-8.7% and 3.0-8.9%), enhanced activities of antioxidant enzymes (superoxide dismutase, peroxidase and catalase activities by 2.2-9.1%, 6.2-9.7% and 4.2-8.4%), balanced the hormone concentrations (increased IAA and GA3 contents by 2.8-17.5% and 10.4-14.1% and decreased ABA contents by 7.2-14.3%), and reduced the toxicity (malondialdehyde, hydrogen peroxide content and O2·- production rate by 5.7-12.4%, 17.7-22.8% and 19.1-19.1%) of the cellular membranes. Furthermore, the wheat root physiology in R2 significantly improved as the root surface area and dry weight increased by 5.0-6.6% and 4.7-6.6%, and P and K accumulation increased by 7.4-11.3% and 12.2-15.4% compared to R1, respectively. Overall, the postponed application of P and K fertilizers enhanced the physiological function of the root system, maintained root morphology, and promoted the accumulation of wheat nutrients under the stress of LSC.

Improved Straw Decomposition Products Promote Peanut Growth by Changing Soil Chemical Properties and Microbial Diversity

The ameliorative effects of straw decomposition products on soil acidification have been extensively studied. However, the impact of chemically treated straw decomposition products on crop productivity and the underlying microbial mechanisms remain unclear. This study aimed to investigate the effects of two dosages of Ca(OH)2-treated straw decomposition products of peanuts on red soil acidity, fertility, and bacterial and fungal diversity through a pot experiment. The pot experiment included four treatments: chemical nitrogen, phosphorus, and potassium (NPK) fertilization alone (CK), NPK chemical fertilization combined with peanut straw decomposition products (PS), NPK chemical fertilization combined with 4% Ca(OH)2-treated peanut straw decomposition products (PS4Ca), and NPK chemical fertilization combined with 8% Ca(OH)2-treated straw decomposition products (PS8Ca). High-throughput sequencing was performed to investigate the effects of these treatments on soil microbial diversity. The treatments with PS, PS4Ca, and PS8Ca significantly increased soil pH, exchangeable base cations, and nutrient content, whereas they decreased the exchangeable acid, especially exchangeable aluminum. The peanut growth improved substantially with the application of straw decomposition products. Specifically, PS4Ca significantly increased the Shannon and Richness indices of fungi. The principal coordinate analysis showed that the soil microbial communities in the straw decomposition product treatments were significantly different from CK. Linear discriminant analysis effect size identified unique bacteria and fungi between treatments. The Mantel test indicated that exchangeable base cations and pH were significantly positively correlated with bacterial communities, whereas available potassium was positively correlated with fungal communities. The partial least squares path modeling revealed that the bacterial communities positively and directly affected all peanut agronomic traits. In contrast, the fungal communities had a negative and direct effect only on peanut 100-pod weight. Therefore, adding Ca(OH)2-treated straw decomposition products could effectively improve crop productivity by alleviating soil acidification, increasing soil nutrients, and subsequently changing microorganisms.

The Crop Phosphorus Uptake, Use Efficiency, and Budget under Long-Term Manure and Fertilizer Application in a Rice–Wheat Planting System

Little is known about the effect of the long-term application of organic and inorganic fertilizers on P-use efficiency, P budget, and the residual effect of P fertilizer. To clarify the effect of different fertilization on soil P balance in a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) rotation system is helpful to promote the sustainable development of agriculture. Thus, a thirty-five-year fertilizer experiment was conducted with eight treatments, including an unfertilized control (CK); chemical nitrogen (N), phosphorus (P), and potassium (K) fertilizers; and organic manure (M) either alone or in combination treatments (N, NP, NPK, M, MN, MNP, and MNPK). The results indicated that crop yields and P uptake were higher in the combined application of manure and chemical fertilizer treatments than in the manure or chemical fertilizer alone treatments. Soil P budget indicated a 23.4–55.4 kg P ha−1 yr−1 surplus in the organic combined with or without mineral fertilizer treatments, but the soil P budget indicated a 20.0 and 21.9 kg P ha−1 yr−1 deficit in the control and N treatments. The proportion of residual fertilizer P converted to soil available P in NP, NPK, M, MN, MNP, and MNPK treatments was 4.5%, 4.8%, 19.1%, 19.0%, 11.5%, and 13.3%, respectively, over a 35-year period. Furthermore, according to the higher P content and crop uptake in organic manure treatment compared with chemical P fertilizer alone, an organic addition could effectively reduce the use of chemical fertilizer and become an effective way of sustainable development in practice. Therefore, the combined application of organic and inorganic fertilizer will be a practical method to increase crop yields and soil P status in a rice–wheat planting system.

Investigation of the Potential of Potassium-Containing Additives Based on Mineral Raw Materials and Industrial Waste on the Quality and Yield of Potatoes

The soils of the Komi Republic are characterized as sod-podzolic. It is known that agricultural cultivation of such soils requires the introduction of various mineral and organic fertilizers, liming, deepening of the arable layer, and erosion control. The soils of the region are depleted of potassium, part of which is carried out by agricultural crops, therefore potash fertilizers, where potassium is in an affordable form, are among the most in demand in agriculture. This paper presents the results of a study of the material composition and textural characteristics of analcime-containing siltstones, potassium alkaline syenites and bark ash and their possible use as potash additives to improve potato productivity.

Nitrogen fertilization and soil nitrogen cycling: Unraveling the links among multiple environmental factors, functional genes, and transformation rates

Anthropogenic nitrogen (N) inputs substantially influence the N cycle in agricultural ecosystems. However, the potential links among various environmental factors, nitrogen functional genes, and transformation rates under N fertilization remain poorly understood. Here, we conducted a five-year field experiment and collected 54 soil samples from three 0–4 m boreholes across different treatments: control, N-addition (nitrogen fertilizer) and NPK-addition (combined application of nitrogen, phosphorus and potassium fertilizers) treatments. Our results revealed pronounced variations in soil physiochemical parameters, metal concentrations and antibiotic levels under both N and NPK treatments. These alternations induced significant shifts in bacterial and fungal communities, altered NFG abundance and composition, and greatly enhanced rates of nitrate reduction processes. Notably, nutrients, antibiotics and bacteria exerted a more pronounced influence on NFGs and nitrate reduction under N treatment, whereas nutrients, metals, bacteria and fungi had a significant impact under NPK treatment. Furthermore, we established multidimensional correlations between nitrate reduction gene profiles and the activity rates under N and NPK treatments, contrasting with the absence of significant relationships in the control treatment. These findings shed light on the intricate relationships between microbial genetics and ecosystem functions in agricultural ecosystem, which is of significance for predicting and managing metabolic processes effectively.

Quantitative records of paleotemperature in Qarhan Salt Lake, Qaidam Basin and its relationship with potassium deposits

Qarhan Salt Lake, located in the Qaidam Basin on the Qinghai-Tibet Plateau in northwestern China, is the largest potash production base in China. The main potash deposit in Qarhan Salt Lake is a comprehensive deposit in which the liquid potassium resources dominated by potassium-rich and lithium-rich brine coexist with the low-grade solid potassium salt deposit composed of solid potash minerals (polyhalite, carnallite, sylvite). Polyhalite is one of the representative potassium minerals, widely distributed in the Bieletan area of Qarhan Salt Lake, coexisting with halite, and its deposition indicates that the paleo-temperature of brine in this area once fluctuated obviously. Twenty core samples from two boreholes in the Bieletan area of the Qarhan Salt Lake were subjected to fluid inclusions thermometry, and homogenization temperatures reflecting the brine temperatures during the precipitation of evaporite minerals in the Salt Lake were obtained, ranging from 12.4 to 28.9 °C and 9.2 to 19.8 °C, respectively. By scanning electron microscopy, acicular polyhalite and pompom-like aggregate of polyhalite have been identified in the sampling layer, indicating that evaporite deposition have reached the stage of potassium salt deposition. The temperature fluctuations of the fluid inclusions and the elemental chemical data are compared vertically, and the sections with significant temperature fluctuations are close to the layers where polyhalite were deposited. It shows that the paleo-temperature fluctuation impact the sedimentary environment of brine, and then affected the polyhalite deposition of Qarhan Salt Lake.