Search Results (2,470)

Salinization is a growing global problem, particularly in arid and semi-arid areas, where salt concentration interferes with the soil structure, altering natural cycling, decreasing agricultural outputs, and threatening food security. Although many soil amendments have been studied, there is still a limited understanding of their interaction with soil after mixture application and the geochemical processes and long-term sustainability that govern their effects. To address this knowledge gap, this review elucidated the effectiveness and sustainability of soil amendments, biochar, humic substances, and mineral additives in restoring saline and sodic soils of arid and semi-arid region to explore the geochemical processes that underlie their impact. A systematic search of 174 peer-reviewed studies was conducted across multiple databases (Web of Science, Google Scholar, and Scopus) using relevant keywords and the findings were converted into quantitative values to evaluate the effects of biochar, gypsum, zeolite, and humic substances on key soil properties. Biochar significantly improved cation exchange capacity, nutrient retention, microbial activity, and water retention by enhancing soil porosity and capillarity, thereby increasing plant-available water. Gypsum improved phosphorus availability, while zeolite facilitated the removal of sodium and supported microbial activity. Humic substances enhanced soil porosity, water retention, and aggregate stability. When applied together, these amendments improved soil health by regulating salinity, enhancing nutrient cycling, while also stabilizing soil conditions and ensuring long-term sustainability through improved geochemical balance and reduced environmental impacts. The findings highlight the critical role of multi-functional amendments in promoting climate-resilient agriculture and long-term soil health restoration in saline-degraded regions. Further research and field implementation are crucial to optimize their effectiveness and ensure sustainable soil management across diverse agricultural environments. Full article

To investigate the effects of different Trichosanthes kirilowii Maxim. varieties on leaf nutrients, soil nutrients, and microbial community composition, this study selected Yuelou No. 3 and Huiji No. 2, two major cultivars from the primary production area of Shishou City. The two varieties were cultivated at different locations under standardized agronomic management practices, and a systematic comparative analysis was carried out over a 10-month sampling period from March to December 2024. The analysis encompassed their leaf nutrients (total nitrogen, total phosphorus, total potassium, and relative chlorophyll content), soil nutrients (organic matter, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium), and microbial community characteristics. The results revealed significant varietal differences in leaf nutrient content: the average total phosphorus content of Yuelou No. 3 (0.44%) was higher than that of Huiji No. 2 (0.39%), while Huiji No. 2 exhibited higher total nitrogen (3.73%), total potassium (3.86%), and SPAD (44.72). Leaf nutrient content in both varieties followed a pattern of nitrogen > potassium > phosphorus, with peak phosphorus and potassium demand occurring earlier in Yuelou No. 3. Additionally, Yuelou No. 3 contained higher organic matter (12.73 g/kg) and alkali-hydrolyzable nitrogen (103.02 mg/kg), while Huiji No. 2 showed enhanced soil pH (7.02), available phosphorus (6.96 mg/kg), and available potassium (180.00 mg/kg). Soil available nutrient dynamics displayed a pattern of slow change during the early stage, a rapid increase during the middle stage, and stabilization in the later stage. Microbial analysis revealed no significant differences in alpha diversity between the two varieties, although Yuelou No. 3 showed marginally higher diversity indices during early to mid-growth stages. In contrast, beta diversity showed significant separation in PCoA space. Proteobacteria, Acidobacteria, and Ascomycota were the dominant microbial phyla. Dominant genera included Kaistobacter, Mortierella, and Neocosmospora, among others, with variety-specific relative abundances. Redundancy analysis further supported the variety-specific influence of soil physicochemical properties on microbial community structure, with available phosphorus, available potassium, and alkali-hydrolyzable nitrogen identified as key factors shaping community composition. This study provides a theoretical basis for understanding the impact of different Trichosanthes kirilowii Maxim. varieties on soil–plant–microbe interactions and suggests potential directions for future research on fertilization and management strategies tailored to varietal differences. Full article

Aiming at the problems of tree vigor decline and unstable fruit quality caused by soil impoverishment and easy nutrient loss in the Ziziphus jujuba Mill. ‘Huizao’ (Huizao) producing areas of southern Xinjiang, the application effect of bag-controlled slow-release fertilizer (BCSRF) in this region remains unclear. In this study, a field experiment was conducted with four fertilization concentration gradients, including CK (0 kg/ha), T1 (22 kg/ha), T2 (44 kg/ha), and T3 (66 kg/ha), to investigate the effects of BCSRF on soil nutrient dynamics and plant growth, as well as the fruit yield and quality of Huizao. The results showed that BCSRF could effectively maintain the supply levels of soil alkali-hydrolysable nitrogen, available phosphorus, and available potassium during key growth periods, among which the T3 treatment exhibited the most significant effect. This treatment not only significantly increased the yield per plant of Huizao by 39.34% compared with the control, but also markedly enhanced the contents of the endogenous substance, including soluble sugar and cyclic adenosine monophosphate. This study confirms that under the condition of sandy loam soil in southern Xinjiang, a single basal application of an appropriate amount of BCSRF can achieve continuous nutrient supply, simultaneously improve soil fertility and fruit quality, providing a theoretical basis and technical guidance for simplified and efficient fertilization in local jujube orchards. Full article

Carbon (C) is crucial for nutrient cycling and the assembly of microbial populations in the soil. However, it is still unclear how the C-source utilization characteristics of microbes in distinct types of soils respond to changes in soil phosphorus (P) activity. This study investigated how the addition of different C sources with different decomposition rates (glucose, hemicellulose, and lignin) affects P transformation in two distinct agricultural soils (i.e., Mollisols and Fluvo-aquic soil). Results revealed that the short-term glucose addition to soil induced rapid acidification and microbial biomass accumulation, thereby significantly increasing labile P (NaHCO₃-P_i, NaOH-P_o) content in Fluvo-aquic soil. Lignin amendment promoted gradual HCl-P release in Mollisols, reflecting differential microbial utilization strategies. Glucose stimulated phosphatase activity (2.5–3.0× control) and phoD gene abundance (4.8×) in Fluvo-aquic soil in the early stage, favoring the growth of Pseudomonas and Burkholderia, whereas lignin sustained the mineralization of fungal-associated P in Mollisols (1.8–2.3× phosphatase activity) by enhancing the abundance of Streptomyces and Bradyrhizobium. Soil type dictated P mobilization efficiency. The Fluvo-aquic soil exhibited rapid but transient P release via bacterial dominance, while Mollisols retained slower yet persistent P availability through specialized microbial consortia. Notably, glucose enhanced organic P mineralization by stimulating C decomposition by microbes, particularly in C-rich Mollisols. Lignin increased P availability in Mollisols via Fe/Al-P desorption. However, in Fluvo-aquic soil, lignin reduced the availability of P through microbial immobilization. These findings highlight that C source degradability and soil properties interactively govern microbial-mediated P cycling in soil. Therefore, organic amendments in contrasting agroecosystems need to be optimized. Full article

Background/Objectives: Ash made from juniper trees and added to cornmeal-based dishes may have provided calcium (Ca) to traditional Indigenous diets. Few studies have quantified the mineral content of juniper ash, including its Ca content. The objective of this study was to determine whether juniper ash could serve as a safe source of non-dairy Ca in an intervention study. Methods: Branches from two varieties of Juniper (Rocky Mountain Juniper, or Juniperus scopulorum and Eastern Red Cedar, or Juniperus virginiana) were harvested and burned to ash in a laboratory setting. Juniper ash from the southwestern U.S. available for retail purchase was used for comparison. All samples were tested for content of 10 nutritive elements (Ca, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, selenium, and zinc) and 20 potentially toxic elements (silver, aluminum, arsenic, barium, beryllium, cadmium, cobalt, chromium, mercury, lithium, molybdenum, nickel, lead, antimony, tin, strontium, thallium, uranium, and vanadium) as well as n = 576 pesticide residues. Results: All samples contained both nutritive and potentially toxic elements. Each teaspoon of ash contained an average of 445 ± 141 mg Ca. However, the samples also contained lead in amounts ranging from 1.09 ppm to 15 ppm. Conclusions: Information on the nutritive and potentially toxic elemental content of juniper ash and how it may interact within a food matrix is insufficient to determine its safety as a Ca source. Further investigation is needed on the bioavailability of calcium oxide and its interaction with other dietary components to clarify the potential role of juniper ash in contemporary food patterns. Full article

Municipal wastewater contains high amounts of nitrogen (N) and phosphorus (P), as well as other compounds that are harmful to the environment; however, it can also be used as an algae growth medium. In this study locally (Lithuania) isolated algae Scenedesmus quadricauda were cultivated in local (Vilnius city) municipal wastewater. Data show that Scenedesmus algae can be grown in municipal wastewater as successfully as in Bold’s basal medium for 14 days. Algae cultivation significantly reduced the concentration of organic nitrogen forms and phosphate levels. The nitrogen concentration in wastewater after cultivation was reduced to 8 mg N L⁻¹ (up to 89% reduction in total nitrogen concentration). Phosphorus concentration was reduced to 5.4 mg P L⁻¹ (up to 86%). The analysis indicates that the optimal temperature for S. quadricauda cultivation is 25 °C; temperatures higher or lower than this result in a reduction in algal biomass. A higher amount of light leads to higher yields. No statistically significant differences were found comparing cultivation in BB medium and wastewater under different conditions. The analysis showed that the main factors influencing algae biochemical composition were final total nitrogen concentration and available total nitrogen amount per unit of algae biomass produced, as well as molar N:P ratios. Algae biomass cultivated in wastewater contained a consistent lipid concentration (on average 14.94 ± 2.38%), a lower final total nitrogen concentration, and overall lower total nitrogen availability, leading to higher carbohydrate concentrations (up to 51.10%) and a lower protein content (down to 15.52%). Algae biomass that was cultivated in the BB medium biochemical composition was not dependent on environmental factors and remained consistent (on average 22.89 ± 3.85% carbohydrate, 39.32 ± 3.89% protein, and 13.99 ± 2.21% lipid). Full article

In the context of climate change, alterations to the physico-chemical properties of soils, particularly in Mediterranean regions, are a growing source of preoccupation. This study analyzes the ecological plasticity and biochemical adaptability of Thymus saturejoides to changes in soil physico-chemical properties in four contrasting environments in Morocco’s western High Atlas (TM: Tidili msfioua, SF: Sti fadma, TA: Taouss, TN: Tisi ntast). It highlights the influence of edaphic characteristics on the physiology and metabolic composition of the species, revealing marked soil heterogeneity between sites. The results for the physico-chemical characteristics of the soil revealed marked heterogeneity between sites. Tisi ntast and Taouss soils had the highest values in terms of electrical conductivity (TN: 0.25 dS/m, TA: 0.18 dS/m), available phosphorus (TN: 18.58 ppm and TA: 26.06 ppm) and total nitrogen (TN: 0.27% and TA: 0.14%), associated with a silty texture, suggesting higher fertility. Conversely, the soil at the TM site was characterized by low total nitrogen content (0.09%), a high C/N ratio (24.4) and a sandy-silty texture, indicating more constraining conditions for plant growth. From a physiological standpoint, plants from the TA site had the lowest chlorophyll levels (17.10 mg g⁻¹FW), while those from the TN site showed the highest levels (31.08 mg g⁻¹FW), accompanied by increased protein content and reduced polyphenol oxidase and peroxidase. In contrast, TM plants showed significant accumulation of total soluble sugars (30 mg g⁻¹FW), proline (22.53 µmol g⁻¹FW), hydrogen peroxide (1.33 nmol g⁻¹FW) and malondialdehyde (62.97 nmol g⁻¹FW), reflecting strong activation of oxidative stress responses. On the other hand, plants from the TA site displayed significantly lower levels of these stress markers compared to other sites, suggesting greater physiological resilience. These results highlight the pivotal role of interactions between edaphic and environmental conditions in modulating plant physiological and biochemical responses, shedding light on the ecological adaptation mechanisms of plant species to the contrasting ecosystems of the Western High Atlas. Full article

To investigate the impacts of the continuous application of urban sewage sludge on heavy metal pollution risks in wine grape orchards, this study conducted a five-year field plot experiment using wine grapes as the test crop. The experimental design included three sludge application rates and a control without sludge application. Soil physicochemical properties, the single-factor and integrated pollution indices (PI and NIPI) of heavy metals, potential ecological risk indices (EI and RI), and the safe application duration of sludge were analyzed. The results suggest that sludge application significantly increased soil organic matter, total nitrogen, total phosphorus, and available phosphorus by 39.99–46.56%, 59.37–73.69%, 83.57–143.19%, and 88.79%, respectively, while reducing soil bulk density by 8.70–27.92%. The PI and EI of Cd exhibited significant linear increases with the duration of sludge application, with annual increments of 0.010 and 0.31, respectively. Hg was influenced by both the application rates and duration, with annual increments of 0.013 and 0.52 for the PI and EI, respectively. These two elements collectively drove overall increases of 7.31–24.96% in NIPI and 32.51–59.90% in RI, with mean annual increases of 0.0064 and 0.84, respectively. In contrast, Cr, Pb, and As showed no significant changes. Based on the calculated environmental capacities of Cd and Hg, the safe application durations were estimated to be 46.99–126.93 and 48.58–131.21 years, respectively. These results demonstrate that under the current application intensity, sludge can improve soil fertility in the short term with controllable ecological risks. However, considering their potential environmental risks, the continuous accumulation of Cd and Hg necessitates vigilance. Full article

The introduction of understory vegetation can increase species diversity and potential productivity in forest ecosystems, which is considered a viable solution to the global problem of declining soil quality caused by deteriorating climatic conditions and human activities. The forest management model that achieves economic and ecological benefits by introducing legumes is widely used. However, there have been rare studies on the effects of introducing legumes under Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations on soil nutrient content and microbial diversity. In this study, we investigated the soil chemical properties, microbial diversity, and enzymatic activities in Chinese fir plantations introduced with Spatholobus suberectus (SRS), Dalbergia balansae (DRS), both species (BS), and in a monoculture plantation (CK). As indicated by the results, soil pH, total phosphorus (TP), available phosphorus (AP), available potassium (AK), urease activities, and the ratios of C:P and N:P decreased in SRS, DRS, and BS treatments, whereas soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), phosphatase, and sucrase activities increased. The decrease in soil pH and the effects of Chytridiomycota and Glomeromycota elevated phosphatase activity. Accordingly, the mineralization rate of soil phosphorus increased. This increase enhanced phosphorus availability and the risk of loss, resulting in the depletion of soil phosphorus and the inhibition of urease activity. The findings of this study reveal that the introduction of legumes effectively improves the soil microbial community and nitrogen accumulation in Chinese fir plantations while resulting in phosphorus depletion, highlighting the need for balanced nutrient management. Full article

Bacterial communities in the rhizosphere and endorhizosphere of plants show distinct composition, function, and ecological roles during adaptation to diverse habitats. This study examines how rhizosphere and endophytic microbes associated with Aeluropus sinensis—a salt-excreting halophyte—contribute to its salt tolerance across saline-alkali environments. Microbial diversity and composition were analyzed via 16S rRNA gene amplicon sequencing. Soil physicochemical properties were measured to evaluate environmental effects. Linear regression assessed microbial–environment relationships, and co-occurrence networks identified key taxa and their adaptive strategies along environmental gradients. Soil salinity significantly affected rhizosphere bacterial diversity, with moderate levels increasing richness. Proteobacteria dominated both root and rhizosphere microbiomes across habitats. The endorhizosphere community strongly correlated with soil nutrients such as available phosphorus (AP) and total nitrogen (TN). Co-occurrence analysis reveals that chemoheterotrophic microbes in the A. sinensis rhizosphere employ distinct adaptive strategies across gradients, and ammonia-oxidizing bacteria (AOB) may support nitrogen cycling in the Yellow River Delta saline–alkaline ecosystem. This study underscores microbial adaptability in salt-tolerant grasses, demonstrating that comparing rhizosphere and endorhizosphere microbiomes in Poaceae under stress improves understanding of microbial functions in harsh environments. Full article

Keeping the levels of soil major nutrients (total nitrogen, TN; available phosphorous, AP; and available potassium, AK) in optimum condition is important to achieve the goals of precision agriculture systems. To address the issues of slow speed and low accuracy in soil nutrient detection, this study developed a prediction model for soil major nutrients content based on an improved Extreme Learning Machine (ELM) algorithm. This model utilizes a soil major nutrients detection system integrating pyrolysis and artificial olfaction. First, the Bootstrap Aggregating (Bagging) ensemble strategy was introduced during the model integration phase to effectively reduce prediction variance through multi-submodel fusion. Second, Generative Adversarial Networks (GAN) were employed for sample augmentation, enhancing the diversity and representativeness of the dataset. Subsequently, a multi-scale convolutional and Efficient Lightweight Attention Network (ELA-Net) was embedded in the feature mapping layer to strengthen the representation capability of soil gas features. Finally, adaptive hyperparameter tuning was achieved using the Adaptive Chaotic Bald Eagle Optimization Algorithm (ACBOA) to enhance the model’s generalization capability. Results demonstrate that this model achieves varying degrees of performance improvement in predicting total nitrogen (R² = 0.894), available phosphorus (R² = 0.728), and available potassium (R² = 0.706). Overall prediction accuracy surpasses traditional models by 8–12%, with significant reductions in both RMSE and MAE. These results demonstrate that the method can rapidly, accurately, and non-destructively estimate key soil nutrients, providing theoretical guidance and practical support for field fertilization, soil fertility assessment, and on-site decision-making in precision agriculture. Full article

Phosphorus (P) is an essential nutrient in plant development, but its availability in the soil is often limited due to chemical fixation and poor solubility. This study presents the development, characterization and evaluation of a novel granular bioinoculant formulated with Aspergillus tubingensis (P-solubilizing) and Trichoderma virens (P-mineralizing) using clinoptilolite (CZ) as a carrier to improve P bioavailability. The formulation process included the evaluation of the proposed components, the standardization of conidia production in different media cultures and conditions, the elaboration and characterization of the bioinoculant and its evaluation in plants. In this study, in vitro analysis demonstrated the synergistic effect of the components, showing that in all treatments with dual inoculation and CZ, the amount of soluble phosphorus (SP) was higher than in their counterparts (from 27.8 to 36.8 mg·L⁻¹). A concentration greater than 1 × 10⁹ CFU·mL⁻¹ was obtained by standardizing the production of conidia in different media (PDA, V8-Agar and Molasses Agar), which were then used to produce granular batches containing at least 2 × 10⁷ CFU·g⁻¹. Furthermore, the size (88% of the granules measured <4.5 mm), purity (<2 CFU·g⁻¹ in 10⁻⁴ dilution), and moisture content of the prototype granules (3.3–3.8%) were confirmed to be within established international quality parameters. Plant evaluations in chili and tomato demonstrated the formulation efficacy, showing an increase in both soluble and foliar P content (with at least 30% more than controls), alongside improvements in all parameters evaluated that are related to plant growth promotion (with at least 15% more growth than controls). The development of this formulation prototype represents a focused effort toward process standardization and optimization required to validate developed formulations, thus promoting the advancement of applied biotechnology. Full article

Nutrient additions including nitrogen (N) and phosphorus (P) are widely considered as an important strategy for enhancing grassland productivity. However, the effects of these nutrients additions on soil nitrous oxide (N₂O) emissions and the underlying mechanisms remain debated. We conducted a two-year field experiment in an alpine grassland on Kunlun Mountain in northwestern China to assess the effects of N and P additions on N₂O emissions, in relation with nitrifying enzyme activity (NEA), denitrifying enzyme activity (DEA), and key functional genes abundance responsible for nitrification (amoA and Nitrobacter-like nxrA) and denitrification (narG, nirS, nirK and nosZ). Compared to the Control without nutrient addition (CK), N addition alone substantially increased cumulative N₂O emission (ƩN₂O) by 2.0 times. In contrast, P addition or combined N and P (N+P) addition did not significantly affect ƩN₂O, though both treatments significantly increased plant aboveground biomass. Such results indicate that P addition may mitigate N-induced N₂O emission, likely by reducing soil N availability through enhanced plant and microbial N uptake. Compared to CK, N or N+P addition significantly elevated NEA but did not affect DEA. Structural equation modeling (SEM) indicated that NEA was directly influenced by the gene abundances of ammonia-oxidizing bacteria (AOB) and Nitrobacter-like nxrA but not by ammonia-oxidizing archaea (AOA). However, SEM also revealed that soil environmental variables including soil temperature, pH, and water-filled pore space (WFPS) had a stronger direct influence on N₂O emissions than the abundances of nitrifiers. These results demonstrate that soil environmental conditions play a more significant role than functional gene abundances in regulating N₂O emissions following N and P additions in semi-arid alpine grasslands. This study highlights that the N+P application can potentially decrease N₂O emissions than N addition alone, while increasing productivity in the alpine grassland ecosystems. Full article

Soil fertility plays a crucial role in crop productivity, particularly in cocoa cultivation, which is highly dependent on soil quality that directly influences both productivity and sustainability. Understanding how to achieve and maintain soil fertility on cocoa farms is fundamental to sustaining higher yields. Cocoa production in Ghana and Togo remains low, at 350–600 kg/ha, compared to the potential yield of over 1–3 tons per hectare. Given the growing demand for cocoa and limited arable land, adequate soil nutrients are essential to optimise productivity. Soil fertility indices (SFIs) have been widely used as soil metrics by integrating multiple physical, chemical, and biological soil properties. In this study, standard analytical methods were employed to evaluate the SFI through laboratory analyses of 49 surface soil samples collected at a depth of 0–30 cm with an auger. Eleven soil chemical indicators were analysed: pH (water), organic matter (OM), potassium (K), calcium (Ca), magnesium (Mg), available phosphorus (P), total nitrogen (N), cation exchange capacity (CEC), electrical conductivity (EC), and carbon-to-nitrogen ratio (C/N). Principal component analysis, followed by normalisation, was used to select a minimum dataset, which was then integrated into an additive SFI. Results indicated that N, Ca, Mg, CEC, and pH were within the optimal range for most surveyed locations (96%, 94%, 92%, 73%, and 63%, respectively), while OM and C/N were within the optimal range in approximately half of the study area. Available P, K, and C/N were highly deficient in 100%, 67%, and 96% of surveyed locations, respectively. Soil fertility varied significantly among locations (p = 0.007) and was generally low, ranging from 0.15 to 0.66. Only 20% of the soils in the study area were classified as adequately fertile for cocoa cultivation. Therefore, it is necessary to restore soil nutrient balance, especially the critically low levels of K and P, through appropriate management practices that improve fertility over time and help close the yield gap. Full article

The vulnerability of reservoirs in Mediterranean regions to eutrophication is attributable to two key factors: strong seasonal hydrological variability and intensive agricultural activity. The present study evaluated the trophic state of 47 reservoirs in the Ebro Basin in Spain using two complementary approaches: the Organisation for Economic Co-operation and Development (OECD) classification system and the criteria set out in Royal Decree (RD) 47/2022. Chlorophyll-a, total phosphorus and transparency data were monitored from 2023 to 2024. While most of reservoirs were classified as oligotrophic to mesotrophic under the OECD thresholds, the RD 47/2022 identified 87% as being at risk of eutrophication. A significant variation in transparency was observed among the different reservoir types (p < 0.05), with high-altitude systems showing higher levels of water transparency. However, chlorophyll-a and total phosphorus had a significant spatial variability, exhibiting only modest correlations. Chlorophyll-a was weakly but significantly correlated to transparency (r = −0.21), while total phosphorus was not significantly associated with either variable, suggesting a decoupling between nutrient availability and phytoplankton biomass. The observed discrepancy between the two classification frameworks is indicative of divergent conceptual approaches (ecological condition versus management risk). It underscores the requirement for integrated monitoring that incorporates chemical, biological and catchment-scale indicators. These findings offer new insight into the trophic dynamics of Mediterranean reservoirs and highlights the importance of adapting regulatory assessment methods to region-specific climatic and hydrological contexts. Full article