Search Results (127)

Vacuum degassing (VD) is a critical refining step in electric arc furnace (EAF) steelmaking for producing clean steel with reduced nitrogen and hydrogen content. This study develops an Effective Equilibrium Reaction Zone (EERZ) model focused on denitrogenation (de-N) by simulating interfacial reactions at the bubble–steel interface (Z1). The model incorporates key process parameters such as argon flow rate, vacuum pressure, and initial nitrogen and sulfur concentrations. A robust empirical correlation was established between de-N efficiency and the mass of Z1, reducing prediction time from a day to under a minute. Additionally, the model was further improved by incorporating a dynamic surface exposure zone (Z_eye) to account for transient ladle eye effects on nitrogen removal under deep vacuum (<10 torr), validated using synchronized plant trials and Python-based video analysis. The integrated approach—combining thermodynamic-kinetic modeling, plant validation, and image-based diagnostics—provides a robust framework for optimizing VD control and enhancing nitrogen removal control in EAF-based steelmaking. Full article

Dutch elm disease is one of the most devastating plant diseases, primarily spread through bark beetles. Scolytus scolytus is a key vector of this disease. In this study, distribution data of S. scolytus were collected and filtered. Combined with environmental and climatic variables, an ensemble model was developed using the Biomod2 platform to predict its potential geographical distribution in China. The selection of climate variables was critical for accurate prediction. Eight bioclimatic factors with high importance were selected from 19 candidate variables. Among these, the three most important factors are the minimum temperature of the coldest month (bio6), precipitation seasonality (bio15), and precipitation in the driest quarter (bio17). Under current climate conditions, suitable habitats for S. scolytus are mainly located in the temperate regions between 30° and 60° N latitude. These include parts of Europe, East Asia, eastern and northwestern North America, and southern and northeastern South America. In China, the low-suitability area was estimated at 37,883.39 km², and the medium-suitability area at 251.14 km². No high-suitability regions were identified. However, low-suitability zones were widespread across multiple provinces. Under future climate scenarios, low-suitability areas are still projected across China. Medium-suitability areas are expected to increase under SSP370 and SSP585, particularly along the eastern coastal regions, peaking between 2041 and 2060. High-suitability zones may also emerge under these two scenarios, again concentrated in coastal areas. These findings provide a theoretical basis for entry quarantine measures and early warning systems aimed at controlling the spread of S. scolytus in China. Full article

Nitrogen (N) critically regulates wheat growth and grain quality, yet the molecular mechanisms underlying foliar nitrogen application remain unclear. This study evaluated the effects of foliar nitrogen application (12.25 kg ha⁻¹) on the growth, grain yield, and quality of spring wheat, as well as its molecular mechanisms. The results indicated that N was absorbed within 3 h post-application, with leaf nitrogen concentration peaking at 12 h. The N treatment increased whole-plant dry matter accumulation and grain protein content by 11.34% and 6.8%, respectively. Amino acid content peaked 24 h post-application, increasing by 25.3% compared to the control. RNA-sequencing analysis identified 4559 and 3455 differentially expressed genes at 3 h and 24 h after urea treatment, respectively, these DEGs being primarily involved in nitrogen metabolism, photosynthetic carbon fixation, amino acid biosynthesis, antioxidant systems, and nucleotide biosynthesis. Notably, the plastidic glutamine synthetase gene (GS2) is crucial in the initial phase of urea application (3 h post-treatment). The pronounced downregulation of GS2 initiates a reconfiguration of nitrogen assimilation pathways. This downregulation impedes glutamine synthesis, resulting in a transient accumulation of free ammonia. In response to ammonia toxicity, the leaves promptly activate the GDH (glutamate dehydrogenase) pathway to facilitate the temporary translocation of ammonium. This compensatory mechanism suggests that GS2 downregulation may be a key switch that redirects nitrogen metabolism from the GS/GOGAT cycle to the GDH bypass. Additionally, the upregulation of the purine and pyrimidine metabolic routes channels nitrogen resources towards nucleic acid synthesis, and thereby supporting growth. Amino acids are then transported to the seeds, culminating in enhanced seed protein content. This research elucidates the molecular mechanisms underlying the foliar response to urea application, offering significant insights for further investigation. Full article

Microplastic pollution threatens coastal wetland ecosystems, yet its impacts on the dominant plant species and soil properties remain poorly understood. We investigated the effects of four microplastic types (PP, PE, PS, PET) at three concentrations (0.1%, 0.5%, 1% w/w) on Scirpus mariqueter, a keystone species in the coastal wetlands of China, and the associated soil physicochemical properties. In a controlled pot experiment, microplastics significantly altered the plant biomass, vegetative traits, and reproductive strategies, with type-specific and concentration-dependent responses. PET and PE strongly suppressed the belowground and total biomass (p < 0.05), with reductions in the belowground biomass of 42.87% and 44.13%, respectively, at a 0.1% concentration. PP promoted seed production, particularly increasing the seed number by 25.23% at a 0.1% concentration (p < 0.05). The soil NH₄⁺-N, moisture, and EC were key mediators, with NH₄⁺-N declines linked to biomass reductions via nitrogen limitation. The Spearman correlations confirmed strong associations between the plant traits and soil properties, particularly nitrogen forms. These findings reveal that microplastics disrupt wetland plant performance and soil environments, potentially impairing carbon sequestration and ecosystem stability. Our study underscores the urgent need for microplastic risk assessments in coastal wetlands and highlights soil–microbe–plant interactions as critical mechanisms for future investigation. Full article

Mineral nutrition management in sweet cherry orchards remains a critical challenge due to the lack of site-specific fertilization guidelines, particularly in Greece, a significant cherry-producing country. This study aimed to develop a predictive framework for total nutrient losses in sweet cherry orchards by proposing simplified estimations using fresh fruit yield as the sole input variable. Field experiments were conducted in two orchards with distinct rootstocks (MxM 14 and CAB-6P), analyzing soil properties, leaf nutrient status, and uptake patterns on different plant components. Results indicated that despite differences in soil texture and pH, nutrient availability was generally sufficient, with only Fe and Zn marginally below optimal levels in leaf tissue. Principal Component Analysis (PCA) revealed distinct nutrient distribution patterns, with N evenly distributed across fruits, peduncles, and prunings, while K was concentrated in fruits and peduncles, and Ca and Mg predominantly in fallen leaves. Notably, K was redistributed from leaves to fruits under high yields, evidenced by negative correlations between leaf biomass and K uptake. Strong relationships (r² > 0.8) were found between fresh fruit yield and uptake of N, P, K, Mg, B, and Cu, enabling reliable predictions of total nutrient losses. Estimated annual nutrient removals were 85.6 kg ha⁻¹ N, 8.94 kg ha⁻¹ P, 42.7 kg ha⁻¹ K, and 12.0 kg ha⁻¹ Mg, with significant fractions retained in prunings and fallen leaves (e.g., 51.8 kg ha⁻¹ N, 6.2 kg ha⁻¹ P). The developed yield-based models provide a practical tool for optimizing fertilization strategies, while our findings highlight the potential for nutrient recycling through sustainable residue management. Full article

Fertilizer application is a critical component of turfgrass management as it influences growth, color, stress tolerance, and overall quality. However, limited information exists on how fertilizer application, particularly nitrogen (N), affects hybrid bermudagrass performance and actual plant evapotranspiration (ET_a) in both well-watered and deficit irrigation scenarios. A 7-week greenhouse experiment was conducted over two replicated runs to evaluate responses of ‘TifTuf’ hybrid bermudagrass (Cynodon dactylon × C. traansvalensis Burtt Davy) to three nitrogen rates (0, 2.4, and 4.8 g N m⁻² month⁻¹) and three irrigation levels (1.0, 0.65, and 0.30 × ET_a). Fertilized turfgrass exhibited 11–12% greater ET_a compared to unfertilized turfgrass, with no significant differences between the two fertilizer rates. Under well-watered conditions (1.0 × ET_a), the high nitrogen rate significantly improved visual quality (7.8) relative to the unfertilized control (7.1) and the low-rate treatment (7.4). High-rate fertilizer application significantly enhanced visual quality at both deficit levels (7.2 and 6.6, at 0.65 and 0.30 × ET_a, respectively) compared to the unfertilized control (6.2 and 5.9, at 0.65 and 0.30 × ET_a, respectively). At 0.30 × ET_a, low-rate fertilizer application also significantly improved visual quality (7.0) compared to the unfertilized control. Soil nitrate-N levels increased with higher nitrogen application (1.30 ppm, 0.48 ppm, and 0.37 ppm, respectively, for high-rate, low-rate, and unfertilized), and shoot tissue analysis revealed greater N concentration in fertilized turfgrass (1.51%, 1.24%, and 0.85%, respectively, for high-rate, low-rate, and unfertilized). Clipping production and water use efficiency (WUE) were also improved with fertilization, although root development was hindered at the 0.30 × ET_a irrigation level. These findings demonstrate that nitrogen fertilization improves visual quality, shoot growth, WUE, and drought response; however, tradeoffs such as elevated water use and nitrate-N leaching risk necessitate careful management to balance turfgrass performance with water conservation and ecosystem service preservation. Full article

Heavy metals in peatland pose significant ecological risks due to their persistence, bioaccumulation, and dynamic mobilization under fluctuating environmental conditions. Understanding heavy metal dynamics in subtropical peatlands is critical for addressing global gaps in wetland metal cycling, as these ecosystems face intensified organic decomposition and climatic fluctuations that amplify mobilization risks—contrasting starkly with stable northern counterparts. This study investigates the geochemistry of heavy metals (Cr, Cu, Cd, and Pb) of Dajiuhu peatland in central China, using sequential extraction, gradient diffusion (DGT), and random forest modeling. The mean concentrations of Cr, Cu, Cd, and Pb in peat samples were 24.6 ± 13.7 mg/kg, 14.9 ± 2.51 mg/kg, 1.15 ± 0.62 mg/kg, and 54.9 ± 16.16 mg/kg. Principal component analysis identified three sources: plant-derived litter, bedrock weathering, and atmospheric deposition. Metal speciation revealed the predominance of residual fractions (Cr: 64%, Cu: 61%, Pb: 65%, Cd: 35%), with Cd exhibiting higher mobility (exchangeable: 20%, reducible: 25%). DGT measurements further confirmed distinct migration behaviors, as Cd stored in peat actively diffuses into the surrounding environment, while Pb present in the environment becomes immobilized within the peat matrix. Environmental factors regulate heavy metal speciation through distinct mechanisms. The exchangeable fractions of Cu and Cr are primarily controlled by the C/N ratio, whereas their oxidizable forms are significantly associated with Al content and pH levels. The exchangeable fractions of Pb and Cd are largely influenced by oxidation-reduction potential (ORP) and Ca concentrations, and their reduced forms are closely linked to total sulfur (TS) content. Furthermore, the reducible fractions of Cr and Cd are not only regulated by ORP but also modulated by TS. Our study highlights that the mobility of heavy metals in subtropical peatlands is likely to increase substantially as a result of environmental changes. Full article

The integration of manure and straw substantially affects soil organic carbon (SOC) dynamics, transformation, and long-term stabilization in agricultural systems. Dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MOC) are the three main components of the SOC pool, each influencing soil carbon dynamics and nutrient cycling. Current research gaps remain regarding how combined fertilization practices affect the inputs of plant-originated and microbe-derived carbon into SOC pools and stability mechanisms. Our investigation measured SOC fractions (DOC, POC, MOC), SOC mineralization rate (SCMR), microbial necromass carbon, lignin phenols, enzyme activities, and microbial phospholipid fatty acids (PLFAs) over a long-term (17 years) field experiment with four treatments: mineral fertilization alone (CF), manure-mineral combination (CM), straw-mineral application (CS), and integrated manure-straw-mineral treatment (CMS). The CMS treatment exhibited notably elevated levels of POC (7.42 g kg⁻¹), MOC (10.7 g kg⁻¹), and DOC (0.108 g kg⁻¹), as well as a lower SCMR value (1.85%), compared with other fertilization treatments. Additionally, the CMS treatment stimulated the buildup of both bacterial and fungal necromass while enhancing the concentrations of ligneous biomarkers (vanillin, syringyl, and cinnamic derivatives), which correlated strongly with the elevated contents of fungal and bacterial PLFAs and heightened activity of carbon-processing enzymes (α-glucosidase, polyphenol oxidase, cellobiohydrolase, peroxidase, N-acetyl-β-D-glucosidase). Furthermore, fungal and bacterial microbial necromass carbon, together with lignin phenols, significantly contributed to shaping the composition of SOC. Through random forest analysis, we identified that the contents of bacterial and fungal necromass carbon were the key factors influencing DOC and MOC. The concentrations of syringyl phenol and cinnamyl phenols, and the syringyl-to-cinnamyl phenols ratio were the primary determinants for POC, while the fungal-to-bacterial necromass carbon ratio, as well as the concentrations of vanillyl, syringyl, and cinnamyl phenols, played a critical role in SCMR. In conclusion, the manure combined with straw incorporation not only promoted microbial growth and enzyme activity but also enhanced plant- and microbial-derived carbon inputs. Consequently, this led to an increase in the contents and stability of SOC fractions (DOC, POC, and MOC). These results suggest that manure combined with straw is a viable strategy for soil fertility due to its improvement in SOC sequestration and stability. Full article

The determination of an optimal nitrogen (N) fertilization rate is critical for the sustainable large-scale cultivation of Cinnamomum camphora var. linaloolifera for essential oil production. Both suboptimal and excessive nitrogen inputs can adversely affect plant sustainable development and essential oil biosynthesis, underscoring the necessity of precise nutrient management. This study investigated the effects of five N application rates (0, 45, 90, 135, and 180 kg·hm⁻²) on vegetative growth, essential oil yield, and quality. Growth parameters, including plant height, basal diameter, specific leaf area (SLA), and essential oil yield and yield rate. Oil composition was characterized via gas chromatography–mass spectrometry (GC-MS). The application of 90 kg·hm⁻² N significantly enhanced plant height (74.31%), basal diameter (54.95%), SLA (20.91%), and biomass (181.8%) relative to the nitrogen-free control. Nitrogen uptake was concentrated in foliar tissues, accounting for 82.8% of total plant nitrogen accumulation. This fertilization rate also maximized essential oil yield (9.15 g·plant⁻¹) and yield rate (2.44%), reflecting increases of 178.9% and 24.49%, respectively. Linalool was the predominant oil constituent (89.84–91.81%), with its highest concentration observed at the 90 kg·hm⁻² treatment. At this rate, the relative abundance of oxygenated compounds increased by 0.97%, while hydrocarbon content decreased by 0.62%, indicating a qualitative improvement in oil composition. The findings reveal a threshold response to nitrogen input, wherein rates exceeding 90 kg·hm⁻² did not confer further benefits and may reduce efficiency. Collectively, these results suggest that a nitrogen application rate of 90 kg·hm⁻² optimally enhances vegetative growth, nitrogen assimilation, and both the quantitative and qualitative traits of essential oils in C. camphora var. linaloolifera. Full article

The production of fruit crops plays a vital role in the agricultural sector, contributing significantly to the social and economic development of rural communities. In Brazil, fruit production is diverse due to favorable edaphoclimatic conditions, with avocado (Persea americana Mill.) emerging as an important crop. Its production continues to expand in both cultivated areas and yield, making it a key export to non-producing countries. However, despite its importance, nutritional management information, crucial for achieving high yields, remains limited. Current guidelines on nutrition monitoring are outdated, general, and based on data from other countries with different edaphoclimatic conditions, making them not directly applicable to Brazilian orchards. Furthermore, outdated nutritional information becomes less reliable over time, as climate change alters soil conditions and crop nutrient concentrations and requirements, reinforcing the need for the establishment of up-to-date and specific nutritional information. This study aimed to establish nutritional standards for ‘Hass’ avocado production using the Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND) methodologies, and to define sufficiency ranges (SRs) and Critical Levels (CLs) for both macronutrients (N, P, K, Ca, Mg, and S) and micronutrients (B, Cu, Fe, Mn, and Zn). The analyses were based on yield (t ha⁻¹) and leaf nutrient content data from commercial orchards, with datasets divided into younger (4–9 years) and older (10–26 years) plant groups. The DRIS effectively established nutritional standards for younger plants, explaining 11% of yield variation through nutritional balance. CND, in turn, was effective for both groups, accounting for 14% of yield variation and outperforming DRIS in associating nutritional status with productivity. SRs and CLs for ‘Hass’ avocado production were defined using both DRIS and CND. Together, these indices and diagnostic parameters offer valuable tools for enhancing nutritional monitoring and fertilization strategies in Brazil. Notably, SRs and CLs varied according to plant age. Full article

Effectively utilizing aquatic plants to absorb nitrogen from water bodies and convert it into organic nitrogen via nitrogen assimilation enzyme activity reduces water nitrogen concentrations. This serves as a critical strategy for mitigating agricultural non-point source pollution in the Yellow River Basin However, emergent plants’ rate and mechanism of uptake of different forms of nitrogen remain unclear. This study determined the nitrogen uptake rates, nitrogen assimilation activities, root properties, and photosynthetic parameters of four emergent plants, Phragmites australis, Typha orientalis, Scirpus validus, and Lythrum salicaria, under five NH₄⁺/NO₃⁻ ratios (9:1, 7:3, 5:5, 3:7, and 1:9) using ¹⁵N hydroponic simulations. The results demonstrated that both the form of nitrogen and the plant species significantly influenced the nitrogen uptake rates of emergent plants. In water bodies with varying NH₄⁺/NO₃⁻ ratios, P. australis and T. orientalis exhibited significantly higher inorganic nitrogen uptake rates than S. validus and L. salicaria, increasing by 11.83–114.69% and 14.07–130.46%, respectively. When the ratio of NH₄⁺/NO₃⁻ in the water body was 9:1, the uptake rate of inorganic nitrogen by P. australis reached its peak, which was 729.20 μg·N·g⁻¹·h⁻¹ DW (Dry Weight). When the ratio of NH₄⁺/NO₃⁻ was 5:5, the uptake rate of T. orientalis was the highest, reaching 763.71 μg·N·g⁻¹·h⁻¹ DW. The plants’ preferences for different forms of nitrogen exhibited significant environmental plasticity. At an NH₄⁺/NO₃⁻ ratio of 5:5, P. australis and T. orientalis preferred NO₃⁻-N, whereas S. validus and L. salicaria favored NH₄⁺-N. The uptake rate of NH₄⁺-N by the four plants was significantly positively correlated with glutamine synthetase and glutamate synthase activities, while the uptake rate of NO₃⁻-N was significantly positively correlated with NR activity. These findings indicate that the nitrogen uptake and assimilation processes of these four plant species involve synergistic mechanisms of environmental adaptation and physiological regulation, enabling more effective utilization of different nitrogen forms in water. Additionally, the uptake rate of NH₄⁺-N by P. australis and T. orientalis was significantly positively correlated with glutamate dehydrogenase (GDH), suggesting that they are better adapted to eutrophication via the GDH pathway. The specific root surface area plays a crucial role in regulating the nitrogen uptake rates of plants. The amount of nitrogen uptake exerted the greatest total impact on the nitrogen uptake rate, followed by root traits and nitrogen assimilation enzymes. Therefore, there were significant interspecific differences in the uptake rates of and physiological response mechanisms of emergent plants to various nitrogen forms. It is recommended to prioritize the use of highly adaptable emergent plants such as P. australis and T. orientalis in the Yellow River irrigation area. Full article

Fly ash is produced in thermoelectric power plants and is commonly used in the construction industry due to its pozzolanic properties. This study investigates the relationship between the chemical composition and the radioactive content of fly ash (FA) from 10 different samples and bottom ash (BA) from one of these samples. The results indicate a significant correlation between the chemical composition of FA and its content of natural radionuclides from the uranium and thorium series, along with ${}^{40}\mathrm{K}$. The oxides ${\mathrm{P}}_2{\mathrm{O}}_5$, ${\mathrm{K}}_2\mathrm{O}$, and $\mathrm{N}{\mathrm{a}}_2\mathrm{O}$ exhibited a greater influence compared to $\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3$ and $\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ in relation to the radioactive content of FA. Furthermore, the presence of $\mathrm{C}\mathrm{a}\mathrm{O}$ and $\mathrm{S}{\mathrm{O}}_3$ showed an inverse relationship with the content of natural radionuclides from the uranium series. On the other hand, the radionuclides of the thorium series were associated with the presence of the oxides $\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ and $\mathrm{T}\mathrm{i}{\mathrm{O}}_2$. FA and BA exhibited significant differences in their composition, with higher activity concentrations in BA than in FA, except for ${}^{210}\mathrm{Pb}$ and ${}^{40}\mathrm{K}$. The most critical estimated annual effective dose for workers was $43.7\hspace{0.25em}\mathsf{\mu }\mathrm{S}\mathrm{v}\hspace{0.25em}{\mathrm{y}}^{-1}$, indicating no significant radiological risk for workers. Full article

Reservoirs and downstream rivers draining Oregon’s Cascade Range provide critical water supplies for over 1.5 million residents in dozens of communities. These waters also support planktonic and benthic cyanobacteria that produce cyanotoxins that may degrade water quality for drinking, recreation, aquatic life, and other beneficial uses. This 2016–2020 survey examined the sources and transport of four cyanotoxins—microcystins, cylindrospermopsins, anatoxins, and saxitoxins—in six river systems feeding 18 drinking water treatment plants (DWTPs) in northwestern Oregon. Benthic cyanobacteria, plankton net tows, and (or) Solid-Phase Adsorption Toxin Tracking (SPATT) samples were collected from 65 sites, including tributaries, reservoirs, main stems, and sites at or upstream from DWTPs. Concentrated extracts (320 samples) were analyzed with enzyme-linked immuno-sorbent assays (ELISA), resulting in >90% detection. Benthic cyanobacteria (n = 80) mostly Nostoc, Phormidium, Microcoleus, and Oscillatoria, yielded microcystins (76% detection), cylindrospermopsins (41%), anatoxins (45%), and saxitoxins (39%). Plankton net tow samples from tributaries and main stems (n = 94) contained saxitoxins (84%), microcystins (77%), anatoxins (25%), and cylindrospermopsins (22%), revealing their transport in seston. SPATT sampler extracts (n = 146) yielded anatoxins (81%), microcystins (66%), saxitoxins (37%), and cylindrospermopsins (32%), indicating their presence dissolved in the water. Reservoir plankton net tow samples (n = 15), most often containing Dolichospermum, yielded microcystins (87%), cylindrospermopsins (73%), and anatoxins (47%), but no saxitoxins. The high detection frequencies of cyanotoxins at sites upstream from DWTP intakes, and at sites popular for recreation, where salmon and steelhead continue to exist, highlight the need for additional study on these cyanobacteria and the factors that promote production of cyanotoxins to minimize effects on humans, aquatic ecosystems, and economies. Full article

Nitrogen (N) availability is critical for cucumber (Cucumis sativus L.) growth and yield in greenhouse production. In this study, we investigated the effects of different N doses on the bioimpedance spectroscopy (BIS) parameters of cucumber plants (ES.22.17 F1 genotype), focusing on extracellular fluid resistance ($R_1$), intracellular fluid resistance ($R_2$), vacuole fluid resistance ($R_4$), and cell membrane capacitances ($C_m$, $C_t$). The results showed that low N supply significantly increased $R_1$and reduced $C_m$ in the leaves, indicative of decreased nitrate (NO₃⁻) concentration and impaired membrane fluidity. Higher N supply lowered resistance and increased cell membrane capacitance, reflecting improved ion transport and storage efficiency. A strong positive correlation was observed between total N and NO₃⁻ content (r = 0.9), while NO₃⁻ content negatively correlated with extracellular fluid resistance ($R_1$, r = −0.8) and vacuole fluid resistance ($R_4$, r = −0.9). The optimal N supply for cucumber plants was associated with $R_1$ values of 47,121.07–52,953.93 Ω, $R_4$ values of 0.348–0.529 Ω, and $C_m$ values of 3.149 × 10⁻¹⁰–3.781 × 10⁻¹⁰ F. These BIS parameters showed high sensitivity to plant N status, highlighting BIS as a promising, minimally invasive technique for real-time nutrient monitoring. By integrating BIS data and horticultural best practices, growers can refine N fertilization strategies for better resource efficiency and potentially higher yields and fruit quality. Full article

Plant nitrogen (N), phosphorus (P), and potassium (K) concentrations and ratios serve as critical indicators of nutrient constraints in coastal ecosystems. However, the response of leaf–soil N-P-K stoichiometry in tropical coastal shelterbelt forests to seasonal rainfall variations remains poorly understood. This study measured total N, P, and K contents in leaves and soils of three typical tropical coastal shelterbelt forests in Wenchang, China—Casuarina equisetifolia L., Cocos nucifera L., and Pinus elliottii × caribaea—during August 2022 (wet season) and February 2023 (dry season). Key findings are as follows: (1) All three forests exhibited low N-P-K contents in both leaves and soils, with significant stand-specific variations. Soil N:P ratios were consistently below 14, indicating chronic N limitation for plant growth. (2) Wet seasons significantly altered leaf–soil N-P-K contents and stoichiometric ratios. (3) Leaf and soil stoichiometric traits exhibited strong correlations, but these relationships diverged under seasonal transitions. (4) Shifts from wet to dry seasons increased the sensitivity of N-P-K stoichiometric homeostasis, reflecting weakened nutrient buffering capacity. This study reveals stand-specific nutrient cycling patterns in tropical coastal shelterbelts, with seasonal rainfall modulating soil–leaf nutrient coupling and stoichiometric stability. These findings provide a theoretical basis for optimizing nutrient management and species configuration in tropical coastal ecosystems under climate variability. Full article