Search Results (302)

Rice seedlings are typically grown in high-phosphorus nursery soils in practice, which reduces rice root growth and the plant’s ability to adapt to adverse conditions after transplantation to the paddy field. Thus, it is important to improve rice root development in high-phosphorus nursery soils. Rice root developments are closely connected with soil microorganisms. Arbuscular mycorrhizal fungi (AMF) can promote rice root growth and help improve rice performance in resisting adverse conditions. To illustrate the mechanisms of rice seedlings with AMF inoculation under suitable and high-phosphorus nursery soils in resisting adverse conditions, rice seedlings were cultivated in suitable and high-phosphorus nursery soils inoculated with AMF JD5 (Paraglomus sp.) and transplanted into soda saline–alkaline soils following successful AMF inoculation. Results showed that under high-phosphorus conditions, AMF JD5 inoculation significantly promoted plant height and root elongation, likely through increased total chlorophyll content. Concurrently, proline content was reduced, whereas soluble sugar and soluble protein contents were elevated, indicating alleviation of osmotic stress induced by saline–alkaline conditions. Moreover, AMF JD5-inoculated seedlings exhibited increased CAT activity, which efficiently scavenged reactive oxygen species (ROS) generated under salt–alkaline stress and reduced lipid peroxidation. However, thiobarbituric acid reactive substances (TBARS) content was significantly decreased with AMF inoculation in high-phosphorus conditions. Collectively, these findings suggest that AMF JD5 inoculation in high-phosphorus nursery soils establishes a physiological and biochemical foundation that maintains rice resilience against saline–alkaline stress throughout early growth. Full article

Characterizing surface runoff and the transport process of non-point source pollutants (NSPs) carried by this runoff is crucial for identifying key source areas, estimating pollution loads entering water bodies, and implementing pollution control, which is particularly important in regions dominated by smallholder farming in China. Currently, most of the commonly used NSP models originated from international countries and have shortcomings such as high data requirements, high generalization degrees, and requiring the calibration of numerous parameters in the application process. Therefore, a distributed non-point source pollution model based on the time-varying gain and stormwater runoff response was constructed, designed for application at the watershed scale. This study describes the construction of the model, introducing its principles and structure through three key modules: a rainfall–runoff module, a soil erosion module, and a pollutant migration and transformation module. The proposed model was used to simulate the rainfall–runoff, soil erosion, and nutrient migration and transformation processes at different spatiotemporal scales. Although it achieved the best performance at the monthly and annual scales, its simulation results at the daily and hourly scales still met the relevant requirements, with relative errors within 20% and Nash–Sutcliffe Efficiency (NSE) coefficients of approximately 0.7. The annual sediment delivery ratios for the Yangliu Small Watershed and the basin above the Ankang section in 2022 were determined to be 0.445 and 0.36, respectively. The pollutant processes corresponding to different runoff events in the Yangliu Small Watershed were simulated, and the average NSE for total nitrogen (TN), ammonia nitrogen (NH₃-N), nitrate nitrogen (NO₃-N), total phosphorus (TP), and soluble reactive phosphorus (SRP) were determined to be 0.69, 0.74, 0.79, 0.71, and 0.71, respectively. For the basin above the Ankang section, the NSE coefficients for the simulation of NH₃-N and TP pollutant processes were 0.78 and 0.83, respectively. The model demonstrated robust applicability across various spatial (ranging from small to large watersheds) and temporal (hourly−daily−monthly−annual) scales, and exhibited stability across different basins in a semi-humid region of China. The model is characterized by a parsimonious parameter set, ease of calibration, and strong spatiotemporal versatility, thus providing an efficient and reliable tool for non-point source pollution simulation. Full article

It is widely recognized that microbial inoculants (MI) and bio-organic fertilizers (BOFs) containing beneficial microorganisms can play an important role in improving orchard soil properties and enhancing fruit quality. However, insufficient data regarding the relevant fruit quality effects hindered the supplementary MI and BOFs in kiwifruit cultivation. Using conventional fertilization management as the control, this study investigated the impacts of supplementary applications of MI and BOFs at two gradient dosages on the harvest-time quality and cold storage characteristics of ‘Puyu’ yellow-fleshed kiwifruit. Regarding leaf physiological indices and soil pH, MI-3.0 and BOF-20 treatments significantly elevated total chlorophyll content at 60 days after flowering (DAF) (the fruit expansion stage). Leaf nitrogen (N), phosphorus (P) and potassium (K) contents declined gradually during fruit development, while MI-2.0 and BOF-10 treatments markedly promoted leaf P accumulation at 20–100 DAF. Additionally, the MI-2.0 treatment significantly reduced 20–40 cm subsoil pH, which is favorable for kiwifruit plants that prefer acidic and slightly acidic conditions. On the other hand, appropriate doses of MI and BOF treatments exerted a significant effect on improving the quality of kiwifruit at the ripening stage. These effects were mainly manifested in the increased single fruit weight, firmness, dry matter content and total soluble solids (TSSs) of kiwifruit following MI-3.0 and BOF-20 treatments. Furthermore, MI-3.0 and BOF-10 notably elevated the fructose and glucose contents in both flesh and core, as well as sucrose and ascorbic acid (AsA) contents in the flesh; MI-2.0 and BOF treatments significantly increased citric and malic acids in the core and quinic acid in the flesh. During cold storage, the BOF-20 treatment not only delayed the occurrence of the ethylene peak by 20 d and significantly reduced its peak value, but also alleviated the decline in total acid content at the middle storage stage (20–40 d). Additionally, MI-2.0 and BOF-20 treatments effectively delayed kiwifruit softening at the early storage stage (0–10 d), and MI treatments maintained a high AsA content in the core during 10–20 d of cold storage. MI and BOF fertilization treatments had little effect on the dynamic change trends of sucrose synthase (SuS), sucrose phosphate synthase (SPS) and acid invertase (AI) in kiwifruit during cold storage, only exerting significant effects at specific time points. In conclusion, supplementary applications of MI and BOFs could improve kiwifruit quality at the harvest stage by positively regulating the accumulation of dry matter, soluble sugars and organic acid contents, and also have the potential to enhance the storage performance of kiwifruit. These findings provide a scientific basis for establishing an effective fertilization regime for kiwifruit. Full article

Saline–alkali stress is a severe abiotic factor that limits plant growth and development. Endophytic bacteria can improve plant tolerance to such stress through various mechanism, including osmoregulatory substance accumulation and antioxidant enzyme activity. In this study, four saline–alkali-tolerant endophytic strains, designated SYM-2, SYM-4, SYM-9, and SYM-15, were isolated from the roots of alfalfa grown in saline–alkali soil. Though 16S rDNA sequencing, morphological observations, and physiological–biochemical characterization, the strains were identified as closely related to Bacillus cereus, B. thuringiensis, B. halotolerans, and Pantoea agglomerans, respectively. These strains demonstrated the ability to produce 1-aminocyclopropane-1-carboxylate (ACC) deaminase, siderophores, and indole-3-acetic acid (IAA), as well as solubilizing phosphorus. Under saline–alkali conditions, inoculation with these strains significantly increased alfalfa growth parameters. Plant height increased by 4.07–33.90% and root length by 7.49–27.94%, and fresh and dry weight (both above and below ground) increased compared with the control. Strain SYM-15 showed the highest promoting effects, increasing plant height by 33.90%, root length by 27.94% and shoot dry weight by 59.26%. Additionally, root activity increased by 11.23–40%, proline content by 19.09–129–87%, and soluble protein by 7.71–42.49%, and the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) were significantly elevated across treatments. At the same time, inoculation reduced the levels of hydrogen peroxide (H₂O₂), superoxide anion (O₂⁻), and malondialdehyde (MDA). Compared with the control and other treatments, including SYM-9, the peroxidase activity and superoxide dismutase activity of alfalfa significantly increased after the SYM-15 treatment, while hydrogen peroxide content, phosphorus content, and neutral detergent fiber and acid detergent fiber contents decreased (p < 0.05). Therefore, SYM-15 plays an important role in promoting growth and represents a promising, high-quality strain resource for the large-scale development of microbials aimed at improving alfalfa tolerance under saline–alkali conditions. Full article

Coastal saline–alkali farmland typically experiences poor crop growth and low yields. Clarifying soil quality and identifying the primary constraining factors are crucial for improving productivity. This study systematically investigated the spatial heterogeneity and vertical distribution of soil physicochemical properties in a coastal reclamation area using large-scale field sampling. The results revealed that the plow layer soil in the coastal reclamation zone is characterized by typical saline–alkali conditions, low fertility, and weak nutrient-holding capacity, with a pH range of 8.0 to 9.2. Over 60% of the region had soluble salt (SS) content exceeding 2.0 g/kg, and soil organic matter (SOM), total nitrogen (TN), and cation exchange capacity (CEC) ranged from 7.2 to 24.9 g/kg, 0.45 to 1.42 g/kg, and 1.4 to 15.7 cmol⁺/kg, respectively. Correlation analysis showed significant positive correlations between SOM and TN, available potassium (AK), and CEC, while a strong negative correlation was found between pH and AP. Vertically, the soil demonstrated a notable risk of salt efflorescence and nutrient leaching. Soil salinity and alkalinity increased with depth, while SOM, TN, available phosphorus (AP), and nitrate content decreased. In conclusion, effectively suppressing soil salinization, lowering pH, and increasing organic matter content are essential strategies for improving soil structure, enhancing nutrient retention, and boosting the quality of coastal saline–alkali farmland. Full article

The behavior of phosphorus (P) fertilizers in soil is governed not only by fertilizer solubility, but also by P mobility and vertical redistribution within the soil profile under contrasting water regime. This study aimed to investigate the combined effects of water regime, fertilizer type, and soil properties on the vertical redistribution of ammonium acetate–lactate extractable phosphorus (P-AL) in the surface soil layer under controlled pot conditions. Experiments were conducted using three soils with contrasting chemical properties: AC-LO (acidic loam, pH 5.9), NE-CL (neutral clay loam, pH 6.8), and AL-SL (alkaline sandy loam, pH 8.0). Four simulated rainfall regimes were applied at a constant rate of 25 mm day⁻¹, corresponding to cumulative water inputs of 0 mm (W0), 50 mm (W50), 100 mm (W100), and 150 mm (W150). Fertilizer treatments included an unfertilized control (NF), a liquid NP 4–18 fertilizer applied at a low dose (L1), a liquid NP 4–18 fertilizer applied at a high dose (L2), and a solid NPK 15–15–15 fertilizer (S). Water regime exerted the strongest control on P mobility, with P-AL increasing by approximately 40–60% from W0 to W150, depending on soil type. In AC-LO, strong P fixation under low moisture minimized differences among fertilizer treatments, whereas under higher moisture (W100–W150), liquid fertilizers—particularly L2—resulted in P-AL levels approximately 10–30% higher than those of the solid fertilizer. In NE-CL, P mobility was moderate and, under W100–W150, L2 produced P-AL values approximately 10–15% higher than the solid fertilizer, promoting a more uniform P redistribution within the 2–8 cm layer. In AL-SL, the response under wet conditions depended on the water regime: at W100, L2 generated P-AL values comparable to the solid fertilizer, whereas at W150, L2 increased P-AL by approximately 11% relative to the solid form. Overall, the results indicate that soil chemical properties primarily regulate the extent of phosphorus redistribution, while water regime controls its intensity and fertilizer form influences the initial spatial configuration of P within the surface soil layer. The findings provide mechanistic insight into short-range phosphorus transport in soil, without allowing direct inferences regarding agronomic efficiency or crop response. Full article

To address freshwater scarcity in agriculture, the use of brackish and reclaimed water for alternate irrigation has emerged as a viable alternative. This study evaluated four biochars (rice husk, peanut shell, rice straw, and wheat straw, applied at 2%) and three silicon fertilizers (Lang-Si (S1), Nayou-Si (S2), and sodium metasilicate pentahydrate (S3)) as amendments for sandy loam soil (Lang-Si, Nayou-Si, foliar spray at 1000× dilution; sodium metasilicate pentahydrate, foliar spray at 150 mg∙L⁻¹). Their effects on soil salinity, physicochemical properties, and microbial community structure were assessed under alternate irrigation with brackish and reclaimed water. Alternate irrigation reduced soil electrical conductivity and increased total phosphorus (TP) content compared to single-source irrigation. The effects of amendments varied by type. Biochars improved soil fertility and reduced salinity: peanut shell biochar decreased EC by 15.5%; rice husk biochar increased total nitrogen (TN), TP, and organic matter (OM) by 11.8%, 8.2%, and 10.1%, respectively; and wheat straw biochar elevated subsurface soil TN and OM by 14.1% and 40.0%. Straw-derived biochars and sodium metasilicate pentahydrate maintained higher bacterial α-diversity (Shannon index ≥ 6.67). These effects corresponded with the nutrient adsorption capacity of biochars and the ionic stress alleviation by soluble silicon. The correlation analysis identified OM, TN, TP, and EC as the key drivers shifting the microbial community. Straw-derived biochars and sodium metasilicate pentahydrate are suitable amendments for alternate irrigation systems. These materials balance salinity control, fertility improvement, and microbial conservation, offering practical options for sustainable use of brackish and reclaimed water in agriculture. Full article

Forests’ conversion to tea plantations is a land use transition type with high economic value in China. How this conversion affects soil weathering and nutrient characteristics remains unclear. Here, we selected six soil profiles (three pairs) from representative tea plantations and adjacent forests in China. We quantified the weathering intensity (chemical index of alteration (CIA), base-to-alumina ratio (ba), and weathering index of Parker (WIP)) by soil geography and elemental geochemistry methods and revealed nutrient distributions along with soil profiles. The results showed that soluble elements (such as K₂O, CaO, MgO and Na₂O) and SiO₂ were noticeably leached, while Al₂O₃ and P₂O₅ were enriched. The geochemical indices showed that the soil profiles of tea plantations (CIA: 80.6%, ba: 0.3 and WIP: 34.6%) experienced stronger chemical weathering than those of forest soils (CIA: 76.0%, ba: 0.4 and WIP: 39.7%). The mean sensitivity indexes (SI) of soil pH, soil organic matter (SOM), total phosphorus (TP) and total potassium (TK) were −7.0%, −24.8%, 53.7% and −8.6%, respectively. This reflected that tea plantations would lead to soil acidification, organic matter depletion, phosphorus enrichment, and potassium deficiency. Our work underscores the significant impact of anthropogenic tea-garden cultivation on pedogenesis; future management must emphasize rational fertilization to prevent soil degradation. Full article

Traditional Yuluxiang pear cultivation employs wide row spacing to facilitate sunlight penetration and ventilation, but this reduces land use efficiency. Therefore, this study investigated the effects of intercropping dandelions in Yuluxiang pear orchards on soil environment, pear tree growth, and fruit quality. The experiment included three treatments: monoculture (M), dandelion intercropping (DI), and dandelion intercropping combined with microbial organic fertilizer application (DI + MF). Results indicated that the combined DI + MF treatment enhanced soil nutrients by increasing the content of Alkaline Hydrolyzable Nitrogen (AN), Total phosphorus (TP), and Available phosphorus (AP). The DI treatment altered the microbial community structure, enriching beneficial bacteria (such as the phyla Acidobacteriota and Actinomycetota) and fungi (such as the phyla Mucorales and Basidiomycota), thereby enhancing nutrient cycling. Treatment effects were most pronounced in the topsoil layer (0–20 cm) and diminished with increasing depth. Regarding tree physiology, DI treatment increased leaf Symbolic Consistency (Gs) and Intercellular CO₂ Concentration (Ci). The DI + MF treatment significantly boosted leaf chlorophyll content, with both intercropping treatments improving tree photosynthesis and nutritional status. In terms of fruit quality, the DI + MF treatment demonstrated the best overall performance. Its single fruit weight reached the highest values at all stages (143.86 g, 315.48 g, and 515.03 g), while the soluble solids content peaked at 130 days post-flowering, with increased levels of sugars, Vitamin C (VC), total phenols, and flavonoids in the fruit. This significantly enhanced both the external appearance and internal quality of the fruit. Research indicates that the DI + MF treatment can systematically enhance soil quality, tree vitality, and fruit quality in Yuluxiang pear orchards by improving soil physicochemical properties, regulating microbial communities, and boosting tree physiological functions. Full article

Phosphogypsum (PG) and phosphorus tailings (PT) are bulk solid wastes generated by the phosphorus chemical industry whose stockpiling poses significant environmental risks and represents a waste of resources. To achieve the goals of “treating waste with waste” and large-scale disposal, this study proposes a technical pathway involving the co-pyrolysis of phosphogypsum and phosphorus tailings to produce artificial soil-like materials. The effects of raw material ratio, pyrolysis temperature and duration, and biomass addition on the speciation transformation, leaching toxicity, and matrix characteristics of phosphorus (P) and fluorine (F) in the products were systematically investigated. Characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), were employed to elucidate the synergistic immobilization mechanism. The results indicate that under optimized conditions (PG:PT mass ratio of 6:4, pyrolysis temperature of 800 °C, duration of 2–3 h, and biomass addition of 20%–30%), the active forms of harmful elements in the product were significantly reduced. The proportion of water-soluble fluorine decreased from ~39% in raw phosphogypsum to less than 3%, with apatite phosphorus becoming the dominant form of phosphorus. Mechanistic studies reveal that the immobilization process follows a “multi-pathway synergy” mechanism: thermal activation promotes the in situ formation of thermodynamically stable fluorapatite through the reaction of Ca²⁺, PO₄³⁻, and F⁻ (chemical fixation); iron/aluminum oxides in phosphorus tailings and the biochar derived from added biomass provide adsorption sites for surface complexation (physicochemical fixation); and the melting of silicon–aluminum components forms an amorphous silicate network that physically encapsulates pollutant microcrystals. This study provides crucial theoretical foundations and process parameters for the synergistic disposal and soil-like resource utilization of phosphogypsum and phosphorus tailings, demonstrating significant environmental and economic benefits. Full article

Exploring how nitrogen deposition alters the competitive interactions between invasive plants and native plants is critical for predicting the invasion trends of invasive plants and for formulating their control strategies. In this study, the invasive plant Solanum rostratum and its native congener S. nigrum were selected as research subjects, and three different nitrogen (N) concentration treatments (N1: 50 mg·kg⁻¹, N2: 100 mg·kg⁻¹, N3: 150 mg·kg⁻¹) were set up to compare the two species in terms of growth and development, leaf nutrient utilization strategies, stress tolerance, and rhizosphere microbial community differences under competitive conditions. The results showed that the biomass of S. rostratum was 1.4 to 2.3 times that of S. nigrum; the former had a lower root–shoot ratio and a larger crown width, enabling it to seize more living space and light resources. Across all nitrogen treatments, the net photosynthetic rate of S. rostratum leaves was significantly higher than that of S. nigrum, reflecting a stronger carbon sequestration capacity. With the increase in soil nitrogen concentration, the malondialdehyde content in S. rostratum leaves showed a decreasing trend; meanwhile, its leaf soluble sugar and catalase contents were 3.5 to 4.3 times and 1.5 to 2.5 times those of S. nigrum, respectively, indicating a lower oxidative stress level and higher stress tolerance in S. rostratum. The leaf C/P and C/N ratios of S. rostratum increased with the rise in soil N, demonstrating a higher nutrient use efficiency, while the decrease in leaf phosphorus (P) content might be attributed to the element dilution effect caused by the rapid plant growth. In addition, the diversity and stability of the rhizosphere microbial community of S. rostratum gradually increased with increasing soil N and were significantly higher than those of S. nigrum. The rhizosphere-recruited microbes of the genera Comamonas and Chryseobacterium may help promote its root nutrient absorption and thus enhance its competitive ability. Collectively, our findings reveal that under exogenous N application, S. rostratum gains a significant growth advantage over S. nigrum, which is attributed to its stronger capacities for carbon assimilation and spatial resource acquisition, a nutrient strategy characterized by low acquisition and high utilization, as well as a stable and diverse rhizosphere microbial community. Full article

Although plastic film mulching enhances crop yield, it impedes water infiltration, potentially restricting agricultural productivity. To address this issue, we evaluated the effects of different mulching methods on cauliflower growth, yield performance, quality traits, soil properties, and irrigation water use efficiency. We implemented three mulching treatments and two control groups: combined straw and plastic film mulching (T1), partial straw mulching (T2), full straw mulching (T3), no mulching (CK1), and plastic film mulching alone (CK2). These treatments were applied to two consecutive crops of cauliflower over a two-year period (2019–2020) in the arid and semi-arid regions of Gansu Province, China. Our findings revealed that T1 significantly enhanced plant height, stem diameter, and both above- and belowground fresh biomass compared to CK2. Moreover, T1, T2, and T3 promoted the accumulation of nitrogen, phosphorus, and potassium in the roots, stems, and leaves, as well as the concentrations of macro- (N and K), meso- (Ca and Mg), and micro-elements (Fe, Mn, Cu, and Zn) in the cauliflower heads. Compared to CK2, the soluble sugar and vitamin C contents increased by 17.43% and 8.68% in T1, and the soluble protein contents increased by 13.10% and 9.50% in T2 and T3 compared to CK2. Conversely, the nitrate content decreased by 28.28%, 42.06%, and 31.54% in T1, T2, and T3, respectively. Additionally, T1 increased economic yield and irrigation water use efficiency by 16.36–23.80% and 23.94–36.88% in the two years, along with notable improvements in the soil’s total nitrogen, total phosphorus, available phosphorus, and organic matter content. Multivariate classification modeling using principal component analysis (PCA) and hierarchical cluster analysis (HCA) further indicated that T1 enhanced cauliflower quality, yield, and irrigation water use efficiency and boosted soil fertility. These findings provide valuable insights for sustainable agricultural practices in arid and semi-arid regions. Full article

Frequent agricultural and pastoral activities in northern China’s agro-pastoral ecotone have resulted in severe soil salinization. Although phytoremediation is currently the recommended remediation strategy, plant growth is often hindered by microbial deficiencies, nutrient limitations, and high salt content. Arbuscular mycorrhizal fungi (AMF) are prevalent in saline soils and have been shown to facilitate the growth of various forage grasses. However, highly efficient “AMF strain–leguminous forage grass” remediation systems are currently lacking in this area. This study examined the impact of nine AMF strains sourced from the Bank of Glomeromycota in China (BGC) on the growth and salt tolerance mechanisms of Medicago sativa and Astragalus adsurgens via pot experiment. The results showed that all the strains, except Funneliformis mosseae BGC NM04A (Fm-2), exhibited significant promotion of the growth of both leguminous forage species. Specifically, the growth of M. sativa increased by 157% to 354%, and that of A. adsurgens increased by 15.2% to 252%. The impact of different strains on plant-soluble sugar and protein content was found to vary, with Rhizophagus intraradices BGC BJ09 (Rin) and Rhizophagus irregularis MUCL 43194 (Rir-1) having particularly pronounced effects. Most of the AMF strains enhanced the uptake of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in the shoots of both plant species. Additionally, all strains except for Fm-2 exhibited a significant increase in the K⁺/Na⁺ ratio in M. sativa shoots. In contrast, only Claroideoglomus etunicatum BGC GZ03C (Ce-1) and Rir-1 demonstrated a substantial increase in the K⁺/Na⁺ ratio in A. adsurgens. Following a comprehensive assessment, several highly effective combinations were identified: M. sativa in combination with Ce-1, F. mosseae BGC HUN01A (Fm-1), or Rir-1; and A. adsurgens with Rir-1 or Fm-1. These “forage–AMF strain” combinations have been demonstrated to alleviate salt stress by enhancing mycorrhizal effects, regulating ion homeostasis, and optimizing osmotic regulatory substances. Our findings have clarified the intraspecific and interspecific differences in AMF in mitigating salt stress, emphasizing the potential of AMF as a sustainable strategy to improve the stress resistance and productivity of leguminous forages in the saline agro-pastoral ecotone. Full article

Phosphorus (P) is a vital macronutrient involved in key biochemical processes that support plant growth; however, its low bioavailability in agricultural soils remains a major constraint on crop productivity. This limitation is commonly addressed through the application of chemical P fertilisers produced by acidulation of phosphate rock (PR), a process that is costly, energy-intensive, and environmentally hazardous. This study evaluated the P-solubilising potential of culture filtrates from three fungal strains (Aspergillus flavus JKJ7, Talaromyces purpureogenus JKJ12, and Trichoderma koningiopsis JKJ18) grown in National Botanical Research Institute’s Phosphate (NBRIP) liquid medium supplemented with tricalcium phosphate (TCP), and compared their TCP solubilisation efficiency with that of pure acids (citric and sulfuric acid). All three fungal strains solubilised TCP in NBRIP medium, with A. flavus JKJ7 producing the highest concentration of soluble P (259.81 mg L⁻¹), followed by T. koningiopsis JKJ18 (166.41 mg L⁻¹) and T. purpureogenus JKJ12 (47.07 mg L⁻¹). Soluble P concentrations were inversely correlated with pH and positively correlated with titratable organic acidity (TOA). High-performance liquid chromatography (HPLC) identified citric, succinic, tartaric, and gluconic acids as the dominant organic acids associated with P solubilisation. In pure acid treatments, sulfuric acid exhibited concentration-dependent increases in soluble P, whereas citric acid showed reduced solubilisation efficiency at higher concentrations. Although fungal culture filtrates achieved lower maximum TCP solubilisation than strong mineral acids, their higher TOA contributed to improved stabilisation of soluble P by limiting calcium-mediated reprecipitation. These findings demonstrate that crude fungal organic acid mixtures can complement or partially substitute inorganic acids for mobilising P from low-reactivity PR, offering a potentially cost-effective and environmentally sustainable alternative for P fertiliser production. This study supports the development of biologically derived P inputs aligned with circular bioeconomy and sustainable agriculture goals. Full article

This study systematically investigated the effects of stand age (5, 10, 20, and 40 years) on the biochemical components, mineral element accumulation in leaves, and rhizosphere soil properties of the tea shrub Camellia sinensis (L.) Kuntze cv. Wuyi Rougui. Analyses were performed on dried and ground leaf samples, and rhizosphere soil was collected from multiple independent plots per age group (n = 3). The results showed that the contents of tea polyphenols, water extract, caffeine, total flavonoids, and free amino acids in leaves initially increased, peaked at 10 or 20 years, and then decreased with increasing stand age. Soluble sugar content was highest at 5 years. The accumulation patterns of leaf mineral elements (Mg, Mn, K, Na, Fe, Zn, Cu, Ca) were also significantly influenced by stand age. Soil physicochemical properties (pH, total nitrogen, available phosphorus, organic matter, etc.) and enzyme activities (protease, polyphenol oxidase, urease, sucrase) exhibited distinct trends, i.e., pH decreased initially and then increased, while organic matter content increased with stand age. Principal component analysis (PCA) revealed that tea quality indicators, mineral elements, and soil properties clearly separated the 5- and 40-year groups, while the 10- and 20-year groups were closer. Pearson correlation analysis indicated significant positive correlations between leaf total flavonoids and soil ammonium nitrogen (r = 0.82, p < 0.01), and negative correlations between leaf soluble sugar and soil ammonium nitrogen (r = −0.75, p < 0.05). In summary, stand age was associated with systematic changes in both tea leaf composition and soil environment, suggesting that soil nutrient availability and enzyme activity may modulate tea quality formation. These findings provide a theoretical basis for age-specific soil and nutrient management in tea plantations. Full article