Search Results (2,267)

Extensive practice has demonstrated that the continuous pursuit of high yields in the black soil region of Northeast China resulted in imbalances in soil nutrients and declines in both soil quality and water use efficiency. Alternate wetting and drying (AWD) irrigation offers a promising solution for increasing rice yield and maintaining soil fertility. However, the success of this irrigation method largely depends on its scheduling. This study examined the threshold effects of AWD on rice growth, yield, and soil nutrient availability in the Sanjiang Plain, a representative black soil region in Northeast China. A two-year trial was conducted from 2023 to 2024 at the Qixing National Agricultural Science and Technology Park. “Longjing 31,” a local cultivar, was selected as the experimental material. The lower limit of soil water content under AWD was set as the experimental factor, with three levels: −10 kPa (LA), −20 kPa (MA), and −30 kPa (SA). The local traditional irrigation practice, continuous flooding, served as the control treatment (CK). Indicators of rice growth and soil nutrient content were measured and analyzed at five growth stages: tillering, jointing, heading, milk ripening, and yellow ripening. The results showed that, compared to CK, AWD had minimal impact on rice plant height and tiller number, with no significant differences (p > 0.05). However, AWD affected leaf area index (LAI), shoot dry matter (SDM), yield, and soil nutrient availability. In 2023, control had little effect on rice plant height and tiller number among the different irrigation treatments. The LAI of LA was 11.1% and 22.5% higher than that of MA and SA, respectively, while SDM in LA was 10.5% and 17.2% higher than in MA and SA. Significant differences were found between LA and MA, as well as between LA and SA, whereas no significant differences were observed between MA and SA. The light treatment is beneficial to the growth and development of rice, while the harsh growth environment caused by the moderate and severe treatments is unfavorable to rice growth. The average contents of nitrate nitrogen (NO₃⁻-N), available phosphorus (AP), and available potassium (AK) in LA were 11.4%, 8.4%, and 9.3% higher than in MA, and 16.7%, 11.5%, and 15.0% higher than in SA, respectively. Significant differences were observed between LA and SA. This is because the light treatment facilitates the release of available nutrients in the soil, while the moderate and severe treatments hinder this process. Although panicle number per unit area and grain number per panicle in LA were 7.5% and 2.3% higher than in MA, and 10.8% and 2.2% higher than in SA, these differences were not statistically significant. Seed setting rate and thousand-grain weight showed little variation across irrigation treatments. The yield of LA was 10,233.3 kg hm⁻², 9.1% and 14.1% higher than that of MA and SA, respectively, with significant differences observed. Compared with the moderate and severe treatments, the light treatment increases indicators such as the number of panicles per unit area, grains per panicle, thousand-grain weight, and seed setting rate, resulting in significant differences among the treatments. Water use efficiency (WUE) decreased as the control level increased. The WUE of all AWD irrigation treatments was significantly higher than that of the control treatment (CK). Compared with CK, AWD reduces evaporation, percolation, and other water losses, leading to a significant decrease in water consumption. Meanwhile, the yield remains basically unchanged or even slightly increases, thus resulting in a higher WUE than CK. The trends in rice growth, soil nutrient indicators, and WUE in 2024 were generally consistent with those observed in 2023. In 2024, the yield of LA was 9832.7 kg hm⁻², 14.9% and 17.3% higher than that of MA and SA, respectively, with significant differences observed. Based on the results, the following conclusions are drawn: (1) AWD irrigation can affect the growth of rice, alter the status of available nutrients in the soil, and thereby cause changes in yield and WUE; (2) LA is the optimal treatment for increasing rice yield, improving the availability of soil available nutrients, and improving WUE; (3) Both MA and SA enhanced WUE; however, these practices negatively impacted rice growth and the concentration of soil available nutrients, leading to a concurrent decline in yield. To increase rice yield and maintain soil fertility, LA, with an irrigation upper limit of 30 mm and a soil water potential threshold of −10 kPa, is recommended for the Sanjiang Plain region. Full article

Brackish water is becoming an increasingly important resource for agricultural irrigation due to limited freshwater availability; however, concerns persist regarding its potential to degrade soil quality and reduce crop yields. This study evaluated the combined effects of irrigation water quality (brackish water, electrical conductivity (EC) of 2958 µS/cm; agricultural water, EC 796 µS/cm), soil type (agricultural soil and reclaimed desert soil), and compost treatments (no compost, mulch compost, Johnson-Su compost, and mulch compost incorporation) on soil health and chili pepper (Capsicum annuum) growth under greenhouse conditions. Compost amendments significantly improved plant height by 58–213%, root length by 35–166%, and wet biomass by 154–1400% compared to control treatments. Agricultural water maintained lower soil EC (0.553–0.870 mS/cm) than brackish water (0.751–1.104 mS/cm), while Johnson-Su compost most effectively reduced salinity impact on plant growth. Leached water analysis showed higher Na⁺, Cl⁻, and SO₄²⁻ mobility under brackish irrigation, with compost treatments enhancing nutrient retention and soil moisture by buffering salinity stress with carboxylic group and cation exchange capacity. Johnson-Su compost incorporation consistently mitigated the negative effects of brackish irrigation by reducing sodium accumulation, improving chloride mobility, and enhancing soil nitrogen dynamics. These results highlight that combining high-quality irrigation water and biologically active composts improves soil health and plant productivity, while brackish water use requires soil amendments to mitigate salinity risks. Full article

Nitrogen (N) fertilization critically regulates the storage and availability of soil carbon (C) and N pools. However, the internal mechanism through which stratified N application affects soil organic carbon (SOC) sequestration and soil quality index (SQI) remains unclear. To investigate the effects of stratified N application on C sequestration and SQI in both topsoil and subsoil, this study established six treatments (N_0:0, N_1:0, N_4:1, N_3:2, N_2:3, N_1:4) and analyzed soil biochemical indicators. The results showed that compared to N_1:0, stratified N fertilization did not significantly improve soil C and N content in the 0–20 cm layer. In contrast, the N_2:3 and N_1:4 treatments even led to a significant reduction in soil C and N pools in the topsoil. In the 20–40 cm, compared to N_1:0, stratified N fertilization increased SOC, TN, labile C fractions, N fractions (particulate organic N and microbial biomass N), enzyme activity and C pool management index (CPMI), increasing by 0.52–7.94%, 2.05–8.42%, 4.77–42.59%, 14.46–56.01%, 6.34–45.82%, and 31.26–51.93%, respectively. In 0–20 cm, compared to N_0:0, N application increased SQI by 24.84–45.77%, and N_2:3 and N_1:4 treatments were lower SQI than N_1:0. Furthermore, N_2:3, N_3:2, and N_1:4 treatments in 20–40 cm were higher than other treatments. N fertilizer application drives the synergistic changes in C and N fractions by regulating enzyme activity and stoichiometric ratio, thus affecting CPMI and SQI. Thus, the 3:2 stratified N fertilization (0–20 cm:20–40 cm) method achieves synergistic dual-layer enhancement-maintaining surface C and N pools while boosting subsoil C sequestration and quality-through enzyme-mediated precision regulation of C/N stoichiometry. The study provides a scientific foundation for integrated C emission reduction and cropland quality enhancement in the North China. Full article

Land degradation is known to alter soil properties and quality; however, its depth-dependent effects across contrasting land-use types and the key factors limiting soil recovery remain poorly quantified in tropical ecosystems. This study established a forest degradation gradient on Hainan Island, China, encompassing mature forest, secondary forest, rubber plantation, and areca plantation. Soil physical (e.g., bulk density, porosity, water content, field capacity) and chemical (e.g., organic matter, nitrogen, phosphorus, and potassium fractions) properties were measured at three depths (0–20 cm, 20–40 cm, and 40–60 cm). A soil quality index (SQI) was constructed using principal component analysis, and obstacle degree modeling was applied to identify major limiting factors. The results showed that degradation of mature forests significantly reduced topsoil (0–20 cm) quality regardless of subsequent land-use type. In contrast, changes in medium (20–40 cm) and deep (40–60 cm) soil quality were land-use dependent. Conversion to secondary forests and areca plantations resulted in negligible effects, whereas transformation into rubber plantations significantly enhanced soil quality at medium and deep depths. Obstacle degree analysis identified available phosphorus, rather than nitrogen, as the primary limiting factor for soil quality in the region, accounting for 39.7% of all limitations across land-use types. This study demonstrates that the effects of tropical forest degradation on soil quality exhibit dual dependence on both soil depth and land-use type in tropical settings. Furthermore, it highlights the essential role of available phosphorus management in guiding soil restoration and sustainable land-use strategies in these vulnerable ecosystems. Full article

The remediation of contaminated soils is essential for restoring land productivity and soil health. Pteris vittata L., an arsenic hyperaccumulator, has been widely used for phytoremediation, yet its ecological effects on soil systems remain insufficiently understood. In this field study, we evaluated the influence of Pteris vittata L. remediation on soil physico-chemical properties, microbial diversity, and molecular ecological networks. The results showed that long-term arsenic contamination significantly reduced soil total carbon, total nitrogen, and available phosphorus, simplified bacterial network structures, and markedly altered the keystone taxa that maintain microbial interactions. In contrast, soils under Pteris vittata L. remediation exhibited higher nutrient availability, greater bacterial diversity, and more complex microbial networks than contaminated soils, indicating partial recovery of ecosystem functions. These findings demonstrate that Pteris vittata L. remediation can mitigate arsenic-induced soil degradation and provide an important scientific basis for assessing the long-term impacts of arsenic contamination and the role of remediation measures in soil health evolution. Full article

Cultivated land quality is critical for soil productivity and scientific fertilization. This study analyzed its evolution and impact on soil productivity across three ecological regions (southern, central, and northern Shanxi) in Shanxi Province, China, from 1998 to 2021). Using data from 8 long-term experimental sites (1998–2021) and 50 monitoring stations (2016–2021), we employed random forest analysis to evaluate temporal trends in key soil indicators. The results show the following: (1) Northern Shanxi exhibited the greatest improvement in soil fertility, with organic matter increasing by 98.2%, total nitrogen by 57.2%, available phosphorus by 131.7%, and available potassium by 17.1%. (2) Nitrogen fertilizer application increased across all regions, while phosphorus and potassium inputs generally declined. (3) Crop yields improved substantially—southern Shanxi wheat and maize increased by 15.3% and 20.9%, respectively, while central and northern Shanxi maize yields rose by 30.9% and 75.4%. Random forest models identified regional characteristics (40%), nitrogen fertilization (20%), and available phosphorus (18%) as primary influencing factors. Although cultivated land quality improved overall, soil fertility remained medium to low. Region-specific management strategies are recommended: rational nitrogen use in all regions; nitrogen control with phosphorus supplementation in the south; focused improvement of available phosphorus and potassium in the center; and increased organic fertilizer in the north. These measures support scientific nutrient management and sustainable agricultural production. Full article

Biodegradable mulch films (BDMs) have emerged as a promising alternative to conventional polyethylene (PE) films in modern horticulture, yet the effect of film thickness on crop performance remains inadequately understood. In this study, a two-year field experiment (2023–2024) under protected cultivation was conducted to evaluate BDMs with thicknesses (0.006, 0.008, and 0.010 mm) for watermelon production in Beijing, China. The results showed that all BDMs enhanced soil temperature and moisture compared to bare soil (main effect of mulching, p < 0.05) and significantly influenced soil available nitrogen (p < 0.05), while other soil properties were less affected. Year effects were generally not significant, reflecting the stable microclimatic conditions under hoop-house cultivation. Mechanical property assessments indicated substantial declines in tensile load, tensile strength, and elongation at break after field use, especially for thinner films. Notably, Bio-0.006 and Bio-0.008 significantly improved fruit weight and soluble sugar content relative to PE (p < 0.05), leading to higher yields and better commercial quality. These results suggested that appropriately thin BDMs can satisfy agronomic requirements for watermelon under protected cultivation while minimizing plastic residues, offering a practical basis for optimizing biodegradable film thickness to balance mulching performance, productivity, and environmental sustainability. Full article

Schisandra chinensis (Turcz.) Baill. (S. chinensis) is a widely used medicinal plant whose therapeutic efficacy is closely linked to its lignan content. While previous studies have focused on soil fertility and cultivar variation, the interplay among soil nutrients, rhizosphere microbiota, and lignan accumulation remains poorly understood. This study investigated S. chinensis grown across 20 cultivation sites to elucidate the relationships among soil nutrient profiles, fruit lignan composition, and rhizosphere microbial communities. Six major lignans were quantified using HPLC, soil nutrients were analyzed via standard chemical assays, and rhizosphere bacterial communities were profiled using 16S rRNA sequencing. Multivariate analyses revealed significant variation in soil properties and lignan content across sites. Notably, available phosphorus, organic matter, and total nitrogen showed strong correlations with specific lignan compounds. From the top 50 taxa ranked by relative abundance at the genus level, 18 bacterial genera associated with lignan components were identified. Among them, Mycobacterium, Arthrobacter, Haliangium, Bacillus, Sphingomonas, Rhodanobacter, Ellin6067, Bradyrhizobium, Pseudolabrys, Chujaibacter, Gemmatimonas, Bryobacter, MND1, Candidatus Sollbacter, Gaiella, Paenibacillus, RB41, and Candidatus_Udaeobacter were significantly associated with lignan levels, suggesting potential microbial involvement in lignan biosynthesis. These findings provide insights into the ecological factors shaping the medicinal quality of S. chinensis and offer a foundation for targeted cultivation and breeding strategies. Full article

Changes in vegetation type shape the soil microenvironment, thereby regulating the changes in the organic carbon pool by influencing microbial communities and the accumulation of microbial necromass carbon (MNC). This study investigated microbial biomass—via phospholipid fatty acids (PLFAs) analysis—and MNC accumulation across three cold–temperate forest types: Larix gmelinii forest (L), Larix gmelinii–Betula platyphylla Sukaczev mixed forest (LB), and Betula platyphylla Sukaczev forest (B). The results showed that the L had the lowest contents of pH, water content (WC), soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), and total phosphorus (TP), but the highest contents of dissolved organic carbon (DOC), available phosphorus (AP), and carbon to nitrogen ratio (C/N) (p < 0.05). LB had the lowest PLFAs content and the highest ratio of Gram-positive bacteria/Gram-negative bacteria (G+/G−), and total fungi/total bacteriai (F/B) of L was the highest. B had the highest alpha diversity index, and significantly positively correlated with pH, SOC, TN, AN, and TP. TP and C/N were the primary elements for significant differences in microbial community structure. The order of MNC content and its contribution to SOC was B > LB > L. MNC was significantly negatively correlated with PLFAs, DOC, and AP, and significantly positively correlated with pH, SOC, TN, AN, TP, Shannon–Wiener and Pielou indices. In conclusion, this study demonstrates that Betula platyphylla Sukaczev forest retains more carbon, nitrogen, and phosphorus, microbial alpha diversity, and acquires more MNC, which can provide a basis for subsequent forest management and carbon sequestration projects. Full article

Crops nitrogen supply through the in situ mineralization of soil organic matter is a critical process for plant nutrition. However, accurately estimating the contribution of mineralization remains challenging. The complexity of biological, chemical, and physical processes in the soil, influenced by environmental conditions, makes it difficult to precisely quantify the amount of nitrogen available for crops. In this study, we created a database by collecting results from 121 mineralization monitoring experiments carried out between 2015 and 2021 on different experimental plots across Wallonia, Southern Belgium, and assessed the efficiency of predictive mineralization methods. The most impactful analytical parameters on in situ mineralization (ISM), determined using LIXIM program, appeared to be potentially mineralizable nitrogen (PMN) (r = 0.79). PMN, estimated by anaerobic soil incubation, also allowed the effective consideration of the after-effects of grassland termination and manure inputs. A multiple linear regression (MLR) combining PMN, POxC, pH, TOC:N, and TOC:clay significantly improved the prediction of soil nitrogen mineralization available for crops, achieving r = 0.87 (vs. r = 0.58 for the current method), while reducing dispersion by 41% (RMSE 56.35 → 33.13 kg N·ha⁻¹). The use of a more flexible Bootstrap Forest model (BFM) further enhanced performance, reaching r = 0.92 and a 50.8% reduction in dispersion compared to the current method (RMSE 56.35 → 27.76 kg N·ha⁻¹), i.e., about 16% lower RMSE than the MLR. Those models provided practical and efficient tools to better manage nitrogen resources in temperate agricultural systems. Full article

Suboptimal land conditions, characterized by limited nutrient availability and poor soil physical properties, restrict the growth and productivity of maize–soybean intercropping systems. Bioameliorants containing beneficial microorganisms, such as mycorrhizae, offer a sustainable strategy to enhance soil fertility and nutrient uptake efficiency. This study evaluated the effects of different bioameliorant compositions on nitrogen availability, plant growth, and yield in maize–soybean intercropping on suboptimal land. A randomized complete block design with four replicates tested five treatments: F0 (control, no bioameliorant), F1 (10% compost + 10% rice husk charcoal + 10% manure + 70% mycorrhizal biofertilizer), F2 (15% each of compost, manure, charcoal + 55% biofertilizer), F3 (20% each + 40% biofertilizer), and F4 (25% each component). Results showed that the balanced F4 bioameliorant markedly improved nitrogen availability, soil health, and yields in maize–soybean intercropping on sandy soils. These findings highlight its potential as a sustainable strategy to enhance productivity, reduce reliance on chemical fertilizers, and strengthen agroecosystem resilience on suboptimal land. The optimized F4 formulation therefore represents a practical approach to improving nutrient availability and plant performance in maize–soybean intercropping systems under marginal soil conditions. Full article

In response to China’s drive to bring newly cultivated land into production, this study evaluated how combined organic fertilizer and microbial inoculants affect soil quality, bacterial community structure, and maize yield. Four treatments were evaluated: FC (chemical fertilizer only), T50 (50% organic fertilizer + 50% chemical fertilizer), T50M (T50 plus microbial inoculant), and CK (no fertilizer). T50M significantly increased yield compared to FC and CK (p < 0.05), achieving the highest yield of 6995.73 kg ha⁻¹. This was 20.09% greater than FC. Community composition analyses showed that soil in newly cultivated land was dominated by Blastocatellia, Vicinamibacteria, and Alphaproteobacteria, together accounting for over 35.7% of total bacterial abundance. Redundancy analysis at the class level explained 55.7% of variance; soil organic matter (SOM) and available potassium positively correlated with Alphaproteobacteria and Bacteroidia, while available phosphorus and nitrate nitrogen aligned with Actinobacteria and Bacilli. Path analysis indicated that SOM and total nitrogen were the strongest positive drivers of yield. Actinobacteria and Acidobacteriae also showed direct positive effects, whereas Verrucomicrobiae had a negative effect. These results demonstrate that integrated organic–microbial amendments can enhance soil fertility and alter microbial diversity toward taxa that can improve maize productivity. Full article

Land-use type is a key factor influencing soil properties, microbial community composition, and plant nutrient status. In this study, five land-use types (Tibetan barley, rapeseed, walnut, wheat, and weeds) were investigated in a river valley of southeastern Tibet to compare their effects on soil chemical characteristics, microbial communities, and plant nutrients. Soils under walnut trees had significantly higher available phosphorus and microbial biomass phosphorus but lower soil organic matter. Rapeseed fields had higher levels of available potassium and were dominated by the fungal genus Tausonia; rapeseed leaves also contained the highest nitrogen and potassium concentrations. Weed plots supported a distinct fungal community dominated by Helvella. Tibetan barley and wheat increased overall bacterial and fungal diversity, with wheat soils with the highest microbial biomass carbon and nitrogen. Redundancy analysis indicated that soil total nitrogen, available nitrogen, and organic matter were the main drivers of plant nutrient variation, together explaining 93.5% of the total variance. These findings demonstrate how land-use type regulates soil–microbe–plant interactions in alpine valleys and provide empirical references for agricultural management and soil improvement on the Qinghai–Tibet Plateau. Full article

Challenges significantly hinder the sustainable cultivation of tea chrysanthemum, leading to imbalances in soil nutrients, the accumulation of allelopathic phenolic acids, reduced enzymatic activity, and disruptions in rhizosphere microbial communities. To explore potential mitigation strategies, this study systematically evaluated the integrative effects of exogenous methyl jasmonate (MeJA, 0–400 (μmol L⁻¹)) on both soil environmental parameters and plant growth performance under continuous cropping conditions. The results revealed that treatment with 100 (μmol L⁻¹) MeJA significantly enhanced plant height, canopy width, flower number, and fresh flower weight. Concurrently, it improved soil organic matter content, the available nitrogen levels, and redox stability while increasing the activity of key enzymes, including polyphenol oxidase, urease, and catalase. Notably, this treatment markedly reduced the accumulation of allelopathic phenolic acids, such as p-hydroxybenzoic acid and vanillic acid. High-throughput sequencing further demonstrated that 100 (μmol L⁻¹) MeJA optimized the composition of soil microbial communities, increasing the abundance of beneficial taxa, such as nitrogen-fixing and phosphate-solubilizing bacteria, while suppressing pathogenic fungi. Metabolomic analysis showed that this concentration of MeJA activated stress-resistance metabolic pathways involving flavonoids and terpenoids while downregulating degradation-related processes, thereby supporting enhanced plant resilience at the metabolic level. Collectively, these findings demonstrate that an appropriate concentration of exogenous MeJA can effectively alleviate continuous cropping obstacles in Chrysanthemum morifolium, providing both theoretical insights and practical guidance for its eco-friendly and efficient cultivation. Full article

In the Red List of Threatened Species, released by International Union for Conservation of Nature (IUCN), Paphiopedilum helenae has been classified as an endangered species. It exhibits exceptional decorative value and germplasm resource potential. To elucidate the ecological adaptation of this species and the characteristics of its rhizosphere microbiome, bacterial 16S rRNA and fungal ITS sequences of three wild populations of P. helenae were investigated using Illumina high-throughput sequencing technology and the microbial community structures and diversities were systematically compared. These three populations were spanned across distinct geographical locations in Longzhou County, Guangxi. The results showed that the bacterial community in the rhizosphere soil of P. helenae comprised 31 phyla, primarily including Actinobacteriota, Proteobacteria, Chloroflexi and Acidobacteriota. On the other hand, the fungal community consisted of 10 phyla, dominated by Ascomycota and Basidiomycota. There were significant differences in the diversity of rhizosphere microbes across different populations of P. helenae. The LG population had the highest bacterial richness (Chao index: 2912.71 ± 131.73; p < 0.05) and diversity (Shannon index: 6.40 ± 0.06; p < 0.01), while the MQ population had the lowest diversity (Shannon index: 3.47 ± 0.24; p < 0.01) of fungi. The degree of variation in fungal β-diversity was significantly higher than that of bacteria. Soil organic matter (SOM) and available nitrogen (AN) contents were the core factors shaping the microbial communities in the rhizosphere soil of P. helenae, which jointly explained 49.87% and 16.39% of variations in the bacterial and fungal communities. Furthermore, population-specific enrichment of functionally significant microorganisms was evident. Population MQ was enriched with plant growth-promoting and stress-resistant fungi, such as Geminibasidium, Trichoderma, etc. Population LG was enriched with oligotrophic bacteria (e.g., Patescibacteria), while population SL exhibited an overwhelming dominance of Ascomycota (93.25%) and enrichment of pathogenic fungal genus Nigrospora. This research revealed the variations in the functional adaptation strategy of P. helenae and the microbial communities in the rhizosphere soils across different geographical locations. This suggests that microbial community imbalance in rhizosphere soil may be one of the factors leading to the endangerment of this plant species. The study proposed a differentiated protection strategy for endangered plant species based on microbial resources. The results provide a theoretical basis for development of a “microorganism-assisted protection” strategy for ecological restoration and sustainable utilization of endangered orchid plants. Full article