Soil Total Nitrogen Research Articles

Effect of soil and community factors on the yield and medicinal quality of Artemisia argyi growth at different altitudes of the Funiu mountain.

Altitude and ecological factors significantly influence plant growth and the accumulation of secondary metabolites. However, current research on the impact of altitude and ecological factors on the yield and medicinal quality of Artemisia argyi (A. argyi) is limited. This study established sampling sites in wild populations of A. argyi across seven altitude ranges on Funiu Mountain. We quantified the yield, output rate of moxa, and key medicinal ingredients. Additionally, we analyzed the response of yield and medicinal quality of wild A. argyi populations to various ecological factors at different altitudes. The results showed that wild populations of A. argyi exhibited higher yields and medicinal quality at altitudes below 500 m. Yield was positively correlated with higher soil total nitrogen (TN) content and lower soil total phosphorus (TP) content, while the improvements in medicinal quality were positively associated with higher population density and lower contents of both soil TN and TP. The variation in soil C/N, C/P, and N/P ratios across different altitudes was substantial, affecting soil mineralization and subsequently influencing the absorption of mineral elements by A. argyi. Notably, the phosphorus content in leaves and stems was negatively correlated with yield and medicinal quality, respectively. In contrast, the accumulation of nitrogen, phosphorus, and potassium in leaves was positively correlated with yield. The differences in the primary medicinal ingredients between the leaves and stems of A. argyi were maximum at altitudes below 500 m. The contents of neochlorogenic acid and cryptochlorogenic acid in both leaves and stems showed a significant positive correlation. In the principal component analysis, the primary medicinal ingredients from the leaves contributed more significantly to the overall quality than those from stems. These results suggest that A. argyi is best suited for cultivation at altitudes below 500 m. Population density and the soil's TN and TP contents play a crucial role in determining the yield and medicinal quality of A. argyi. Futhermore, the medicinal quality of A. argyi is more indicative of the main medicinal ingredients found in the leaves, while the stems also serve as a key organ for accumulating flavonoids and phenolic acids.

Reinforcing Nitrogen Nutrition Through Partial Substitution with Organic Nitrogen Enhances the Properties of Natural Rubber

The partial substitution of chemical fertilizer with organic fertilizer is a crucial practice for enhancing crop production and quality, although its impact on natural rubber has rarely been explored. In this study, a two-year field experiment was conducted to investigate the impact of different nitrogen application rates and varying proportions of organic nitrogen substitution on dry rubber yield, nitrogen nutrition, and natural rubber properties. Regarding nitrogen application, the control treatment received no nitrogen amendment, while the low-nitrogen treatment was amended with 138 g·tree−1·year−1 of nitrogen. The medium-nitrogen treatment received 276 g·tree−1·year−1 of nitrogen, and the high-nitrogen treatment received 552 g·tree−1·year−1 of nitrogen. In addition, the low-organic-nitrogen substitution treatment and medium-organic-nitrogen substitution treatment were amended with 276 g·tree−1·year−1 of nitrogen each. The results demonstrated that the 50% organic nitrogen substitution treatment resulted in the highest dry rubber yield across all sampling periods, ranging from 46.43 to 94.65 g·tree−1. Additionally, this treatment exhibited superior soil total nitrogen (1067.69 mg·kg−1), available nitrogen (84.06 mg·kg−1), and nitrogen content in roots (1.08%), leaves (3.25%), fresh rubber latex (0.27%), and raw natural rubber (0.44%) compared with other treatments. In terms of the physical properties of natural rubber, the 50% organic nitrogen substitution treatment resulted in advantages in the weight-average molecular weight (1.57 × 106 g·mol−1), number-average molecular weight (0.36 × 106 g·mol−1), plasticity retention index (97.35%), Wallace plasticity (40.25), and Mooney viscosity (81.40). For mechanical properties, natural rubber from the substitution treatment exhibited higher tensile strength (19.84 MPa), greater elongation at break (834.75%), and increased tear strength (31.07 N·mm−1). Overall, the substitution of 50% chemical nitrogen fertilizer with organic nitrogen fertilizer improved nitrogen nutrition in rubber trees by introducing organic nitrogen input, resulting in remarkable enhancements in natural rubber properties. Therefore, the incorporation of organic fertilizer as a substitution for 50% of chemical fertilizer is demonstrated as an effective strategy for improving both the yield and properties of natural rubber.

Biochar affects soil properties over 1 m depth in an alkaline soil of north China Plain

Biochar has been shown to enhance soil quality and agricultural yields. Previous studies about biochar's effect on soil properties mainly concentrated on the top 30 cm layer but less on the subsoils. Given the subsoil's active role in climate change mitigation and its significance for nutrient cycling and crop productivity, understanding biochar's effects at depth is crucial. This study explored the responses of soil organic carbon (SOC), total nitrogen, available potassium, available phosphorus, pH, and electrical conductivity to different doses of biochar addition (0, 10, 20, and 30 Mg/ha) over the 1 m depth of alkaline soil. Additionally, the impact of biochar on soil microbial community was assessed in the top 20 cm. Results demonstrated that biochar addition can increase SOC and improve soil properties in deep soil horizons. Specifically, a 30 Mg/ha biochar addition increased SOC by 1.2–10.1 Mg C/ha in the 10–40 cm layer and by 3 Mg C/ha in the 60–80 cm depth over two years. Additionally, biochar addition at this rate increased total nitrogen by 0.2–0.3 g N/kg in the 10–40 cm depth and elevated available potassium across the 1 m profile, with a maximum increment of 313 mg/kg in the surface 10 cm and a minimum of 97 mg/kg in the 40–60 cm depth. While biochar application did not increase available phosphorus, it resulted in a minor decrease in soil pH (<0.7 units) and a slight increase in electrical conductivity. Moreover, biochar addition did not significantly alter the soil microbial community. Our findings underscore the importance of considering subsoils when evaluating biochar's impact on soil properties. We suggest that subsoils should be considered when estimating the potential of cropland management for increasing soil carbon sequestration and improving soil conditions.

Effects of Cover Measures on Soil Organic Nitrogen Fractions and Total Soluble Nitrogen Pools in Citrus Orchards of the Red Soil Hilly Region of Southern China

Effects of Cover Measures on Soil Organic Nitrogen Fractions and Total Soluble Nitrogen Pools in Citrus Orchards of the Red Soil Hilly Region of Southern China

Evaluating the impacts of area closure on soil properties in south central highland of Ethiopia

Soil degradation affects its quality and productivity of the land. To control soil degradation, various soil and water conservation (SWC) measures, including area closure are implemented. Understanding the impacts of SWC measures could support planning and implementation of land management practices. This study aimed to investigate impacts of area closure on soil properties in south central highland of Ethiopia. To acquire the necessary data, we conducted interviews with 80 households. Furthermore, nine years old area closure with physical soil and water conservation (AC-SWC), open grazing with physical SWC (OG-SWC), and open grazing without physical SWC (OG) were identified and each divided into upper, middle, and lower slope positions. In each slope position, 3 sample plots were established at 25–50 m intervals. A total of 27 composite samples and other 27 core samples for bulk density (3 treatments∗3 slope position∗3 replications) were collected and analyzed for soil properties. The data were analyzed using descriptive statistics and one-way ANOVA. The results showed that about 98 % of the respondents perceived that area closure would be an effective way to restore degraded land. Majority of the farmers (86 %) believed that area closure could reduce soil erosion and replenish soil fertility and thus, is beneficial in improving land productivity. Soil test results revealed that AC-SWC had significantly greater (P < 0.05) clay fractions, pH, available potassium, and available phosphorus than OG-SWC and OG. Variations of soil organic carbon (SOC) and total nitrogen (TN) were more pronounced. The SOC in AC-SWC was 83 % and 314 % greater than OG-SWC and OG, respectively. In the AC-SWC, TN was three and seven times higher than that of OG-SWC and OG, respectively. This could be due to vegetation restoration that reduces erosion, and enhances organic matter, moisture, and nutrient. The SOC, TN, pH, available potassium, and clay were significantly greater (P < 0.05) at lower slope position than upper in all forms of land management, which could be due to deposition at downslope. About 12 % and 11 % variations of clay fractions and SOC were, respectively, observed in between upper and lower slope positions at AC-SWC, but they varied by 25 % and 57 %, respectively, in OG. These imply area closure has had a beneficial effect on soil properties even on sloping land. AC-SWC is an important option to integrate in land management for rehabilitation of degraded soil.

Soil Properties Regulate Soil Microbial Communities During Forest Succession in a Karst Region of Southwest China

Natural vegetation restoration has emerged as an effective and rapid approach for ecological restoration in fragile areas. However, the response of soil microorganisms to natural succession remains unclear. To address this, we utilized high-throughput sequencing methods to assess the dynamics of soil bacterial and fungal communities during forest succession (shrubland, secondary forest, and primary forest) in a karst region of Southwest China. Our study revealed that bacterial α-diversity was significantly higher in secondary forest compared to both shrubland and primary forest. Intriguingly, the soil bacterial community in primary forest exhibited a closer resemblance to that in shrubland yet diverged from the community in secondary forest. Conversely, the soil fungal community underwent notable variations across the different forest stages. Furthermore, analysis of the microbial co-occurrence network revealed that, within these karst forests, the relationships among soil fungi were characterized by fewer but stronger interactions compared to those among bacteria. Additionally, soil properties (including pH, soil organic carbon, total nitrogen, moisture, and available potassium), soil microbial biomass (specifically phosphorus and nitrogen), and plant diversity were the drivers of soil bacterial community dynamics. Notably, soil pH accounted for the majority of the variations observed in the soil fungal community during karst forest succession. Our findings provide valuable insights that can inform the formulation of strategies for ecological restoration and biodiversity conservation in karst regions, particularly from a microbial perspective.

Elevation, Soil and Environmental Factors Determine the Spatial and Quantitative Distribution of Qinghai Spruce Recruitment Biomass in Mountainous (Alpine) Watersheds

Soil heterogeneity observed in the alpine environment plays a very important role in the growth of forest recruitment. However, the mechanisms by which the biomass accumulation and allocation patterns of forest recruitment respond to such environmental differences are unclear, which hinders a thorough understanding of climate change’s impact on forest biomass. We hypothesized that soil heterogeneity influences the distribution of Qinghai spruce recruitment biomass along with elevation. In the frame of this study, carried out in the northern Tibetan Plateau, forest Qinghai spruce recruitment data were combined with soil data derived from 24 sample plots, while permutation multifactor ANOVA and multiple linear regression were utilized to reveal the characteristics of forest recruits’ above- and below-ground biomass and their allocation patterns in response to soil heterogeneity. According to the results, the soil heterogeneity mainly affected the distribution characteristics of recruits’ above- and below-ground biomass at different elevations, while the recruits’ root–shoot ratio variability was influenced by a combination of soil and other environmental factors. Soil organic carbon (SOC) had the greatest effect on the variability of the above- and below-ground biomass of spruce recruits, with R2 of 0.280 and 0.257, respectively. Soil organic carbon and soil moisture content (SMC) had a significant effect on the variability of the root–shoot ratio, with R2 of 0.168 and 0.165, respectively. Soil total nitrogen (TN) and soil organic carbon were the main influencing factors of the above-ground biomass of forest recruits, with contribution rates of 43.15% and 35.28%, respectively. Soil total nitrogen and soil organic carbon were also the main factors influencing the below-ground biomass of forest recruits, with contribution rates of 42.52% and 37.24%, respectively, and both of them had a positive effect on biomass accumulation, and the magnitude of the influence varied with the elevation gradient. Soil moisture content was the main influence factor of spruce recruits’ root–shoot ratio, with a contribution rate of 54.12%. Decreasing soil moisture content would significantly increase the root–shoot ratio of spruce recruits and promote plants to allocate more biomass to root growth. Changes in elevation not only affected the intensity of the effect of soil factors on spruce recruitment biomass and its allocation pattern but even led to a change in the positive and negative effects.

Biological soil crusts significantly improve soil fertility and change soil microbiomes in Qinghai-Tibetan alpine grasslands.

Biological soil crusts (BSCs), a vital component of ecosystems, are pivotal in carbon sequestration, nutrient enrichment, and microbial diversity conservation. However, their impact on soil microbiomes in alpine regions remains largely unexplored. Therefore, this study aimed to determine the influence of BSCs on alpine grassland soil microbiomes, by collecting 24 pairs of soils covered by biological and physical crusts along a transect on the Qinghai-Tibetan Plateau. We found that BSCs significantly increased the contents of soil moisture, organic carbon, total nitrogen, and many available nutrients. They also substantially altered the soil microbiomes. Specifically, BSCs significantly increased the relative abundance of Cyanobacteria, Verrucomicrobiota, and Ascomycota, while decreasing the proportions of Gemmatimonadota, Firmicutes, Nitrospirae, Mortierellomycota, and Glomeromycota. By contrast, microbial abundance and α-diversity demonstrated low sensitivity to BSCs across most study sites. Under the BSCs, the assembly of prokaryotic communities was more affected by homogeneous selection and drift, but less affected by dispersal limitation. Conversely, soil fungal community assembly mechanisms showed an inverse trend. Overall, this study provides a comprehensive understanding of the effects of BSCs on soil properties and microbial communities, offering vital insights into the ecological roles of BSCs.

Surface soil sampling underestimates soil carbon and nitrogen storage of long-term cover cropping

Cover cropping is a promising management practice for soil health and climate change mitigation by improving soil organic carbon (SOC) and total nitrogen (TN) stocks. However, limited studies focused on deeper soil layers (>30 cm depth) where soil C is more stable than that in surface soil (≤30 cm depth). Here, deep soil sampling was conducted in a 15-year cover cropping experiment, in a horticulture-grain system on sandy loam soil. The SOC and TN stocks were expressed on an equivalent soil mass basis using a cubic spline model. Overall, long-term cover cropping had significantly greater SOC and TN stocks by 22 % (95 %CI: 5–43 %) and 26 % (95 %CI: 6–49 %), respectively in the 0–120 cm depth, compared to no cover cropping. Additionally, the mean SOC and TN sequestration rate (0–30 cm depth) was 0.53 Mg C ha−1 yr−1 and 0.06 Mg N ha−1 yr−1, respectively. However, if only 0–15 cm depth was evaluated, long-term cover cropping did not significantly affect SOC and TN stocks. These results indicated that shallow sampling (<15 cm depth) may not provide comprehensive information on the effect of long-term cover cropping on soil C and N storage. To better understand the mechanism of bulk soil C and N storage, we investigated their distribution between particulate and mineral-associated organic matter pools (POM and MAOM). We found POM pool was the main store of bulk SOC and TN stocks in surface soils while it was the MAOM pool in deeper soil layers, without soil texture change with soil depth. These findings indicated that soil C and N sources for bulk SOC and TN accrual differed in surface and deeper soils. Our study demonstrated that long-term cover cropping can facilitate SOC accumulation in the soil below 15 cm deep, which calls into question carbon capture protocols that focus on shallow soil depths.

Rubber-Based Agroforestry Ecosystems Enhance Soil Enzyme Activity but Exacerbate Microbial Nutrient Limitations

Agroforestry ecosystems are an efficient strategy for enhancing soil nutrient conditions and sustainable agricultural development. Soil extracellular enzymes (EEAs) are important drivers of biogeochemical processes. However, changes in EEAs and chemometrics in rubber-based agroforestry systems and their mechanisms of action are still not fully understood. Distribution of EEAs, enzymatic stoichiometry, and microbial nutrient limitation characteristics of rubber plantations under seven planting patterns (RM, rubber monoculture system; AOM, Hevea brasiliensis-Alpinia oxyphylla Miq; PAR, Hevea brasiliensis-Pandanus amaryllifolius Roxb; AKH, Hevea brasiliensis-Alpinia katsumadai Hayata; CAA, Hevea brasiliensis-Coffea Arabica; CCA, Hevea brasiliensis-Cinnamomum cassia (L.) D. Don, and TCA, Hevea brasiliensis-Theobroma Cacao) were analyzed to investigate the metabolic limitations of microorganisms and to identify the primary determinants that restrict nutrient limitation. Compared with rubber monoculture systems, agroforestry ecosystems show increased carbon (C)-acquiring enzyme (EEAC), nitrogen (N)-acquiring enzyme (EEAN), and phosphorus (P)-acquiring enzyme (EEAP) activities. The ecoenzymatic stoichiometry model demonstrated that all seven plantation patterns experienced C and N limitation. Compared to the rubber monoculture system, all agroforestry systems exacerbated the microbial limitations of C and N by reducing the vector angle and increasing vector length. P limitation was not detected in any plantation pattern. In agroforestry systems, progression from herbs to shrubs to trees through intercropping results in a reduction in soil microbial nutrient constraints. This is primarily because of the accumulation of litter and root biomass in tree-based systems, which enhances the soil nutrient content (e.g., soil organic carbon, total nitrogen, total phosphorus, and ammonium nitrogen) and accessibility. Conversely, as soil depth increased, microbial nutrient limitations tended to become more pronounced. Partial least squares path modelling (PLS-PM) indicated that nutrient ratios and soil total nutrient content were the most important factors influencing microbial C limitation (−0.46 and 0.40) and N limitation (−0.30 and −0.42). This study presented novel evidence regarding the constraints and drivers of soil microbial metabolism in rubber agroforestry systems. Considering the constraints of soil nutrients and microbial metabolism, intercropping of rubber trees with arboreal species is recommended over that of herbaceous species to better suit the soil environment of rubber plantation areas on Hainan Island.

A study on hyperspectral soil total nitrogen inversion using a hybrid deep learning model CBiResNet-BiLSTM

Rapid, accurate and non-destructive acquisition of soil total nitrogen (TN) content in the black soil zone is significant for achieving precise fertilization. In this study, the soil types of corn and soybean fields in Jilin Agricultural University, China, were selected as the study area. A total of 162 soil samples were collected using a five-point mixed sampling method. Then, spectral data were obtained and the noisy edge were initially eliminated. Subsequently, the denoised spectral data underwent smoothing by using the Savitzky–Golay (SG) method. After performing the first-order difference (FD) and second-order difference (SD) transformations on the data, it was input to the model. In this study, a hybrid deep learning model, CBiResNet-BiLSTM, was designed for precise prediction of soil TN content. This model was optimized based on ResNet34, and its capabilities were enhanced by incorporating CBAM in the residual module to facilitate additional eigenvalue extraction. Also, Bidirectional Long Short-Term Memory (BiLSTM) was integrated to enhance model accuracy. Besides, partial least squares regression (PLSR), random forest regression (RFR), support vector machine regression (SVR), and back propagation neural network (BP), as well as ResNet(18, 34, 50, 101, 152) models were taken for comparative experiments. The results indicated that the traditional machine learning model PLSR achieved good performance, with R2 of 0.883, and the hybrid deep learning model CBiResNet-BiLSTM had the best inversion capability with R2 of 0.937, with the R2 being improved by 5.4%, compared with the PLSR model. On this basis, we present the LUCAS dataset to demonstrate the generalisability of the model. Therefore, the CBiResNet-BiLSTM model is a fast and feasible hyperspectral estimation method for soil TN content.Graphical abstract

Enhancing soybean yield stability and soil health through long-term mulching strategies: Insights from a 13-year study

Sustainable agriculture systems incorporate important stabilizing mechanisms, such as mulching, for increasing yield and improving soil health. However, the synergistic effects of different long-term mulching practices on soybean yield stability and soil health remain unexplored. In this study, we conducted a 13-year long-term investigation to evaluate the impacts of various mulching methods—no mulching (CK), straw mulching (SM), plastic mulching (PM), and ridged and plastic mulching (RM)—over a 13-year period on soil nutrients, and soybean yield, stability, and sustainability. Our findings revealed that SM, PM, and RM treatments significantly increased the average yields by 28.02 %, 20.49 %, and 51.56 %, respectively. Moreover, SM and RM treatments significantly enhanced yield stability (SM +107.90 %, RM +98.82 %) and sustainability (SM +47.85 %, RM +37.14 %). Additionally, compared to CK, the SM treatment significantly increased the average soil organic carbon (SOC) and total nitrogen (STN) content by 16.78 % and 16.23 %, respectively. Meanwhile, mulching practices also improved soil reactive carbon and nitrogen pools. Compared to CK, plastic mulch reduced microbial biomass carbon (MBC) content (PM −8.85 %, RM −0.73 %) and soil ammonium nitrogen (AN) content (PM −8.19 %, RM −1.20 %), while increasing microbial biomass nitrogen (MBN) content (PM +8.73 %, RM +9.47 %). The SM treatment increased MBC, AN, and MBN contents by 0.24 %, 7.23 %, and 8.94 %, respectively. Additionally, SM and RM treatments significantly increased β-1,4-glucosidase (BG) activity (SM +98.74 %, RM +128.25 %) and decreased and β-1,4- n -acetamido-glucosidase (NAG) + 1-leucine aminopeptidase (LAP) (NAG + LAP) activity (SM −28.74 %, RM −25.33 %) compared to CK. Furthermore, SM, PM, and RM treatments significantly increased the Chao1 index by 35.30 %, 68.08 %, and 52.23 %, respectively, compared to CK. Finally, results of the Mantel test and random forest model indicated that the increases in yield and stability were due to improved soil temperature (ST), active carbon and nitrogen pools, enzyme activity, and diazotrophic bacterial diversity. In summary, our findings suggest that ridged and plastic mulching enhances soil nutrient effectiveness by maintaining soil moisture and regulating diazotrophic bacterial community structure, thereby increasing soybean yields. Conversely, straw mulching continuously supplies nutrients to the soil, enhancing soil quality and diazotrophic bacterial community structure, thus improving yield stability. Over all, our findings provides new insights into global long-term agricultural sustainability.

Relationship between root system-soil C:N:P and soil microbial diversity at different evolutionary stages of Caragana tibetica scrub in arid desert grassland, Northern China.

Scrub root systems play a crucial role in preventing soil erosion and nutrient loss. However, the effects of the root system configuration on soil nutrient dynamics and microbial changes at various evolutionary stages remain poorly understood. In this study, we investigated the relationship between soil physical and chemical properties and the diversity of bacteria and fungi throughout the evolutionary stages of the scrub root systems. This was achieved through a combination of whole-root excavation and root tracing techniques. The results indicated that root diameter was the main factor contributing to the continuous increase in carbon (C): phosphorus (P) and nitrogen (N): P ratios as the scrub sand pile developed. The soil organic carbon (SOC), total soil nitrogen (TN), and total soil phosphorus (TP) contents in the soil in the four evolutionary stages were the highest during the developmental stage, but the change in TP content was not statistically significant (P > 0.05). Partial least squares path modeling and redundancy analysis (RDA) indicated that root system stoichiometric C and N contents were positively correlated with microbial diversity (R2 = 0.85). There was no correlation between the evolutionary stage and soil nutrient TN, whereas soil nutrient TN was negatively correlated with microbial diversity (R2 = -0.92). These findings elucidate the relationship between the evolutionary stage of root chemical measurement characteristics, soil elements and microorganisms, and their subsequent effects on root elemental composition and microbial diversity. This study enhances the current understanding of plant-soil interactions in desert steppe ecosystems.

Effects of Compost Application of Green Waste on Soil Properties: A Meta-Analysis

Objective: With the accelerating urbanization process, the garden area is gradually expanding, and the production of green waste is also increasing. Composting green waste can not only reduce environmental pollution caused by incineration and landfill and improve the utilization efficiency of resources but also improve the soil and increase soil productivity. The study aims to investigate the comprehensive impact of green waste compost (GWC) application on soil nutrient conditions. Through comprehensive data analysis, the impact of compost application of green waste on soil properties was revealed as a reference for compost application and fertilizer reduction. Methods: Based on meta-analysis, we quantitatively investigated the response of soil properties to the application of green waste, collected published experimental data, and integrated 25 domestic and international literature to analyze the effects of different soil properties on soil nutrients. Literature was used to analyze the impact of different application rates of GWC on the physicochemical properties of soils with varying pH levels. The results were compared to control conditions with no GWC application. Results: The application of significantly improved soil quality by reducing soil bulk density and increasing the levels of soil organic matter, organic carbon, total nitrogen, available phosphorus, available potassium, and dehydrogenase activity. The increases in available potassium and soil organic carbon were consistently significant across all subgroups. However, the effects on available phosphorus and organic matter varied in significance depending on initial soil pH. Soil bulk density was influenced by the GWC content, while dehydrogenase activity showed significant effects only when initial soil pH was ≥8. Total nitrogen levels were significantly impacted by GWC application in soil with an initial pH of &lt;8 and at GWC contents of ≥50%. Conclusion: The application of green waste compost demonstrates a positive effect on soil improvement. This study provides a comprehensive database that supports the use of GWC in enhancing soil quality and reducing the need for chemical fertilizers.

The Effects of Acid-Modified Biochar and Biomass Power Plant Ash on the Physiochemical Properties and Bacterial Community Structure of Sandy Alkaline Soils in the Ancient Region of the Yellow River

The application of biochar can effectively enhance soil organic matter (SOM) and improve soil structure. Biomass power plant ash (BPPA) is also rich in essential nutrients for plants, with similar carbon content. Considering production cost and agricultural waste recycling, it is beneficial to apply BPPA to improve soil fertility and quality. However, it remains unclear whether its ameliorative effects surpass those of biochar in alkaline soils. In the study, we set up seven pot experiments of faba beans in sandy alkaline soils from the ancient region of the Yellow River, including the controls (CK), different amounts of acid-modified BPPA (A1, A2, A3), and the same amounts of acid-modified biochar (B1, B2, B3), to compare their effects on soil physiochemical properties and bacterial community structure. The results indicate that the application of both biochar and BPPA can improve soil physiochemical properties. At the same dosage, the biochar application outperformed BPPA treatment in terms of soil physical properties such as bulk density (BD), maximum water-holding capacity (FC), and soil capillary porosity (SP2). Conversely, BPPA treatment displayed advantages in chemical properties such as readily oxidizable organic carbon (ROOC), total nitrogen (TN), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), and electrical conductivity (EC). All the treatments enhanced the richness and diversity of bacterial communities, increasing the relative abundance of eutrophic groups such as Bacteroidota and Firmicutes while decreasing that of oligotrophic groups like Actinobacteriota. BPPA also increased the relative abundance of Proteobacteria, while the opposite was observed for biochar. Correlation analysis showed that the environmental factors such as soil pH, EC, TN, AK, SOM, and SP2 emerged as primary factors influencing the bacterial community structure of alkaline soils, significantly affecting their diversity and abundance. Among them, SP2 and SOM were the dominant physical and chemical factors, respectively. Overall, the application of both acid-modified BPPA and biochar can enhance the physiochemical properties of sandy alkaline soils, while the application of BPPA is superior for improving soil nutrient content and enhancing bacterial community structure. The study explores the potential mechanisms through which the application of acid-modified BPPA affects soil characteristics and microbial features, providing new insight into developing optimizing fertilization strategies for enhancing soil quality in the ancient region of the Yellow River.

Diversity of Mycorrhizal Types Along Altitudinal Gradients in the Tropical Andes

ABSTRACTAimMycorrhizal fungi play key roles in the functioning of terrestrial ecosystems. The main types of mycorrhizal associations are arbuscular mycorrhizae, ectomycorrhizae, ericoid mycorrhizae and orchid mycorrhizae. Previous studies have shown that the abundance of plants with different types of mycorrhizal associations change gradually along latitudinal and altitudinal gradients driven by the effects of climate and soil nutrients. We aimed to understand how altitude and climatic and soil variables shape the distribution patterns of tropical plant mycorrhizal types and nitrogen‐fixing plants along altitudinal gradients in the Andes.LocationColombian Andean mountain range.Time PeriodPresent day.Major Taxa StudiedPlants (vascular and non‐vascular).MethodsWe used a herbarium plant records database and assigned mycorrhizal type to each plant species based on the available literature. Bioclimatic and soil variables were also compiled at a resolution of 10 km. We calculated the proportion of each mycorrhizal association type per grid cell and created a diversity index to explore their spatial distribution and association with abiotic factors based on LMs.ResultsThe diversity of mycorrhizal associations increased with altitude and peaked around 3000 m, in an ecotone belt known as the subpáramo recognised by the high abundance of Ericaceae species. Soil carbon stock and soil total nitrogen were also positively correlated with the diversity of mycorrhizal types. Moreover, the abundance of arbuscular mycorrhizal plants was highest at low elevations and increased with the proportion of nitrogen‐fixing plants per cell.Main ConclusionsOur results indicate that mycorrhizal associations gradually change along altitudinal gradients in the tropical Andes. Climatic factors and the interactions between climatic and edaphic factors have the greatest explanatory power to predict the distribution of types of mycorrhizal associations along the altitudinal gradient. Based on these results we expect that climate change could potentially alter the distribution of mycorrhizal types in tropical mountains with unknown consequences for ecosystem functions.

Prescribed burning alters soil microbial community structure by changing soil physicochemical properties in temperate forests of northern China

Prescribed burning is commonly used to maintain forest ecosystem functions and reduce the risk of future wildfires. Although many studies have investigated the response of microbial community to wildfires in forest ecosystems, the effects of prescribed burnings on soil microbial community structure are less studied. It is also unclear that how post-fire soil physiochemical properties changes affected soil microbial communities. Here, we studied the impacts of prescribed burning on soil microbiome in three typical temperate forests of northern China by collecting soil physicochemical and high-throughput sequencing for 16S rRNA and 18S rRNA was applied to analyze the diversity and community composition of soil microbes (bacteria and fungi). Compared with pre-fire condition, prescribed burning significantly decreased Chao1 index and altered soil bacterial communities (P < 0.05), whereas it had no significant effect on fungal diversity and community structure of the (P > 0.05). Planctomycetes and Actinobacteria made the greatest contributions to the bacterial community dissimilarity between the pre-fire and post-fire conditions. The main variables influencing the post-fire soil microbial community structure are soil pH, available phosphorus, total nitrogen, and the ratio of soil total carbon to soil total nitrogen, which could account for 73.5% of the variation in the microbial community structure in these stands. Our findings demonstrated a great discrepancy in the responses of bacteria and fungi to prescribed burning. Prescribed burning altered the soil microbial structure by modifying the physicochemical properties. Our results pointed that it is essential to evaluate the impact of prescribed burnings on forest ecosystem functions. These findings provide an important baseline for assessing post-fire microbial recovery in the region and offer critical guidance for restoration efforts.

Biochar, Organic Fertilizer, and Bio-Organic Fertilizer Improve Soil Fertility and Tea Quality

Tea, the world’s second most traded commodity, significantly impacts the economies of producing countries. However, prolonged cultivation leads to soil degradation, particularly through acidification and the depletion of essential nutrients, which adversely affects tea quality. This study investigates the effects of biomass materials—biochar, organic fertilizer, and bio-organic fertilizer—on both tea quality and soil properties. The results revealed that all biomass treatments improved the catechin quality index (CQI) of tea, with bio-organic fertilizer (BOF) yielding the highest CQI at 629.41, followed closely by biochar (624.16) and organic fertilizer (581.34). Soil analysis indicated that biochar increased soil pH from 4.53 to 5.54, total carbon by 194.6% (from 12.61 g kg−1 to 24.42 g kg−1), and nitrogen levels by 11.7% (from 14.91 mg kg−1 to 16.17 mg kg−1), while reducing soluble salts significantly. Furthermore, biomass treatments enhanced enzyme activities, with urease and acid phosphatase increasing by up to 136.6% and 149.5%, respectively. Correlation analysis revealed significant positive relationships, with tea amino acid content correlating with soil total nitrogen (r = 0.62, p &lt; 0.05) and tea polyphenols positively correlating with available potassium (r = 0.60, p &lt; 0.05). This study demonstrates that integrating biomass materials into tea cultivation not only enhances tea quality but also contributes to soil health, supporting sustainable tea garden management practices.

Soil organic carbon and total nitrogen stocks related to land use and basic environmental properties − assessment of soil carbon sequestration potential in different ecosystems

Soil organic carbon (SOC) and total nitrogen (TN) stocks are crucial for the development of wild plants and crops. This paper examines the current SOC and TN stocks and their variability within land uses under different environments, assessing the relationships between SOC and TN stocks with basic environmental properties and quantifying the magnitude of SOC sequestration potential for a better land use management. We studied 991 soil profiles, from steppe to wet mountain-soils. The land use was essential in influencing soil organic C and total N stocking, with the forestland showing the significantly highest SOC stocks specifically in mountain soils, followed by grassland and cropland. Altitude, clay content, pH and plant available phosphorous and potassium were other influencers of SOC and TN stocks. The best predictive multiple linear regression model explained 68 % of the 0.5 m depth SOC stock variability for forest, 61 % for grassland and 37 % for cropland, while Random Forest model explained 70 %, 65 %, and 28 % for the same land uses. The obtained models rank factors contribution and may be useful in management. Lands having the highest C sequestration potential occurred within fine-textured soils, mainly in croplands. The most favorable soil depth for further C sequestration is below C-saturated topsoil and this could be achieved by deep-rooting crops and conservative technologies. Additionally, changing some low-fertile soils of cropland into forestland or grassland would improve SOC sequestration. These measures might contribute to sequester additional C amounts in soils, in order to bolster initiatives for climate-change mitigation and adaptation.

Continuous cropping obstacles: Insights from the community composition and the imbalance carbon fluxes within soil nematode food web

Long-term continuouscroppingcan lead to the deterioration of soil environment and the decrease of soil productivity. However, the biological mechanism on the negative effects of long-term continuous cropping has not been extensively explored. Soil nematode food web with multiple trophic levels play critical roles in nutrient cycling and energy flowing in the agroecosystem. Quantifying the carbon flux through different trophic channels within the nematode food web can indicate how continuous cropping influences carbon cycling in the agroecosystem by altering soil biota communities. Therefore, the effects of continuous peanut cropping with different years (1, 5, 20, and 30 years) on soil properties, soil nematode community composition, carbon flux within nematode food web and crop yields were investigated. Results showed that soil pH significantly decreased with increasing continuous cropping years. Differently, soil organic carbon and total nitrogen were the highest in 20-year, and decreased in 30-year of continuous cropping. As continuous cropping years increased, the relative abundance of microbivorous nematodes decreased and that of plant parasites reached as high as 76.11 % and 68.22 % in 20- and 30-year, respectively. Pearson correlation analysis revealed the nematode diversity, the carbon flux uniformity and peanut yield had a significant negative correlation with continuous cropping years. The random forest model indicated that the soil pH and the relative abundance of plant parasites were the key influence factor of the carbon flux uniformity within soil nematode food web. Outbreaks of plant parasites lead to the disruption of carbon flux uniformity within soil nematode food web, which can increase the risk of peanut yield decline after long-term continuous cropping. In conclusion, continuous peanut cropping changed soil properties, reduced soil nematode diversity, and disturbed the multitrophic carbon flux complementarity and uniformity in soil nematode food web, ultimately limiting the crop productivity. This study enhances our understanding of the importance of the resource transfers among soil food web in maintaining sustainable agroecosystem productivity.