Soil Nutrient Elements Research Articles

Long-term intercropping shaped soil bacterial microbiome composition and structure of maize fields in a semiarid region

Intercropping has gained attention for its potential to enhance soil health and increase crop yields in agroecosystems, in which soil microbial community play a key regulatory role. Bacteria is critical for a variety of soil biological processes, so promoting the understanding of soil microbiome within bacteria can improve the agricultural management practices. Here, the responses of soil bacterial community composition, functions, and assembly to long-term intercropping were assessed using 16S rRNA gene sequencing in the mountainous area of Southern Ningxia, spanning approximately 10 years until summer 2022. The experiment comprised three field treatments: maize monoculture (MM), intercropping of maize and potato (MP) and intercropping of maize and soybean (MS). The results showed that intercropping altered the relative abundance of major phyla and genera, and life-history strategies, mainly influenced by microbial biomass carbon and enzyme activities. The ratio of K- to r-strategy bacteria showed a trend of MP (0.77) > MM (0.76)> MS (0.56). Soil bacterial community structure of MP and MS was significantly different and similar to that of MM, respectively. Bugbase and PICRUSt2 analysis predicted the phenotype and metabolic pathways of soil bacterial community in maize fields, revealing that maize-legume intercropping increased the oxygen tolerance of soil bacteria. Moreover, intercropping enhanced the co-occurrence network complexity and the roles of homogeneous selection and drift, while bacterial community assembly was mainly driven by stochastic processes in MM (62.32 %), MP (60.68 %), and MS (59.17 %) soils. A variety of complex factors strongly governed bacterial community and assembly processes, such as soil nutrient elements and moisture. In brief, the study revealed the effect of intercropping on soil bacterial community, contributing to the further understanding of agricultural management practices.

Organic matter accumulation encouraged K-strategy bacteria increase and metabolism variation in karst vegetation restoration

Vegetation restoration plays a critical role in terrestrial carbon sink increase, especially in subtropic Southwest China which has been the hotspot of vegetation restoration areas in recent decades. However, the variations in microbial community diversity resulting from this intervention remain unclear, and further research is needed to elucidate the complex interactions between microorganisms and soil nutrient elements. Soil samples were collected from three vegetation restoration stages in a karst rocky desertification (KRD) valley of Southwest China, which were named dry cropland (CL), 3–8 years grassland (WL), and afforestation land that recovered more than 20 years (AL), to investigate the soil nutrient and bacterial diversity variation during vegetation restoration course. The soil organic carbon (SOC) and total nitrogen (TN) contents are significantly higher in the afforestation land soil compared to the cropland and grassland soils, while the available nutrient contents decrease during the vegetation restoration course. The soil dominant bacteria genus shifts from R-strategy bacteria in cropland to K-strategy bacteria in afforestation land, and the relative abundances of R-strategy genera remain similar in the grassland and cropland soil. The dual-relative bacteria network evaluates from simple correlation net to very complex ones during the vegetation restoration, of which the core influenced factor alters from available nutrients to organic matter. The results of this study suggest that it will take a relatively longer period for the soil nutrient conditions and bacterial community to recover fully, although vegetation restoration could reduce the impacts of agricultural activities. This study refers to the ecological preservation and restoration strategies under the global climate change background, elucidating the nutrient metabolism variation induced by the accordance variation of organic matter accumulation and soil bacterial life strategy during the ecosystem restoration course.

Rhizosphere microbial community construction during the latitudinal spread of the invader Chromolaena odorata

The colonization of alien plants in new habitats is typically facilitated by microorganisms present in the soil environment. However, the diversity and structure of the archaeal, bacterial, and fungal communities in the latitudinal spread of alien plants remain unclear. In this study, the rhizosphere and bulk soil of Chromolaena odorata were collected from five latitudes in Pu’ er city, Yunnan Province, followed by amplicon sequencing of the soil archaeal, bacterial, and fungal communities. Alpha and beta diversity results revealed that the richness indices and the structures of the archaeal, bacterial, and fungal communities significantly differed along the latitudinal gradient. Additionally, significant differences were observed in the bacterial Shannon index, as well as in the structures of the bacterial and fungal communities between the rhizosphere and bulk soils. Due to the small spatial scale, trends of latitudinal variation in the archaeal, bacterial, and fungal communities were not pronounced. Total potassium, total phosphorus, available nitrogen, available potassium and total nitrogen were the important driving factors affecting the soil microbial community structure. Compared with those in bulk soil, co-occurrence networks in rhizosphere microbial networks presented lower complexity but greater modularity and positive connections. Among the main functional fungi, arbuscular mycorrhizae and soil saprotrophs were more abundant in the bulk soil. The significant differences in the soil microbes between rhizosphere and bulk soils further underscore the impact of C. odorata invasion on soil environments. The significant differences in the soil microbiota along latitudinal gradients, along with specific driving factors, demonstrate distinct nutrient preferences among archaea, bacteria, and fungi and indicate complex microbial responses to soil nutrient elements following the invasion of C. odorata.

Ecological Stoichiometry of Multiple Nutrients in Leymus chinensis and Soils Subjected to Long-Term Saline-Sodic Stress in Western Jilin Province, China

L. chinensis is considered an important plant for saline-sodic soil restoration. Ecological stoichiometry of multiple nutrient elements in Leymus chinensis (L. chinensis) and soils subjected to long-term saline-sodic stress remains unclear, which hinders our understanding of the mechanisms regulating nutrient cycling in the plant-soil environment. We examined nutrient element levels in saline-sodic soil and L. chinensis in western Jilin Province. Soil analysis revealed medium to high levels of available N, K, P, Mo, Mn, Fe, Cu, and Zn. The Mn/Fe and N/P ratios exceeded the national soil average of China, while those of Fe/Cu, Fe/Zn, and P/K were comparatively lower. Furthermore, L. chinensis exhibited deficiencies in the Mn, Zn, and P. Mo/Mn, Mo/Zn, and Fe/Zn ratios, which were significantly higher compared to healthy plants, while Mn/Fe and P/K showed the opposite trend. Soil pH had the most significant effect on element stoichiometry in both the soil and in L. chinensis. Particularly, the soil available Mn, Zn, K, along with L. chinensis Mn, Fe, Cu, and P levels exhibited sensitivity to pH fluctuations. Additionally, we observed significant synergistic or antagonistic effects between the soil available element concentration and stoichiometry ratios. Among these, only Mn, Fe, Fe/Zn, Mo/Zn, N/K, and Mo/Fe in L. chinensis were significantly modeled (P < 0.05). The Mo/Fe homeostasis index was the lowest at 0.97, followed by Fe (1.16), N/K (2.28), Mo/Zn (2.59), Fe/Zn (3.38), and Mn (4.92), while other elements and their stoichiometric ratios remained stable. Overall, L. chinensis, as the dominant species in saline-sodic soil, demonstrated high homeostasis.

In the Qaidam Basin, Soil Nutrients Directly or Indirectly Affect Desert Ecosystem Stability under Drought Stress through Plant Nutrients.

The low nutrient content of soil in desert ecosystems results in unique physiological and ecological characteristics of plants under long-term water and nutrient stress, which is the basis for the productivity and stability maintenance of the desert ecosystem. However, the relationship between the soil and the plant nutrient elements in the desert ecosystem and its mechanism for maintaining ecosystem stability is still unclear. In this study, 35 sampling sites were established in an area with typical desert vegetation in the Qaidam Basin, based on a drought gradient. A total of 90 soil samples and 100 plant samples were collected, and the soil's physico-chemical properties, as well as the nutrient elements in the plant leaves, were measured. Regression analysis, redundancy analysis (RDA), the Theil-Sen Median and Mann-Kendall methods, the structural equation model (SEM), and other methods were employed to analyze the distribution characteristics of the soil and plant nutrient elements along the drought gradient and the relationship between the soil and leaf nutrient elements and its impact on ecosystem stability. The results provided the following conclusions: Compared with the nutrient elements in plant leaves, the soil's nutrient elements had a more obvious regularity of distribution along the drought gradient. A strong correlation was observed between the soil and leaf nutrient elements, with soil organic carbon and alkali-hydrolyzed nitrogen identified as important factors influencing the leaf nutrient content. The SEM showed that the soil's organic carbon had a positive effect on ecosystem stability by influencing the leaf carbon, while the soil's available phosphorus and the mean annual temperature had a direct positive effect on stability, and the soil's total nitrogen had a negative effect on stability. In general, the soil nutrient content was high in areas with a low mean annual temperature and high precipitation, and the ecosystem stability in the area distribution of typical desert vegetation in the Qaidam Basin was low. These findings reveal that soil nutrients affect the stability of desert ecosystems directly or indirectly through plant nutrients in the Qaidam Basin, which is crucial for maintaining the stability of desert ecosystems with the background of climate change.

Time scale effect of magnetic ferric oxide modified biochar in-situ remediation of arsenic-contaminated paddy soil

The ferric oxide (Fe3O4)-impregnated magnetic mulberry branch biochar (MBC) was prepared, and a long-term incubation trial was conducted to assess its efficiency in the remediation of As-contaminated soil. The changes in soil physicochemical properties [pH, dissolved organic carbon (DOC), soil organic matter (SOM), and electrical conductivity (EC)], soil nutrient elements, soil enzymes, soil bacterial community structure, and biodiversity at four different doses of MBC (1 %, 3 %, 5 %, and 7 %, wt%) across three aging periods (30, 90, and 180 d) were revealed. The results showed that the residual state of As increased by 161.4 % after 180 day of incubation with 5 % MBC. Spearman correlation and random forest model analyses revealed that available nitrogen had the highest contribution to the arsenic passivation process in soil. The addition of 5 % MBC significantly altered the bacterial abundance and composition in the soil. Actinobacteria, Proteobacteria, Chloroflexi, Bacteroidetes, and Acidobacteriota were identified as the predominant bacteria at the phylum level in all treated groups. The visualizations of soil bacterial co-occurrence networks over different passivate periods indicated more cooperative mutualism and complex interactions from day 30–180. After MBC was added to the soil, the arsenic toxicity was reduced with increasing aging time through bacterial community succession and co-occurrence networks. Overall, MBC facilitated the conversion of available arsenic by influencing the physicochemical factors and microbial community structure of the soil, thus reducing arsenic toxicity. MBC is a promising material for remediating arsenic-contaminated paddy soils.

Rapid and High-Performance Analysis of Total Nitrogen in Coco-Peat Substrate by Coupling Laser-Induced Breakdown Spectroscopy with Multi-Chemometrics

Nitrogen is an important nutrient element for crop growth. Rapid and accurate acquisition of nitrogen content in cultivation substrate is the key to precise fertilization. In this study, laser-induced breakdown spectroscopy (LIBS) was used to detect the total nitrogen (TN) of coco-peat substrate. A LIBS spectrum acquisition system was established to collect the spectral line signal of samples with wavelengths ranging from 200 nm to 860 nm. Synergy interval partial least squares (Si-PLS) algorithm and elimination of uninformative variables (UVE) algorithm were used to select the spectral data of TN characteristic lines in coco-peat substrate. Univariate calibration curve and partial least squares regression (PLSR) were used to build mathematical models for the relationship between the spectral data of univariate characteristic spectral lines, full variables and screened multi-variable characteristic spectral lines of samples and reference measurement values of TN. By comparing the detection performance of calibration curves and multivariate spectral prediction models, it was concluded that UVE was used to simplify the number of spectral input variables for the model and PLSR was applied to construct the simplest multivariate model for the measurement of TN in the substrate samples. The model provided the best measurement performance, with the calibration set determination coefficient () and calibration set root mean square error (RMSEC) values of 0.9944 and 0.0382%, respectively; the prediction set determination coefficient () and prediction set root mean square error (RMSEP) had values of 0.9902 and 0.0513%, respectively. These results indicated that the combination of UVE and PLSR could make full use of the variable information related to TN detection in the LIBS spectrum and realize the rapid and high-performance measurement of TN in coco-peat substrate. It would provide a reference for the rapid and quantitative assessment of nutrient elements in other substrate and soil.

Chemical and Microbial Differences of Root and Rhizosphere Soil among Different Provenances of Fokienia hodginsii

Aims: Fokienia hodginsii is a threatened conifer tree species, known as the dominant nursery-grown species capable of colonizing the challenging woodland environments in southern China due to its strong root penetrating ability. The ecological phenotype of Fokienia hodginsii is not well documented during its breeding process, which limits the potential planting area and its ecological function. This study aims to understand how Fokienia hodginsii associates with microbes to conduct its key ecological function and provide a theoretical basis for further improving the forest nursery management of Fokienia hodginsii. Methods: This study explored the ecological traits of 11 main Fokienia hodginsii provenances in a homogeneous garden experiment by analyzing their nutrient utilization strategies and associated microbial features in the rhizosphere soil and roots. Results: The study found that the paramount difference in the rhizosphere soil among provenances is in Ca and Fe content. Some microbial communities, namely Crenarchaeota, Verrucomicrobiota, and Desulfobacterota, were positively correlated with the amounts of the soil nutrient elements, whereas Abditibacteriota and Dependentiae were negatively correlated. The abundance of N- and Fe-related bacteria in the Fu Jian Chang Ting (FJCT) provenance was significantly higher than that in other provenances, while the C-, P-, K-, and Mg-related fungal communities, respectively, had higher abundances in the FJCT, Fu Jian Long Yan (FJLY), Fu Jian Gu Tian (FJGT), and Fu Jian Xian You (FJXY) provenances than the others. The impacts of the Gui Zhou Li Ping (GZLP), Hu Nan Dao Xian (HNDX), Jiang Xi Shang Yao (JXSY), and Guang Dong Shi Xing (GDSX) provenances on the rhizosphere soil are similar, but the differences in nutrient utilization arise from the plant itself. Conversely, the root nutrient contents of the FJCT, Fu Jian You Xi (FJYX), Fu Jian An Xi (FJAX), FJLY, Fu Jian De Hua (FJDH), FJGT, and FJXY provenances are highly correlated with soil nutrient features. Conclusions: For the native provenances, their economic traits are better than the exotic provenances. The native provenances are more sensitive to local soil conditions, so they should benefit more from human interventions, rendering them more suitable for artificial cultivation. The growth of the exotic provenances is less affected by the soil environment, making them better suited for the ecological transformation of forest stands and soil improvement.

Archaeal communities change responding to anthropogenic and natural treatments of freeze-thawed soils

The coverage of accumulated snow plays a significant role in inducing changes in both microbial activity and environmental factors within freeze-thaw soil systems. This study aimed to analyze the impact of snow cover on the dynamics of archeal communities in freeze-thaw soil. Furthermore, it seeks to investigate the role of fertilization in freeze-thaw soil. Four treatments were established based on snow cover and fertilization:No snow and no fertilizer (CK–N), snow cover without fertilizer (X–N), fertilizer without snow cover (T-N), and both fertilizer and snow cover (T-X). The research findings indicated that after snow cover treatment, the carbon, nitrogen, and phosphorus content in freeze-thaw soil exhibit periodic fluctuations. Snow covered effectively altered the community composition of bacteria and archaea in the soil, with a greater impact on archaeal communities than on bacterial communities. Snow covered improves the stability of archaeal communities in freeze-thaw soil. Additionally, the arrival of snow also enhanced the correlation between archaea and environmental factors, with the key archaeal phyla involved being Nanoarchaeota and Crenarchaeota. Further research showed that the application of organic fertilizers also had some impact on freeze-thaw soil, but this impact was smaller compared to snow cover. In summary, the arrival of snow could alter the archaeal community and protect nutrient elements in freeze-thaw soil, reducing their loss, and its effect is more pronounced compared to the application of organic fertilizers.

Potassium and Magnesium in American Ginseng Roots as Key Factors in Monitoring Soil Quality, Yield, and Quality: Screening, Prediction, and Validation

Understanding the key roles of nutrient elements in soil–plant systems are essential for herbal medicine production and sustainable development. However, the ecological relationships between soil quality and nutrient elements, yield, saponins, or other active compounds in American ginseng remain unclear. In this study, 20 soil indicators, 10 root nutrient indicators, 9 quality indicators, and yields were investigated. The minimum dataset was constructed by principal component analysis, key factors were screened by correlation analysis and PLS-PM analysis, and the prediction model was constructed using linear fitting and tested by a validation test. The minimum dataset, constructed based on principal component analysis, comprised five indicators: SOM, TP, AK, AMg, and ACa. Correlation analysis, PLS-PM analysis, and linear fitting showed that K and Mg were the key factors relating soil quality to the yield and quality of American ginseng and that when AMg was 0.21 g/kg and AK was 0.30 g/kg, soil organic matter was 27%, total phosphorus was 1.19 g/kg in soil, K content in roots was 15.63 g/kg, Mg content was 1.91 g/kg, and the K/Mg of 8.85 could balance American ginseng yield and quality. In predicting and validating the model, predicting the DW, total ginsenoside, Rb1, Rb2, Rc, and Rd of American ginseng using K/Mg were reliable. This study provides a scientific basis for nutrient regulation, selecting planting sites, assessing soil quality, and predicting and evaluating American ginseng quality.

Influence of Decomposed Stubble Return on the Soil Microbial Community Under Perennial Crop Rotation

The aim of this study was to understand how the application of decomposed stubble return (DSR), a type of bio-organic fertilization, affects soil microbial communities under crop rotation. The changes in microbial composition and diversity related to DSR were investigated based on metagenomic sequencing and comparative analysis of two groups of soil samples after a 3-year tomato-pepper-papaya rotation: the DSR and no-DSR (i.e., without DSR) groups, with the soils before crop rotation as the control group. Inter-group comparisons of the crop performance (growth and yield) and physicochemical soil properties (pH value, nutrient elements, and heavy metals) were also conducted to reveal the effects of DSR application on the soil. The relative abundance of bacteria was higher than 90% in all soil samples. Proteobacteria and Actinobacteria in the DSR group and Proteobacteria and Firmicutes in the no-DSR group, whereas Acidobacteria and Proteobacteria in the control, were the two most abundant phyla. The abundance of Proteobacteria decreased, whereas that of Actinobacteria increased, in the DSR-amended soil compared to the no-DSR soil. At genus level, Acidobacterium dominated in the control and genera Pseudomonas, Burkholderia, and Bacillus in the no-DSR group, while Burkholderia, Pseudomonas, and Bacillus in the DSR-amended soil comprised the majority of their microbiomes. The DSR soil had higher microbial diversity and relative abundance of Ascomycota fungi than the no-DSR group after the crop rotation. Along with higher diversity of microbial community, more favorable soil pH, better crop growth, higher crop yields, higher abundance of soil nutrient elements, and lower accumulation of heavy metals in the soil were found in the DSR group compared to the no-DSR one. Furthermore, the DSR soil had more similarities with the control than with the No-DSR soil, in aspects of microbial composition and microbe-derived potential gene functions. It was indicated that decomposed stubble return may improve soil conditions or prevent them from degradation incurred by long-term crop cultivation. It was suggested that the application of the compost derived from fermented post-harvest plant residue may be a general strategy for developing more sustainable agricultural systems.

Variations in soil carbon, nitrogen, and phosphorus concentrations and stoichiometry with stand age in Acacia hybrid plantations in Southern Vietnam

Abstract. Chau M, Quy N, Xu X, Hung B, Cuong LV, Ngoan T, Nguyen T. 2024. Variations in soil carbon, nitrogen, and phosphorus concentrations and stoichiometry with stand age in Acacia hybrid plantations in Southern Vietnam. Biodiversitas 25: 565-573. Soil Carbon (C), Nitrogen (N), and Phosphorus (P) contents are the three most critical soil nutrient elements required for plant growth and development, and their ecological stoichiometric ratios are significant indicators for understanding soil nutrient balance and cycling. This study was conducted to probe variations in the soil organic C (SC), total N (SN), and total P (SP) contents and stoichiometry at five soil depths (0-20, 20-40, 40-60, 60-80, and 80-100 cm) in Acacia hybrid plantations of five different ages (2-, 4-, 6-, 8-, and 10-year-old plantations) in Langa-Dongnai Forestry Company, Southern Vietnam. The results showed that forest age and soil depth substantially impacted soil nutrient contents and their stoichiometric characteristics. The concentrations of SC, SN, and SP as well as C/N, C/P, and N/P ratios increased as the forest stand age increased. The contents of SC, SN, and SP reduced with soil depth, indicating an obvious soil “surface-aggregation” phenomenon. The nutrient restriction varied based on forest stand development, shifting from restricted nitrogen in the earlier growth periods of trees to restricted phosphorus in the later growth periods. The findings demonstrate that to resolve the issue of restricted availability of these nutrient indexes, additional nitrogen should be supplied during earlier growth periods and additional phosphorus during later growth periods. The results further emphasize the importance of understanding SC, SN, and SP interactions and nutritional limitations and provide relevant theoretical support for sustainable Acacia hybrid plantation management in the Southern region.

Biochar and organic fertilizer applications enhance soil functional microbial abundance and agroecosystem multifunctionality

Biochar and organic fertilizer are widely supported to maintain crop production and sustainable development of agroecosystems. However, it is unclear how biochar and organic fertilizer alone or in combination regulate soil functional microbiomes and their relationships to ecosystem multifunctionality (EMF). Herein, a long-term (started in 2013) field experiment, containing five fertilization treatments, was employed to explore the effects of biochar and organic fertilizer applications on the EMF (based on 18 functional indicators of crop productivity, soil nutrient supply, element cycling, and microbial biomass) and the functional microbiomes of bulk soil and rhizosphere soil [normalizing the abundances of 64 genes related to carbon (C), nitrogen (N), phosphorus (P), and sulphur (S) cycles]. Compared with single-chemical fertilization, biochar and organic fertilizer inputs significantly enhanced most ecosystem-single functions and, in particular, the EMF significantly increased by 18.7–30.1%; biochar and organic fertilizer applications significantly increased the abundances of soil microbial functional taxa related to C-N-P-S cycles to varying degree. The combined application of biochar and organic fertilizer showed a better improvement in these indicators compared to using them individually. Most functional microbial populations in the soil, especially the taxa involved in C degradation, nitrification, nitrate-reduction, organic P mineralization, and S cycling showed significantly positive associations with the EMF at different threshold levels, which ultimately was regulated by soil pH and nutrient availability. These results highlight the strong links between soil microbiomes and agroecosystem functions, as well as providing scientific support for inclusion of biochar in agricultural production and services with organic amendments.Graphical

Tree canopy area-dependent changes in soil properties: a comparative study in the southern limit of boreal forest distribution

The forest distribution in relation to mountain slope position and the relationships between forest canopy area and soil physical and chemical properties in Mongolia attract the attention of scientists. In this study, we aimed to determine (1) how the slope aspect affects the forest soil physical and chemical properties, (2) how the soil variables correlate with projected canopy area. For comparative study, we established a total of 18 (20 × 25 m2 sized) sample plots in upper forest edge (UFE), upper slope of the forest (USF), lower slope of the forest (LSF), lower forest edge (LFE), sparse forest (SF), and degraded forest area (DFA) stand types with three replications. We measured the tree height, diameter and crown projection area of each growing tree in the sample plots, and collected soil samples for further soil physical and chemical analyses in the laboratory. Our results showed a high variation in growing stock (p < 0.0001), stand density and projected canopy area (p < 0.0001) in relation to mountain slope position and land-use management. We found that the slight changes in stand canopy area projection cause a high variation in soil physical and chemical properties. Among studied stand types higher means of soil temperature and bulk density and lower moisture content were observed on SF and DFA stand types. Contrary, relatively higher content of soil moisture and nutrient elements were recorded in USF, LSF, LFE. We conclude that tree canopy area becomes key determinant factor that positively influences forest soil moisture and fertility by increasing organic matter content in Mongolia.

ДИФЕРЕНЦІЙНІ ТЕХНОЛОГІЇ ПРЕЦИЗІЙНОГО ЗЕМЛЕРОБСТВА

One of the urgent tasks of modern agricultural production is the problem of further development of agricultural produc-tion on an innovative platform. This will increase labor productivity, save resources, reduce costs, reduce production costs, increase production efficiency and ensure food security of Ukraine, which is one of the largest producers and exporters of wheat, corn, and barley in the world. One of such technologies that can ensure high profitability of agricultural production is the precision farming system.The concept of precision farming is based on the spatial heterogeneity of soil characteristics (relief, soil-forming rocks, snow cover, influence of ground and rainwater, diversity of vegetation cover, the impact of wildlife and human activities, etc.) within one field followed by differential compensation of these differences within one field.One of the key elements of the introduction of precision farming technologies is a differentiated approach to conducting all agricultural operations in the field. At the same time, savings of fuels and lubricants, consumption of seed material, ferti-lizers, plant protection products, water, the machine and tractor park of the enterprise is more effectively used, and the impact of agriculture on the natural environment is mitigated.The purpose of the research is the technology of precision farming in general, and variable rate seeding (Variable Rate Seeding, VRS) in particular, which allow you to correctly and precisely regulate the rate of sowing agricultural crops, applying fertilizers, plant protection products, irrigation in accordance with the properties of the soil, relief, meteorological conditions and a number of other factors. This allows to optimize the use of agricultural resources for each section of the field and improve plant productivity based on data on soil structure, pH, nutrient elements and yield maps.

Multi-elemental stoichiometric ratios of atmospheric wet deposition in Chinese terrestrial ecosystems

Intense human activities have significantly altered the concentrations of atmospheric components that enter ecosystems through wet and dry deposition, thereby affecting elemental cycles. However, atmospheric wet deposition multi-elemental stoichiometric ratios are poorly understood, hindering systematic exploration of atmospheric deposition effects on ecosystems. Monthly precipitation concentrations of six elements—nitrogen (N), phosphorus (P), sulfur (S), potassium (K), calcium (Ca), and magnesium (Mg)—were measured from 2013 to 2021 by the China Wet Deposition Observation Network (ChinaWD). The multi-elemental stoichiometric ratio of atmospheric wet deposition in Chinese terrestrial ecosystems was N: K: Ca: Mg: S: P = 31: 11: 67: 5.5: 28: 1, and there were differences between vegetation zones. Wet deposition N: S and N: Ca ratios exhibited initially increasing then decreasing inter-annual trends, whereas N: P ratios did not exhibit significant trends, with strong interannual variability. Wet deposition of multi-elements was significantly spatially negatively correlated with soil nutrient elements content (except for N), which indicates that wet deposition could facilitate soil nutrient replenishment, especially for nutrient-poor areas. Wet N deposition and N: P ratios were spatially negatively correlated with ecosystem and soil P densities. Meanwhile, wet deposition N: P ratios were all higher than those of ecosystem components (vegetation, soil, litter, and microorganisms) in different vegetation zones. High input of N deposition may reinforce P limitations in part of the ecosystem. The findings of this study establish a foundation for designing multi-elemental control experiments and exploring the ecological effects of atmospheric deposition.

Seasonal changes of soil microbiota and its association with environmental factors in coal mining subsidence area

As a special type of wetland, the new wetland in the coal mining subsidence area is highly sensitive to environmental changes. In recent years, more and more attention has been paid to the studies of soil microbial diversity in newly born wetlands in coal mining subsidence areas. However, there are few reports on the seasonal variation of soil microbial diversity and its relationship with soil physical and chemical properties. In this study, 16S rRNA gene sequencing technology was used to analyze the seasonal changes of soil microbial composition and functional diversity in newly formed wetlands in coal mining subsidence areas, and to determine the seasonal changes of soil nutrient elements and physical and chemical properties in coal mining subsidence areas, so as to analyze the correlation between soil microbial diversity and soil nutrient elements and physical and chemical properties in newly formed wetlands in coal mining subsidence areas. A total of 16,050 OTUs were obtained after sample gene noise reduction. Proteobacteria, Acidobacteriota and Bacteroidota were the highest abundance in the coal mining subsidence area of Jining. The two seasons gathered separately, and temperature (Temp), total phosphorus (TP), available phosphorus (AP), total organic carbon (TOC) and dry matter content (DMC) were the key factors for the seasonal change of soil microbial community in the wetland of the coal mining subsidence area of Jining. The contents of Temp, AP and TP were significantly correlated with the abundance of soil microorganisms in summer subsidence area, while the contents of DMC and TOC were significantly correlated with the abundance of soil microorganisms in winter subsidence area. Soil microbial diversity in coal mining subsidence area was correlated with the seasons. Temp, TP, AP, TOC and DMC were the key factors for the seasonal change of soil microbial community in the wetland of the coal mining subsidence area of Jining.

Predicting Cd accumulation in rice and identifying nonlinear effects of soil nutrient elements based on machine learning methods

The spatial mismatch of Cd content in soil and rice causes difficulties in environmental management for paddy soil. To investigate the influence of soil environment on the accumulation of Cd in rice grain, we conducted a paired field sampling in the middle of the Xiangjiang River basin, examining the relationships between soil properties, soil nutrient elements, Cd content, plant uptake factor (PUFCd), and translocation factors in different rice organs (root, shoot, and grain). The total soil Cd (CdT) and available Cd (CdA) contents and PUFCd showed large spatial variability with ranges of 0.31–6.19 mg/kg, 0.03–3.07 mg/kg, and 0.02–3.51, respectively. Soil pH, CdT, CdA, and the contents of soil nutrient elements (Mg, Mn, Ca, P, Si, and B) were linearly correlated with grain Cd content (Cdg) and PUFCd. The decision tree analysis identified nonlinear effects of Si, Zn and Fe on rice Cd accumulation, which suggested that low Si and high Zn led to high Cdg, and low Si and Fe caused high PUFCd. Using the soil nutrient elements as predictor variables, random forest models successfully predicted the Cdg and PUFCd and performed better than multiple linear regressions. It suggested the impacts of soil nutrient elements on rice Cd accumulation should receive more attention.

Post-Fire Soil Nutrient Dynamics in Seriphium plumosum L. Encroached Semi-Arid Grassland of Gauteng Province, South Africa

Seriphium plumosum L. is an indigenous unpalatable shrub that occurs in fire-prone semi-arid South African grassland areas, yet research proposes the use of fire to control its encroachment of rangelands. This study investigated the interaction effects of burning and soil depth on components of soil fertility. Soil samples were collected from the surface (&lt;10 cm) and subsurface (&gt;10 ≤ 20 cm) soil, before and after burning in randomly selected paired subplots (25 m × 25 m), with six replicates. Data was analysed as a randomised complete block design, with repeated measures (before and after burning) in a 2 × 2 factorial analysis of variance (ANOVA) using generalised linear model (GLM) procedures. Components of soil fertility measured (K, Ca, Mg, Org C, P, pH and TN) showed a significant decrease with increasing soil depth both before and after burning, except for K and P, which were significantly higher in surface soils after burning. The results showed that the response of soil nutrients to fire depends on the temperature tolerance threshold of individual soil nutrient elements. Increasing surface soil available K and P concentrations after burning may improve the conditions for S. plumosum encroachment, with implications for similar environments and species worldwide.

Spatial distribution and quantitative identification of contributions for nutrient and beneficial elements in top- and sub-soil of Huairou District of Beijing, China

To control agricultural and ecological risk, it is significant to monitor the quality of nutrient and beneficial elements (NBEs) in soils, particularly in agricultural area. For this purpose, it is important to clarify NBEs content and distribution, potential sources, and enrichment or depletion mechanism in soils. However, in present studies, the sources identification for soil NBEs and quantification of contributions for multiple sources, remains controversial. In order to solve these problems, in this case, a total of 977 topsoil samples and 258 subsoil samples were collected at Huairou District of Beijing. The content of some NBEs (K, Ca, Mg, V, Mn, F, Ge, N, Se, P, Zn, and S) were analyzed for each sample, and spatial distribution were presented with some values indicating soil properties (TFe2O3, Al2O3/SiO2, total organic carbon (TOC), and pH). The main influence factors of NBEs distibutions in soils were determined by the methods of principal component analysis (PCA), redundancy analysis (RDA), and positive matrix factorization (PMF) analysis. Combined with analysis result and geochemical process, it suggested the enrichment mechanism of NBEs in soils mainly impacted by soil parent material, the local external sources, and elements migration of eluviation in study area. Furthermore, the major contribittions of each NBEs either in topsoil or in subsoil were quantitatively determined. Generally both in topsoils and in subsoils, the source inherited from soil parent material account for 34.65–58.97% contribution to Zn, Mn, Mg, V, F, Ca, K, and Ge; the local external sources accounted 40.66–68.99% for N, S, Se, and Zn; and eluviation contributed 37.45–67.07% of Ca, P, and K. The enrichment degree of NBEs in topsoils were processed by standardized concentration ratio model, which effectively demonstrated elements inheritance from subsoils to topsoils. In addition, the soil quality evaluation was conducted on the basis of NBEs concentration classificaiton. This study quantitatively estimated NBEs sources in soils and their quality, which provided a basis for agricultural activities and ecological environment protection in typical suburban area.