Soil Samples Research Articles

Spent Mushroom Substrate Improves Microbial Quantities and Enzymatic Activity in Soils of Different Farming Systems

Organic fertilizers, such as spent mushroom substrate (SMS), improve soil fertility, but studies comparing their effects on different agricultural soils are limited. In this study, the effects of standard, SMS and composed fertilizers on soils from conventional–integrated, organic and biodynamic farming were investigated. Soil samples were analyzed for microorganisms and the activity of β-glucosidase (β-GLU), β-1,4-N-acetylglucosaminidase (NAG), urease (URE), arylamidase (ARN), phosphatase (PHOS), acid phosphatase (PAC), alkaline phosphatase (PAH) and arylsulphatase (ARS). Biodynamic soil showed the highest microbial counts and enzyme activities, followed by organic and conventional soils. SMS significantly increased the number of microorganisms and enzyme activities, especially in biodynamic and organic soils. Seasonal variations affected all microorganisms and most enzymes in all soils, except NAG in conventional and organic soils. Biodynamic soil showed stable activity of enzymes and microorganisms throughout the year, indicating greater stability. This study concludes that soil microorganisms and enzyme activities respond differently to fertilization depending on the soil type, with SMS demonstrating beneficial effects in all tested soils.

Assessment of the Levels of Pesticide Residues and Trace Metal Elements (TME) in Soils in the Cotton-Growing Region of North-West Benin

ABSTRACT The objective of the study was to evaluate the levels of pesticide residues and trace metal elements (ETM) in the soils of the cotton-growing zone in north-west Benin. The soils under cotton, maize and soybean were retained in a Complete Random Block design with 12 repetitions. 36 sites were sampled, with 12 of them being allocated to each crop. The analysis involved determining permethrin, cypermethrin, and glyphosate from soil samples taken by HPLC. The determination of Cd and Pb was carried out by mass spectrometry with inductively coupled plasma after organic matter destruction. A analysis of variance was used to compare soil types with the data obtained. Linear regression equation models were created to estimate trace metal elements values based on pesticide residue values. The results showed that the average amounts of permethrin (0.61 ± 0.03 µg/mg), cypermethrin (0.69 ± 0.07 µg/mg), glyphosate (0.82 ± 0.01 µg/kg), cadmium (Cd) (1.78 ± 0.21 µg/kg), lead (Pb) (1.04 ± 0.14 µg/kg) were higher (p < 0.05) in soils under cotton crops. As for lead, it can only be estimated using permethrin (Pb = 0.18 + 0.37 Per) or cypermethrin (Pb = 0.24 + 0.34Cy) or both with high determination coefficient R2 (R2= 82.01%).

High Density Soil Survey of CRC -1 by the Use of Laboratory Methods

A field experiment was carried out during the year 2024 in the Department of Soil Science &amp; Agricultural Chemistry, School of Agriculture, ITM, Gwalior. Surface (0-15 cm) and sub surface (15-30 cm) soil sample were collected by systematic survey with location data using global position system from CRC-1 farm, ITM, Gwalior District, Madhya Pradesh. A total numb of collected soil sample was 120 sample. pH was varied between 7.21 to 8.69 at 0–15 cm depth and 7.18 to 8.57 at 15–30 cm depth. The pH is slightly alkaline. The Electrical conductivity (EC) ranging from 0.23 to 0.52 dsm-1 at 0 -15 cm depth and 0.31 to 0.59 dsm-1 at 15 -30 cm depth emphasizing that the fact that the soil is safe limit of EC. Organic carbon was varied between 0.31 to 0.39% in 15–30 cm depth and 0.35 to 0.42% in 0–15 cm depth. The OC status is low to medium. Nitrogen (N) was ranged between 134.5 to 139.9 kg ha-1 at a depth of 0–15 cm and 132.4 to 135.5 kg ha-1 at a depth of 15–30 cm. Phosphorus(P) ranging from 8.42 to 12.20 cm at 0–15 cm depth and 6.28 to 10.68 cm at 15–30 cm depth. Potassium (K)ranging from 8.42 to 12.20 kg ha -1 at 0–15 cm depth and 6.28 to 10.68 kg ha -1at 15–30 cm depth. Sulphur(S) was ranged between 15.36 to 20.54 kg ha-1 at a depth of surfaced and 13.64 to 18.74 kg ha -1 at a depth of sub surfaced.

Developing a novel ultraselective and ultrasensitive label-free direct spectrofluorimetric nanobiosensors for direct highly fast field detection of explosive triacetone triperoxide

BackgroundDirect detection of the notorious explosive triacetone triperoxide (TATP) is very difficult because it lacks facile ionization and UV absorbance or fluorescence. Besides, the current indirect methods are time-consuming and need a pre-step for TATP cleavage to hydrogen peroxide. Moreover, they commonly show significant false-positive results in the presence of some camouflage which limits their field applications. Herein, for the first time, a novel label-free field-applicable spectrofluorimetric nanobiosensor was developed for direct TATP detection using a novel activated-protein protected gold nanocluster (ABSA-AuNCs; QY=28.3%) synthesized by a combined protein-assisted-ultrasonication procedure. ResultsThe ABSA-AuNCs revealed a fluorescence spectrum centered at 330.0 nm which was significantly quenched by TATP (binding constant=154.06 M-1; ΔG=-12.5 kJ mol-1; E(%)=88.5%). This phenomenon was used as a basis for direct TATP quantification, providing a working range of 0.01-40.0 mg L−1 and a detection limit of 6.7 μg L−1 which is the lowest LOD provided for TATP detection up to now. A %RSD of 0.9% and 1.56% was obtained for repeatability and inter-day reproducibility, respectively. The selectivity was checked against a variety of camouflages, revealing ultra-selectivity. Several synthetic samples prepared by several camouflages and real samples (clay soil and real water media) were analyzed, revealing quantitative recoveries of TATP. SignificanceDuring the production of the notorious explosive TATP, it can be discharged into water and soil. This novel method eliminated the false-positive results of traditional methods and is applicable for direct quantitative detection of camouflaged TATP and its residues in real soil and water samples in a highly short response time (2 min). The camouflaged TATP analysis is important for tracking the terrorist attacks in field conditions and analysis of soil and water can provide a first indication of the location of the production site.

The influence of exploration activities of a potential lithium mine to the environment in Western Serbia

The proposed exploitation of the Jadar Valley lithium/borate deposit in Serbia, by the Rio Tinto Corporation, indicates that it would become large-scale processing of boron- and lithium-containing ore. It would be one of the world’s very first lithium mines in populated and agricultural area. The company claims that the envisioned mining will be in accordance with environmental protection requirements. The Jadar Valley deposits have been claimed to cover 90% of Europe’s current lithium needs. Yet, local opposition to the mining has arisen due to potential devastating impacts on groundwater, soil, water usage, biodiversity loss, and waste accumulation. Research drilling by the mining company has already produced environmental damage, with mine water containing high levels of boron leaking from exploratory wells and causing crops to dry out. Furthermore, our investigations reveal substantially elevated downstream concentrations of boron, arsenic, and lithium in nearby rivers as compared to upstream regions. Additionally, here we show that soil samples exhibit repeated breaches of remediation limit values with environmental consequences on both surface and underground waters. With the opening of the mine, problems will be multiplied by the tailings pond, mine wastewater, noise, air pollution, and light pollution, endangering the lives of numerous local communities and destroying their freshwater sources, agricultural land, livestock, and assets.

Soil basal respiration and nitrogen mineralization from C3 and C4 grass dominated plant communities respond differently to temperature and soil water variation

Key environmental influences on soil basal respiration (Rs) and nitrogen mineralization (ΔIN) are temperature and soil water content (SWC) and both are being altered by climate change. Yet we cannot expect that variation in temperature and SWC will equally affect all ecosystems. We examine the influences of temperature and SWC on Rs and ΔIN in two grassland plant communities dominated by C3 or C4 species. We collected soil samples from these communities and incubated them at temperatures (5 °C, 10 °C, 15 °C, and 25 °C) and four SWC (10%, 20%, 30% and 40% by weight). After four one-month incubation experiments, we found that (1) plant communities, temperature, and SWC significantly influenced Rs and ΔIN; (2) the highest Rs and ΔIN occurred at 25 °C and 30% SWC in the C4 plant community; (3) in the driest soils, N was immobilized in both communities regardless of temperature. We suggest that there is a greater limitation to C and N mineralization in the C3 plant community than in the C4 plant community making the C3 community less sensitive to variation in temperature and SWC.

Profiling of rhizosphere bacterial community associated with sugarcane and banana rotation system

BackgroundGuangxi is the leading sugarcane-producing area in China. Due to the Panama disease outbreak in banana gardens, sugarcane and banana rotation was recommended. A field experiment with the newly released sugarcane cultivar Zhongzhe 1 (ZZ1) was conducted to understand the role of the sugarcane–banana rotation system in shaping the rhizosphere microbiota. Fields in the region possess characteristics of red laterite soil.ResultsUsing Illumina HiSeq sequencing to analyze soil samples’ 16S rRNA V3-V4 region, the preceding banana rotation field had relatively greater bacterial diversity than the monoculture sugarcane field. Proteobacteria, Chloroflexi, Actinobacteria, and Acidobacteria were the dominant phyla, with distinct taxa enriched in each environment. However, the preceding sugarcane monoculture field enriched functional groups related to nitrogen fixation and cellulolysis. Network analysis highlighted contrasting network structures between sugarcane and banana rhizospheres, suggesting differential stability and susceptibility to environmental influences. Furthermore, correlations between soil properties and bacterial alpha-diversity underscored the influence of preceding crops on rhizosphere microbial communities.ConclusionThis research enhances our understanding of crop rotation effects on soil microbial ecology and provides insights into optimizing agricultural practices for enhanced soil health and crop productivity. Future studies should explore the underlying mechanisms driving these interactions and evaluate the long-term impacts of crop rotation on soil microbial dynamics.Graphical abstract

Isolation and Molecular Characterization of Pigment Producing Bacteria from Soil of Different Locality of Assam

Pigment is the most attractive attribute and integral part of human life. The source of the pigment used for different applications is chemically synthesised. However, pigment produced from natural sources (such as plants and microorganisms) can also be applied as a coloring agent. In addition to being colorants, many natural pigments are also fascinating bioactive substances with possible health benefits. Agrochemicals, food, medicine, pharmacology, cosmetics, and numerous other industries use these compounds. In this study, a total of 7 pigmented colonies were isolated from the soil samples of different areas of Assam. Out of 7 pigmented colonies, 3 colonies showed orange color and 4 colonies showed yellow color. Based on the similarity of growth pattern and high intensity of pigmentation one colony from each pigment was picked for further studies. The isolated orange and yellow pigments were denoted as S1 and S2, respectively. With the help of Bergey’s Manual of Determinative Bacteriology the isolated pigmented strains were preliminary identified based on their morphological, microscopic, and biochemical characteristics and after that 16S rRNA gene sequencing helped to identify the bacteria at the species level and the strains were identified as (S1) Micrococcus aloeverae ON377368 and (S2) Exiguobacterium aestuarii ON377409. The identified strains Micrococcus aloeverae and Exiguobacterium aestuarii showed a high pigment production rate at specific optimized conditions such as at temperature 37°C, pH 6, and NaCl concentrations at 1.5-2% and strains also showed a good characteristic growth pattern at a specific time interval. Therefore, the present study may be a helpful step towards the large-scale manufacture of pigments and the extraction, purification, and characterization of the pigment extracted from these strains will lead to provide a potent eco-friendly natural dye in the industrial sector.

Exploiting Soil and Remote Sensing Data Archives for 3D Mapping of Multiple Soil Properties at the Swiss National Scale

Soils play a central role in ecosystem functioning, and thus, mapped soil property information is indispensable to supporting sustainable land management. Digital Soil Mapping (DSM) provides a framework to spatially estimate soil properties. However, broad-scale DSM remains challenging because of non-purposively sampled soil data, large data volumes for processing extensive soil covariates, and high model complexities due to spatially varying soil–landscape relationships. This study presents a three-dimensional DSM framework for Switzerland, targeting the soil properties of clay content (Clay), organic carbon content (SOC), pH value (pH), and potential cation exchange capacity (CECpot). The DSM approach is based on machine learning and a comprehensive exploitation of soil and remote sensing data archives. Quantile Regression Forest was applied to link the soil sample data from a national soil data base with covariates derived from a LiDAR-based elevation model, from climate raster data, and from multispectral raster time series based on satellite imagery. The covariate set comprises spatially multiscale terrain attributes, climate patterns and their temporal variation, temporarily multiscale land use features, and spectral bare soil signatures. Soil data and predictions were evaluated with respect to different landcovers and depth intervals. All reference soil data sets were found to be spatially clustered towards croplands, showing an increasing sample density from lower to upper depth intervals. According to the R2 value derived from independent data, the overall model accuracy amounts to 0.69 for Clay, 0.64 for SOC, 0.76 for pH, and 0.72 for CECpot. Reduced model accuracies were found to be accompanied by soil data sets showing limited sample sizes (e.g., CECpot), uneven statistical distributions (e.g., SOC), and low spatial sample densities (e.g., woodland subsoils). Multiscale terrain covariates were highly influential for all models; climate covariates were particularly important for the Clay model; multiscale land use covariates showed enhanced importance for modeling pH; and bare soil reflectance was a major driver in the SOC and CECpot models.

Monitoring Slope Movement and Soil Hydrologic Behavior Using IoT and AI Technologies: A Systematic Review

Landslides or slope failure pose a significant risk to human lives and infrastructures. The stability of slopes is controlled by various hydrological processes such as rainfall infiltration, soil water dynamics, and unsaturated soil behavior. Accordingly, soil hydrological monitoring and tracking the displacement of slopes become crucial to mitigate such risks by issuing early warnings to the respective authorities. In this context, there have been advancements in monitoring critical soil hydrological parameters and slope movement to ensure potential causative slope failure hazards are identified and mitigated before they escalate into disasters. With the advent of the Internet of Things (IoT), artificial intelligence, and high-speed internet, the potential to use such technologies for remotely monitoring soil hydrological parameters and slope movement is becoming increasingly important. This paper provides an overview of existing hydrological monitoring systems using IoT and AI technologies, including soil sampling, deploying on-site sensors such as capacitance, thermal dissipation, Time-Domain Reflectometers (TDRs), geophysical applications, etc. In addition, we review and compare the traditional slope movement detection systems, including topographic surveys for sophisticated applications such as terrestrial laser scanners, extensometers, tensiometers, inclinometers, GPS, synthetic aperture radar (SAR), LiDAR, and Unmanned Aerial Vehicles (UAVs). Finally, this interdisciplinary research from both Geotechnical Engineering and Computer Science perspectives provides a comprehensive state-of-the-art review of the different methodologies and solutions for monitoring landslides and slope failures, along with key challenges and prospects for potential future study.

Engineering Evaluation of Laterite Derived from Sedimentary Rock for Use as Subgrade and Sub-Base Materials

Geotechnical assessment of lateritic soils obtained from along the Ojota and Shagamu ends of the Lagos–Ibadan expressway was conducted to evaluate their suitability for use as sub-grade and sub-base materials. Laboratory tests, including moisture content, specific gravity, particle size distribution, fabric/plasticity, compaction, and California Bearing Ratio (CBR), were performed on eight (8) soil samples following British Standards (BS) 1377 methods for soil testing. The lateritic soils were classified as clayey sand, silty clay, and silty to clayey sand. They exhibited moderate plasticity and semi-pervious characteristics, suggesting suitability for use as sub-grade materials. Samples 3, 5, 7, and 8 were identified as more suitable for road construction materials, while Samples 1, 2, 4, and 6 showed susceptibility to seasonal volume changes due to high clay content. These samples would require minor soil stabilization to mitigate the effects of their active clay contents. Adequate drainage systems were recommended to prevent water accumulation, soil volume changes, loss of load-bearing capacity, and potential material failure beneath road pavements. The geotechnical properties of the lateritic soils from the tropical area of Ojota–Shagamu differed significantly from those of other lateritic soils found in southwestern Nigeria.

Irrigated corn yield and soil phosphorus response to long‐term phosphorus fertilization

AbstractLong‐term experiments can help to understand soil phosphorus (P) dynamics and improve nutrient management strategies. This research evaluated long‐term (2002–2021) soil P dynamics and yield response to a range of P fertilizer rates in a continuous high‐yielding irrigated corn (Zea mays L.) experiment with low initial soil phosphorus test (SPT, 10.5 mg kg−1). The experiment was established near Clay Center, NE, and five P rates (0, 10, 20, 39, and 59 kg P ha−1) were evaluated. Soil samples at 20‐cm depth were collected in eight cropping seasons. Yield response to P fertilizer increased after 20 years from 0.64 to 2.79 Mg ha−1. The application of 39 kg P ha−1 year−1 increased soil Bray‐1 P to 19.5 mg kg−1, outyielded all other P treatments, and resulted in a positive relative P balance. Over 20 years, 0 kg P ha−1 year−1 decreased Bray‐1 P from 10.5 to 5.5 mg kg−1. Annual P rates of 0, 10, and 20 kg P ha−1 produced a negative relative P balance and SPT below the critical soil test value (CSTV). The CSTV was 22.2 mg kg−1 for a continuous irrigated corn cropping system. A 53% increase in the P fertilizer rate (from 39 to 59 kg P ha−1 year−1) produced a threefold increment in the soil test P build‐up rate. High‐yielding irrigated continuous corn production systems (&gt;14 Mg ha−1) are required to apply at least 39 kg P ha−1 year−1 to maintain SPT and a positive relative P balance over years.

New porous organic framework Py-PDA CHOF as fluorescent chemosensor for detecting 2,4,6-trinitrophenol in environmental samples

Covalent bonds and hydrogen bonds linked porous organic frameworks (CHOFs) as a new type of porous organic framework connected by both covalent bonds and hydrogen bonds has been reported recently. Py-PDA CHOF was synthesized using 4,4′,4′’,4′’’-(pyrene-1,3,6,8-tetrayl)tetraaniline (Py) and 2,6-pyridinedicarboxaldehyde (PDA) as building blocks. It has porous crystalline framework and exceptional thermal stability. The suspension of Py-PDA CHOF in ethanol exhibits a highly selective and sensitive “on-off” fluorescence response towards 2,4,6-trinitrophenol (TNP), with exceptionally low detection limits. The powder X-ray diffraction (PXRD) confirmed the collapse of the Py-PDA CHOF after interaction with TNP and acid, and this result further indicated the presence of hydrogen bonds within the framework. The absorption competition quenching (ACQ) and photoinduced electron transfer (PET) mechanism are responsible for fluorescence quenching of Py-PDA CHOF by TNP. As a fluorescent chemosensor capable of detecting explosives, Py-PDA CHOF holds potential application for the identification and detection of TNP in water and soil samples.

ПОЧВЕННЫЕ БАКТЕРИИ ИЗ АВТОХТОННЫХ МИКРОБНЫХ СООБЩЕСТВ ЦЕНТРАЛЬНОЙ СИБИРИ В БИОЛОГИЧЕСКОЙ ЗАЩИТЕ ПШЕНИЦЫ ОТ ALTERNARIA TENUISSIMA

The most powerful soil bacteria from autochthonous microbial communities of Central Siberia against phytopathogenic fungi Alternaria tenuissima were selected. Isolation from soil samples and cultivation of bacterial isolates were performed on the artificial nutrient medium for bacteria PD-agar. Antagonistic activity was measured on GRM Saburo. In this case, Alternaria tenuissima was sown in a dish on GRM Saburo, and the selected bacterial strains were sown around the micromycete. As a result of joint growth of the test culture and soil bacteria, the most powerful antagonists in the suppression zone of Alternaria tenuissima were identified. The most powerful bacteria-antagonists in reducing the intensity and prevalence of root rot were identified by the method of artificial infection of Alternaria tenuissima. Before infection with micromycete, bacterization of spring wheat seeds Novosibirskaya-15 with the studied bacterial isolates was carried out. Mathematical processing of the obtained results was fulfilled by one-way variance analysis and two-sample F-test for variance. The results of the study on the use of soil autochthonous antagonist microorganisms in biological protection of spring wheat from the causative agents of root rot Alternaria tenuissima showed that the studied bacterial isolates statistically significantly (p &lt; 0.01) reduced the intensity and prevalence of this disease. The maximum effect in reducing the intensity and prevalence of the disease was shown by isolates B2 and B4 (according to preliminary identification of Bacillus sp.). Also, the studied bacterial strains showed a positive effect on the length of sprouts. At the same time, isolate B2 showed a statistically significant (p &lt; 0.001) effect on the length of spring wheat sprouts. The stimulating effect was manifested in an increase in the length of sprouts compared to the control. Therefore, this strain can be recommended not only for protection against Alternaria tenuissima, but also for stimulating wheat growth.

Detoxification of contaminated soils from hydrocarbon rocket fuel used in «Soyuz» launch vehicles using the bioremediation method

Rocket and space activities are developing worldwide, but environmental concerns are overlooked in pursuing new technologies. The Republic of Kazakhstan's "Baikonur" Cosmodrome routinely launches rockets in emergencies, causing toxic fuel to spill onto and contaminate the soil. This study examines the effect of T-1 kerosene, a hydrocarbon rocket fuel of toxic hazard class 4, on the soil microbial community from the aeration zone in laboratory conditions. In three different soil samples, 15 g/kg, 30 g/kg, and 50 g/kg of T-1 kerosene were tested according to their utilization by microbes throughout three, ten, and thirty days.Based on scientific research, several strains of microorganisms were able to utilize T-1 kerosene rocket fuel, such as Acinetobacter calcoaceticum-18, Bacillus sp.-20, Micrococcus roseus-25, and Candida sp.-12/5, purifying it from 70 to 90 %. According to a study conducted after 30 days of microbiological detoxification of calcisols (loamic) (site 196) and dystric arenosols (site 31), with an initial load of 50 g/kg of T-1 kerosene, the concentration was determined. Microorganisms that produce 5 + 20 (99.83 %) and 18+20+25+12/5 (99.80 %) oil products are well utilized. During decontamination of soils contaminated with hydrocarbons was found to be present in the soil after 60 days when microorganism № 20 was used at 9.3 mg/kg, and the association of microorganism 5 + 25 at 8.88 mg/kg. The article describes the developed technology for soil detoxification using the microbiological method.

The Influence of Biochar on Heavy Metals Phytoaccumulation by Okra and Fluted Pumpkin Plants in Soil Contaminated With Petroleum Hydrocarbons

ABSTRACTThe study is aimed at assessing the impact of biochar on the phytoaccumulation of heavy metals by okra and fluted pumpkin plants in soil polluted with petroleum hydrocarbons, and its corresponding environmental and health‐related risks. A field experiment was conducted at the automobile workshop (commonly called mechanic village) using a randomized complete block design (RCBD). The field was divided into plots and three replicates. Maize stalk biochar (MSB) and nipa palm biochar (NPB) were treated differently in each plot at a rate of 20 t ha−1. Plots containing no biochar were used as controls. The soil samples were analyzed for petroleum hydrocarbon content (PHCt), selected heavy metals as well as some other soil physicochemical properties. Plant samples were only analyzed for heavy metal contents. Analysis of variance was used to analyze the data generated. The PHCt and heavy metal content in the soil were compared with the target values set by the Department of Petroleum Resources of Nigeria whereas heavy metals in plants were compared with FAO/WHO guidelines. Okra and fluted pumpkin were evaluated for phytoaccumulating potential using bioaccumulation factor (BAF). Ecological risk assessment was done using a hazard quotient (HQ). The PHCt, cadmium (Cd), chromium (Cr), and nickel (Ni) were significantly decreased following the application of biochar. The NPB recorded the lowest values for PHCt (64.4 mg kg−1), lead (16.0 mg kg−1), and Ni (12.8 mg kg−1) contents while MSB had the lowest values for Cd (0.3 mg kg−1) and Cr (7.6 mg kg−1) contents. The HQ analysis showed that Cr (2.93 mg kg−1) and Pb (156.83 mg kg−1) posed a very high ecological risk to the local ecosystem. The phytoaccumulated heavy metals in plants were above the maximum allowable levels, except Ni where the content was below the maximum allowable levels. Fluted pumpkin had the highest BAF values for Cd, Cr, Pb, and Ni. Therefore, fluted pumpkin can be used as an efficient phytoremediator for soil contaminated with Cd, Cr, Pb, and Ni.

Sampling data of macro-invertebrates collected in grasslands under restoration succession in a lowland stream-valley system.

Publication of data from past field studies on invertebrate populations is of high importance, as there is much added value for them to be used as baselines to study spatiotemporal population and community dynamics in these groups. Therefore, a dataset consisting of occurrence data on epigaeic invertebrates collected in 1996 was standardised into the Darwin core format and cross-checked in order to make it publicly available following FAIR data principles. With publication, it can contribute to the biodiversity assessment of terrestrial invertebrates, thereby improving the availability and accessibility of much-needed historical datasets on macro-invertebrates.Here, we present sampling event data on invertebrates from four grasslands taken out of agricultural production over the span of several decades, effectively displaying a chronosequence on the effects of agricultural extensification. The data were collected by means of a standardised sampling design using pyramid traps, pitfall traps and soil samples. The raw data presented in this data paper have not been published before. They consist of 20,000+ records of nearly 70,000 specimens from 121 taxonomic groups. The data were collected using a standardised field study set-up and specimens were identified by taxonomic specialists. Most groups were identified up to family level, with eight groups identified up to species level. The occurrence data are complemented by information on plant composition, meteorological data and soil physical characteristics. The dataset has been registered in the Global Biodiversity Information Facility (GBIF): http://doi.org/10.15468/7n499e.

Evaluation and development of pedotransfer functions of saturated hydraulic conductivity for subtropical soils

The determination of soil saturated hydraulic conductivity (Ks) is crucial in environmental and engineering fields. However, the current direct measurement methods of Ks are time-consuming and labor-intensive. As an alternative method, many researchers have developed a series of pedotransfer functions (PTFs) that estimate Ks based on easily accessible soil properties. Unfortunately, most existing PTFs of Ks focus on temperate and tropical regions in the United States and Europe. There is a lack of research discussing the applicability of Ks models in subtropical areas. To resolve this issue, we conduct a study using 515 subtropical soil samples to test the performance of existing PTFs of Ks. The Ks values of investigated soils range from 1.4 × 10-4 to 290 cm h−1. Among the affecting factors, soil bulk density (ρb) and effective porosity (φe) are found to be the most important variables. Current PTFs considering soil pore structural property (i.e., φe) or soil texture solely are not effective in assessing Ks of subtropical soils. To address this limitation, we integrate soil pore structural and textural properties and develop a new PTF based on the Kozeny-Carman equation. The performance and reliability of the new PTF are evaluated using independent Ks datasets from various regions. The results show a significant positive correlation between the measured Ks and the predicted Ks from the new PTF for subtropical soils with an R2 of 0.69, an average RMSE in log10Ks (cm h−1) of 0.496, and a mean bias value of 0.070. Besides, the new PTF is found to perform as well as widely used machine learning tools.

Study on the effect of deformation and strength characteristics of microencapsulated phase change materials on modified silty clay under dry and wet cycles

To prevent the cracking of silty clay under cyclic wet-dry cycling (W-D), which leads to the increase of deformation and strength attenuation of silty clay, microencapsulated phase change material (mPCM) was used to improve it. The deformation and strength characteristics of silt with different dosages (1 %, 2 % and 4 %) of mPCM and their changing patterns were analyzed and studied by indoor compaction test, crack observation test, consolidation test and straight shear test, and compared with silt without modifier. The results showed that with the increase of mPCM dosage, the optimum water content of silt and the maximum dry density decreased. A 2 % dosage of mPCM inhibited the development of silty clay cracks, reduced crack width and deformation, and increased the compression modulus of the soil samples by nearly 2.3 times. Under dry and wet cycling conditions, the cohesion decay of silty clay is greater than the angle of internal friction. The addition of 2 % mPCM significantly increased the shear strength of silty clay, cohesion by nearly 2.1 times, and internal friction angle by 1.4 times. The mPCM inhibits crack development mainly by regulating the internal temperature field of soil samples, thus improving soil strength. This study provides a reference for inhibiting soil cracking from a new temperature perspective.

Distribution and soil threshold of selenium in the cropland of southwest mountainous areas in China

To investigate the distribution characteristics of selenium (Se) in mountainous soil-crop systems and examine the threshold value of Se-rich soil, 275 soil samples and 153 associated crop samples (rice, maize, tea, nuts, konjac, mushrooms, buckwheat, and coffee) were collected in Ximeng County, a typical mountainous area in southwest China. The total Se, available Se, organic matter, pH, sampling point elevation, and crop Se content were analyzed to examine the distribution characteristics of soil Se and the ability of primary crops to enrich Se in Ximeng County. Random forest and multiple regression models were established to identify the factors influencing the available soil Se and the crop Se enrichment coefficient. Finally, the Se-rich soil threshold was examined based on the total Se, available Se, and Se content in primary crops (rice, maize, and tea). The results showed soil Se resource abundance in the study region, with high Se soil accounting for 64.72% of the entire area. The soil Se content displayed significant spatial autocorrelation. The average Se enrichment coefficient of the main cultivated crops included mushrooms > nuts > rice > coffee > tea > maize > buckwheat > konjac. The total Se content in the soil had the highest impact on the available Se content in the soil and the Se enrichment coefficient of crops. A Se-rich soil threshold of 0.3 mg·kg−1 was used for rice and maize, while that of tea was 0.4 mg·kg−1. This result provided a theoretical basis for developing and utilizing Se resources in mountainous soil in southwestern China and dividing the Se-rich soil threshold.