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Karst collapse as a unique environmental geological hazard in karst areas, easily causes changes in surrounding water and soil environments. Train-induced vibration is a significant inducement for shallow karst ground collapse. Previous studies on the dynamic properties of surrounding soil under train vibration loads often neglected the impact of time intermittent effects. Taking the red soil covering a typical potential karst collapse area along a high-speed railway in China as the research object, field monitoring of the vibration characteristics of the surrounding environment was conducted. A series of continuous loading and continuous-stop-continuous dynamic triaxial tests and scanning electron microscopy (SEM) tests were designed considering factors such as loading frequency, intermittent duration, and dynamic stress amplitude. The effects of loading intermittence on the dynamic response and microstructure of red soil were compared and analyzed. The experimental results show that the drainage and unloading of red soil samples during the intermittent phase dissipate the accumulated excess pore water pressure and adjust the internal particle and structure of the soil, reducing the accumulation of plastic deformation during subsequent loading stages. The residual strain under vibration loading conditions considering the time intermittent effect is significantly reduced, and the residual strain decreases significantly with the increase of time intervals. The weakening effects of both macro and micro characteristics of red soil in karst-prone areas are significantly enhanced with the increase of intermittent time. The research results are of great significance for the prevention and control of karst ground collapse in karst areas. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biochar pyrolysis at high temperature with limited oxygen plays an important role in the resource utilization of agricultural waste, carbon sequestration and emission reduction, indicating the great potential of biochar for remediating contaminated environment. As a functional material for soil remediation, its ability of adsorption and fixation for heavy metals is still insufficient, which limits the large-scale promotion and application of biochar. Nowadays, it has been an increasingly important research area to enhance the adsorption and fixation capacity of biochar through modification design of engineered materials. In this study, wood chips were used as raw materials to prepare biochar (BC), and then lanthanum modified biochar (LBC) was manufactured. Aiming to remediate arsenic contaminated red soil and compare the immobilization difference, these two kinds of amendments (LBC, BC) were applied into the experimental soils separately, and the blank soil without material addition was used as control treatment. All these above treatments was cultivated for 30days under the soil moisture content with 30%, 70%, and 100% field water capacity respectively, and the corresponding remediation effects of arsenic contaminated red soil by using LBC and BC were investigated. The results were as following: (1) LBC addition was beneficial for alleviating the acidification of southern red soils. When the cultivation experiment was finished, soil pH treated by LBC was enhanced obviously and the increased pH ranged from 0.86 to 1.20 units under three kinds of soil moisture content with 30%, 70%, and 100% field water capacity. In comparison with BC treatment, the soil pH also increased by 0.09-0.44 units after LBC addtion. (2) LBC application led to the obvious immobilization effect of arsenic in red soils, and the related fixation efficiency under three kinds of soil water content was up to 54.7%-90.0% during the whole soil cultivation period, and the immobilization efficiency reached 81.0%-85.8% after 30days of cultivation. On the contrary, soil treated by BC resulted in the arsenic activation of soils with the increased percent 135.4%-895.9% compared to the control. (3) The immobilization effect of LBC on soil arsenic is mainly related to the transformation of arsenic in various speciation, especially from non-specialized adsorption forms to more stable ones such as residue forms. In the meanwhile, BC resulted in the enhancement of non-specialized adsorption arsenic and promoted the activation of soil arsenic. (4) LBC was capable of immobilizing arsenic in red soils with high efficiency, and did not obviously excert negative influence on soil enzyme activity. The application of LBC was able to improve the activity of soil urease and catalase although it led to a slight decrease in soil phosphatase and sucrase activities. It is worth mention that LBC treatment remained higher soil sucrase activities than those for BC treatments. Overall, it manifest that LBC has great potential for remediating arsenic contaminated red soil. [ABSTRACT FROM AUTHOR]

Magnetic studies of loess–paleosol sequences have shown that the magnetic properties of loess and its parent material are sensitive to weathering degree. However, the relationship between magnetic properties and weathering processes in red soils of southern China remains unclear due to the diversity of parent rocks and the influence of climate. This study focused on red soils developed on weakly magnetic sandstone, in tropical and subtropical regions of Yunnan, China. The principal element content, magnetic susceptibility, temperature-dependent susceptibility curve (χ–T curve, where χ represents the magnetic susceptibility at the corresponding temperature during the heating and cooling process of the sample, and T represents the temperature during the heating and cooling process.), hysteresis loop and Isothermal Remanent Magnetization (IRM) of the samples were determined, the weathering characteristics and magnetic properties of profile samples were analyzed, and their relationship was examined, as well as the impact of climate change on fine-grained ferrimagnetic minerals and magnetic properties. The results revealed that red soils developed on weakly magnetic sandstone exhibited significant correlations between three magnetic indices, low-frequency magnetic susceptibility (χlf), frequency-dependent susceptibility (χfd), (χpost-pre + χd)/χpara, and the silica-sesquioxide ratio (SAF), indicating that these indices can be used to assess soil weathering. Additionally, this study proposed a new index based on the 1 < Log10Bh < 1.5 mT component obtained from decomposition of the IRM curve, which can also be used to assess soil weathering. The enhancement of magnetic properties in red soils along a single profile was found to be related to the increase in the content of fine-grained ferrimagnetic com-ponents controlled by weathering. Comparing the two climatic regions, it was found that in Yunnan, China, as the climate changes from subtropical humid to tropical humid, the weathering of the red soil profiles becomes stronger, and the fine-grained ferrimagnetic components increase, indirectly enhancing the magnetic properties of red soils. [ABSTRACT FROM AUTHOR]

To investigate the effects of applying calcium fertilizer on peanut reproductive growth in barren red soil dry land, this study selected the large grain variety Xianghua 2008, the medium grain variety Xianghua 55, and the small grain variety Lanshanxiaozi. Two treatments were set up: one with calcium fertilizer application and the other without. Column cultivation was conducted, and the developmental dynamics of peanut flowers, pegs, and pods were observed and measured. The results indicated that: (1) Application of calcium fertilizer promoted early flowering, controlled mid-late flowering, and shortened the flowering period. The total number of flowers for large, medium, and small-sized varieties decreased by 50.59%, 38.47%, and 26.55% respectively. It reduced the number of flowers at higher positions while increasing the number of flowers at lower positions, thus enhancing the overall flowering within the effective flowering period. (2) Applying calcium increased the total number of fruit needles in the early stage, while decreasing the number of fruit needles in the later stages of development and the number of nonembedded fruit needles. However, the impact on the number of non-embedded fruit needles in the early stages was not significant. Among them, calcium fertilizer had a greater effect on large-sized varieties compared to medium-sized and small-sized varieties, resulting in reductions of 68.38%, 53.55%, and 54.83% respectively. (3) Calcium application increased the total number of fruits, especially medium and large-sized fruits, while reducing the number of immature fruits in the later stages. Furthermore, the impact of calcium fertilizer on large and medium-sized peanut varieties was greater than on small-sized varieties. (4) Application of calcium fertilizer improved yield with better outcomes observed in larger-sized peanut varieties compared to medium and small-sized ones. Therefore, variations in the adaptability of different peanut varieties to calcium-deficient red soil in the southern area exist. From a crop yield perspective, it is suggested to utilize larger-sized peanut varieties and enhance the application of calcium fertilizer during cultivation. [ABSTRACT FROM AUTHOR]

Thailand’s fossil forests hold international importance for a variety of reasons. The operation of a gravel mine exposed sediment layers containing petrified wood logs, highlighting the critical need to preserve these unique artifacts and address associated environmental concerns. A comprehensive lithological study was conducted on pit walls. Employing 2D ERT and 2D IP methods, geology was classified from the ground surface and validated through drilling logs. The sediment and deposit categorization at gravel pit sites revealed four distinct units: Unit I, conglomeratic sand, exhibiting characteristics typical of fluvial deposits; Unit II, indicating alluvial fan deposition with lenticular gravel and sand highlighting the presence of petrified wood logs; Unit III, massive gravel suggesting channel deposits of an alluvial fan with an abundance of petrified wood; and Unit IV, red soil (collapsible soil). The 2D ERT method successfully examined the boundary sediment layer and mudstone, though classification of sediment units was not achieved. Quaternary terrace sediments underlie the mudstone, identified as an aquitard that effectively prevents surface contamination of the groundwater aquifer. The data from this study serves as fundamental geological information, providing remarkable and essential evidence for the preservation of petrified wood and the safeguarding of the groundwater environment. This site is particularly an outstanding geosite. This research contributes to our understanding of depositional environments and geological processes and proposes conservation strategies. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a promising alternative water source to alleviate irrigation water scarcity in red soil regions in southern China, low-quality water could enhance regional water resource utilization and promote sustainable agriculture. However, its soluble salt and ions could affect soil solute distribution and transport, potentially hindering crop growth. Undoubtedly, it is necessary to understand the mechanism of solute transport in red soil under low-quality water irrigation with different water salinity levels. Therefore, a one-dimensional vertical water infiltration experiment and a solute breakthrough experiment were conducted to evaluate the solute transport (soluble salt, Na+, and Cl−) in unsaturated and saturated homogenous red soil at different salinity levels [1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g/L] when irrigated with simulated low-quality water using analytical-grade NaCl. Moreover, the potential factors affecting salt distribution in unsaturated red soil were determined. The findings indicate positive linear relationships between accumulations of three solutes and irrigation water salinity. Generally, the depth of maximum solute concentration increased with the increase in irrigation water salinity. Soluble salt, Na+, and Cl− exhibited early breakthrough and trailing in red soil, but higher irrigation water salinity could reduce PV and retardation. A mobile and immobile water model (MIM) showed that convection was dominant in solute transport in red soil under low-quality water irrigation. D decreased as a power function with increasing irrigation water salinity, while v and R decreased linearly. Furthermore, the red soil can adsorb Cl− resulting from its special charge characteristics under low-quality water irrigation, which may be the main source of salt adsorption. Additionally, v > soil pH > βsalt primarily influenced salt distribution in the 0–40 cm soil profile. This study can provide insights into solute transport in red soil under low-quality water irrigation, facilitating soil fertility and structure, as well as low-quality water irrigation strategy optimization. [ABSTRACT FROM AUTHOR]

In recent years, exploring interactions between sunlight, semiconducting minerals and microorganisms in nature has attracted great attention. However, relatively little research has been conducted on the interaction between minerals and microorganisms in the plain areas of the Yellow River Basin under sunlight. In this study, the mineral composition and microbial community of red soil from the Ningxia Plain, China were analyzed. X–ray diffraction (XRD) results showed that red soil contained semiconducting minerals such as birnessite, hematite and goethite. 16S rRNA analysis found that electroactive microorganisms such as Proteobacteria, Firmicutes and Actinobacteriota were enriched in in–situ microbial community of red soil. Afterwards, electrochemical tests such as linear sweep voltammetry (LSV) and I–t curves, indicated that red soil exhibited good semiconducting properties under light irradiation. Finally, a dual chamber system and electrochemical techniques were used to explore the electron transfer relationship between red soil and microorganisms. The open circuit voltage (350 mV) and maximum power density (1242.72 mW/m2) of red soil cathode system were significantly improved compared to blank graphite electrode, indicating that red soil could serve as electron acceptors for microbial extracellular respiration. Red soil electrode in live bacteria exhibited the highest photocurrent density (0.29 μA/cm2) and the lowest charge transfer resistance (Rct) (223 Ω) under light conditions, indicating that red soil accelerated the rapid transfer of electrons, reduced polarization loss, and enhanced extracellular electron transfer (EET) process under light conditions. This study demonstrated that the participation of semiconducting minerals in microbial EET processes under sunlight in the Ningxia Plain, China. [ABSTRACT FROM AUTHOR]

The chlorination of surface waters leads to the formation of thrihalomethans (THMs) and haloaceticacids (HAAs) due to the presence of natural organic matters. Thus, the removal of fulvic acid (FA) as one of the most prominent natural organic matters in water is necessary. Therefore, this study was aimed to evaluate the efficiency of catalytic ozonation of FA in the presence of the local montmorillonite (Mnt). The soils were collected from the Ardabil Sarcham area and used as a catalyst, after the required preparation. The variables in this study including initial solution pH, catalyst dosage, reaction time, and initial pollutant concentration were examined. For the ozonation of the samples, an ozone generator with a capacity of 5 g/h was used. It was found that, with increasing contact time, pH, and catalysts dosage, as well as decreasing initial FA concentration, the performance of the catalytic ozonation process increased significantly. The results demonstrated that radical scavengers like nitrate, chloride, sulfate, and carbonate a high concentration had very low effect on the efficiency of this process compared to conventional ozonation. The kinetic data was found to fit into the pseudo-first-order kinetic model (R2 = 0.98) than the zero and pseudo-second-order model. The Green Mnt was more effectual than the Red Mnt at pH: pH = 7, FA concentration = 25 mg/L, time = 30 min, catalyst dosage = 1.25 g/L, inlet ozone concentration = 2.2 mg/L-min; which gave COD removals of 84.68 and 78.25%, respectively. As a whole, green and red soils increase highly the efficiency of FA removal in the catalytic ozonation process, because of low costs and availability of these soils. [ABSTRACT FROM AUTHOR]

Purpose: Investigating the contributions of different soil properties and their influences on changes in soil P fractions and availability is helpful for soil P management. Methods: Soil samples were collected in 2018 from a long-term red soil field experiment established in 1990. The unfertilized control (CK), chemical NK, NP, NPK, NPK with straw (S) (NPKS), NK + lime, NP + lime, NPK + lime, and NPKS + lime fertilization treatments, which were arranged in a randomized complete block design, were selected. Results: Compared with no lime, lime addition significantly increased the labile P/total P ratio in the NPK and NPKS treatments by 12.35% and 11.75%, respectively. The results further revealed that fertilization treatments without lime application (NK, NP, NPK, and NPKS) significantly reduced the soil pH, Mehlich-3 (M3)-Mg and M3-Ca compared with those in the CK and lime treatments during 2018. In contrast, lime application reduced the M3-Fe and M3-Al concentrations by 2% and 3%, respectively. Long-term P fertilization improved soil organic matter, M3-P, M3-Fe, and M3-Al. While soil pH exhibited a strong and positive relationship with M3-Mg (r = 0.780**) and M3-Ca (r = 0.788**) and a strong and negative correlation with M3-Fe (r = -0.395*) and M3-Al (r = -0.584**), the transformation and discharge of various P pools in red soil were facilitated by soil OM, M3-Fe, and M3-Al as the key contributors. Conclusion: NPK and NPKS combined with lime addition could be useful approaches for increasing the available P (labile P/total P) by enhancing M3-Ca and M3-Mg and soil pH while reducing M3-Fe and M3-Al in red acidic soil. [ABSTRACT FROM AUTHOR]

Abstract Selenium (Se) is an essential element for humans and animals, and Se deficiency-related diseases are a significant global health concern. Tea may help ameliorate Se deficiencies. However, the mechanisms of natural Se enrichment in tea remain poorly understood, particularly in high-Se soils, such as those in Jiangxi Province. This study conducted a comprehensive field survey of 67 soil and tea samples from Jiangxi, a major tea production region in China, to analysis spatial variation in Se concentrations and identify key driving mechanisms. The average soil Se concentration across Jiangxi was 0.44 mg kg− 1, exceeding both global (0.15 mg kg− 1) and Chinese (0.29 mg kg− 1) averages. Soil Se content was significantly influenced by soil organic matter (SOM), total potassium (K), iron (FeOX) and aluminium (AlOX) oxides, and tea planting duration, contributing 15%, 6%, 20%, 22%, and 10%, respectively. Soil Se levels increased with SOM and planting duration, but decreased with total K content. Conversely, the average Se content in tea leaves was only 0.10 mg kg− 1, and primarily driven by soil Se (29%), followed by FeOX (13%), AlOX (15%), SOM (5%), available K (5%), as well as inputs of nitrogen and K fertilizer (6% and 5% respectively), each. Partial least squares models identified four key pathways in which environment and human management practices, directly or via interactions with soil properties (SOM, K, FeOX, AlOX), influenced Se transfer from soil to tea leaves. Overall, our findings indicate that tea cultivation is more suitable in areas with high soil Se, such as central Jiangxi Province, and suggest that tea Se content can be enhanced by increasing levels of soil Se, SOM, K, FeOX, and AlOX.

This research investigates the characteristics of rainfall runoff and soil moisture variation in limestone soil and red soil slopes in the karst area of Northwest Guangxi. A self-made soil tank is utilized to simulate limestone soil and red soil slopes. The process of rainfall-runoff and soil moisture content of different depths of the soil layer (10 cm and 30 cm) are monitored under natural rainfall conditions, so as to compare and analyze the characteristics of different soil types in terms of rainfall runoff and soil moisture variation. The results are as follows. ① The runoff generation on limestone soil slopes is dominated by subsurface runoff, with an average subsurface runoff coefficient of 0.087; the runoff generation on red soil slopes is dominated by surface runoff, with an average surface runoff coefficient of 0.088. ② The runoff generation on limestone soil slopes starts only when the rainfall is moderate, and there is no significant change in the surface runoff coefficient with the increase of rainfall grade. The change of the coefficient of subsurgace runoff is complicated by the increase in rainfall level, with a down-up-down trend. The surface runoff coefficient of red soil slopes increases with higher rainfall levels; the runoff coefficient of subsurface runoff tends to decrease with increasing rainfall levels. ③ Under different rainfall levels, the runoff depth on limestone soil slopes is highly significantly correlated with the rainfall amount and rainfall duration, while the runoff on red soil slopes is highly significantly correlated with the rainfall duration. ④ The overall average soil moisture content of the limestone soil slopes (24.77%) is significantly lower than that of the red soil slopes (25.15%). The soil moisture content responds more rapidly to rainfall on the calcareous soil slopes than on the red soil slopes. The research results can provide a reference and reasonable opinions for the optimal allocation of precipitation resources on karst slopes.

Phosphorus (P) application can enhance soil P availability and alter P fractions. However, the P accumulation and transformation of different P sources in low-phosphorus red soil remain unclear. Two-year (2018–2019) field experiments were conducted to investigate the effects of five P source treatments (CK—no phosphorus; SSP—superphosphate; MAP—calcium–magnesium phosphate; DAP—monoammonium phosphate; and CMP—diammonium phosphate) on the P accumulation of maize and soil P fractions in low-P red soil using the Hedley Sequential Method. The results showed that P application significantly increased P uptake, Olsen-P, total phosphorus, and most of the soil P fractions. Compared to the CMP, MAP, and DAP treatments, SSP had a relatively higher P accumulation and labile P pool, with a slightly lower moderately labile P pool. The SSP treatment mainly increased soil-available P content and crop P uptake by increasing the labile P pool (resin-P and NaHCO3-Pi) and reducing the moderately labile P pool and non-labile P pool. The P activation coefficient (PAC%) and Olsen-P were positively correlated with labile P (resin-P, NaHCO3-Pi, and NaHCO3-Po) and moderately labile P (NaOH-Pi and 1 M HCl-Pi) and negatively correlated with Fe2O3 and Al2O3. The results suggest that SSP has a priority effect on the crop P uptake and soil P availability in low-P red soil. [ABSTRACT FROM AUTHOR]

Water pollution is currently a critical global issue. Various research groups have developed active adsorbent materials. This study aims to enhance the adsorption of water pollutants, particularly fluoride, by modifying the electronic structure of red soil through in-situ chemical oxidative polymerization techniques. The synthesized materials were characterized using techniques including powder XRD, FT-IR, UV spectroscopy, and Conductometer, followed by testing their adsorption performance. The XRD analysis revealed that while the crystal structures of embedded red soil remained amorphous, polyaniline (PANI) and PANI/red soil (RS) nanoparticles became polycrystalline. The maximum adsorption capacity (qmax) of fluoride ions by PANI/RS was determined to be 9.35 mg/g. Optimization experiments showed that PANI/RS exhibited maximum adsorption performance for fluoride ions under specific conditions: pH 4.0, a contact time of 50 min, temperature of 35 °C, and an initial concentration of 15 mg/L with 2 mg of adsorbent, achieving a removal efficiency of 99.9%. Both Langmuir and Freundlich isotherm models demonstrated a good fit with the experimental data, with R² values of 0.94 and 0.95, respectively. This suggests that PANI/RS is an effective adsorbent material for removing fluoride ions from wastewater. Overall, PANI/RS outperformed red soil alone, demonstrating potential for practical application in water treatment processes. [ABSTRACT FROM AUTHOR]

The evaluation of ecological environment quality (EEQ) is an important method to measure the quality of ecosystem services. Therefore, the EEQ of Changting County, located in the red soil region of southern China, was assessed by using the remote sensing ecological index (RSEI) based on Landsat images from 1995 to 2019, and its spatiotemporal variability was identified by using the Global Moran's I index, standard deviational ellipse, and kernel density estimation. The results showed that, firstly, the EEQ degraded from 1995 to 2000, then improved from 2000 to 2019; secondly, the spatial distribution of the RSEI for each study year was not random and had a strong positive correlation; thirdly, the directional distributions of the RSEI for all the grades were almost in the direction of southwest to northeast, and the spatial discrete characteristics of the moderate- and good-grade areas were almost consistent from 1995 to 2019; fourthly, the kernel density distribution of the moderate- and good-grade EEQ was located in towns within the Tingjiang River Basin and in the surroundings of the study area, respectively. This study can help managers to better understand the spatial–temporal variations in the EEQ in the study area, supporting the government in formulating a better ecological restoration strategy. [ABSTRACT FROM AUTHOR]

Returning livestock manure to the cropland as organic fertilizer is a sustainable and environmentally friendly treatment method, but its application also alters the soil microenvironment. However, the impact of soil microbial community disturbance and pollutant accumulation from different types of organic fertilizers remains largely unknown in South China. To fill this gap, we investigated the effects of organic fertilizers, including chicken manure, pig manure and vermicompost on the soil bacterial and fungal communities and environmental risks. The results show that applying organic fertilizer effectively increases the soil nutrient content. High-throughput sequencing of bacteria and fungi showed that the application of different organic fertilizers had differential effects on microbial community structure, with the highest number of microbe-specific OTUs in the vermicomposting treatment. Additionally, this study found no risk of heavy metal (Cu, Zn, Pb, Cr and Cd) contamination from short-term organic fertilizer application, but there was a risk of antibiotic (ENR and CHL) contamination. Functional microorganisms regulating heavy metals and antibiotics were identified by RDA analysis. This study facilitates the screening of types of organic fertilizers that can be safely returned to the field as well as developing strategies to regulate functional microbes. [ABSTRACT FROM AUTHOR]

Red soil, the most critical soil resource in tropical/subtropical regions worldwide, faces tremendous threats, including nutrient deficiency, acidification, and heavy metal contamination. There is a great demand for multifunctional eco-materials capable of modifying this situation. Herein, we used widely distributed soil and biomass to develop a zeolite/biochar composite for synergistic red soil remediation and amendment. With the composite material, the Pb2+ and Cd2+ remediation efficiencies reached 92.8% and 92.9%, respectively, in stems under optimal conditions. Moreover, the acidity and nutrient deficiency conditions of red soil significantly improved. The atomic-scale interaction mechanism during the remediation and amendment process was elucidated with complementary characterization methods, which revealed that in the zeolite/biochar composite material, zeolite contributes to long-term heavy metal remediation effects. Simultaneously, biochar is responsible for soil quality amendment and short-term heavy metal remediation. Furthermore, for the first time, single-atom heavy metal ions were observed on biochar during the remediation process, indicating the broad distribution of single atoms in the natural environment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shenyang Agricultural University is the property of Journal of Shenyang Agricultural University Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

MOF supported on the red soil was synthesized thru simple method by Cu˗MOF and red soil with ratio of 1 : 5. The structure and morphology of MOF supported on the red soil was considered by FTIR and Raman spectroscopy, FESEM, TGA and BET methods. The results showed MOF supported on the red soil have mesoporous nanostructure (20–25 nm). A simple and efficient synthesis of tetrazolo[1,5-a]pyrimidines was accomplished by three-component reaction of a mixture of aromatic aldehyde, 5-aminotetrazole and ethyl acetoacetate or methyl acetoacetate using MOF supported on the red soil as heterogenic catalyst. The reactions were carried out in water and ethanol at 70°C. MOF supported on the red soil operated as a sufficient recyclable, effective, low cost and eco-friendly catalyst for synthesis of tetrazolo [1,5-a] pyrimidines. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated the effect of sulphur and boron fertilization on crop growth, yield, qualities and productivity of blackgram under agroforestry system (AFS). Topics discussed include biometric observations of plants at maturity, effect of sulphur and boron nutrition on growth parameters of blackgram, and effect of sulphur and boron nutrition on economics of blackgram under AFS.

Studying the effects of maize and soybean intercropping for improving the maize yield and sustaining stability of the maize yield under different phosphate (P) application rates in red soil is crucial for promoting maize productivity, improving soil fertility and optimizing P nutrient management in southwest China. The objective of this study was to evaluate the dynamic changes in maize yield, yield stability and soil fertility under monoculture and intercropping maize with different P application rates. A six-year field experiment was conducted from 2017 to 2022 to investigate the effects of maize intercropping with soybean on the yield stability and sustainability of maize according to the changes in the maize yield, biomass, partial land equivalent ratio of yield (pLERY), actual yield loss index (AYL), contribution rate of soil capacity and fertilizer (SCR, SFCR) over time, as well as the differences in the coefficient of variation (CV) and sustainable yield index (SYI) at four P application rates (0 kg P2O5 ha−1, P0; 60 kg P2O5 ha−1, P1; 90 kg P2O5 ha−1, P2; and 120 kg P2O5 ha−1, P3) based on the two-factor randomized block design. The linear-platform model was utilized to simulate the relationship between the grain yield, the SYI and the amount of P fertilizer under different P application rates. The maize yield in intercropping was significantly superior to the maize yield in monoculture throughout the entire six-year experiment. For all planting years, the yield and biomass of the intercropping were higher than those of the matched monoculture average by 56.0% and 56.1%, respectively. Intercropping had an advantage of pLERY and AYL for maize. Otherwise, intercropping reduced the CV by 30.8% and 39.1% and increased the SYI by 39.4% and 23.0% in P0 and P3 compared with the matched monoculture, respectively. For all planting years, the average SFCR in intercropping treatment was higher than that in monoculture treatment. The linear-plateau model fitted showed that intercropping increased the yield and SYI by 19.8% and 40.7% on the platform and reduced the P application rate by 37.8% and 11.9% at the inflection point, respectively. These results demonstrate that maize and soybean intercropping could achieve a higher yield, a higher yield stability and an SYI with a lower P input than monoculture. Maize and soybean intercropping could be a sustainable practice for promoting the maize productivity and the yield sustainability in the red soil of southwest China. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shenyang Agricultural University is the property of Journal of Shenyang Agricultural University Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Investigating the effects of natural rainfall on the soil moisture for sloping farmland is extremely important for comprehending a variety of hydrological processes. Rainfall regimes can elicit different responses to soil moisture at the depth of soil layers, and the responses may differ depending on the landscape position of the sloping farmland. This paper utilized the surface runoff natural rainfall and soil moisture measured on sloping farmland with conventional tillage and contour tillage in the red soil area of China to investigate the influence of natural rainfall events on soil moisture content and to evaluate if the response results were consistent across the four rainfall regimes. Natural rainfall events were classified into different four regimes in line with rainfall duration, rainfall amount, and the maximum 30 min rainfall intensity (I30) by the k-means clustering method, including advanced, intermediate, uniform and delayed regimes. The result showed that the advanced regime was the predominant one in the study area, which represented 45.9% of the total rainfall events. The rainfall regimes influenced the surface runoff coefficient and runoff depth on sloping farmland for conventional and contour tillage, with the uniform regime generating the highest runoff coefficient (5.20% and 5.82%) and runoff depth (2.00% and 2.05%), respectively. For the conventional tillage, soil moisture at a depth of 0–20 cm increased appreciably when the rainfall amount was larger than 20 mm and larger than 30 mm for the advanced regime. For the contour tillage, soil moisture in 20–40 cm layer increased for the advanced regime when the rainfall amount was larger than 15 mm and 30 mm, while the values were modified with rainfall duration and the antecedent dry day (ADD). A longer rainfall duration had a more obvious effect on soil moisture increasing in deep soil. At a depth of 20 cm, the ADD showed an appreciably positive correlation with the increment in soil moisture, which means that a brief ADD produces a compounding effect for a natural rainfall event. The present results underline the complexity of the effect of the rainfall events on soil moisture under two tillage measures for different rainfall regimes and suggest that the advanced regime significantly affects the distinction of soil moisture and the contour tillage can effectively reduce soil water loss and enhance water storage on the sloping farmland with red soil, presenting a theoretical basis for local soil and water conservation research and sloping farmland conservation tillage management. [ABSTRACT FROM AUTHOR]

The global spread and distribution of antibiotic resistance genes (ARGs) has received much attention whereas knowledge about the transmission of ARGs from one matrix to another is still insufficient. In this study, the paddy fields fertilized with chemical fertilizer, swine compost, and no fertilizer were investigated to assess the transfer of ARGs from soil to rice. Soil and plant samples were collected at day 0, 7, 30 and 79 representing various stages of paddy growth. High throughput qPCR was applied to quantify ARGs using a set of 144 primers. Gene copy number of ARGs measured in soil initially decreased and then increased in soil with no fertilizer and chemical fertilizer, indicating that crop planting and flooding conditions did influence the ARGs profiles in soil. Application of swine compost significantly enhanced the relative abundance and gene copy number of ARGs in paddy soil. Rice seedlings contained substantial amount of ARGs and their relative abundance continually decreased after transplant. Compared with initial stage, detection frequencies of ARGs increased in soil without swine compost at harvest time (day 79), indicating the transmission of ARGs from irrigation water to soil. Detection frequencies of ARGs increased in soil and rice root with swine compost at harvest time, indicating the transfer of ARGs from swine compost to soil and rice root. There was no significant difference in abundance and diversity of ARGs in rice grains with these three different fertilizations. The source of the ARGs in rice grain still needs further exploration.

Appropriate nitrogen (N) management system is essential for effective crop productivity and minimizing agricultural pollution. However, the underlying mechanistic understanding of how N fertilizer regulates crop yield via soil properties in soils with different fertilities remains unresolved. Here, we used a field experiment that spanned 3 cropping seasons to evaluate the grain yield (GY), aboveground biomass and N recovery efficiency (NRE) after treatment with five N fertilizer application rates (N0, N75, N112, N150, and N187) in soils with three levels of fertility. Our results indicated that the highest GY across low, moderate, and high fertility soils were 1.5 t hm-2 (N150), 4.9 t hm-2 (N187), and 5.4 t hm-2 (N112), respectively. The highest aboveground biomass and NRE were observed at N150 for all three levels of soil fertility, while only the N uptake by aboveground biomass of low and high fertility soils decreased at N187, confirming that excessive N fertilization results in a further decline in crop N uptake. The relationship between GY, NRE and N fertilizer application rates fit the unary quadratic polynomial model. To achieve a balance between grain production and environmental benefits in N fertilizer, appropriate N fertilizer rates were determined to be 97.5 kg hm-2, 140 kg hm-2 and 131 kg hm-2 for low, moderate and high fertility soils, respectively. Structural equation modeling suggested that GY was significant correlated with soil microbial biomass carbon (SMBC) and N directly in low fertility field, with SMBC directly in moderate fertility field, and via SOC and NO3-N in high fertility field. Therefore, a soil-based management strategy for N fertilizers could enhance food security while reducing agricultural N fertilizer inputs to mitigate environmental impacts. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Red soil is one of the typical soil types in China, which is widely distributed in 17 provinces with a total area of 569,000 km², accounting for about 1/5 of the total land area in China. It is a widely distributed soil type in Yunnan Province. Compared with other natural soils, red soil has high viscosity, high water content, low shear strength, serious loss of organic matter and nutrients, and changes in soil structure and quality, which leads to low root characteristic parameters of root-soil complex and cannot meet the needs of engineering practice. However, the roots of herbaceous plants are mostly dense and fine roots, which have a good reinforcement effect on shallow soil, consolidate soil and prevent erosion, and their root characteristic parameters can better reflect the contribution of roots to soil shear strength. It is of certain significance to study the mechanical properties of root-soil complex of herbs through root characteristic parameters. In order to find out the influence mechanism of root characteristics on the shear characteristics of herb root-soil complex under different mass fractions (0, 0.5%, 2.5% and 5.0%) of wood fiber reconstruction red soil, the shear strength of root-soil complex of white clover and ryegrass was measured by direct shear test, and four root characteristic parameters, such as root surface area index, root volume ratio, root length and underground biomass, were measured by WinRHIZO root analysis system, and their resistance was further revealed. The results showed that proper wood fiber addition was beneficial to the growth of fibrous root herbs. When the wood fiber content is high, the root length of Lolium perenne and white clover are 456.27 and 438.35 cm respectively, and the underground biomass are 0.410 and 0.150 mg respectively. With the increase of root characteristic parameters, the shear strength of ryegrass root-soil composite is greater than that of white clover root-soil composite, and the shear strength of both is better than that of single wood fiber composite soil or root soil, with the increase ranges of 26.55% - 47.20% and 26.21% - 35.07% respectively, but there is a certain change threshold. The Mohr-Coulomb model is used to simulate the shear characteristic parameters of the root-soil complex. When the characteristic parameters of root system reach the change threshold, the change of cohesion is obviously and plays a leading role, but has little influence on internal friction angle. The shear strength of root-soil complex increases first and then decreases. When the root parameter value exceeds the threshold, the shear strength of wood fiber rootsoil composite decreases, showing a trend of increasing first and then decreasing. This study has important theoretical and engineering practice value for further study of slope protection, vegetation restoration and land consolidation in red soil region. [ABSTRACT FROM AUTHOR]

To assess the effects of reforestation on ecosystem carbon storage, a long-term Forest Restoration Experimental Project (FREP) was established in 1991 on southern degraded red soil in Taihe County, Jiangxi Province, China. In this study, we selected five types of plantations: Schima superba plantation (SS), Liquidambar formosana plantation (LF), Pinus massoniana plantation (PM), Pinus elliottii plantation (PE), and P. elliottii and broadleaf mixed plantation (MEB). The unforested land was used as an experimental control check (CK). We aimed to assess the changes in carbon storage in plantations and the factors affecting them. Thirty years after reforestation, the ecosystem carbon storage of the five types of plantations was significantly higher than that of the control site, and there were also significant differences in the ecosystem carbon storage between the different plantation types (p < 0.05). The ecosystem carbon storage of SS, MEB, LF, PM, and PE were 211.71 Mg ha−1, 199.02 Mg ha−1, 160.96 Mg ha−1, 155.01 Mg ha−1, and 142.88 Mg ha−1, respectively. Compared to the CK, these values were increased by 436.8%, 404.6%, 308.1%, 293.1%, and 262.3%, respectively. The ecosystem carbon storage was significantly positively correlated with soil porosity, total nitrogen (TN), and stand density, and was significantly negatively correlated with pH, Pielou's evenness index (PEI), and the Shannon–Weiner diversity index (SWDI). The soil water content (SWC), bulk density (BD), SWDI, and stand density can be used as indicators of the impact of reforestation plantings on ecosystem carbon storage. The research results has shown that reforestation plantings significantly increase ecosystem carbon storage, and that afforestation should be encouraged on degraded land. [ABSTRACT FROM AUTHOR]

The features of the degradation of the ''green'' plastic poly(3-hydroxybutyrate) [P(3HB)] in the soil of various geographical regions were studied: in red ferralitic soil under tropical conditions (Kerala, India) and in chernozem soil under conditions of a sharply continental climate (Eastern Siberia, Russia). Significant differences in the chemical composition, temperature, and humidity of the studied soils were revealed. The number of bacteria and mycelial fungi in the Siberian chernozem was higher than in the red soil of India, from 2-3 to 10 or more times. The degradation of P(3HB) films in the chernozem occurred faster than in the red soil, which was drier, with a low content of humus and minerals, and fewer microorganisms than the chernozem. The half-life of polymer samples in Siberia and India was 64.8 and 126.4 days, respectively. During degradation, a decrease in the molecular weight and an increase in the degree of crystallinity of polymer samples were revealed, which indicates a more active biodegradation of the amorphous phase of the polymer by soil microorganisms. The primary degraders of the polymer have been isolated and identified, and it has been shown that the complexes of degrading bacteria and fungi in different types of soils did not have common species. Despite the presence of species with pronounced depolymerase activity, the rate of film degradation in red ferralitic soils was slowed down by unfavorable environmental conditions. The obtained results confirm the importance of studying the process of PHA degradation in natural conditions.

Background: To control mosquito vectors causing human diseases, bacterial biopesticides are currently in use. Indeed, the recent development of resistance to these bacterial agents has impeded its applications. Under these circumstances, the search for novel bacterial agents with mosquitocidal activity is unavoidable. In this study, a novel mosquitocidal bacterium was isolated from red soils of agricultural field. Objectives: The objective of this study was to isolate and identify new mosquitocidal bacteria from the natural environment. Materials and Methods: Soil samples were collected during 2021–2022 from Tirupathur district of Tamil Nadu, South India. The samples were bioprocessed for culturing the bacterial colony in a suitable culture medium (Nutrient Yeast Salt Medium), and after 72 h, the bacterial cell mass was removed and lyophilized. Bioassays (mosquito toxicity assays) were carried out to screen the bacterial colonies for mosquitocidal effect. The potential colony was further analyzed, and identified for its application in mosquito control. Results: The new isolate screened from red soil was identified as Bacillus thuringiensis subspecies israelensis (VCRC B647) as per the ilvD gene sequence analysis. The strain was found to be potentially effective in controlling mosquito larvae, and further biochemical analyses, bacterial growth, biomass, and protein content were investigated. The new isolate did not show any toxic effect on nontarget aquatic organisms. Conclusion: It is significant to depict that the mosquitocidal action of this new isolate (Bti) is highly significant than the reference strain of Bti-H14. It is concluded that this is the first report that an indigenous strain of Bti VCRC B647 is very effective in mosquito control.

The evaluation of ecological environment quality (EEQ) is an important method to measure the quality of ecosystem services. Therefore, the EEQ of Changting County, located in the red soil region of southern China, was assessed by using the remote sensing ecological index (RSEI) based on Landsat images from 1995 to 2019, and its spatiotemporal variability was identified by using the Global Moran’s I index, standard deviational ellipse, and kernel density estimation. The results showed that, firstly, the EEQ degraded from 1995 to 2000, then improved from 2000 to 2019; secondly, the spatial distribution of the RSEI for each study year was not random and had a strong positive correlation; thirdly, the directional distributions of the RSEI for all the grades were almost in the direction of southwest to northeast, and the spatial discrete characteristics of the moderate- and good-grade areas were almost consistent from 1995 to 2019; fourthly, the kernel density distribution of the moderate- and good-grade EEQ was located in towns within the Tingjiang River Basin and in the surroundings of the study area, respectively. This study can help managers to better understand the spatial–temporal variations in the EEQ in the study area, supporting the government in formulating a better ecological restoration strategy.

ABSTRACTWe analyzed the characteristics of red soils that are often considered collapsible soils. In this study, we examined the depositional environment and lithologic characteristics, analyzed stratigraphy, and conducted mechanical sieve, X-ray fluorescence, X-Ray diffraction, scanning electron microscope, X-ray fluorescence analyses and optically stimulated luminescence dating. The samples were collected from the gravel pits to examine and reveal details of their depositional processes. The abrupt particle size change in the overlying soil formed a pseudo-disconformity with the subjacent gravel bed. The soil was unstratified with granule gravels scattered throughout the soil layer. The soil consisted of mostly sand (~70%), with minor silt and clay contents (~30%); thus, the soil was classified as silty sand. The soil samples contained a large amount of silicon, a high percentage of quartz. V-shaped micro textures represented percussion and abrasion mechanisms on the surface of individual grains, suggesting transport by fluvial processes. The deposition occurred during the Late Pleistocene, and the absence of desert environment suggested different conditions than those associated with aeolian deposition. Consequently, the lithology, physical and chemical properties, and chronology were consistent with termite mounding, which plays an important role in the upward transportation of small particles and causes large sediments to descend.

Visible-near-and-short-wave-infrared hyperspectral images (HSI) have proven helpful for mapping the soil types over bare soils pixels. However, the accuracy of the traditional pixel-based classification methods decreases due to the spectral mixing between the significant agricultural features such as vegetation, soil and crop residue. In this context, spectral unmixing algorithms are handy for estimating the sub-pixel abundances of soil over sparsely vegetated areas. Most of the spectral unmixing methods focus on analyzing the HSI by considering the pixels as independent entities. However, in the HSIs of agricultural fields, the endmembers are spatially and temporally variable. It is also known that there exists a strong spatial correlation among neighbourhood pixels over agricultural fields. Therefore, both endmember variability and the neighbourhood spatial-spectral information are critical to estimate soil abundance accurately. Here we address the issue of estimating the abundances of two major soil types with spectral variability. The proposed approach combines the endmember bundle extraction with the spectral-spatial weighted unmixing approach (SSWU-SV). Experimental analysis has been carried out on the airborne HSI acquired by airborne-visible-and-infrared-imaging- spectrometer-next-generation (AVIRIS-NG) sensor. The quantitative analysis reveals that the proposed method consistently achieves a better unmixing performance than the traditional linear mixing model in terms of spectral angle mapper (SAM), and root-mean-square error (RMSE). Our results also indicate the saturation of normalized difference vegetation index (NDVI) at high vegetative fractions obtained from SSWU-SV. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to investigate the effects of microplastics on the structure and carbon, nitrogen, phosphorus stoichiometric characteristics of red soil with different levels of iron enrichment, and to provide theoretical basis for guiding the improvement of soil quality and pollution management in red soil areas. [Method] Using subtropical red soil as the research object, low density polyethylene (M0, M1, M2) with 0, 0.1%, 1.0% mass and iron (Fe0, Fe1, Fe2) with 0, 10 and 20 g/kg mass were added through indoor cultivation experiments to simulate the pollution level of microplastics and the degree of iron enrichment in red soil. The distribution characteristics of water stable aggregates and the stoichiometric characteristics of carbon, nitrogen and phosphorus in red soil polluted by microplastics under different iron enrichment conditions were studied. [Result] Under the condition of Fe0o, compared with M0, the aggregate content (WSA), mean weight diameter (MWD) and geometric mean diameter (GMD) of M1 with particle size > 0.25 mm decreased, and the WSA, MWD and GMD of M2 increased significantly; Under Fe0, conditions, there was no significant difference in the stability indicators of aggregates among M0, M1 and M2; Under Fe2 conditions, both M1 and M2 significantly reduced the WSA, MWD and GMD of soil aggregates. In terms of carbon, nitrogen and phosphorus content and their stoichiometric characteristics, M1 and M2 under Fe0 conditions could significantly increase soil organic carbon content (SOC); Under Fe0, and Fe2 conditions, microplastic treatment had no significant effect on SOC. The total nitrogen content (TN) of the soil decreased significantly under Fe0, and Fe1, conditions, while microplastic treatment had no significant effect on TN under Fe2 conditions; The total phosphorus content (TP) of the soil showed M0 > M1 > M2. The changes in soil nutrients ultimately led to a significant increase in C/N, C/P and N/P of all microplastic treatments (except for Fe0, M1, Fe2 M1 and Fe2 M2). [Conclusion] The effects of different treatments on the stability of soil aggregates vary. Under the current existing red soil conditions, low micro plastic pollution can reduce the stability of soil aggregates, while high micro plastic pollution can increase the stability of soil aggregates. Under relatively light iron rich red soil conditions, both low and high microplastic pollution have no significant impact on the stability of soil aggregates. Under relatively high iron rich red soil conditions, both low and high microplastic pollution can reduce the stability of soil aggregates. M0reover, the changes in soil aggregate structure under different treatments led to significant differences in the stoichiometric characteristics of carbon, nitrogen and phosphorus in the soil. Overall, microplastic pollution can significantly improve the C/N, C/P and N/P of red soil. [ABSTRACT FROM AUTHOR]