Undisturbed Soil Research Articles

SOIL CHARACTERIZATION: INTEGRATING IN-SITU TEST, LABORATORY ANALYSIS, AND TERRAIN PARAMETERS

This research introduces an innovative methodology for characterizing geotechnical parameters of soils, crucial for designing foundations for various structures. Rather than relying on general correlations from geotechnical books, the primary goal is to obtain specific characteristic values tailored to the study area. The methodology establishes correlations between in-situ tests and laboratory tests to determine soil parameters in the Valley of the Chillos. The Valley of the Chillos is a geographical region in the southeastern part of Quito, Ecuador. It falls within the administrative zone of Los Chillos in the Metropolitan District of Quito. The valley is surrounded by the inactive Ilaló volcano to the north and the Pasochoa, Antisana, and Lomas de Puengasí mountains to the south, east, and west, respectively. To achieve the research objective, soil samples were collected using the Standard Penetration Test (SPT) at depths ranging from 1 to 15 meters, following the ASTM D-1586 standard. Additionally, undisturbed soil samples from the thin-walled Shelby tube were obtained in the field and subsequently tested in the laboratory. These tests covered aspects such as natural moisture content, granulometric analysis, Unified Soil Classification System, classification, liquid limit, plasticity index, specific gravity, void ratio, and degree of saturation. The results from both field and laboratory tests will be used to calculate the load capacity of foundations specifically for characteristic soils in the Los Chillos Valley, considering their classifications.

The normalized difference vegetation index value of volcanic paddy soils of Mt. Talang using Landsat 8 image

Abstract Accurate and up-to date information on the spatial distribution of paddy fields in volcanic soils is important. The volcanic soil in West Sumatra covers an area about 602.500 ha. Soils of volcanic origin are considered fertile and productive soils. They are widely used to grow annual and perennial crops. Paddy cultivation in volcanic soils is commonly practiced in West Sumatra. Remote sensing data can be used to observe the condition of rice plants in volcanic soils from by calculating the vegetation index value through the NDVI (Normalized Difference Vegetation Index). This study aims to determine the vegetation index of paddy grows in Mt. Talang by using Landsat 8 satellite imagery and correlate the index value with the total carbon and fractions content. Soil samples were collected using the 1x1 km interval grid method from 5099,78 ha of volcanic paddy fields. Soil samples were collected undisturbed and disturbed condition. The undisturbed soil samples were used to analyze bulk density (BD). The disturbed soil samples were dried and sieved with a 2-mm sieve and then analyzed for soil pH (H20 and KCl), Organic C, Labile C, and Very Labile C. All of soil samples have low bulk density (0.76-0.89 Mg/m3). Soil pH is considered neutral (6.50 to 6.93). The average vegetation index value was high, with a maximum value of 0.60 and a minimum value of 0.39. The results of the regression analysis showed that there was no relationship between NDVI and soil chemical properties. Determination of the vegetation index during the growing period of paddy is very useful to improve the accuracy of paddy identification sites at the regional scale and to predict the potential paddy production in due time.

Effects of transient flow conditions on colloid-facilitated release of decabromodiphenyl ether: Implications for contaminant mobility at e-waste recycling sites

Polybrominated diphenyl ethers (PBDEs) are ubiquitous contaminants, especially in the soil and groundwater of contaminated sites and landfills. Notably, 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209), one of the most frequently and abundantly detected PBDE congeners in the environment, has recently been designated as a new pollutant subject to rigorous control in China. Colloid-facilitated transport is a key mechanism for the release of PBDEs from surface soils and their migration in the aquifer, but the effects of hydrodynamic conditions, particularly transient flow, on colloid-facilitated release of PBDEs are not well understood. Herein, we examined the effects of typical transient flow conditions on the release characteristics of colloids and BDE-209 from surface soil collected from an e-waste recycling site ​by undisturbed soil-core leaching tests involving multiple dry–wet cycles (with different drying durations) and freeze–thaw cycles. We observed significant positive correlations between BDE-209 and colloid concentrations in the leachate in both the dry–wet and freeze–thaw leaching experiments, highlighting the critical role of colloids in facilitating BDE-209 release. However, colloids mobilized during the dry–wet cycles contained higher contents of BDE-209 than those in the freeze–thaw cycle tests, and the difference was primarily due to the more intensive disintegration of soil aggregates and elution of newly formed inorganic colloidal particles (mainly primary silicate minerals such as quartz and albite) with low BDE-209 content during the freeze–thaw process. These findings underscore the necessity of considering transient flow conditions when assessing the fate and risks of PBDEs at contaminated sites.

Optimized fertilization mitigated carbon and nitrogen losses in a Solonchak

AbstractWith the rapid expansion of agriculture on saline–alkaline soils, environmental problems such as increased greenhouse gas (GHG) emissions, eutrophication and soil degradation are becoming increasingly serious. To clarify the characteristics of carbon (C) and nitrogen (N) cycling and their loss mechanisms in cultivated saline–alkaline soils, an undisturbed soil column experiment was conducted to analyse C and N leaching and GHG emissions by applying different fertilizer rates. The experiment had six treatments using N‐(NH4)SO4 over a 40‐day seedling stage, with and without maize. Treatments were: no N with maize (0Nmaize: 0 kg N ha−1), reduced N with maize (RNmaize: 63 kg N ha−1), conventional N with maize (CNmaize: 160 kg N ha−1) and their equivalents without maize (0Nsoil: 0 kg N ha−1; RNsoil: 63 kg N ha−1; CNsoil: 160 kg N ha−1). The results indicated that reduced N with maize reduced the N2O emission by 21%, with N leaching (TN: 41%, NO3−–N: 19%, NH4+ − N: 63%) within 15 days after fertilization, but had no significant effect on CH4 emission compared to conventional N with maize. Therefore, reduced N with maize had the smallest N loss, which accounted for 1.5% of the relative percentage of N flow including N2O (0.3%), N leaching (2%), aboveground biomass N (76%) and root biomass N (22%). Compared to conventional N with maize, reduced N with maize significantly reduced N leaching by 40% because conventional N with maize greatly exceeded the crop N uptake when maize root length was only within 20 cm. Reduced N without maize reduced CO2 emission (19%) compared to conventional N without maize. Uncultivated saline–alkaline soils face greater N overuse and leaching risk because higher NO3−–N leaching (6.9 mg L−1) that occurred in bare soils without fertilization, which increased by 2.6–3.6 times when the N input increased from 63 to 160 kg N ha−1 compared to control. In conclusion, reducing conventional N fertilizer inputs by 60% is not only an effective strategy to reduce CO2 and N2O emission and N leaching but also effectively absorbs C, and the N retained in the soil tillage layer can help to meet maize seedling growth requirements in Solonchaks.

Microstructure development in lacustrine, fine-grained sediments traced by in situ and laboratory testing

Soil microstructure, often defined as the combination of particle arrangement and bonding, can strongly influence the stiffness and strength of sedimentary deposits. As undisturbed soil sampling is a challenging task in fine-grained soils, seismic in situ testing is becoming increasingly more important to investigate its mechanical behaviour. The aim of this article is to evaluate the influences of sediment depositional age and structure-forming processes on the degree of soil structure development in Alpine deposits. Seismic in situ and laboratory testing comprising X-ray diffraction (XRD), scanning electron microscopy (SEM), pore water chemical analysis and hydrochemical modelling were executed at three Austrian test sites, namely Lokalbahn Salzburg, Rhesi and water reservoir Raggal. Based on the comparison of in situ shear wave velocities (VS,SDMT) with bender element results (VS,BE), executed on reconstituted soil specimens, it is shown that the Pleisto–Holocene-aged deposits are characterized by a VS,BE/VS,SDMT ratio of < 1, indicating the presence of microstructure. However, the youngest sediments (< 50 years) exhibit the weakest microstructure (VS,BE/VS,SDMT ≈ 1). The increase of soil structure with sediment age is represented by the updated normalized small-strain rigidity index, K*G, which is situated at the proposed transition between structured and unstructured soils (K*G = 330), ranging between 250 and 350, at all test sites. The development of microstructure can be attributed to the precipitation of calcite (CaCO3) cements in open pores, which strengthens the interparticle bonding between detrital quartz, feldspar, clay minerals and carbonate grains, subsequently reducing the soil`s porosity with increasing sediment age.

Soil heavy metal pollution and ecological risk assessment in disturbed and undisturbed soil of Morigaon, Assam

Soil heavy metal pollution and ecological risk assessment in disturbed and undisturbed soil of Morigaon, Assam

Effect of the incorporation of ashes from the Calbuco volcano on the porous function of an andosol

Soils derived from volcanic ashes represent >60% of the arable land in Chile. Permanent volcanic activity makes seeking solutions for the management of volcanic material deposited after an eruption essential. The aim of this research was to evaluate how incorporating ashes from the eruption of the Calbuco Volcano affected the structure of a volcanic soil in southern Chile. Undisturbed soil samples were collected in 2022, under three field conditions: soils from which the ashes were entirely removed after the eruption (c), soils in which the ashes were incorporated (c/i) and soils on which the ashes remained on the surface (s/i). The pore-size distribution and the air conductivity were determined based on the water retention curve (WRC), the coefficient of linear extensibility (COLE), the pore shrinkage index (PSI) and the air permeability (Ka). Under c/i field conditions, an increase in total porosity (TP) of 5.57 and 3.48% was found when compared to the control and s/i field conditions, respectively. The highest volume of plant available water capacity (PAWC) was observed in the s/i field conditions, which increased by 65% compared to the other soil conditions. The incorporation of ash into the first 20 cm of depth did not guarantee an increase in usable water for plants; nonetheless, changes in structure did generate a redistribution in the pore size. Therefore, it is essential to evaluate how volcanic ash deposits and their incorporation affect soil physical properties under field conditions.

Effect of water salinity and sodicity on soil least limiting water range

AbstractThis study aimed to evaluate the effects of water salinity and sodicity on the least limiting water range (LLWR) of two clay loam and sandy loam soils. The undisturbed soil samples were subjected to different water qualities, including three levels of sodium adsorption ratio (SAR, 1, 5, and 12) and electrical conductivity (EC, 1, 6, and 10 dS m−1). Our findings indicate that increasing EC at each SAR led to greater soil water retention. This was attributed to salinity affecting pore size distribution toward smaller pores by altering the diffuse double layer and causing soil particle flocculation. With increasing SAR levels at each EC level, soil water content at the wilting point also rose due to structural changes, clay swelling, and dispersion, resulting in more micropores and increased adsorptive surfaces in the soil. Additionally, soil volumetric water content at a 10% air‐filled porosity decreased, while values at a critical penetration resistance of 2 MPa increased with higher bulk density across all treatments. The LLWR showed a negative correlation with bulk density in clay loam soil across all SAR and EC treatments. The LLWR increased with higher water EC but decreased with increasing water SAR. The highest LLWR was observed at SAR = 1 and EC = 10 dS m−1, while the lowest occurred at SAR = 12 and EC = 1 dS m−1. The results revealed that elevated values of SAR in irrigation water reduced soil water accessibility for plants. However, as irrigation water salinity increased, the detrimental effects of SAR diminished.

Study on Strength of Slip Soil–Tuff Contact Surfaces in Tuff Landslide Based on Model Test

In the exploration tunnels of the Xiageliao landslide, slide failures were found not only inside the slip soil but also on the contact surface between the slip soil and the tuff. The undisturbed slip soil was collected from the exploration tunnel for testing to explore the pattern of slide failure occurrence. The surfaces of concrete blocks of different shapes were used to simulate slip soil–tuff contact surfaces of different roughness. The shear strength of these contact surfaces with different roughness was tested using a large-scale shear test system and analyzed through comparison with the shear strength of the slip soil. The test results showed that the interface roughness significantly affected the shear strength of the slip soil contact interface and determined the shear failure mode of the slip soil. When the roughness is below a certain level, the shear strength of the contact surface is less than the soil shear strength, and when the roughness reaches a certain level, the shear strength of the contact surface exceeds the strength of the slip soil itself. Thus, the strength of the slip soil itself sometimes differs from the strength of the slip surface. Based on the Moore–Cullen law, the test results found a formula for calculating the contact surface shear strength. These results provide some references for the risk evaluation of landslides.

Characterization of soil pores in strip-tilled and conventionally-tilled soil using X-ray computed tomography

Changes in soil pore size distribution and connectivity can affect contaminant transport. Climate, soil type, and agricultural management practices can influence these characteristics. Conservation tillage practices, such as strip tillage, have been promoted as agricultural management practices that can help reduce soil erosion and nutrient loss in runoff. However, limited information exists in the literature on the effect of strip tillage on soil pore characteristics. Thus, the objective of this research study was to assess the effects of different tillage practices i.e., conventional tillage (CT) vs. strip tillage (ST), on soil pore properties and quantify change in soil pore characteristics as a function of season. Undisturbed cylindrical soil columns (150 mm diameter and 640 mm length) were collected from a field in Alabama, USA planted with cotton (Gossypium hirsutum L.) under ST and CT treatments during two seasons i.e., fall 2021 and spring 2022. Soil cores were collected from CT and ST portions of the field, in the fall, following cotton harvest and before planting a cover crop (season 1), and in the spring, after the cover crop had matured (season 2). X-ray computed tomography was used to scan the soil cores and quantify soil pore characteristics. Results show that the ST treatment had significantly (p < 0.05) greater macroporosity values, network density, macropore length density, and interconnectivity compared to the CT in season 1. This was attributed to ST being a minimally disturbed treatment: thereby, it has a better chance of preserving cracks and biological activity as compared to CT, which is more prone to destruction of large macropores. The pore properties also showed a drastic decrease in values during season 2, especially for the top 200 mm of the soil profile in response to rainfall induced soil reconsolidation in both the tillage systems. Overall, this study showed that pore morphology can be affected by tillage and seasonal aspects associated with them.

X-ray chemical imaging for assessing redox microsites within soils and sediments

Redox reactions underlie several biogeochemical processes and are typically spatiotemporally heterogeneous in soils and sediments. However, redox heterogeneity has yet to be incorporated into mainstream conceptualizations and modeling of soil biogeochemistry. Anoxic microsites, a defining feature of soil redox heterogeneity, are non-majority oxygen depleted zones in otherwise oxic environments. Neglecting to account for anoxic microsites can generate major uncertainties in quantitative assessments of greenhouse gas emissions, C sequestration, as well as nutrient and contaminant cycling at the ecosystem to global scales. However, only a few studies have observed/characterized anoxic microsites in undisturbed soils, primarily, because soil is opaque and microsites require µm-cm scale resolution over cm-m scales. Consequently, our current understanding of microsite characteristics does not support model parameterization. To resolve this knowledge gap, we demonstrate through this proof-of-concept study that X-ray fluorescence (XRF) 2D mapping can reliably detect, quantify, and provide basic redox characterization of anoxic microsites using solid phase “forensic” evidence. First, we tested and developed a systematic data processing approach to eliminate false positive redox microsites, i.e., artefacts, detected from synchrotron-based multiple-energy XRF 2D mapping of Fe (as a proxy of redox-sensitive elements) in Fe-“rich” sediment cores with artificially injected microsites. Then, spatial distribution of FeII and FeIII species from full, natural soil core slices (over cm-m lengths/widths) were mapped at 1–100 µm resolution. These investigations revealed direct evidence of anoxic microsites in predominantly oxic soils such as from an oak savanna and toeslope soil of a mountainous watershed, where anaerobicity would typically not be expected. We also revealed preferential spatial distribution of redox microsites inside aggregates from oak savanna soils. We anticipate that this approach will advance our understanding of soil biogeochemistry and help resolve “anomalous” occurrences of reduced products in nominally oxic soils.

Conversion of Marginalized Tea Lands into Timber Plantations and its Impact on Soil Organic Carbon Content: A Case Study in Central Highlands of Sri Lanka

Tea (Camellia sinensis) plantations can be in production for about 100 years under well-managed conditions. However, soil degradation makes the tea lands marginalized and uneconomical. Land use conversion is an option for marginalized tea lands that could gain numerous environmental and economic benefits. This study estimated and compared the soil organic carbon stocks (SOC) in the surface soil layer (0–30 cm) of marginalized tea lands against those converted to timber plantations in the Badulla and Nuwaraeliya districts. Disturbed and undisturbed soil samples were collected from the top layer (0-30 cm) of the selected sites of marginalized tea lands and those converted to timber plantations for analysis. Organic matter percentage in the site-level dry soil samples was analysed using the loss on ignition method. The final carbon stocks (t C ha-1) for samples from both land use types were then estimated using the SOC percentages and bulk density estimates. The carbon stocks for the soil samples collected at marginalized tea lands and the marginalized tea lands converted to timber plantations were then statistically analysed (descriptive statistics, normality tests and two-sample t-tests) using Minitab 21.2 software. The pH of marginal tea lands (5.34±0.14) and the marginal tea lands converted to timber plantations (5.20±0.13) was slightly acidic in nature. The bulk density estimates of marginalized tea lands and marginalized tea lands converted to timber plantations were very close and estimated as 1.15±0.02. The statistical analysis showed that overall mean SOC was significantly higher under the marginalized tea lands converted to timber plantations (155.3±10.0 t C ha-1) compared to the marginalized tea lands (126.7±5.8 t C ha-1). Land use conversion has increased the SOC stocks gradually after forest establishment. The increased carbon stocks could be attributed to consistent addition of litter layer on the soil, less soil disturbance, and retarded soil erosion contributing to the buildup of soil organic matter and SOC. On the other hand, low carbon stocks in the marginalized tea land could be attributed to unsustainable agronomical practices. Our findings suggest that converting marginalized tea lands in central highlands into timber plantations could enhance the sequestration of atmospheric CO2, significantly contributing to climate change mitigation.&#x0D; Keywords: Soil organic carbon, Land use change, Climate change, Tea plantations

Dynamics of soil quality in a conserved landscape in the highland sub humid ecosystem, Northwestern Ethiopia

Several studies have assessed the dynamics of soil quality induced by soil and water conservation (SWC), but many showed disagreement over the efficacy of SWC interventions in the Ethiopian highlands. This study used a before and after soil and water conservation practices (SWCP) comparison approach to evaluate the effect of SWCP on soil quality dynamics. Fifty-four composite and 10 undisturbed soil samples were collected in 2012 (before SWCP) and 2022 (after SWCP). Statistical mean, analysis of variance, and principal component analysis were applied to test the significant differences among treatments. The findings demonstrated that SWCP has significantly improved most of the soil quality indicators such as soil organic matter, total nitrogen, available phosphorous, pH, total porosity, field capacity, and available water, and reduced the value of bulk density and coarse fragments. The interaction effect of landscape position and types of structures provided statistically significant results for soil organic matter, total nitrogen, magnesium, calcium, and base saturation. Soil and stone-faced soil bunds treated at lower landscapes were superior in improving soil quality attributes. The soil quality indexing showed, the overall soil quality improvement as a result of SWCP was about 32.15%. The level of improvement for different SWCPs was 32% for stone faced soil bunds and 33% for soil bunds. The findings revealed that SWCP implementation can improve soil quality. Soil organic matter is a key biological quality component that contributed 25% to the soil quality index and highly impacted soil physicochemical properties. We suggest additional assessment of best and integrated land management practices to ensure further improvement in soil quality, crop productivity, and ecosystem services in the subhumid ecosystems.

Increased Hg Methylation Risks in Management-Induced Terrain Depressions in Forests with Organic-Matter-Rich Soils

Mercury (Hg) is a toxic contaminant that bioaccumulates in trophic chains in its organic form—methylmercury (MeHg). Hg methylation is driven by microorganisms in favourable conditions, stagnant water pools being among potential methylation hotspots. In the present study, we estimated the total Hg and MeHg concentrations in the sediments of water-filled management-induced terrain depressions (ruts, mounding pits and a partly functional drainage ditch) and in nearby undisturbed soil in six hemiboreal forest sites with organic-matter-rich soils in Latvia. Environmental samples were taken in the spring, summer and autumn of 2022. Furthermore, we evaluated the risks of element leaching from the depressions using high-resolution digital terrain models (DTM) and meteorological data. The results suggested a possible leaching of Hg in the past as THg concentrations in the sediments of the depressions were significantly lower than in the surrounding soil. Furthermore, significantly higher MeHg and %MeHg concentrations were found in the sediments than in the surrounding soil identifying the management-induced depressions as Hg methylation hotspots. Spatial analysis of the DTMs pointed to a very likely periodical leaching of elements from the depressions during high precipitation episodes as well as during snowmelts. Moreover, it was observed that ruts left by heavy machinery often channel surface runoff.

Organic Carbon Storage and Structural-Hydraulic Properties of Ultisol under Agricultural Land Use Systems at Umuahia

The extent and pattern of interaction among organic carbon, structural and hydraulic properties of soils under varying land use systems are of great concern in the overall management of soil fertility and productivity. This study was conducted to examine the relationship among soil organic carbon storage, structural and hydraulic properties of soils under different agricultural land use systems at Umuahia, Abia State. The treatments were the four (4) land use systems (continuously cultivated arable farmland, 3 – year fallow land, oil palm plantation, and forest land) in which nine (9) replicates each of disturbed and undisturbed soil samples were randomly collected to give thirty six observational units laid out in a randomized complete block design. The soil samples were prepared and analysed in the laboratory. Analyses of variance, regression and correlation analyses were conducted on the data collected using Genstat version 14 and SPSS version 20. Results show that organic carbon had significant positive relationship with saturated hydraulic conductivity, macro porosity and total porosity but significant negative relationship with bulk density at all the land use systems. However, the influence of organic carbon on the other parameters was greatest at continuously cultivated arable land followed by the 3 – year fallow land. There is need to increase organic matter input at the continuously cultivated arable land and 3 – year fallow land through increased organic manuring and extension of the fallow period, respectively.

Evaluation of Per- and Polyfluoroalkyl Substances Leaching from Biosolids and Mitigation Potential of Biochar through Undisturbed Soil Columns

Evaluation of Per- and Polyfluoroalkyl Substances Leaching from Biosolids and Mitigation Potential of Biochar through Undisturbed Soil Columns

The Effects of Soil Salt Stress on the Nitrogen Uptake, Yield Response and Nitrogen Use Efficiency of Cotton in Arid Areas

Soil salinity is a major soil threat, causing severe environmental problems. Soil salt stress limits N uptake and cotton growth, especially in arid regions. However, the mechanism underlying stress tolerance in cotton plants under different soil salinity levels has not been fully elucidated. Therefore, the aim of this study was to examine the proportion and mechanism of cotton N uptake and transport under salt stress using the 15N isotope labeling technique. Cotton plants were grown in four undisturbed loamy soils (CK, non-salinity, &lt;2 dS m−1; C1, low salinity, 2–4 dS m−1; C2, mid-salinity, 4–8 dS m−1; and C3, high salinity, 8–15 dS m−1) in the test pit experiments. The findings indicated that the cotton N uptake was limited by the soil salt stress and total N content, and the cotton 15N use efficiency decreased by 25–27% with increasing salinity (&gt;4.0 dS m−1). The N transported to cotton from the 0–20 cm soil layer in C1 treatment was higher than from the 40–60 cm layer. Furthermore, the cotton fruit cultivated in C1 exhibited a notably elevated dry matter content compared to those cultivated in the control treatment. As the soil salt stress increased from the control treatment to C1, the cotton stems and fruits demonstrated a gradual enhancement in their N uptake and regulatory capabilities, albeit with a slight decrease observed in the leaves. These findings emphasize that soil salt stress diminishes cotton nitrogen uptake and transport, potentially exacerbating nitrogen pollution in the absence of optimized nitrogen fertilization.

Trichoderma Diversity in Mexico: A Systematic Review and Meta-Analysis

Trichoderma is a genus of cosmopolitan fungi with more than 375 species described today. Despite its global significance in agriculture, ecosystems, and industry, few studies have focused on studying the diversity and distribution of this genus in Mexico. In this systematic review and meta-analysis, we aimed to understand the diversity and distribution of Trichoderma species in Mexico, both in ecosystems and agroecosystems. For this systematic review, we used the PRISMA methodology. We reviewed forty-one scientific articles, two book chapters, and the GBIF database. We recorded a total of 1082 isolates, revealing the presence of 57 species of the genus Trichoderma in 29 states of Mexico. We found that species from the genus Trichoderma were reported in 20 agroecosystems and 6 ecosystems. T. harzianum was the predominant species in both agricultural and undisturbed soil. Tabasco and Veracruz were the states with the highest species diversity, with 20 and 14 species reported, respectively. Chiapas had the highest diversity indices (Menhinick had 3.20, Simpson had 0.89, and Margalef had 4.16). The coffee crop was the agroecosystem with the highest diversity, with 12 species reported. In the undisturbed ecosystems, tropical rainforests featured 12 different species. This study highlights the distribution of the genus Trichoderma as a cosmopolitan genus. We argue for the importance of the species that comprise the genus and its applications for social benefits.

Evaluate the effectiveness of soil and water conservation interventions in the upper Awash Basin, Ethiopia

AbstractThe central highland of Ethiopia is facing significant challenges due to land degradation, which resulted in changes to the soil's physicochemical properties. This study aims to assess the effectiveness of different conservation methods in enhancing soil physicochemical properties, reducing soil loss and erosion, and maximizing land productivity in Ankober District of Kenseta watershed. For this study, two land uses (conserved and non‐conserved land), three slope positions, and three replication with the soil depth of 0–30 cm were used for undisturbed and disturbed soil samples data collection and analysis. The survey data were collected and evaluated from 106 randomly selecting respondents' households. The results showed significant variation in the mean value of soil physical properties (bulk density, soil moisture content, soil texture) within and between conserved and non‐conserved land. The chemical properties, including pH, EC, exK, CEC, OC, OM, and available P, also changed significant across land management types and along slope position (p &lt; 0.05). Soil managed with stone face soil bund demonstrated significant improvement in soil physicochemical properties. The results were statistically significant difference at (p &lt; 0.05) level of significance. Majority of the respondents' households explained the soil loss and rate of soil erosion were declined and land productivity status increased after the adoption of soil and water conservation practices in the study area. Therefore, proper conservation practices are vital in minimizing the rate of soil loss, ameliorating physical and chemical properties of the soils, and enhancing land productivity.

Impact of stockpile depth and storage time on soil microbial communities

Soil removal and stockpiling prior to mining activities have adverse effects on soil health, which raises concerns about the suitability of stockpiled soils as a reclamation substrate. Due to the fundamental roles microbes play in ecosystem function and services, they can be used as indicators of soil health and quality. We analyzed the prokaryotic microbial communities in a chronosequence of 0.5–28-year-old stockpiles at increasing depths (0–300 cm), in two oil-extraction locations in northern Alberta. Our results indicate that the microbial communities of the seven stockpiles examined were more similar to each other than to the undisturbed soils used as reference, which might indicate that stockpiling shifts the microbial community composition outside the range of natural variability. Furthermore, while microbial communities in younger and older stockpiles were dissimilar to the reference soils, the communities of intermediate-age stockpiles were more similar to those in the reference soils. We interpret these divergences in similarity to indicate that initial disturbance leads to a shift in the microbial community, which then recovers following several years of storage, but eventually, long-term storage leads to a secondary divergence from the range of natural variability. Additionally, the bacterial diversity decreased significantly with increasing stockpile depth, which could be attributed to the harsh conditions of the deeper stockpile layers and the scarcity of nutrients. Our findings provide important insights into the impact of soil stockpiling on microbial communities and complement those of earlier studies highlighting the importance of stockpile depth and storage time as predictors of variability of soil microbial diversity and community composition. Furthermore, due to the crucial functions played by microbes in soils, our conclusions should serve for reclamation agencies to modify the stockpiling protocols in order to mitigate the impact of stockpiling on soil microbial communities.