Subsurface Soil Layers Research Articles

Effect of Different Temperatures on Reactions of Potassium Adsorption and Availability in Saline Soils within Nineveh Governorate, Iraq

Thermodynamic criteria were used to evaluate the adsorption and release of potassium in saline soils. The study was conducted on three sites that differ in salt content in Nineveh Governorate - Iraq, and each site is divided into two depths (surface and subsurface). The study was conducted at three temperatures (278, 298, 318 Kelvin). The results of the study showed that there was an increase in the amount of potassium adsorbed and the percentage of adsorption with an increase in the amount of potassium added in all the studied soil samples. For the ability of the soil to the adsorption, the results showed a sudden increase in the adsorption of potassium at the application of the high levels (1 and 2 mmolL-1) of potassium in all the studied soils. Also, the highest value of the ionic activity of potassium (ARk) was (14.05 × 10-3 molL-1/2), at a temperature of 298 K in the subsurface soil layer of the first site, while the lowest one was (1.61 × 10-3 molL-1/2), in the same layer of the first site at a temperature of 278 K. The values ​​of free energy of potassium, ΔGK, in the studied soils ranged from the highest value reached (-14.85×10-3 kJ) at a temperature of 278 K, to the lowest value, reached (-10.56×10-3 KJ) at a temperature of 298 K, in the subsurface soil layer of the first site. Regarding the values ​​of entropy reaction, they ranged from the highest value of -53.43 Jmol-1 in the subsurface depth of the first site at a temperature of 278 K to the lowest value of -35.46 in the same layer of the first site at a temperature of 298 K. On the other hand, the enthalpy values ​​of the studied soil samples were negative, which indicates that the reaction is of the exothermic type, where the highest negative value for enthalpy was -29.70 kJmol-1 at a temperature of 278 K in the subsurface soil layer of the first site and the lowest negative value, was -20.42 kJmol-1 in the same layer of the first site at a temperature of 298 K.

Influence of Annual Ryegrass (Lolium multiflorum) as Cover Crop on Soil Water Dynamics in Fragipan Soils of Southern Illinois, USA

Fragipans are dense subsurface soil layers that severely restrict root penetration and water movement. The presence of shallow fragipan horizons limits row crop production. We hypothesized that the roots of cover crop might improve soil physiochemical properties and biological activity, facilitating drainage and increasing effective soil depth for greater long-term soil water storage. To evaluate annual ryegrass as one component of a cover crop (CC) mix for promoting the characteristics and distribution of soil water, on-farm studies were conducted at Marion and Springerton in southern Illinois, USA. Soil samples were collected at 15 cm increments to 60 cm (Marion) and 90 cm (Springerton) depths during the fall of 2022. Both sites had low total soil carbon and nitrogen contents and acidic soil pH (≤6.4). A soil water retention curve was fitted using the van Genuchten equation. At Springerton, the CC treatment increased saturated (thetaS) and residual (thetaR) soil water contents above those of the no cover crop (NCC) at the 60–75 cm and 75–90 cm depths. Changes in volumetric soil water content were measured using a multi-depth soil water sensor for the Springerton site during late July to early August of the soybean growing phase of 2022; NCC had higher soil water than CC within the 0–15 cm depth, but CC had higher soil water than NCC at the 30–45 cm depth. These findings indicate that cover crop mix has the potential to improve soil water movement for soils with restrictive subsoil horizon, possibly through reducing the soil hydraulic gradient between the surface and restrictive subsurface soil layers.

Application of electrical resistivity and induced polarization for identification and erosion assessment in fine-grained soils – A case study

Electrical Resistivity Imaging (ERI) and Induced Polarization (IP) are the non-destructive and rapid methods used for mapping the subsurface. This paper presents an application of these methods for erodibility characterization. These tests and Erosion Function Apparatus (EFA) tests were conducted on identical samples with plasticity indices ranging from low to high to establish a correlation of ERI, IP and erosion rates. Erosion rate and erosion category were determined through the analysis of soil Electrical Resistivity (ER) and IP values. Then, the ERI and IP surveys were performed at a site that had CPT data to analyze the subsurface soil layers. In order to verify the developed correlation, three holes were hand augured and Shelby tube samples were extracted from the site to conduct EFA testing. The results show that ER and IP methods can be used to predict soil erosion characterization in the preliminary stages of bridge site developments with concerns about erosions around bridge piers.

Spatio-temporal variability of soil water content across plot scales within a vineyard

Understanding spatio-temporal variability of soil water content (SWC) at different scales is of great importance for designing monitoring networks and assimilating observed data in hydrological modeling. The objective of the study was to examine spatio-temporal variability of SWC for different soil layers at different extent scales within an agricultural field. Spatio-temporal variability of SWC and the relationship between variability and mean were investigated at three extent scales for different soil layers of 0–100 cm in different years within an intensively irrigated vineyard. Nested sampling grids were used, and at each scale, there was a total of 16 points distributed regularly at the grids. The distance between any two adjacent sampling points was 25-m, 50-m, and 75-m for the three scales respectively. Overall, there was no consistent pattern regarding the change of mean, standard deviation (SD), and coefficient of variation (CV) with scales during the three years. For the surface soil layer, mean SWC was similar between scales, while SD was closely related to soil clay content at the sampling locations of each scale. For subsurface soils, the overall magnitude of variability of SWC was greater, whereas the difference in the variability between scales was lower than that of the soil texture of the corresponding soil layer. The proportional decrease of CV with increasing mean was found to be largely consistent between different years for all soil layers excluding 20–40 cm, but variable between scales and soil layers. For subsurface soil layers, the CV vs. mean relationship differed between relatively wet and dry years, indicating that factors controlling SWC dynamics for the layers below the surface layer were different depending on climatic conditions. Variance partitioning analysis showed that spatial variance accounted for at least 57 % of total variance for all cases, and the temporal variance at different scales fluctuated within a narrow range for subsurface soils for the three years. The results could benefit soil water content monitoring network design, calibration of soil moisture related parameters and assimilation of observed soil moisture data into field soil water modeling.

Scots pine roots (Pinus sylvestris L.) as dendrogeomorphological indicators of soil erosion on a hiking trail in the Brodnica Lakeland, Poland NE

Trampling on hiking trails leads to vegetation degradation, promoting soil erosion. Erosion removes the topsoil, causing lasting changes and exposing tree roots. Yet, little is known about the environmental factors affecting soil erosion rates determined from tree root analysis. This study, exclusively utilizing microscopic preparations, examines tree root anatomical changes on a lowland trail in Brodnica Lakeland. It aims to understand the temporal and spatial variability of soil erosion rates using dendrogeomorphological records of Scots pine (Pinus sylvestris L.) roots. Up to 64 % of samples show exposure due to continuous denudation, significantly shaping the trail’s relief. Abrupt exposures and secondary growth occur in only 22 % and 14 %, respectively. The average soil erosion rate, calculated from 76 root exposures at the Bachotek site, is 1.93 ± 0.82 mm/year, ranging from 0.71 to 3.80 mm/year, with recently exposed roots exhibiting the highest average soil erosion values on the hiking trail. 45 % of root samples exhibit above-average erosion rates. Statistical analyses reveal that erosion rates (ER) are influenced by soil compaction (COM), bulk density (BULK), root orientation (ASP), and exposure length (EXP). Higher compaction and bulk density correlate with increased erosion, while roots parallel to the trail experience more erosion. Conversely, greater root exposure length leads to decreased erosion rates. These findings suggest that soil erosion on the hiking trail primarily results from gradual geomorphological processes. Wood anatomical analyses of pine roots confirm the role of trampling in initiating and accelerating these processes, altering the trail’s subsurface soil layers, and indirectly affecting soil erosion dynamics. Scots pine roots prove valuable as indicators of the temporal and spatial variability of soil erosion along the lowland trail.

Gradual and abrupt increase in atmospheric CO2 concentrations trigger divergent responses of microbial necromass accumulation in paddy soils

Microbial necromass C (MNC) plays a critical role in promoting soil organic C (SOC) formation and stabilization, particularly in the context of climate change. Most investigations on the impact of elevated CO2 concentrations (eCO2) on MNC have been performed by exposing ecosystems to an abrupt increase in CO2. However, the atmospheric CO2 increase is a gradual process, and knowledge about the response of necromass to gradual increase in CO2 is lacking. We tested the hypothesis that microbial necromass would show different responses to abrupt and gradual CO2 increases. Furthermore, it is still unknown whether eCO2 will trigger similar responses between surface and subsurface soil layers. Here, we determined the MNC concentrations and their proportions in SOC in surface and subsurface soil layers via open-top chambers. CO2 treatments included ambient control, abrupt CO2 increase by 200 ppm above control, and gradual CO2 increase by 40 ppm each year until reaching 200 ppm over five years. Overall, compared with the ambient control, abrupt eCO2 induced a significantly stronger decrease in necromass (20.3 %) when averaged across three soil layers, while gradual eCO2 led to insignificant variations in necromass (6.7 %). The necromass proportion in SOC decreased with depth under both eCO2 treatments with a significant decline occurring in abrupt eCO2 treatment. The observed greater magnitude of eCO2 effects on fungal necromass relative to bacterial necromass in subsurface layers illustrates a distinct microbial community response to climate change. Taken together, abrupt and gradual eCO2 approaches differed in their impact on MNC, and its response to eCO2 may be somewhat overestimated by abrupt eCO2 approach. Furthermore, MNC in subsurface soil witnessed a more sensitivity or vulnerability to eCO2 than that of topsoil. We suggest vigilant attention will need to be paid to the feedback of necromass C in deep soil poised by future climate change.

The microbiome structure and shifts in surface and subsurface soil horizon of Haplic Luvisol under different crops cultivation

The presented study investigated the comparative approach to evaluate prokaryotic and fungal soil communities in association with various plant crops along the genetic soil horizon using a high-throughput sequencing technique, with special emphasis on subsoils. We evaluate the diversity, abundance and structure of soil microbiome through the depth profiles in Haplic Luvisol (Cutanic) soil collected from lucerne, pear orchard, vineyard, and wheat crop. The structure of soil microbial communities differed due to crop type as well as depth of soil layer. Additionally, some basic physicochemical properties (e.g. total organic carbon - TOC, total nitrogen - TN, dissolved organic carbon - DOC, dissolved nitrogen – DN, pH, clay content) as well as mass and morphological parameters of the plant roots were determined. The highest clay content was noted in illuvial (Bt) horizons (in all profiles). The content of the studied C and N forms was the highest in the Ap horizon and in some subsurface layers and generally decreased with depth. Generally, the highest TOC, TN and DOC content was noted in the orchard profile, while the lowest occurred in the vineyard profile. The opposite trend was found for available Mg content. In turn, the highest DN was determined in the winter wheat profile. Overall, the decrease of the abundances of the most dominant phyla with depth was observed. Using a holistic approach via microbiome investigation of bacterial and fungal communities along soil horizon in a long-term land use with different plant cultivation, we showed that land management not only affect α-diversity but also shift the structure and the composition of bacterial and fungal communities in response to land use, in particular we identified the highest values of biodiversity indicators were found under lucerne and the lowest under vineyard. Future work needs to include the importance of soil type in shaping soil microbial communities under the same land use and plant cultivation, especially under subsurface soil layers.

Divergent effects of long-term fertilization on the carbon management index across soil profiles in key Chinese croplands

Evidence for the variability of the carbon (C) management index (CMI) across surface and subsurface soil layers due to long-term fertilization in diverse agroecological settings is inadequate. Thus, our study aimed to explore the variations in soil organic C (SOC), CMI, and its response ratio (RR-CMI) along soil profiles (0–60 cm) across four croplands in China. These croplands represented two high-fertility sites in Gongzhuling (GZL) and Chongqing (CQ) and two low-fertility sites in Zhengzhou (ZZ) and Qiyang (QY). We evaluated various treatments: control (CK; no fertilizer), inorganic fertilizer (NPK), NPK combined with standard manure (MNPK), and 1.5 times the standard rate of manure and NPK (1.5MNPK). The results indicated a significant increase in SOC content across all depths, ranking as 1.5MNPK > MNPK > NPK > CK, with ranking for the pattern observed across sites as GZL > CQ ≈ QY > ZZ. This led to the most substantial increases, reaching 107, 86, 105, and 62 % more than CK across the soil profile (0–60 cm) under 1.5MNPK across all sites. Moreover, the same treatment showed a significantly higher CMI at 0–60 cm compared to CK, with increases of 37, 19, 65, and 25 % for ZZ, QY, GZL, and QY, respectively. Notably, for the low-fertility soils (ZZ and QY), a higher CMI was observed in the 0–20-cm soil layer), whereas the opposite was true for the high-fertility soil (GZL). Consequently, low-fertility soils exhibited a higher RR-CMI in the 0–20-cm soil layer, whereas the high fertility site (GZL) showed a higher RR-CMI in the 40–60-cm soil layer, suggesting differential accumulation and loss of SOC regulated by soil depth and inherent site fertility. Partial least squares regression analysis further indicated that soil and climatic factors predominantly influenced CMI under long-term fertilization in typical Chinese soils. In conclusion, the long-term application of manure combined with inorganic fertilizer promotes SOC sequestration and enhances CMI, presenting a viable management strategy for enhancing soil quality in the studied regions.

Quantitative importance of subsoil nitrogen cycling processes in Andosols and Cambisols under temperate forests

Nitrogen availability often limits plant growth in forest ecosystems. Plants, including trees, utilize soil inorganic nitrogen transformed via nitrogen cycling processes, including mineralization and nitrification. While most plant fine roots are distributed in surface soil layers, plants take up nitrogen even from subsurface soil layers in addition to the surface soil layers, especially under high nutrient competition. However, there is still limited knowledge about nitrogen cycles within deeper soil layers. In this study, we investigated the vertical profiles (0–60 cm) of the net nitrogen mineralization and nitrification rates at four Japanese forest sites with two different soil types (Andosols and Cambisols). The partial least square path modeling (PLS-PM) was used to determine factors affecting nitrogen cycling processes. The net nitrogen mineralization and nitrification rates per unit soil weight were considerably higher in the surface soil layer than in the deeper soil layers in Andosols but not in Cambisols. PLS-PM analysis showed that microbial biomass and soil organic matter quantities were the important factors influencing the net nitrogen mineralization and nitrification rates, indicating that a similar mechanism, which drives the spatial variations of nitrogen cycling processes in the surface soil layer, predominantly regulates the vertical variations of the processes. Moreover, it was estimated that the net nitrogen mineralization rate could be comparable at all soil types and depths when the rate was expressed per unit soil volume. Therefore, subsoil layers could be a quantitatively important source of plant-available nitrogen in Andosols and Cambisols.

Non-flooding conditions caused by water table drawdown alter microbial network complexity and decrease multifunctionality in alpine wetland soils

Several soil functions of alpine wetland depend on microbial communities, including carbon storage and nutrient cycling, and soil microbes are highly sensitive to hydrological conditions. Wetland degradation is often accompanied by a decline in water table. With the water table drawdown, the effects of microbial network complexity on various soil functions remain insufficiently understood. In this research, we quantified soil multifunctionality of flooded and non-flooded sites in the Lalu Wetland on the Tibetan Plateau. We employed high-throughput sequencing to investigate the microbial community responses to water table depth changes, as well as the relationships between microbial network properties and soil multifunctionality. Our findings revealed a substantial reduction in soil multifunctionality at both surface and subsurface soil layers (0–20 cm and 20–40 cm) in non-flooded sites compared to flooded sites. The α-diversity of bacteria in the surface soil of non-flooded sites was significantly lower than that in flooded sites. Microbial network properties (including the number of nodes, number of edges, average degree, density, and modularity of co-occurrence networks) exhibited significant correlations with soil multifunctionality. This study underscores the adverse impact of non-flooded conditions resulting from water table drawdown on soil multifunctionality in alpine wetland soils, driven by alterations in microbial community structure. Additionally, we identified soil pH and moisture content as pivotal abiotic factors influencing soil multifunctionality, with microbial network complexity emerging as a valuable predictor of multifunctionality.

Evaluation of soil temperature in CMIP6 multimodel simulations

Soil temperature plays a crucial role in understanding land-atmosphere interactions. The Sixth Phase of Coupled Model Intercomparison Project (CMIP6) provides valuable information on soil temperature, however, the performance of these models in capturing soil temperature variations remains unclear. To comprehensively assess the performance of CMIP6 in simulating soil temperature, we employed a set of in-situ observation data, observation-derived gridded data (TS-GCB) and reanalysis data (ERA5L) to build various evaluating metrics for the surface (0–5 cm) and subsurface (5–15 cm) soils. At the global scale, the multimodel ensemble mean (MME) of CMIP6 generally captured the spatial, annual and seasonal variations of soil temperature, but overestimated measured soil temperature by 1.86 °C (vs. TS-GCB, surface) and 2.16 °C (vs. TS-GCB, subsurface), indicating more heat accumulated in soils than the reality. Surface soil temperature was better represented by MME compared to the subsurface soil layer (vs. TS-GCB). In addition, we found the largest simulation bias in the tropical zone, and both positive and negative bias in the arid regions. The large model spread of the individual models in representing soil temperatures in cold regions or periods highlights the needs of improved understanding of how snow and freeze-thaw affect soil thermal dynamics. Overall, the performance of MME is superior to that of the majority of individual models (vs. TS-GCB). Locally, the large discrepancy among observation-derived data, reanalysis data and CMIP6 simulations suggested that it is imperative to acquire more ground-truth soil temperature to better inform model simulation and forecasting.

Irrigation Practices and Their Effects on Soil Quality and Soil Characteristics in Arid Lands: A Comprehensive Geomatic Analysis

Comprehension of the long-term effects of irrigation on basic soil characteristics and quality is essential for sustainable land management and agricultural production, particularly in arid regions where water availability is limited. This study aimed to investigate long-term irrigation effects on soil quality, soil organic carbon (SOC), and nitrogen (N) stocks in the arid lands of Egypt. Seventy soil samples were collected and analyzed to determine various soil properties. A soil quality index (SQI), SOC, and N stocks were computed. ANOVA and PCA analyses were used to identify significant differences between alluvial soils in the southwest part of the investigated area and coastal marine soils in the northeast of the study area. The results demonstrated that most of the studied soil parameters had significantly greater values in alluvial compared to coastal marine soils. Long-term irrigation led to an 8.00% increase in SOC and 7.22% increase in N stocks compared to coastal marine soils production. Furthermore, a 39.53% increase was found in the SQI upon long-term irrigation practice. These results suggest that shifting from rain-fed in coastal marine areas to irrigated production systems in alluvial fields can improve soil quality, SOC, and N stocks. Therefore, further studies are required to investigate the impact of additional factors, such as irrigation method and salinity status of sub-surface soil layers, to enhance agricultural productivity and sustainable land use.

Определение повреждений неудаляемых и удаляемых окон перспективных пенетраторов от ударного воздействия высокоскоростных частиц реголита при ударном внедрении в грунт Луны

The article discusses promising penetrators with non-removable transparent and removable opaque windows, created mainly from corundum and ice composite, respectively. Their use will expand the scientific research program due to visualization capabilities for video recording of the movement of the penetrator in the subsurface layers of soil and their optical methods of studying, as well as direct contact with them. The calculation method and the calculated values of damage to these windows from the impact of spherical particles of lunar regolith with diameters of 1,0 and 1,5 mm, colliding with them at speeds of up to 1 km/s in the angular range from 70° to 80°, obtained using numerical modeling or based on an engineering model, are discussed.

Unveiling the soil physicochemical dynamics of bare soils in Southeast Kazakhstan: A comprehensive study in the Akdala Massif

This study addresses desertification in Kazakhstan's Akdala region, aiming to propose sustainable solutions by examining the effects of various plants on soil properties and nutrient dynamics. Desertification poses a threat to land productivity in arid areas, and this research aims to determine its impact on soil and identify plants for mitigation. Field experiments over three years in the Akdala region utilized crops such as rice, corn, soybean, sudan grass, and sorghum to assess their influence on key soil parameters. Results revealed diverse effects on soil bulk density, agronomically valuable aggregates, water-stable aggregates, labile and total organic carbon, easily hydrolyzable nitrogen, nitrate, available phosphorus, and exchangeable potassium. While no significant differences in bulk density were observed among crops, variations in surface and subsurface soil layers emphasized the importance of depth-specific considerations. Sorghum stood out as a particularly influential crop, significantly increasing labile and total organic carbon levels, highlighting its potential role in enhancing soil quality. The experiments were conducted on the fields of "Birlik" LLP in the Balkhash district of the Almaty region from 2015 to 2017. The chosen crops, each with distinct characteristics, provided a comprehensive understanding of their impact on soil dynamics. Advanced techniques for soil sampling and analyses ensured accurate measurements of various soil parameters. The study site's sharply continental climate, marked by temperature variations, snowy winters, and hot, dry summers, added complexity to the investigation due to its influence on plant growth and soil interactions. In conclusion, this comprehensive study offers valuable insights into the intricate relationships between different crops and soil parameters for combating desertification. The findings contribute significantly to the development of sustainable soil management practices, providing a foundation for identifying suitable crops for soil improvement in arid regions. By understanding how different plants impact soil properties, this research supports informed decision-making in agricultural practices, promoting the long-term sustainability of farming in regions vulnerable to desertification.

Degree of compaction, aeration, and soil water retention indices of a sugarcane field without soil disturbance after initial tillage

Soil compaction after initial soil tillage for crop establishment has been a major problem in crop fields because of its deleterious effects on soil functioning and crop performance. Therefore, the study aimed to determine the degree of compaction, soil air capacity, near-surface optimum ratios, and water retention characteristics in a sandy loam. Dystrophic Paleudalf initially under different tillage methods for sugarcane crop but without tillage for two seasons in southern Brazil. Initial soil tillage systems consisted of no-tillage (NT), compacted no-tillage (NTC), conventional tillage, and chiseling of no-tillage (Ch). Disturbed and undisturbed soil was sampled from 0 to 10, 10 to 20, 20 to 40, and 40 to 60 cm layers to determine degree of compaction, air capacity, near-surface optimum ratios, soil water retention characteristics, and soil physical quality index S. Initially, NT treatment had the significantly ( p < 0.05) lowest degree of compaction (87%), highest soil air capacity (0.104 cm3 cm−3), air capacity/total porosity ratio (0.261), and better water retention characteristics in the surface layer. Over time, Ch had improved the structure of the subsurface soil layers with the lowest degree of compaction (≈88%) and highest air capacity (≈0.140 cm3 cm−3), while the measured indices were poor in NTC. Irrespective of tillage, the surface layer showed resilience during the years without soil disturbance with low degree of compaction, increased water retention, and air capacity. NT could be a good soil management option for sugarcane production, while mechanical chiseling is advocated for ameliorating compacted soils.

The Short-Term Effect of Olive Mill Wastewater Application on Humic Acid in Subsurface Soil Layers of the Arid Region of Tunisia

ABSTRACT Few studies have assessed the changes in soil quality based on humic acids (HA) in relation to the fresh olive mill wastewater (OMW) application. Qualitative changes to soil organic matter (SOM) under the application of OMW in real conditions have been little investigated. To make a contribution in this context, an experimental field was established in an arid Tunisian area, which included a control soil, a soil treated with 10 L m˗ 2 OMW and another amended with 10 kg m˗ 2 manure. Soil samples were collected from soil depths: 0–20 cm, 20–40 cm and 40–60 cm on the first day of OMW and manure application (day 0) and after 4 months (120 days). Results revealed that soil treated with OMW had the highest SOM content (1.42 ± 0.13%), cation exchange capacity (CEC) (3.03 ± 0.51 (cmol(c) kg−1)) and soil pH value. OMW mineralization supplied soluble ions which enhanced the electrical conductivity (EC) (1.44 ± 0.34 dS m−1). Infrared (IR) spectroscopy showed higher aliphatic, aromatic and phenolic groups in OMW amended soil than the manured soil for initial and final dates. Spreading OMW on soils provides a favorable environment for improving soil humic acids (HAs), recycling organic matter (OM) and enhancing soil properties by transferring aromatic and aliphatic structures into deeper horizons, which in turn increased the sequestration of soil organic carbon (SOC).

Investigating the Potential of Fusarium solani and Phanerochaete chrysosporium in the Removal of 2,4,6-TNT.

Past and recent applications of 2,4,6-trinitrotoluene (TNT) in military and civilian industries have led to contamination of soil and marine ecosystems. Among various TNT remediation techniques, biological remediation is widely accepted for its sustainability, low cost, and scalable applications. This study was designed to isolate a fungus strain from a TNT-contaminated soil to investigate its tolerance to and potential for removal of TNT. Thus, a soil column with a history of periodic TNT amendment was used to isolate dominant strains of fungi Fusarium solani isolate, which is not commonly reported for TNT mineralization and was found predominant in the subsurface layer of the TNT-amended soil. F. solani was investigated for TNT concentration tolerance at 30, 70, and 100mg/L on agar plates and for TNT removal in liquid cultures at the same given concentrations. F. solani activity was compared with that of a reference soil-born fungus that has been intensively studied for TNT removal (Phanerochaete chrysosporium) obtained from the American Type Culture Collection. On agar media, F. solani showed a larger colony diameter than P. chrysosporium at similar TNT concentrations, indicating its high potential to tolerate toxic levels of TNT as found in contaminated sites. In the liquid culture medium, F. solani was able to significantly produce higher biomass than P. chrysosporium in all TNT concentrations. The TNT removal percentage from the liquid culture at the highest TNT concentration of 100mg/L reached about 85% with F. solani, while P. chrysosporium was no better than 25% at the end of an 84-h incubation period. Results indicate a significant potential of using F. solani in the bioremediation of polluted TNT soils that overcome the high concentration barrier in the field. However, further investigation is needed to identify enzymatic potential and the most effective applications and possible limitations of this method on a large scale.

Understanding relationship between physical quality indicators and organic carbon in soils affected by long-time continuous cultivation under sub-humid ecosystem

The objectives of this present study were to analyses soils and find out some soil quality properties and check relationship between soil compaction, crust formation and erodibility - K of the soils with the soil organic carbon (SOC) amount in the surface (0-20 cm) and subsurface (20-40 cm) soils affected by long-time continuous cultivation under sub-humid environmental condition. The research out comes showed that soil compaction, crust formation, erodibility K is highly significantly (P < 0.001) related to organic carbon, organic carbon stock, organic matter and between each other. The research also identifies that the study area generally, has clay texture, neutral pH, low amount of the CaCO3, high amount of OC and OM in top layer (0-20 cm) and moderate amount in bottom layer (20-40 cm). It was not identified significant differences between the soil properties in surface and subsurface soil layers.

Functional diversity and behavioral changes of microbial communities under salt affected soils

Salt-affected soils (SASs) are globally distributed especially in the arid and semi-arid regions of the world which highly affect the crop growth and productivity. The soil physico-chemical and biological properties largely vary with different types of SASs which trigger the crop yield, nutrient imbalance and soil quality. Therefore, to understand the changes in soil microbiology in relation to soil characteristics, a micro plot study was conducted to evaluate the impact of soil salinity/sodicity on physical, chemical properties at surface (0–15 cm) and subsurface (15–30 cm) soils in relation to soil microbial population, activities and functional diversity with focusing on community-level physiological profiling (CLPP) study. Five types of soils based on pH, electric conductivity (EC) and salt concentration maintained for last 25 years - highly saline, moderately saline, highly sodic, moderately sodic and normal were evaluated in micro plots to understand the changes in soil biological properties in relation to salt concentration. The results revealed that the highest value of pHs, ECe (EC of soil saturated paste extract), cation exchange capacity (CEC), exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), anions and cations concentrations, bulk density (BD), infiltration rate (IR), penetration resistance (PR) were observed in highly saline and highly sodic soils at surface and subsurface soil layer. In surface and subsurface layers, organic carbon (0.67 and 0.52 %) and available N (110 and 195 kg ha−1) were found higher under normal soils than SASs (% OC: 0.20–0.34 and 0.17–0.38; available N: 75–80 and 47–77 kg ha−1), respectively. In relation to changes in soil physicochemical properties, average well color development (AWCD) was found highest with normal soils followed by moderately saline and moderately sodic soils and lowest was found in highly sodic soils at surface soils which indicates interference of salts in metabolic activities of microbes. The utilization of amino acids, amines, carboxylic acids, phenolic compounds and polymers was highest for normal soils followed by moderately saline and lowest was recorded for highly sodic soils. But AWCD for carbohydrates was highest in highly saline soils, followed by highly sodic soils in contrast to normal soil and lowest was found under moderately sodic soils. Shannon diversity index (H) and substrate richness (SR) were found higher (3.19 and 24.07) in normal soils than SASs. Similarly, effect of salt load was also reflected on less soil enzymatic activities such as dehydrogenase, aryl sulfatase, invertase, etc. under varying types of SASs. Thus, with the increasing salt load, chemical and physical properties of soils were found to deteriorate and directly affected the microbial population, activities and their diversity in soil. This study indicated that soil physico-chemical properties, functional diversity, population and community of microbes were highly influenced by nature of salts and their concentration that may affect the soil quality and crop yield.

Estimation of Groundwater Potential at Khalid Bin Walid Boarding School Using the Schlumberger Configuration Geoelectric Method

Khalid Bin Walid Islamic Boarding School is one of the Islamic boarding schools in Rokan Hulu Regency. This school is located in a water crisis area with complex groundwater sources. This study aims to determine the potential of groundwater as a reference for drilling wells and to determine the structure of the subsurface layer by using the geoelectrical method. The geoelectrical method is a method that is widely used, and the results are promising, namely, to obtain an overview of the subsurface soil layers and the possibility of groundwater presence. The configuration used in this study is the Schlumberger configuration using the basic principle of current propagating in the earth when injected in all directions and the assumption that the potential of the subsurface rock layer is the same. Data will be collected on four tracks, with a track length of 100-200 m. From the data processing results, it was found that potential sources of groundwater on track 3 with a depth of 13.7–30.3 m with alluvium rocks were suspected. Groundwater on this track can be used as a source of clean water using drilling.