Search Results (1,517)

The use of living organisms to treat human by-products, such as residual sludge, has gained interest in the last years. Fungi have been used for bioremediation and improving plant performance in contaminated soils. We investigated the impact of the mycorrhizal fungus (MF) Gigaspora roseae and the saprophytic fungus (SF) Coriolopsis rigida on the survival and growth of Quillaja saponaria seedlings cultivated in a sandy substrate supplemented with residual sludge. Q. saponaria is a sclerophyllous tree endemic to Chile, known for its high content of saponins. We inoculated plants with the MF, the SF, and a combination of both (MF + SF). Following inoculation, varying doses of liquid residual sludge equivalent to 0, 75, and 100% of the substrate’s field capacity were applied. After 11 months, we found a positive influence of the utilized microorganisms on the growth of Q. saponaria. Particularly, inoculation with the SF resulted in higher plant growth, mycorrhizal colonization percentage, and higher enzymatic activity, especially after the application of the sludge. This increase was more evident with higher doses of the applied sludge. These results highlight the potential of combined microorganism and residual sludge application as a sustainable strategy for enhancing plant growth and reducing waste. Full article

Background: Soil microbes play a vital role in the ecosystem as they are able to carry out a number of vital tasks. Additionally, metagenomic studies offer valuable insights into the composition and functional potential of soil microbial communities. Furthermore, analyzing the obtained data can improve agricultural restoration practices and aid in developing more effective environmental management strategies. Methodology: In November 2023, sandy soil samples were collected from ten sites of different geographical areas surrounding natural lakes and artificial water points in the Tubaiq conservation area of King Salman Bin Abdulaziz Royal Natural Reserve (KSRNR), Saudi Arabia. In addition, genomic DNA was extracted from the collected soil samples, and 16S rRNA sequencing was conducted using high-throughput Illumina technology. Several computational analysis tools were used for gene prediction and taxonomic classification of the microbial groups. Results: In this study, sandy soil samples from the surroundings of natural and artificial water resources of two distinct natures were used. Based on 16S rRNA sequencing, a total of 24,563 OTUs were detected. The metagenomic information was then categorized into 446 orders, 1036 families, 4102 genera, 213 classes, and 181 phyla. Moreover, the phylum Pseudomonadota was the most dominant microbial community across all samples, representing an average relative abundance of 34%. In addition, Actinomycetes was the most abundant class (26%). The analysis of clustered proteins assigned to COG categories provides a detailed understanding of the functional capabilities and adaptation of microbial communities in soil samples. Amino acid metabolism and transport were the most abundant categories in the soil environment. Conclusions: Metagenome analysis of sandy soils surrounding natural lakes and artificial water points in the Tubaiq conservation area of KSRNR (Saudi Arabia) has unveils rich microbial activity, highlighting the complex interactions and ecological roles of microbial communities in these environments. Full article

Groundwater, which is widely used in arid regions due to scarcity of surface sources, has excellent quality and, under certain conditions, can be consumed directly. Human activities have caused climate change, leading to decreased precipitation and increased temperatures, which reduces water recharge and increases underground extraction volume. To estimate the natural recharge of the Chupaderos aquifer, located in the State of Zacatecas, México, a spatiotemporal analysis methodology was used, using a soil moisture balance, which includes satellite information on precipitation and temperature, to obtain infiltration, evapotranspiration, and moisture. Using a Geographic Information System (GIS), a distributed spatial model was created in which the potential recharge areas that can be defined by raster images. The results show that there is a maximum annual recharge of 137 mm in the soil where Fluvisol and Kastanozem predominate, an indicator of a texture of sandy soil and franco-sandy area, which is mainly covered by forest and scrub. This result confirms that these characteristics are indispensable for the use of water in soil. Therefore, the preservation of the ecosystem is essential for aquifer recharge. Full article

Due to the unique geographic location of A’er Xiang, there is a natural landscape where sandy land and lake-marsh wetlands coexist. However, the wetland degradation caused by the disturbance of anthropogenic activities has led to the change in land use. In this study, the spatial-temporal substitution method was used to select five sample plots: the original wetland converted to forest land for reuse area of five years and ten years; the original wetland converted to cropland for reuse area of five years and ten years; and the native wetland. It aims to investigate the variations in carbon, nitrogen, and phosphorus and their stoichiometric characteristics of soil-microorganisms-extracellular enzymes before and after reuse, and to analyze potential interactions among these elements. The results indicated that following wetlands degradation, changes in land use for five years did not significantly affect the content of soil organic carbon (TOC), total nitrogen (TN), or total phosphorus (TP). However, after ten years, both TOC and TN, except for TP, decreased significantly. Microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) contents in cropland were consistently higher than those in WL, showing a trend of first increasing and then decreasing with longer conversion periods. In contrast, forest land values were lower than in WL and increased as the conversion period lengthened. The microbial biomass phosphorus (MBP) content was ranked across the five sample sites as follows: 10 CL > 5 CL > 5 FL > 10 FL > WL. β-1,4-glucosidase (BG) activity was significantly increased after conversion to forest land and significantly decreased after conversion to cropland. β-1,4-N-glucosidase (NAG) and L-leucine aminopeptidase (LAP) activities were ranked as follows among the five sites: 5 FL > WL > 5 CL > 10 FL > 10 CL. Phosphatase (PHOS) activity showed no significant changes post-conversion, though it was consistently lower compared to WL. Full article

Under the increasing severity of drought issues and the urgent need for the resourceful utilization of agricultural waste, this study aimed to compare the soil water retention properties of hydrogels prepared from Chinese cabbage waste (CW) and banana peel (BP) using grafting techniques with acrylic acid (AA) and acrylamide (AAm). Free radical polymerization was initiated with ammonium persulfate (APS), and N, N′-methylene bisacrylamide (MBA) served as the crosslinking agent to fabricate the grafted polymer hydrogels. The hydrogels were subjected to detailed evaluations of their water absorption, reusability, and water retention capabilities through indoor experiments. The optimal hydrogel was identified and its applicability in wheat seedling growth was assessed. The findings revealed that the CW-gel, with an equilibrium swelling ratio of 551.8 g/g in ultrapure water, demonstrated remarkable performance and sustained a high water retention of 57.6% even after drying, which was markedly superior to that of the BP-gel. The CW-gel with the best comprehensive properties significantly improved water retention in sandy soil by 78.2% and prolonged the retention time by five days, indicating its potential for long-term irrigation management. In contrast, the BP-gel showed better performance in clay soil, with an increased water-holding capacity of 43.3%. The application of a 1.5% CW-gel concentration under drought stress significantly improved wheat seedling growth, highlighting the role of hydrogels in agriculture and providing a new path for sustainable water resource management in dryland farming. Full article

Water conservation and effective irrigation management are vital for sustainable agriculture in arid regions. While organic soil amendments have been widely used to enhance water retention in sandy soils, research on the use of date palm waste-derived biochar remains limited. Thus, this study aimed to explore the innovative application of biochar produced from date palm waste, focusing on its effects on the hydrological properties of sandy soil. Biochars of varying particle sizes (0.5, 1, and 2 mm) and pyrolysis temperatures (300 °C, 450 °C, and 600 °C) were produced and their impacts were assessed under both saturated and unsaturated conditions on soil hydrological properties. The biochar was incorporated into soil columns at application rates of 0%, 1%, 3%, and 5% (w/w) within a 10 cm layer on top of 35 cm deep soil columns. The soil columns were placed vertically into water basins for saturation. Evaporation, infiltration, and saturated hydraulic conductivity were measured. The findings revealed that the application of 1%, 3%, and 5% biochar significantly increased soil water retention by 36.80%, 34.18%, and 29.66%, while cumulative evaporation decreased by 7.30%, 2.00%, and 1.35%, respectively, as compared to the control. Water retained at the end of the experiment was increased by 100.63%, 112.29%, and 101.68%, while unsaturated hydraulic conductivity decreased by 21.27%, 26.15%, and 26.17% after amending the soil with 1%, 3%, and 5% biochar, respectively, as compared to the control. The water retention ranged between 30.34 and 42.51%, 22.59 and 43.20%, and 22.48 and 38.81% for biochar produced at 300 °C, 450 °C, and 600 °C, respectively. Water infiltration rate and pore size was decreased with the increased pyrolysis temperature. Overall, the application rates of 3% and 5% with particle sizes of 1 and 0.5 mm and low pyrolysis temperature were most efficient for improving soil properties such as water retention, reducing unsaturated hydraulic conductivity, reducing the rate and volume of infiltration, and enhancing the micro-porosity reduction of sandy soils. In a nutshell, this study highlights the potential of date palm waste-derived biochar as an effective soil amendment, significantly enhancing water retention by up to 112.29% and reducing evaporation. By optimizing irrigation management in sandy soils, these findings contribute to more sustainable agricultural practices. Full article

This study examines CH₄ and N₂O fluxes during the dry season in two distinct areas of the Pantanal: Barranco Alto Farm (BAF), dominated by grasslands, and Passo da Lontra (PL), a forested region. As climate change increases the occurrence of droughts, understanding greenhouse gas (GHG) fluxes in tropical wetlands during dry periods is crucial. Using static chambers, CH₄ and N₂O emissions were measured from soils and tree stems in both regions, with additional measurements from grass in BAF. Contrary to expectations, PL—characterized by clayey soils—had sandy mud samples that retained less water, promoting oxic conditions and methane uptake, making it a CH₄ sink. Meanwhile, BAF’s sandy, well-drained soils exhibited minimal CH₄ fluxes, with negligible methane uptake or emissions. N₂O fluxes were generally higher in BAF, particularly from tree stems, indicating significant interactions between soil type, moisture, and vegetation. These findings highlight the pivotal roles of soil texture and aeration in GHG emissions, suggesting that well-drained, sandy soils in tropical wetlands may not always enhance methane oxidation. This underscores the importance of continuous GHG monitoring in the Pantanal to refine climate change mitigation strategies. Full article

In the context of contaminated site remediation, the fate of chlorinated solvents in the subsurface and subsequent groundwater contamination is influenced by soil properties governing sorption. The solid–water distribution coefficient (K_d) is a key parameter for modeling contaminant distribution and transport, essential for risk assessment and remediation planning. This study evaluated tetrachloroethene sorption isotherms in 34 low-organic-carbon soils from the Czech Republic, assessing the influence of soil properties on K_d. Soil samples exhibited variability in organic carbon content (˂0.05–0.81%), with clay ranging from 0% to 64.9%, silt 5.1% to 71.2%, and sand 5.2% to 88.9%, specific surface area (0.41–64.39 m² g⁻¹), particle density (2.05–4.09 g cm⁻³), and porosity (43.5–67.3%). Batch experiments were conducted using standard procedures, with K_d values ranging from 0.379 to 2.272 L kg⁻¹. Statistical analysis grouped the soils into three textural classes: sandy, clayey fine, and silty loam. The findings reveal that organic carbon content and specific surface area are the primary predictors of K_d, while clay and sand also play a significant role in shaping sorption behavior. Multivariate regression models explained 63.6% to 98.5% of K_d variability with high accuracy, as indicated by low root means square error (0.070–0.329) and mean absolute percentage error (3.8–28.8%) values. These models offer reliable predictions of sorption behavior, providing valuable tools for risk assessment and remediation strategies. Full article

A nondestructive approach for accurate crop yield prediction at the field scale is vital for precision agriculture. Considerable progress has been made in the use of the spectral index (SI) derived from unmanned aerial vehicle (UAV) hyperspectral images to predict crop yields before harvest. However, few studies have explored the most sensitive wavelengths and SIs for crop yield prediction, especially for different nitrogen fertilization levels and soil types. This study aimed to investigate the appropriate wavelengths and their combinations to explore the ability of new SIs derived from UAV hyperspectral images to predict yields during the growing season of spring maize. In this study, the hyperspectral canopy reflectance measurement method, a field-based high-throughput method, was evaluated in three field experiments (Wang-Jia-Qiao (WJQ), San-Ke-Shu (SKS), and Fu-Jia-Jie (FJJ)) since 2009 with different soil types (alluvial soil, black soil, and aeolian sandy soil) and various nitrogen (N) fertilization levels (0, 168, 240, 270, and 312 kg/ha) in Lishu County, Northeast China. The measurements of canopy spectral reflectance and maize yield were conducted at critical growth stages of spring maize, including the jointing, silking, and maturity stages, in 2019 and 2020. The best wavelengths and new SIs, including the difference spectral index, ratio spectral index, and normalized difference spectral index forms, were obtained from the contour maps constructed by the coefficient of determination (R²) from the linear regression models between the yield and all possible SIs screened from the 450 to 950 nm wavelengths. The new SIs and eight selected published SIs were subsequently used to predict maize yield via linear regression models. The results showed that (1) the most sensitive wavelengths were 640–714 nm at WJQ, 450–650 nm and 750–950 nm at SKS, and 450–700 nm and 750–950 nm at FJJ; (2) the new SIs established here were different across the three experimental fields, and their performance in maize yield prediction was generally better than that of the published SIs; and (3) the new SIs presented different responses to various N fertilization levels. This study demonstrates the potential of exploring new spectral characteristics from remote sensing technology for predicting the field-scale crop yield in spring maize cropping systems before harvest. Full article

Pinus radiata D. Don is the most widely planted forest species in Chile, making it crucial to understand carbon pools in adult plantations. This study aimed to evaluate the effect of soil type and site productivity on the total carbon stock in adult radiata pine plantations, considering sites with contrasting water and nutrient availability. We selected 10 sites with sandy and recent volcanic ash soils, representing a productivity gradient. At each site, three 1000 m² plots were established to quantify the carbon stock of total biomass using allometric equations and in situ carbon assessments of the forest floor and mineral soil (up to 1 m deep). The results indicated significantly higher carbon stocks in the mineral soil of recent ash sites (281.4 Mg ha⁻¹) compared to sandy soils (139.9 Mg ha⁻¹). The total site carbon was also higher in recent ash (473.2 Mg ha⁻¹) than in sandy sites (330.9 Mg ha⁻¹). A significant relationship was found between stand productivity and soil organic carbon (r² = 0.88), as well as total carbon stock (r² = 0.91) when considering soil type. These findings highlight the importance of including assessments up to 1 m depth and developing soil type and productivity models to improve site carbon stock estimates. Full article

This research aimed to assess the bioaccumulation capacity of the Buddleja species and Schinus molle L. using organic amendments to the phytoremediation of total chromium in the mid-zone of the Añashuayco Ravine, Uchumayo, Arequipa, impacted by tanneries from the Rio Seco Industrial Park. Additionally, it analyzed total chromium concentrations, soil physicochemical properties, and morphological changes in plants with and without organic matter. Samples of the Buddleja species and Schinus molle L. were distributed into groups with and without compost, along with control groups. They were monitored over 6 months, every 60 days, showing significant morphological variations. The results highlight an important finding: the remarkable bioaccumulation capacity of the species studied all exceeded 30%. The samples without compost showed a lower percentage of total chromium bioaccumulation in plants compared to the samples with the organic amendment. The Buddleja species demonstrated a 39.01% chromium bioaccumulation with compost compared to 37.99% without it. Likewise, Schinus molle L. achieved 33.99% chromium accumulation with compost and 31.84% without it. These findings emphasize the superior ability of these species to bioaccumulate heavy metals, highlighting that the Buddleja species has mayor bioaccumulation capacity and more remotion of total chromium in the soil. Full article

Permafrost, as a soil type under unique environmental conditions, has bearing characteristics that are highly susceptible to thermo-hydraulic environments. Rapid evaluation of the bearing characteristics of in situ permafrost at various depths in perennially frozen regions is a critical scientific issue urgently needing resolution in the road design and construction sectors in China. To address this, this study investigates the correlation between CPT parameters and laboratory mechanical indices under the combined effects of multiple factors in frozen sandy soils. By conducting both CPT and CBR tests on frozen sandy soils, the study analyzes the trends in changes in cone tip resistance (q_c) and CBR values under the influence of temperature (T), moisture content (ω), and compaction degree (K) and establishes a functional relationship between them. Based on the standard requirements for indoor CBR, an evaluation criterion using q_c for assessing the bearing capacity of frozen sandy soil is proposed. The results indicate that both CBR values and q_c increase initially and then stabilize as K increases. With decreasing temperature, both indices stabilize after an initial increase, with turning points at −3.1 °C for CBR values and −2.5 °C for q_c. As ω increases, both indices first increase and then stabilize, with a turning point at 40%ω. There is a robust linear relationship between the CBR values and q_c, with the ratio of predicted CBR values to actual values showing a histogram and log-normal distribution accounting for 81% and 51.3%, respectively, within a 20% accuracy level, indicating good predictive performance. Referring to the highway subgrade specifications for indoor CBR, a standard for evaluating the bearing capacity of frozen sandy soils using CPT technology is proposed. This study provides new insights for geological surveys in perennially frozen regions and a theoretical basis for the application of CPT technology in evaluating the bearing capacity of permafrost. Full article

Benggangs are a unique type of soil erosion commonly found in southern China, with the gully wall being the most dynamic component of the Benggang system and is crucial for assessing its overall progression. The unsaturated shear strength of soil in Benggang areas is a key factor influencing the stability of the gully wall. However, quantitative analyses of the unsaturated shear strength in the gully walls of Benggangs remain limited. In this study, the soil–water characteristic curves (SWCC) and shear strengths of undisturbed soil samples from four different soil layers in the gully wall of Benggang were measured using a pressure membrane meter and a quadruple direct shear apparatus. The results revealed that the water holding capacity of the soil decreased gradually with increasing matrix suction, and the order of the water holding capacity was the sandy soil layer > transition layer > laterite layer > clastic layer. With an increasing soil water content (SWC), the shear strength, cohesion (c), and internal friction angle (φ) of the four soil layers decreased significantly, and the φ showed a power function decreasing curve (p < 0.05), whereas c in the laterite layer and transition layer exhibited a power function decreasing curve (p < 0.01). The c of the sandy soil layer and clastic layer decreased linearly and logarithmically (p < 0.01) with increasing SWC, respectively. The unsaturated shear strength model for the four soil layers was developed based on the Vanapalli model. The root mean square error (RMSE) of the simulated and measured values was less than 29.349, while the Nash–Sutcliffe efficiency (NSE) and R² values were greater than 0.638 and 0.788, respectively. The model can be used to analyze and predict the unsaturated shear strength in different layers of Benggang gully walls, providing a theoretical foundation for studying the erosion mechanisms of Benggangs. Full article

Brazil leads globally in achieving high lint yields for rain-fed cotton in large-scale fields, with about 92% of its cotton area unirrigated. This study hypothesized that cotton could achieve high yields when favorable climate conditions and management practices favor high fruit load. The objective was to analyze the impact of these factors on cotton yields by examining two commercial fields in Brazil in the same climatic zone (Aw, Koppen)—one in Sapezal (SPZ) and the other in Riachão das Neves (RN). The SPZ field (cv. TMG 47B2RF) spanned 20 hectares, while the RN field (cv. FM 974GLT) covered 90 hectares. The soils of both fields were classified as oxisols, with SPZ possessing a clayey texture and RN a sandy loam texture. The findings indicate that the high lint cotton yields—3111 kg·ha⁻¹ in SPZ and 3239 kg·ha⁻¹ in RN—were achieved through a combination of ideal weather conditions, high-quality soil, and effective management practices, which favored boll retention, and an optimal plant architecture with short stature (<1.1 m), 19–22 nodes, and ~165 bolls m⁻². Boll weights averaged 1.85–1.91 g of lint, and fruit retention rates were 61.6% in SPZ and 66.2% in RN. The study reveals a significant yield gap compared to Brazil’s average lint cotton yield (~1900 kg·ha⁻¹) and other high-yield commercial fields (~3500–3900 kg·ha⁻¹ of lint). The results underscore that bridging this gap—ranging from 1200 to 2000 kg·ha⁻¹—could enhance the sustainability of cotton farming in Brazil by maximizing existing cultivated areas. Ultimately, the insights from this study highlight the role of combining climate suitability, management practices, and soil quality improvement to achieve higher cotton productivity and reduce environmental pressures from agricultural expansion. Full article

The stability of slopes is a critical challenge in various civil engineering projects, such as embankments, cut-slopes, landfills, dams, transportation infrastructure, and riverbank restoration. Stabilizing slopes using bioengineering methods is a sustainable approach that limits the negative impact of engineering works; such methods should be implemented and adopted worldwide. Geosynthetic materials and plant roots are sustainable for preventing erosion and surface landslides. The plants used for this paper are known to have beneficial effects on erosion control, namely Festuca arundinaceous, Dactylis glomerata, Phleum pratensis, Trifolium pratense, and Trifolium repens. Using vegetation as a bio-reinforcement method is often more cost effective and environmentally friendly than traditional engineering solutions, making a more sustainable engineering solution for shallow slope stabilization applications. The paper presents the erosion process that occurred on sandy slopes protected by organic soil layers and geosynthetic materials under rainfall simulation in scaled model tests. Full article