Soil Aggregate Stability Research Articles

Assessment of Tamarix smyrnensis for Phytoremediation Capacity of Laterite Mine Spoils

The phytoremediation potential of the halophytic plant, Tamarix smyrnensis (T. smyrnensis), was examined in toxic metal spoils assisted by biochar and irrigation by air nanobubbles. The substrate (spoil) used in the present study was derived from areas close to laterite (Ni-containing ores) mines. The efficiency of biochar addition in two rates (5 t/ha and 20 t/ha) to improve microbial properties and stabilize soil aggregates was also examined. Furthermore, the effect of irrigation with air-nanobubble-supplemented water was evaluated for the remediation of toxic metal spoils. The physiological condition of the plant species was investigated in terms of biomass, height, chlorophyll content, and antioxidant enzymes. The alkali and heavy metal accumulation and their distribution in the plant parts were assessed to explore whether toxic metals could accumulate in the root and further translocate to the aboveground tissues. The growth of T. smyrnensis was not adversely affected by its cultivation in lateritic spoil, and the highest rate of biochar exhibited a beneficial effect on plant growth in terms of weight (aerial and subterranean biomass). The highest biochar application rate led to significant increases in total chlorophyll content, showing a 97.6% increase when biochar is used alone and a 136% increase when combined with nanobubble irrigation. Remarkably, only when combining irrigation with air nanobubbles and low biochar supplementation did the translocation of the metals from soil to the aboveground tissues occur as the translocation factor was estimated to be greater than unity (TF > 1). The bioconcentration factors remained below 1.0 (BCF < 1) across all treatments, demonstrating limited mobilization from soil to plant tissues despite the application of soil amendments. Finally, the application of nanobubbles increased slightly but not substantially the total uptake of metals, which showed a significant decrease compared to the control groups when the lower dosage of biochar was utilized.

The Role of Plant Diversity in the Soil Aggregate Stability of a Degraded Coal Mine

The Role of Plant Diversity in the Soil Aggregate Stability of a Degraded Coal Mine

Compost amendments up to one inch restore dry rangeland soil health

Societal Impact StatementRangelands harbor immense diversity and provide ecosystem services across vast swaths of land while supporting rural economies and the food system, but degraded rangelands may require active management to restore diversity and function. We added varying amounts of compost to understand if there are linear or saturating effects on vegetation and soil characteristics. We found linear effects on water movement and soil carbon, but little effect on vegetation community or abundance. Our results provide guidance for grassland managers to make cost–benefit analyses for using compost in their own situations.Summary Dry rangelands systems coproduce food and other ecosystem services, but degradation of productivity, diversity, and water holding capacity may require active intervention to restore function. Compost amendments on grasslands have improved vegetation, soil carbon, and water characteristics, but practitioners lack guidance of optimal use to meet their management goals. We compared surface‐dressed compost additions up to 2.5 cm at two ranches in New Mexico, USA, and measured plant composition and biomass, soil bulk density, hydraulic conductivity, aggregate stability, and total carbon content (0–10 cm depth) up to two years after addition. We used model selection to determine if response relationships with compost amount were supported, linear, or non‐linear. We found that 2.5 cm compost additions nearly doubled litter cover after two years. Soil carbon increased linearly with compost depth, with the 2.5 cm depth nearly doubling carbon content compared to control after two years. Hydraulic conductivity increased linearly with compost depth in the first year at one site. Other variables showed little response to compost. Overall, we did not identify strong saturating responses over this range of compost additions. Our results provide guidance for land stewards to assess their resources and management goals to optimize compost addition to build rangeland soil health.

Evaluation of Soil Physical Properties in Natural and Conventional Farming in the Northern Dry Zone of Karnataka, India

This study examines variations in soil properties resulting from natural and conventional farming (Farmer Practices) methods across three distinct duration categories (less than 5 years, 5 to 10 years and 10 to 15 years) in the Northern Dry Zone of Karnataka. The results revealed that natural farming consistently produced lower soil bulk density, higher soil porosity, greater water-holding capacity and improved aggregate stability when compared to conventional farming practices. Over time, natural farming led to a decrease in bulk density; however, conventional practices showed an increase. Soil porosity, water-holding capacity and aggregate stability also saw improvement with natural farming because of the incorporation of organic matter, no-tillage methods and minimal disturbance. Conventional farming practices, which involved intensive tillage and the application of chemical inputs, resulted in soil compaction and structural degradation. Additionally, soil color became darker over time under natural farming, indicating a higher organic matter content; whereas, conventional practices contributed to lighter soil hues.

Soil Aggregate Stability and Characteristics of Nitrogen, Phosphorus, and Potassium Contents in Cut Slope Soils With Different Aspects in Plateau Areas

ABSTRACTSlope aspects can affect the soil‐forming process. The implementation of road construction projects in plateau regions has resulted in the formation of numerous cut slopes. However, the soil aggregate stability and the characteristics of soil nitrogen (N), phosphorus (P), and potassium (K) nutrients under different cut slope aspects (east‐facing slope (EFS), west‐facing slope (WFS), south‐facing slope (SFS) and north‐facing slope (NFS)) are still unclear. In this context, the present study aims to assess the characteristics and influencing factors of soil aggregate stability, as well as N, P, and K contents, under different slope aspects in typical cut slope soils with the four different aspects in the southwestern plateau of China. In addition, the relationships of the soil aggregate stability with the soil N, P, and K contents were further explored in this study. The results showed significant differences in the soil aggregate stability (MWD, mean weight diameter) between the four slope aspects. The MWD values of the WFS and SFS were 1.18 and 1.16, respectively, which were significantly higher than those of the EFS and NFS (p < 0.05). Large macroscopic aggregates (LMA) showed the greatest contribution to the MWD values. The soil total phosphorus (TP), total nitrogen (TN), total potassium (TK), alkali‐hydrolyzed nitrogen (AN), available phosphorus (AP), available potassium (AK), and soil organic carbon (SOC) contents showed significant differences between the four slope aspects and soil particle sizes. However, comparatively lower SOC contents were observed in the silt and clay fraction (SCA). The SOC contents and soil pH were the major factors influencing the LMA and SCA, which, in turn, affected the soil aggregate stability and contents of N, P, and K. The current study provides a useful reference for improving the quality of cut slope soils.

Application of green manure combined with synthetic nitrogen fertilizer enhances soil aggregate stability in an arid wheat cropping system

Application of green manure combined with synthetic nitrogen fertilizer enhances soil aggregate stability in an arid wheat cropping system

Long-Term Effects of Crop Treatments and Fertilization on Soil Stability and Nutrient Dynamics in the Loess Plateau: Implications for Soil Health and Productivity

Soil degradation and erosion pose significant threats to agricultural sustainability in fragile ecosystems, such as the Loess Plateau in northern China. This study examines the long-term impacts of fertilization regimes and land-use systems on soil health, focusing on soil aggregate stability, fertility, and crop productivity. Six treatment combinations were evaluated in our study, including three continuous alfalfa fields (AL-CK, AL-P, and AL-NPM) and three continuous wheat fields (WH-NPM, WH-NP, and WH-P), each representing a combination of land use and three fertilization treatments: (1) no fertilization (CK), (2) inorganic fertilization (120 kg ha−1 N, 60 kg ha−1 P-NP), and (3) a combination of organic and inorganic fertilization (75 t ha−1 cow manure-NPM). Soil samples were collected from three depths (0–10 cm, 10–20 cm, and 20–30 cm) to assess physical and chemical properties. We evaluated the long-term effects of different fertilization treatments on soil stability, fertility, and crop yield to explore the interactions among soil’s physical and chemical properties under two land-use types and to assess the effectiveness of combined organic and inorganic fertilization strategies in improving soil health and mitigating erosion in vulnerable landscapes. The study revealed significant depth-specific variations with surface layers (0–10 cm) showing the greatest improvement under NPM treatments, particularly in continuous alfalfa fields, which exhibited higher soil fertility, improved soil structure, and crop yield. In contrast, continuous wheat fields with minimal fertilization demonstrated significantly lower soil quality and productivity. Using the combination of mineral fertilizers and organic amendments, such as cow manure, proved to be the most effective strategy for significantly enhancing nutrient availability and overall soil health. Partial Least Squares Modeling (PLS-M) and Mantel analysis highlighted the critical role of fertilization management in maintaining soil quality, boosting crop productivity, and mitigating erosion in high-risk areas. This study emphasizes the importance of integrated nutrient management for sustainable land use and soil conservation in erosion-prone regions.

Soil Aggregation, Aggregate Stability, and Associated Soil Organic Carbon in Huron Mountains Forests, Michigan, USA

Soil organic carbon (SOC) plays a critical role in regulating the global carbon (C) cycle, with forest soils serving as significant C sinks. Soil aggregate stability and the distribution of SOC in different aggregate fractions would be affected by different forest types. In this study, we investigate the distribution and dynamics of SOC within different soil aggregate fractions across three main forest types in the Huron Mountains, Michigan, USA: white birch–eastern hemlock mixed forest, eastern-hemlock-dominated forest, and sugar maple forest. We hypothesize that variations in species composition and soil depth influence SOC storage and aggregate stability through mechanisms such as root interactions, microbial activity, and soil structure development. Soil samples were collected from three depth intervals (0–20 cm, 20–40 cm, and 40–60 cm) and analyzed for aggregate size distribution and SOC content. The results showed that aggregate size distribution and SOC stocks differ significantly across forest types, with the white birch–eastern hemlock mixed forest exhibiting the highest proportion of large aggregates (>1.0 mm), which contribute to more stable soil structures. This forest type also had the highest total aggregate mass and mean weight diameter, indicating enhanced soil stability. In contrast, sugar maple forest displayed a greater proportion of smaller aggregates and a lower macroaggregate-to-microaggregate ratio, suggesting fewer stable soils. SOC stocks were closely linked to aggregate size, with macroaggregates containing the highest proportion of SOC. These differences in SOC distribution and soil aggregate stability can be attributed to several underlying mechanisms, including variations in plant root interactions, microbial activity, and the physical properties of the soil. Forests with diverse species compositions, such as the white birch–eastern hemlock mixed forest, tend to support more complex root systems and microbial communities, leading to improved soil aggregation and greater SOC storage. Additionally, forest management practices such as selective thinning and mixed-species planting contribute to these processes by enhancing soil structure, increasing root biomass, and promoting soil microbial health. These interactions play a crucial role in enhancing C sequestration and improving soil health. Our findings emphasized the importance of forest composition in influencing SOC dynamics and soil stability, offering insights into the role of forest management in C sequestration and soil health. This study provided a reference to a deeper understanding of SOC storage potential in forest ecosystems and supports the development of sustainable forest management strategies to mitigate climate change.

Responses of Soil Aggregate Stability and SOC to Different Tillage Modes and Straw Input Level

Responses of Soil Aggregate Stability and SOC to Different Tillage Modes and Straw Input Level

Exploring the utility of different bulking agents for speeding up the composting process of household kitchen waste

Household kitchen waste (HKW) is produced in large quantity and its management is difficult due to high moisture content and complex organic matter. Aerobic composting of HKW is an easy, efficient, cost-effective and eco-friendly method. This study is designed to achieve a zero-waste concept and to convert HKW. We optimized the type and size of three different bulking agents to speed up the composting process. The tested bulking agents were fallen leaves, sawdust and fly ash. The results showed a higher and longer thermophilic phase (55oC) for 11 days in C2. Higher moisture content (69%) and higher organic matter degradation (38.4%) were also observed in C2. The pH range in all compost treatments was 7-8.5, Electrical conductivity range was 1.8–3.55 mS/cm, C/N ratio range was 15.4–18.1, water holding capacity range was 3.25–4.3 g water/g dry sample, total potassium range was 1.52–1.61%, total phosphorous range was 0.83–1.14%. The highest germination index (119.1%) was also obtained in C2. The highest chili height (16.7 cm), greater number of leaves (20), greater shoot fresh weight (4.75 g) and root fresh weight (1.2 g) was obtained in the presence of C2. Similarly, greater water WHC (2.8 g water/g DW), higher porosity (55.49%) and higher aggregate stability (54.14%) of soil was also obtained by C2. This research effectively reduced the maturation time to 32 days and converted kitchen waste into compost (resource). This is a very practical idea for home composting and kitchen gardening to combat food security issues in developing countries.

Relationship Between Soil Aggregate Stability and Associated Carbon and Nitrogen Changes Under Different Ecological Construction Measures in the Karst Region of Southwest China

Relationship Between Soil Aggregate Stability and Associated Carbon and Nitrogen Changes Under Different Ecological Construction Measures in the Karst Region of Southwest China

Mitigating soil compaction and enhancing corn (Zea mays L.) growth through biological and non-biological amendments

Soil compaction is a pressing issue in agriculture that significantly hinders plant growth and soil health, necessitating effective strategies for mitigation. This study examined the effects of sugarcane bagasse, both in its raw form and as biochar, along with biological activators (Bacillus simplex UTT1 and Phanerochaete chrysosporium) on soil characteristics and corn (Zea mays L.) plant biomass in a compacted soil. Using a completely randomized factorial design, we assessed their impact on soil bulk density, porosity, nutrient concentrations, and plant growth parameters. Results indicated that combining organic amendments with microbial inoculation (B. simplex UTT1 + P. chrysosporium) significantly reduced soil bulk density (7–14%) (p < 0.05) and enhanced soil aggregate stability (38%), soil permeability coefficient (52%), and total porosity (40%) (p < 0.01) compared to controls. Notably, the application of biochar and microbial inoculants improved soil moisture retention (p < 0.05) and soil nutrient availability, particularly potassium and phosphorus, which increased by 18% and 23%, respectively. Plant biomass responses (10–35%) varied, with combined microbial treatments (B. simplex UTT1 + P. chrysosporium) yielding optimal outcomes (p < 0.01) compared to individual applications. The study emphasizes that integrating organic amendments with biological processes not only mitigates soil compaction but also fosters soil health and productivity. These findings support the need for sustainable agricultural practices, highlighting the role of effective resource management in enhancing soil structure and crop yields. Future research should focus on understanding the underlying mechanisms of these interactions and their long-term implications for soil health and agricultural sustainability.Clinical trial number Not applicable.

Microtopography-induced hydrological heterogeneity promotes the co-assembly of vascular plant and biocrust communities, providing synergistic protective functions for the Great Wall.

The Great Wall in China, constructed from rammed earth, faces threats from natural erosion. Vascular plants and biocrusts have enhanced the stability of the Great Wall through various mechanisms; however, understanding of the colonization processes of vascular plants and biocrusts on the wall, as well as their protective mechanisms, remains limited. This study investigated the vascular plant communities, biocrusts, soil moisture content, soil properties, aggregate mechanical stability, aggregate water stability, and soil erodibility factors across seven fine-scale microtopographies of the Great Wall (lower, middle, and upper zones on the east and west faces, as well as the wall crest). After rainfall events and under no-rainfall conditions, soil moisture content was higher at the crest compared to the lower zones on both sides; this demonstrates that microtopography significantly influences soil moisture distribution through rainfall distribution. Soil moisture content was positively correlated with variables associated with vascular plant communities (except evenness) and moss crust (p<0.05). This suggests that the microtopography of the wall and its induced water heterogeneity drive the distribution pattern of vascular plant communities and moss crusts. Vascular plant communities and moss crusts significantly enhanced the mechanical and water stability of soil aggregates, reducing soil erosion susceptibility by providing physical protective cover, increasing the content of mechanically stable and water-stable macroaggregates, and enhancing soil silt and clay content, soil porosity, and water-holding capacity. Based on the regulation of vascular plant communities and biocrusts by microtopography, a restoration framework was proposed, offering a theoretical foundation and practical methods for the protection of the wall and similar earthen heritage sites.

SLAKES Smartphone Application to Identify the Difference in Soil Aggregate Stability Under Cover Crop Management for Soils with Fragipan Horizon

ABSTRACT Fragipan subsoil horizons have poor soil aggregate stability that slakes in rise with the water table. The intensity of slaking can be used as a proxy to identify the presence of fragipan horizon in a soil profile. Fairly new, ‘Slakes,’ a smartphone application provides an aggregate stability index (ASI) based on fitting a Gompretz function over changes in area of disintegrating soil peds immersed in water for over 10 min through the analysis of images taken by a smartphone camera. Objectives of this study were twofold: first, to identify changes in ASI values with the adoption of cover crops, and second, to apply Slakes value to identify the fragipan horizon. We compared ASI values for with (CC) and without (NCC) a cover crop mix at two on-farm fields with fragipan subsoil horizons in southern Illinois. The conventional wet aggregate stability method did not show any differences (p = .10) between CC and NCC for the surface Ap horizon at both sites. However, the ASI score of CC was higher than NCC for the site with 10 years under CC, but the opposite trend was observed for the other site. In general, the Ap horizon had the highest ASI score with an average value of 0.48 and it significantly declined for the Bt horizon (0.29). This study showed that the Slake-ASI score has value to identify changes in management practices on surface soils. However, applying Slakes to identify the fragipan horizon would require a shorter time length (<10 min) and large-scale calibration.

Role of Arbuscular Mycorrhizal Fungi in Maintaining Sustainable Agroecosystems

Arbuscular mycorrhizal (AM) fungi play a crucial role in maintaining sustainable agroecosystems by forming mutualistic relationships with plant roots, improving soil health, facilitating nutrient uptake, and enhancing resilience to abiotic stresses. The mutualistic relationship between AM fungi and plants promotes a balanced microbial community and improves soil structure by forming stable soil aggregates. Additionally, AM fungi can lower the adverse effects of high soil phosphorus (P) while also enhancing plant tolerance to drought, salinity, and heavy metal toxicity through osmotic regulation and antioxidant production. Arbuscular mycorrhizal fungi also support beneficial microorganisms, such as potassium (K)-solubilizing microbes and nitrogen (N)-transforming bacteria, which enhance the nutrient dynamics in soil. However, intensive agricultural practices, including heavy tillage and continuous monoculture, disrupt AM fungal networks and reduce microbial diversity, impairing their effectiveness. Adopting conservation practices such as reduced tillage, crop rotation, and organic amendments supports AM fungal growth. Incorporating mycorrhizal crops and utilizing native fungal inoculants can enhance AM fungal colonization and plant growth. These strategies collectively bolster soil health, crop productivity, and resilience, offering a promising solution to the environmental and agricultural challenges posed by intensive farming. By promoting AM fungi growth and colonization, agroecosystems can achieve long-term productivity and increased sustainability.

Nitrogen addition enhances soil aggregate stability by increasing the contents of microbial gluing agents in a subalpine forest

Nitrogen addition enhances soil aggregate stability by increasing the contents of microbial gluing agents in a subalpine forest

The dissimilarity between multiple management practices drives the impact on soil properties and functions

Higher dissimilarity between restoration factors boosted soil microbial activities when multiple factors jointly applied.More diverse management practices enhanced soil aggregate stability and improved soil pH.Increasing restoration factors up to 8 factors only influenced soil properties (water stable aggregates and soil pH) but not soil microbial activities.A range of land management practices are available to achieve better soil quality, but their combined effects remain understudied. We hypothesize that more diverse management practices, meaning higher dissimilarity, lead to stronger effects on soil functions and properties. Eight practices (biochar, compost, clay, amorphous silica, basalt, microbial inoculum, reduced physical disturbance and organic matter diversity) were selected with 20 replicates for treatments involving 2, 4, or 6 factors and 10 replicates for 8 factor treatments. We investigated the impact of individual factors, factor number, factor dissimilarity and factor composition on soil respiration, soil enzymatic activities (β-glucosidase, β-D-cellobiosidase, β-N-acetylglucosaminidase and phosphatase), soil pH, water stable aggregates and permanganate oxidizable carbon fraction. By including dissimilarity in addition to factor number, variance explained for soil respiration and enzymatic activities increased up to 54.21%. For soil pH and water-stable aggregates, explained variability increased to 65.57% and 57.38%, respectively. More diverse management practices boosted soil microbial activities, enhanced soil aggregate stability, improved soil pH while reducing labile carbon, whereas factor number only influenced water stable aggregates and soil pH. Our study highlights the importance of management practices diversity in soil functions and properties and calls for further research on synergistic combinations of diverse interventions.

Bioenhanced remediation of dibutyl phthalate contaminated black soil by immobilized biochar microbiota

To address the contamination caused by DBP residues prevalent in black soils, this study developed a multifunctional bioremediation material (BHF@DK-P3) using humic acid and iron-modified corn stover biochar in combination with microbiota. The microbiota contained DBP-degrading bacteria (Enterobacterium sp. DNB-S2), phosphorus-solubilizing bacteria (Enterobacter sp. P1) and potassium-solubilizing bacteria (Paenibacillus sp. KT), and formed a good mutualistic symbiosis. In the biochar microenvironment, the microflora had lower DBP biotoxicity responses and more cell membrane formation. The addition of BHF@DK-P3 brought the structure of the DBP-contaminated black soil closer to the optimal three-phase ratio. The microbiota was able to perform their biological functions stably under both DBP stress and acid-base stress conditions. The stability of soil aggregates and the efficiency of N, P, K nutrients were improved, with available phosphorus increasing by 21.45%, available potassium by 12.54% and alkali-hydrolysable nitrogen by 14.74%. The relative abundance of copiotrophic bacterial taxa in the soil increased and the relative abundance of oligotrophic bacterial taxa decreased, providing a good mechanism for the conversion and utilization of soil nutrients. Biochar and microbiota jointly influenced soil carbon and nitrogen metabolism in response to DBP.

Soil structural stability improvement using arbuscular mycorrhizal fungi and biochar in water repellent and non‐water repellent soil

AbstractSoil hydrophobicity has increased in recent years due to the expansion of arid lands. In these lands soil inoculation with arbuscular mycorrhizal fungi (AMF) and application of biochar are two soil improvement strategies. The formation and stability of soil aggregates can be significantly influenced by these management practices. In the present study, the simultaneous effect of sugarcane biochar (0%, 1% and 2%) and AMF (+AMF and −AMF) on the improvement of water repellent (WR) and non‐water repellent (NWR) soil structure was investigated under corn cultivation in greenhouse. Incorporation of 2% biochar into NWR soil increased soil organic carbon by 155% and 94% in AMF and non‐AMF treatments, respectively, compared to the control (without biochar). However, this increase was less pronounced in WR soil. The difference in soil carbohydrate concentration between AMF and non‐AMF treatments enhanced with increasing biochar application level from 25% to 144% in non‐water repellent soil and from 51% to 147% in water repellent soil. The results indicated that the interaction between AMF and biochar had a significant positive effect on both soil microbial respiration and glomalin concentration. To measure the soil aggregate stability, the high‐energy soil moisture characteristic curve (HEMC) method was used. The positive effects of biochar and AMF on soil structural stability indices were observed in both studied soils. However, these positive effects were influenced by their interactive effects. Two percent biochar application in non‐water repellent soil, limited the positive effect of AMF on soil stability improvement by 73%. While, in water repellent soil, structural stability indices improved with 1% and 2% biochar application by 13.4% and 19.7% respectively, due to soil wettability improvement and consequently better microbial activities. Finally, in addition to the interactive effects of microbial activities and biochar on soil structural characteristics, the level of soil hydrophobicity is also effective in improving soil structure under these studies managements.

The stability of soil aggregates in Sweet Cherry (Prunus avium L.) orchards of different ages and varieties

The stability of soil aggregates in Sweet Cherry (Prunus avium L.) orchards of different ages and varieties