Aggregate Stability Research Articles

Small-size polyethylene and polylactic microplastic alterations on soil aggregate formation with soil sterilization

Soil microplastic contamination is emerging as a significant environmental concern affecting soil properties and biota, including soil aggregation. This study aimed to determine the influence of soil microplastics on soil aggregation, their impact through effects on soil microorganisms, and their effects on water and mechanical stability of soil aggregates. Soil incubation experiments were conducted using sterilized and non-sterilized soils with 15-μm polyethylene and polylactic microplastics over one month. Sterilized soils showed more water-stable aggregates, particularly in the 0.25–0.5 mm fraction (+49%), with both polyethylene and polylactic MPs significantly increasing this fraction (+34% and +35%, respectively). However, no significant effects of soil sterilization and MP addition were found on mechanical stability. The addition of MPs tended to decrease aggregate surface roughness but not significantly (−17～21%). The study provides insights into the complex interactions between microplastics and soil aggregation, suggesting that MP effects may not necessarily be related to their toxicity on soil microbes but could involve various physical interactions.

Multiple soil health indicators are responsive to summer cover crops on an irrigated organic farm

While cover crops (CC) are known to enhance soil health, outcomes are often subtle and confined to a shallow surface soil layer. We assessed 15 soil health indicators over three CC trials with a 15-species Blend polyculture, a Mustard biculture (white ( Sinapsis alba L.) and brown ( Brassica juncea (L.) Czern.) mustards), Buckwheat ( Fagopyrum esculentum Moench), and Faba bean ( Vicia faba L.) monocultures, and a Weedy fallow (no CC, weeds allowed to grow) on an organic farm in southern Alberta. Soil sampling times included (i) summer pretermination; (ii) fall post-termination; and (iii) spring post-termination of CC. Twelve of 15 soil health indicators showed significant effects of CC treatment for at least one sampling time. Soil organic C (SOC) ranked highest with 80% of sampling times showing significant CC effects. N-related indicators (total N (TN), nitrate-N)) were also quite sensitive, being significantly affected by CC treatment at 60% of sampling times. Three soil health indicators (acid phosphomonoesterase (AcP), wet aggregate stability, and free-living nematodes (FLN)) were consistent in their nonresponses to CC treatment at all sampling times. Comparing CC treatments with a Weedy fallow, showed that not all enhancements of soil health were explained by inclusion of a CC, with Weedy fallow as effective for some indicators. A polyculture Blend significantly enhanced soil health over a monoculture CC or Weedy fallow in 46% of instances of soil health indicator improvement. While CC led to enhancement of soil health, results were not always consistent, being contingent on specific indicators.

Mangrove wetland recovery enhances soil carbon sequestration capacity of soil aggregates and microbial network stability in southeastern China

Mangrove wetlands are highly productive ecosystems in tropical and subtropical coastal zones, play crucial roles in water purification, biodiversity maintenance, and carbon sequestration. Recent years have seen the implementation of pond return initiatives, which have facilitated the gradual recovery of mangrove areas in China. However, the implications of these initiatives for soil aggregate stability, microbial community structure, and network interactions remain unclear. This study assesses the impacts of converting ponds to mangroves—both in natural and artificially restored settings—on soil aggregate stability and microbial networks at typical mangrove restoration sites along China's southeastern coast. Our observations confirmed our hypothesis that pond-to-mangrove conversions resulted in an increase in the proportion of large aggregates (>0.25 mm), improved soil aggregate structural stability, and increased carbon sequestration. However, mangrove recovery led to a decrease in the abundance and diversity of soil fungi communities. In terms of co-occurrence networks, naturally restored mangrove wetlands exhibited more nodes and edges. The naturally recovered mangrove wetlands demonstrated a higher level of community symbiosis compared to those that were manually restored. Conversely, bacterial networks showed a different pattern, with significant shifts in key taxa related to carbon sequestration functions. For instance, the proportion of bacterial Desulfobacterota and fungi Basidiomycota in natural recovery mangrove increased by 15.03 % and 7.82 %, respectively, compared with that in aquaculture ponds. Soil fungi and bacteria communities, as well as carbon sequestration by aggregates, were all positively correlated with soil total carbon content (P < 0.05). Both bacterial and fungal communities contributed to soil aggregate stability. Our study highlights the complex relationships between soil microbial communities, aggregate stability, and the carbon cycle before and after land-use changes. These findings underscore the potential benefits of restoring mangrove wetlands, as such efforts can enhance carbon storage capacity and significantly contribute to climate change mitigation.

No-tillage facilitates soil organic carbon sequestration by enhancing arbuscular mycorrhizal fungi-related soil proteins accumulation and aggregation

No-tillage is known to optimize soil structure and enhance soil organic carbon (SOC) stocks in cropland. However, the exact mechanisms driving the accumulation of SOC are still unclear, especially concerning the regulation of arbuscular mycorrhizal fungi (AMF) communities and diversity in SOC sequestration. Here, this study aims to elucidate the intricate relationship between AMF community, glomalin-related soil proteins (GRSP), and SOC within bulk soil and aggregates across four tillage treatments (i.e. FA, fallow; RT, rotary tillage; DT, deep tillage; NT, no-tillage) based on a 7-year tillage experiment. Results showed that the contents of SOC and GRSP were significantly higher by 1.14–1.46 mg/g and 0.43–0.72 mg/g in the bulk soil under NT relative to RT and DT, respectively. The contribution of GRSP-C to SOC under NT was also higher than RT and DT, especially in > 53 μm particle size. Additionally, NT increased AMF diversity and the abundance of glomerales and diversisporales, all showing a strong positive correlation with GRSP (p < 0.05), indicating their potential regulatory role in GRSP production. The positive correlations between GRSP and the mass percentage of the > 53 μm particle size fraction (R2 = 0.74; p < 0.01) and MWD (R2 = 0.63; p < 0.01) suggested that no-tillage may drive large aggregates (>53 μm) formation and enhance aggregate stability through GRSP levels. Overall, increased AMF diversity and keystone taxa abundance at the order level via no-tillage promoted SOC accumulation through the production of GRSP and the protection of large aggregates. This study highlights that no-tillage is an effective and sustainable soil management strategy for enhancing soil quality in agricultural ecosystems.

Aggregation of Albumins under Reductive Radical Stress.

The reactions of radicals with human serum albumin (HSA) under reductive stress conditions were studied using pulse radiolysis and photochemical methods. It was proved that irradiation of HSA solutions under reductive stress conditions results in the formation of stable protein aggregates. HSA aggregates induced by ionizing radiation are characterized by unique emission, different from the UV emission of non-irradiated solutions. The comparison of transient absorption spectra and the reactivity of hydrated electrons (eaq-) with amino acids or HSA suggests that electron attachment to disulfide bonds is responsible for the transient spectrum recorded in the case of albumin solutions. The reactions of eaq- and CO2•- with HSA lead to the formation of the same products. Recombination of sulfur-centered radicals plays a crucial role in the generation of HSA nanoparticles, which are stabilized by intermolecular disulfide bonds. The process of creating disulfide bridges under the influence of ionizing radiation is a promising method for the synthesis of biocompatible protein nanostructures for medical applications. Our Raman spectroscopy studies indicate strong modification of disulfide bonds and confirm the aggregation of albumins as well. Low-temperature measurements indicate the possibility of electron tunneling through the HSA protein structure to specific CyS-SCy bridges. The current study showed that the efficiency of HSA aggregation depends on two main factors: dose rate (number of pulses per unit time in the case of pulse radiolysis) and the temperature of the irradiated solution.

Assessing the formation and stability of paddy soil aggregate driven by organic carbon and Fe/Al oxides in rice straw cyclic utilization strategies: Insight from a six-year field trial

Soil organic carbon (SOC) and iron/aluminum (Fe/Al) oxides are key cementing agents in driving soil aggregate formation, yet their direct effects and interactions on aggregate under long-term rice straw cyclic utilization (LSCU) in cold regions are still unclear. We compared chemical fertilizer (CF) with LSCU strategy: rice-straw (RS), biochar (RB), and biochar-based fertilizer (BF). We showed that the increase of macroaggregate (2–0.25 mm) is associated with SOC, dissolved organic carbon (DOC), humin carbon (HUC), amorphous and organic complexed Fe/Al oxides (Feo, Fep, Alo, Alp), and in each size of the aggregate, there exists an interaction between SOC (fractions) and Fe/Al oxides. Furthermore, aggregate stability was determined by Feo, Fep, and Alo. LSCU enhances macroaggregate and aggregate stability by increasing SOC and Fe/Al oxides in the bulk soil and aggregates, but there are differences among LSCU. In all treatments, RS had more DOC, fulvic acid carbon (FAC), humic acid carbon (HAC) and Fep; while RB had more SOC, HUC, free Fe/Al oxides (Fed, Ald), Feo, Alp; and BF had more Alo in bulk soil. Over the years, RS increased the DOC, FAC and HAC, whereas RB enhanced the stable SOC fractions (HUC) and promoted high reactive Fe/Al oxides formation (Feo, Fep, Alo), and BF increased DOC, Feo, Fep and Alo. Moreover, RB increases the direct pathway of SOC and Fe/Al oxides to aggregate, promoting aggregate formation. Our study provides new perspective on the mechanisms and promising practice for improving rice straw utilization efficiently, paddy soil fertility and productivity sustainably in cold regions.

Dynamics of structural indices and organic carbon pool across a haplic acrisol under secondary tropical rainforest at Umudike Abia State

Differences in vegetation types over a landscape influences the structural behaviour and organic carbon pool of soils thereby affecting site-specific management decisions. This study aimed at establishing the differences in structural indices and organic carbon pool across a soil under secondary rainforest vegetation. Nine replicates of auger and core soil samples were randomly collected from the site at 0 – 20 cm depth. Soil samples were prepared and analysed at a laboratory. Data obtained were subjected to geospatial analysis using a Geographical Information System (GIS) software package. Results showed that changes in organic carbon storage ranged from 40 – 48 ton / ha, BD ranged from 1.39 – 1.42 mg / m3, clay flocculation index ranged from 50 – 68 %, aggregated silt + clay ranged from 9 – 12 %, clay dispersion index ranged from 32 – 42 %, dispersion ratio ranged from 26 – 32 %, mean weight diameter ranged from 0.75 – 1.05 mm, saturated hydraulic conductivity ranged from 3.1 – 3.8 cm / mins and total porosity ranged from 46.4 – 47.6 %. Regions of weak micro aggregaion dominated the land while regions of increased stability of macro aggregates were dominant. Regions of increased soil organic carbon storage occupied about half portion of the land. Greater portion of the land was noted for increased bulk density, reduced total porosity and saturated hydraulic conductivity. Consequently, there were changes in soil structural properties and organic carbon storage across the studied area.

Cross‐correlating soil aggregate stability methods to facilitate universal interpretation

Cross‐correlating soil aggregate stability methods to facilitate universal interpretation

Aggregate Stability Indices of a Typic Hapludult under Different Land-Use Types and Varying Depths at Umuahia

Aggregate Stability Indices of a Typic Hapludult under Different Land-Use Types and Varying Depths at Umuahia

Impact of freeze–thaw cycling on the stability and turnover of black soil aggregates

During freeze–thaw cycling, aggregates undergo a dynamic change in breakdown–formation (turnover), however, how the turnover occurs between aggregates of various particle sizes is not clear. To clarify the influence of freeze–thaw cycling on the dynamic changes in the particle size of soil aggregates, soil aggregates from the Black Soil Region of Northeast China were selected as the research objects. The study conducted in situ dynamic monitoring experiments, innovatively applying the rare earth oxide (REO) tracer method to natural conditions of freeze–thaw cycles (autumn freeze–thaw period, freezing period, and spring freeze–thaw period), accurately tracking the turnover paths and quantifying the turnover rates between aggregates of various particle sizes. The results revealed that the total value of the formation paths of the 2–5 mm aggregates and 0.25–2 mm aggregates increased during the autumn freeze–thaw period. The number of freeze–thaw cycles and accumulated snowfall were significantly positively correlated with aggregate stability, with an increase in the number of freeze–thaw cycles and accumulated snowfall resulting in an increase in the proportion of aggregates > 0.25 mm, which improved aggregate stability. In addition, the total value of the breakdown path of macro-aggregates increased during the spring freeze–thaw cycling period. Soil moisture was significantly negatively correlated with aggregate stability, with increased soil moisture resulting in a decrease in the percentage of aggregates > 0.25 mm, which resulted in a decrease in aggregate stability. The study can provide a reference understanding for the effects of freeze–thaw cycles on the structure of black soil and provide a theoretical basis for improving the quality of arable land.

Effect of jujube orchard abandonment time on soil properties and enzyme activities at soil profile in the Loess Plateau

In the Loess Plateau, the impact of abandoned farmland on soil properties and enzyme activity, along with its temporal variations and potential driving factors, remains a mystery. This study was designed to systematically and comprehensively examine the variations in soil enzyme activities, particle size distribution, and stability of soil aggregates at different stages of ecological recovery in the Loess Plateau. Our findings reveal a nuanced temporal pattern: with the progression of cropland abandonment, there is a notable decrease in soil bulk density. Concurrently, a dynamic trend in enzyme activities is observed—initially exhibiting a decline, followed by an increase over extended periods of recovery. Notably, prolonged abandonment leads to marked enhancements in soil structure. Parameters such as the mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates show an overall increasing trend. In terms of the Relative Dissipation Index (RSI), our data indicate a sequence of control > 2 years of abandonment > 4 years > 6 years > 14 years. From this, it can be seen that fallowing may be an effective natural restoration strategy for improving the physical structure of soils in the Loess Plateau and restoring soil nutrients. However, positive changes may take a long time to become evident.

Capillary mediated vitrification is a novel technique that enables storage of antibody critical reagents at ambient temperature: Impact on binding, structure, and laboratory sustainability

Antibodies and antibody conjugates are essential components of life science research, but their inherent instability necessitates cold storage or lyophilization, posing logistical and sustainability challenges. Capillary-mediated vitrification has shown promise as a tool for improving biomolecule stability. In this study, we assess the feasibility of shipping and storing CMV-stabilized antibody reagents at ambient temperature using a purified rabbit polyclonal as a model system. The conditions tested included a simulated temperature excursion, ambient shipping, and storage for approximately two months at room-temperature. Antibody function was measured by both ELISA and Octet bio-layer interferometry kinetic measurements. Yield, aggregation, and thermal stability were assessed by UV/VIS, Size Exclusion Chromatography (SEC), thermal melting, and thermal aggregation studies. Results indicate >97 % protein yield and no impact on the binding activity. No evidence of aggregation or oligomer formation was detected. Addition of the vitrification buffer to the sample matrix resulted in an increase in the aggregation on-set temperature, indicating enhanced thermostability. A slight shift in both the SEC retention time for the main peak and a difference in aggregation behavior at high temperatures were noted post-vitrification. We hypothesize that these differences are related to the interaction of the protein with the saccharide component of the vitrification matrix and the stabilization mechanism of sugars. The cumulative data supports the use of Capillary Mediated Vitrification as a viable alternative to frozen reagent storage, with the potential to significantly impact reagent stability, assay performance, laboratory operations, and sustainability initiatives.

Vascular plants and biocrusts ameliorate soil properties serving to increase the stability of the Great Wall of China

The Great Wall, as a World Heritage Site, is constructed with rammed earth and is currently facing the threat of erosion from wind and rain. Vascular plants and biocrusts are the main coverings of the Great Wall, and their role in mitigating soil erosion has attracted increased amounts of attention; however, the understanding of their underlying mechanisms is limited. Here, we conducted an extensive survey of vascular plants, biocrusts, soil properties (soil organic and inorganic binding materials, aggregates, and texture), soil aggregate stability, and soil erodibility at the top of the Great Wall in four different defensive zones in Northwest China. Vascular plants covered 13.6 % to 63.9 % of the tops of the Great Wall, and their rich diversity was mainly derived from perennial herbs. Moss, lichen, and cyanobacterial crusts collectively covered 36.3 % to 67.8 % of the top of the Great Wall. Redundancy analysis and structural equation modeling revealed that the synergistic effects of vascular plants and biocrusts enhanced soil aggregation stability (including geometric mean diameter, GMD; water-stable macroaggregate content, R) by increasing the accumulation of soil organic carbon (SOC), amorphous iron oxide (Feo), and amorphous alumina (Alo) and promoting the formation of macroaggregates (ASD>0.25 mm) and microaggregates (ASD0.053-0.25 mm). Furthermore, soil erodibility was primarily influenced negatively by the synergistic promotion of SOC accumulation by vascular plants and biocrusts and positively by the reduction in soil sand (PSD>0.05 mm) content by biocrusts. Our work highlights the mechanisms and importance of vascular plants and biocrusts as natural covers for altering the intrinsic properties of soil for the protection of the Great Wall. These findings provide reliable theoretical support for the protection of the Great Wall from erosion by vascular plants and biocrusts and offer new insights for the conservation of global earthen sites and similar wall habitats.

Time-dependent regulation of soil aggregates on fertilizer N retention and the influence of straw mulching

Fertilizer nitrogen (N) turnover is highly controlled by soil aggregation. However, the functions of the various aggregates that regulate long-term fertilizer N retention under conservation management remain unexplored. In this study, 15N-labeled fertilizer was initially applied in situ to investigate the effects of maize straw mulching on fertilizer N allocation in soil aggregates at a decadal scale. The topsoil was fractionated into macroaggregate, microaggregate, and silt-clay (SC) fractions. Macroaggregate was further divided into particulate organic matter (POM) and mineral-associated organic matter (MAOM). A higher enrichment factor of fertilizer N than of soil total N in macroaggregate indicated that the fertilizer N was more apt to incorporation into macroaggregate. The fertilizer N in the bulk soil declined gradually to 84.0% by the 13th year. Temporally, the reduction proportion of fertilizer N in the SC fraction was the largest before 5th years, whereas macroaggregate was the main reactive spot for fertilizer N transformation from 9 to 13 years. Therefore, the function of aggregates was time-dependent in controlling fertilizer N retention and turnover via the release of previously entrapped fertilizer N, but encapsulated the subsequently applied N (i.e., unlabeled fertilizer), whereas mineral adsorption contributed to the long-term stabilization of fertilizer N. Compared with fertilization alone, straw mulching improved aggregates stability, favored the initial fertilizer N retention in macroaggregate by enriching fertilizer N in POM, and reduced the proportion of N loss in MAOM after 9 years. These finding indicate that the improvement in fertilizer N stability related to straw decomposition was sequentially attributed to the enhancement of aggregate encapsulation and persistent interaction with soil minerals. Therefore, this study provides new insights into the functional heterogeneity of soil aggregates at different time stages and the intricate interplay between carbon availability-controlled fertilizer N retention and the improvement in soil aggregation.

Primary Non-Inversion Shallow Tillage Versus Moldboard Plowing Prior to Growing Potatoes: Short-Term Impacts on Potato Yield and Soil Properties in Eastern Canada

Potato (Solanum tuberosum L.) production often requires intensive tillage with the moldboard plow (MP), which involves deeper soil tillage and turning of the soil to provide enough loose soil for proper tuberization. Although tillage with the MP allows better potato seedbed preparation and lower weed pressure, it is also associated with increased soil compaction, soil aggregate destruction, and increased soil organic matter (SOM) mineralization. The objective of this four-year (2019–2022) study conducted in 14 commercial fields was to compare the use of MP with primary non-inversion shallow tillage (ST) in terms of their effect on selected soil health indicators, soil moisture, potato petiole nitrate concentration, potato yield, and specific gravity. Commercial fields ranged from 1.5 ha to 19 ha where the main field was split in half, with one side tilled using MP (22.5–30 cm plowing depth) and the other half using ST (15–30 cm plowing depth). Soil and plant tissue samples were taken within four sub-replicates (91 m2) created per each treatment per each site and three to four sites were used as replicates per each year. Compared to MP, ST increased active carbon by an average of 9%, soil respiration by an average of 26%, and aggregate stability by an average of 8%. Biological N availability (BNA) increased by an average of 20% with ST, and the effect was statistically significant in three out of four years. Soil moisture at 20 cm depth tended to be higher with MP than ST in three out of four years. Although not statistically significant, when averaged across four years, potato petiole nitrate concentrations were 5% and 12% higher with ST than MP in samples collected at the flowering and post-potato flowering stages, respectively. Total and marketable potato yields, along with specific gravity, were comparable for the two tillage regimes. Signs of soil improvement were observed at the early stages of ST adoption. Marketable yield was negatively correlated with the soil nitrate levels measured during the growing season but was positively correlated with active carbon, aggregate stability, and soil moisture. Future studies could compare both tillage regimes over multiple growing seasons to assess their impacts over a full cycle of rotation. The novelty of the present study was that it was conducted in real-life conditions across large growers’ fields with different conditions and across four years.

The role of agroecological systems in cation interaction and aggregate formation in drylands of northeastern Brazil

Agroecological production systems are used in dryland agroecosystems. Therefore, it is necessary to verify their contributions, especially with regard to the functionality of soil attributes. From this perspective, this study aimed to evaluate the influence of soil use and management on the structural, hydraulic, and chemical attributes of a Haplic Cambisol in the Apodi Plateau, RN, Brazil. The experimental design adopted was completely randomized, with treatments distributed in a 5×3 factorial arrangement corresponding to five sampling locations (fruit farming, horticulture, agroecological, intercropping of Zea mays and Vigna unguiculata (L.) Walp), and three soil layers (0.00-0.10, 0.10-0.20, and 0.20-0.30 m), in addition to the correlation matrix and principal component analysis as multivariate statistical techniques. The parameters evaluated included soil pH, nutrient levels (available P, K+, Ca2+, and Mg2+), total organic carbon, soil density, total porosity, field capacity, permanent wilting point, available water, aggregation, aggregate stability, weighted mean diameter of aggregates, and the content of organic matter, Ca2+, and Mg2+ in different soil aggregate classes. The study concluded that continuous soil use practices such as intercropping Z. mays and V. unguiculata and horticulture significantly reduce nutrient availability, organic carbon content, moisture, and soil aggregation. However, areas under agroecological management and fruit cultivation, which involve minimal soil disturbance, promote the improvement of these properties.

Aggregate Stability and Aggregate-Associated Organic Matter along a Soil Chronosequence on the Galápagos Archipelago

Aggregate Stability and Aggregate-Associated Organic Matter along a Soil Chronosequence on the Galápagos Archipelago

Modeling of the Particle Abrasion Process and a Discrete Element Method Study of Its Shape Effect.

This study introduces a novel method for particle abrasion derived from fundamental natural phenomena and mechanical principles, allowing precise control over the degree of abrasion and more accurately mimicking natural processes. The method's validity is confirmed using a specific shape index. Through conventional triaxial tests, the mechanical behavior of granular aggregates with varying degrees of abrasion was analyzed. The findings indicate that increased particle abrasion leads to a decrease in the average coordination number and sliding amount, while the rotation amount increases. This suggests an inverse relationship between the degree of abrasion and the structural stability and interlocking of the particle aggregate. The fabric anisotropy of the system is mainly attributed to the anisotropy of the contact normal force, which decreases as particle abrasion increases. The partial stress ratio of the particle system is influenced by fabric anisotropy and remains independent of particle shape. Additionally, the internal friction angle may be overestimated in conventional triaxial tests.

Physical property responses of soils subjected to different degrees of erosion and seasonal freeze-thaw cycles in Northeast China

Changes in soil pores and aggregate stability due to freeze-thaw cycles (FTCs) are important causes of increased soil erosion during snowmelt. Soil erosion causes spatial redistribution of soils, enhancing soil heterogeneity and potentially impacting soil responses to FTCs. Nonetheless, there is minimal knowledge of the responses of soils subjected to different degrees of erosion to seasonal FTCs. To reveal the impact of seasonal FTCs, the dynamic variations of pore characteristics and aggregates of soils with four different degrees of erosion (original, degraded, deposited and parent soil) were measured, and the connections between influencing factors and soil properties were analyzed. The results showed that FTCs altered the structure of the soils and weakened their resistance to erosion and that soils with different degrees of erosion responded differently to FTCs. After seasonal FTCs, soil porosity increased (0.4 %-11.9 %) to some extent in all soils, with greater changes observed in the more eroded soils. Notably, capillary porosity exhibited a complex changing trend compared to total porosity. Degraded and parent soils showed a stable bulk density, while the original soil showed a decrease (2.1 %) in bulk density and the deposited soil showed an increase (18.4 %) in bulk density. With the increase of FTCs, the field capacity of original, degraded, and deposited soils exhibited a gradual decrease (15.1 %-18.5 %), while that of the parent soil slightly increased (0.9 %). After seasonal FTCs, the saturated hydraulic conductivity decreased for original and deposited soils (19.5 %-41.5 %), while it increased for degraded and parent soils (29.2 %-41.6 %). Throughout the FTCs, the proportion of the large aggregates decreased and the small aggregates increased, and the transformation was greater on the less eroded soils. The mean weight diameter and geometric mean diameter of the soils gradually decreased with increasing FTCs, while the change was smaller for the more eroded soils. After seasonal FTCs, the less eroded soils were at greater risk of erosion. Our results demonstrated that the number of FTCs had a more significant impact on soil physical properties compared to the temperature difference and soil water content. Overall, freeze-thaw action reinforced the spatial heterogeneity of soil properties, potentially intensifying soil erosion. These findings help reveal the effects of FTCs on the physical properties of soils with different degrees of erosion and deepen the understanding of the mechanism of FTCs on soil erosion processes.

Long-Term Planting of Taxodium Hybrid ‘Zhongshanshan’ Can Effectively Enhance the Soil Aggregate Stability in Saline–Alkali Coastal Areas

Not enough research has been conducted on the mechanisms influencing the stability of soil aggregates in coastal saline–alkaline soil and the dynamic changes in aggregates in the succession process of coastal saline–alkaline soil brought on by longer planting times. In this study, soil aggregate composition, stability, and influencing factors of 0–20 cm, 20–40 cm, and 40–60 cm soil layers in different planting time stages were analyzed in the reclaimed land at the initial stage of afforestation and the Taxodium hybrid ‘Zhongshanshan’ plantation with planting times of 6, 10, 17, and 21 years. The results show that, with the increase in planting time, the aggregate stability of the plantation increased significantly. In the 0–20 cm soil layer, the geometric mean diameter (GMD) and aggregate size &gt;0.25 mm (R0.25) increased by 81.15% and 89.80%, respectively, when the planting time was 21 years, compared with the reclaimed land. The structural equation (SEM) showed that planting time had a direct positive effect (path coefficient 0.315) on aggregate stability. However, soil sucrase (0.407) and β-glucosidase (0.229) indirectly improved the stability of aggregates by affecting soil organic carbon. In summary, the establishment of Taxodium hybrid ‘Zhongshanshan’ plants on coastal saline–alkali land is beneficial for stabilizing soil aggregates, improving soil structure, and boosting soil quality. Long-term planting of Taxodium hybrid ‘Zhongshanshan’ can be an effective measure for ecological restoration in this region.