Search

Amendment significantly improves soil structure and promotes crop growth. To combat soil degradation and low crop yields in facility agriculture, it is crucial to study the optimal application rate of amendments. This study analyzed the effects of biochar, vermicompost, and mineral-source potassium fulvic acid on the stability of aggregate structure, soil nutrient content, and tomato yield in cambisols, providing a theoretical basis for improving the soil quality of plastic greenhouses in Southern China. A pot experiment on tomato cultivation was carried out in yellow-brown soil in plastic greenhouses. The experiment included eight treatments: 1% biochar (B1); 3% biochar (B3); 5% biochar (B5); 3% vermicompost (V3); 5% vermicompost (V5); 0.1% mineral-source potassium fulvic acid (F1); 0.2% mineral-source potassium fulvic acid (F2); and the control condition without adding soil amendments (CK). The results showed that the biochar and vermicompost treatments effectively reduced soil bulk density and increased total soil porosity. Compared to the control, treatments with soil amendments significantly increased soil pH and had different effects on soil nutrients: F2 showed the most significant improvement in the content of available nitrogen, available phosphorus, and available potassium, with an increase of 133.33%, 834.59%, and 74.34%, respectively; B3 treatment had the highest increase in dissolved organic carbon (DOC), while B5 treatment had the highest organic matter content. Compared to the CK, the particle size of the biochar treatment was mainly 0.053~0.25 mm, while the V3, F1, and F2 mainly occurred with a particle size > 0.25 mm; and V3 has the best aggregate stability. Biochar, vermicompost, and mineral potassium fulvic acid can all promote tomato yield, with the F2 and V3 treatments having a yield increase effect of over 30%. Furthermore, Pearson's correlation analysis showed a highly significant positive correlation between geometric mean diameter (GMD) and mean weight diameter (MWD), water-stable macroaggregate content (R0.25), and a positive correlation between alkaline-dissolved nitrogen, available phosphorus, dissolved organic carbon content, and aggregate stability indicators. Adding 0.2% mineral-source potassium fulvic acid optimizes cambisols' properties, enhances aggregate formation and stability, boosts tomato yield, and shows great application potential. [ABSTRACT FROM AUTHOR]

Recycling organic waste and water treatment residues in nanoform is a promising technology in various farming systems, and its effect on aggregate stability, biological activity, and canola production in degraded soils is largely unknown. Hence, we evaluated the effect of nano-biochar (nB) and nano-water treatment residues (nWTR) at levels 50, 100, and 250 mg kg−1 as compared to soil without amendments on the aggregate stability, biological activity, and canola yield in degraded soil. The results showed that the structure coefficient (SC) values are higher when nB and nWTR are added at 100 mg kg−1 soil than at levels 50 and 250 mg kg−1. In our study, the high aggregate stability in the soil treated with nB and nWTR is likely due to their higher content of nutrients, organic carbon, clay, and CEC. The seed weight of the canola plant increased with increasing nB by more than 64%, while it decreased with increasing nWTR. Microbial biomass carbon (MBC) and the activity of dehydrogenase (DHA) and catalase (CLA) increased significantly in the treated pots with the addition of nB and nWTR at various rates. The results of the pot experiment recommended that the applications of nWTR and nB could be used as a promising strategy to improve soil quality and crop yield while also increasing the recycled efficiency of WTR and rice straw. [ABSTRACT FROM AUTHOR]

Fenced enclosures, a proven strategy for restoring degraded grassland, have been widely implemented. However, recent climate trends of warming and drying, accompanied by increased extreme rainfall, have heightened soil erosion risks. It is crucial to assess the long-term effectiveness of fenced enclosures on grassland restoration and their impact on soil physicochemical properties and water infiltration capacity. This study investigated the effects of enclosure duration on soil organic matter, aggregate composition and stability, and infiltration capacity in Yunwu Mountain Grassland Nature Reserve, comparing grasslands with enclosure durations of 2, 14, 30, and 39 years. Results showed that grasslands enclosed for 14, 30, and 39 years had infiltration rates increased by 20.66%, 152.03%, and 61.19%, respectively, compared to those enclosed for only 2 years. After 30 years of enclosure, soil quality reached its optimum, with the highest root biomass, soil organic matter, aggregate stability, and a notably superior infiltration rate. The findings suggest that long-term fenced enclosures facilitate grassland vegetation restoration and enhance soil infiltration capacity, with the most significant improvement observed at the 30-year enclosure milestone, followed by a gradual decline in this effect. [ABSTRACT FROM AUTHOR]

Soil erosion is a key concern with regard to ecosystem functionality and food, fibre and bioenergy productions worldwide. Therefore, understanding the mechanisms and controls of soil erosion, particularly the link between soil aggregate stability and soil erodibility, is of utmost importance. The use of disturbed samples and sieved soil to determine the involved erodibility and aggregate stability is standard in soil erosion studies. However, soil erodibility estimation based on disturbed‐soil samples can be inaccurate as it involves changes in the architecture of the considered soil, possibly leading to overestimations. Moreover, a necessity for evaluating soil erodibility beyond intrinsic soil characteristics (e.g. texture) exists. The objective of this research was to assess the erodibility impact of soil disturbance. Undisturbed‐soil cores with dimensions of 45 cm (length) × 30 cm (width) × 10 cm (depth) were extracted while preserving their architecture. An A horizon corresponding to brown clayey subtropical oxisol soil from Southern Brazil was used for performing an experiment that involved simulation of 58–mm h−1 rain for 30 min. A total of seven replicate experiments were performed for each soil condition (i.e. undisturbed and disturbed soils). Results show that soil architecture deterioration had a larger impact on the involved soil loss than runoff. Further, soil structure failure did not affect the aggregate stability per se. Notably, the soil erodibility and loss were approximately 10 times larger under the disturbed‐soil condition than under the undisturbed‐soil condition (interrill erodibility: 4.30 × 107 and 4.39 × 106 kg s m−4, respectively; soil loss: 0.925 and 0.094 kg m−2, respectively). Overall, the intrinsic soil characteristics did not change; however the soil architecture deterioration considerably increased the erodibility. [ABSTRACT FROM AUTHOR]

In this study we aimed to assess the role of wild red deer, along with other ungulates such as roe deer and wild boar, in the soil's physical properties, namely soil penetration resistance and depth (used as a proxy for soil compaction), hydraulic conductivity (a proxy for water infiltration), and the proportion of soil stable aggregates. Results showed that, at the density level found in our study area, red deer have a neutral effect at the soil level, not causing significant soil compaction or significantly influencing measured soil functions. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is known to vary among different ecosystems and soilscapes, yet the degree of variation remains uncertain. Comparing SOC levels in undisturbed ecosystems like forests with those in gradually altered ecosystems can provide valuable insights into the impact of land use on carbon dynamics. This study aimed to evaluate the effects of different land uses on soil fertility parameters in the tropical region of Kerala, focusing on forests as well as cultivated agricultural landscape such as coconut, pepper, tapioca, acacia plantations, and mixed home garden cropping systems. Significant variations were observed among different crops and land use systems in terms of soil fertility. Forests exhibited the highest SOC content at 3.78 g kg−1, while acacia plantations showed the lowest at 0.76 g kg−1. Additionally, various soil properties such as different carbon fractions (e.g., humic acid, fulvic acid), total nitrogen, carbon, available nutrients, physical properties, aggregate size fractions, microbial biomass carbon, and spectral signatures differed significantly across the different land uses. These findings suggest a decline in soil fertility in altered ecosystems compared to adjacent forest soils, highlighting the vital role of forests in conserving natural resources and maintaining soil health. In addition, among the different landscapes studied, mixed cropping systems of home gardens sustained soil fertility better than monocropping systems. The observed variations in soil physicochemical properties among different land use types indicate a threat to sustainable crop production. Effective management practices aimed at improving soil fertility and sustaining crop production in these altered ecosystems are essential. This study highlights the importance of adopting appropriate management strategies to conserve soil health and ensure sustainable crop production in tropical landscapes like Kerala. The holistic approach adopted in this study, encompassing a wide range of soil fertility parameters across various land uses, along with its implications for sustainable land management, adds significant novelty and relevance to the existing literature on soil dynamics in tropical regions like Kerala. [ABSTRACT FROM AUTHOR]

Soil organic matter and pores distribution within aggregates were studied using X-ray computed tomography (XCT; Nikon XT H 225ST and GE Phoenix L240) and advanced 2D/3D measurements by the digital Keyence VHX-6000 microscope (Japan). A new methodological approach with computed tomography involvement for studying the spatial arrangement of pores, porosity, and soil morphology is presented. Changes in studied parameters are documented along the transect of intensively used Haplic Chernozem. Soil disturbance due to erosion and colluvial soil profile formation is reported. Moreover, soil organic matter quality and aggregate stability were evaluated. Obtained results showed statistically significant differences between the control and eroded sites and between eroded and accumulated sites. The correlation coefficients were the highest for soil organic carbon (SOC) and humic substances CHS (r = 0.805) and CHS and CHA/CFA (r = 0.764). The highest porosity, aggregates stability and coefficients stability were confirmed on the eroded site. The computed tomography measurements also document the high disturbance of Haplic Chernozem on the control site and the newly formed profile of Colluvisol. Despite excellent complementary technique further research is necessary to improve micro-XCT resolution and capacity for the soil micromorphological study.

Soil nutrient cycling, the distribution of soil aggregates, and their stability are directly influenced by soil texture. Different sizes of soil aggregates provide microhabitats for microorganisms and therefore influence soil carbon (C) and nitrogen (N) mineralization. The purpose of the present study was to assess the aggregate stability and dynamics of carbon and nitrogen in macroaggregate size fractions (1-8 mm) with different clay content from meadow soils. Surface soil samples (0-15 cm) were collected from 4- to 5-year-old forage crops. Four macroaggregate size classes were isolated by dry sieving and analyzed for their mass proportions: fine macroaggregates (FM) (less than 1 mm), medium-fine macroaggregates (MFM) (1-2 mm), medium-coarse macroaggregates (MCM) (2-4 mm), and large-coarse macroaggregates (LCM) (4-8 mm). The dry mean weight diameter (MWD), organic carbon (OC), total nitrogen (TN), carbon and nitrogen of microbial biomass (C-MB, N-MB) were determined. CO2 emission and net nitrogen mineralized (NM) were measured after 14 weeks of incubation. The amounts of FM were significantly lower than those of intermediate macroaggregates (MCM and MFM) and decreased markedly with increasing clay content within soil macroaggregates. In general, the amounts of macroaggregate size fractions were lowest in soils with high clay content. MWD exhibited a significant correlation with particle size distribution, OC, and MB-C. OC, TN, MB-C, and MB-N contents within macroaggregates increased with decreasing macroaggregate size and increasing clay content of macroaggregate fractions. The CO2 emission and NM content increased with increasing macroaggregate size, indicating higher organic C and N mineralization activity in larger macroaggregates. Mineralization of OC was lowest in macroaggregate fractions with the highest clay content. We conclude that clay content can increase the protection of microbial biomass in meadow soils. Small macroaggregates tend to contain more recalcitrant organic matter compared to larger macroaggregates.

[Objective] This study aimed at elucidating the effects of different vegetation restoration modes on soil water-stable aggregates and stability in the water level fluctuation zone (WLFZ). [Methods] The characteristics of soil water-stable aggregates and their stability indexes were determined and analyzed by the wet sieve method on the soil under artificially and naturally restored vegetation in the WLFZ in the hilly region of central Sichuan Basin. [Results] The content of >0.25 mm water-stable macroaggregates in WLFZ soils was 4.21% lower compared to unflooded area. The soil water stability macroaggregates content decreased by 12.27% under naturally restored vegetation and increased by 3.84% under artificially restored vegetation compared to unflooded area; With the rise of water elevations, the soil water stability macroaggregates content showed an increasing trend, the microaggregates content showed an overall decreasing trend, and the soil aggregate stability gradually increased with the rise of water elevations; The soil water-stable aggregates composition differed significantly (p

The properties of biochar may vary depending on feedstock type and producing temperature. The aim of this research was to understand the short-term effects of different pyrolysis temperatures and application rates of olive pomace biochar (OPB) on soil carbon (C), aggregate stability (AS), and aggregate size distribution for sandy loam soil. OPB was produced at low (350 °C) and high (700 °C) temperatures and incorporated into the soil at different rates and incubated for 6 months under controlled temperature and moisture conditions. OPB350 had low pH, high carbon, and nitrogen (N) values compared to OPB700. As the temperature increased the concentration of zinc, iron, manganese, copper, sodium, potassium, and magnesium in biochar increased. The BET surface area of OPB350 was 1.076 m2 g−1, and OPB 700 was 107.7 m2 g−1. Application of OPB improved soil aggregate stability and carbon content while the proportion of > 4 mm-aggregates and aggregate mean weight diameter decreased. OPB addition to soil increased microaggregate percentages and decreased macroaggregate percentages. OPB produced at high temperatures significantly increased soil AS value compared to OPB350. [ABSTRACT FROM AUTHOR]

Anaerobically mineralized nitrogen (AN) is a suitable soil health indicator. The AN is sensitive to soil use changes and is related to soil and particulate organic carbon and aggregate stability. This work aims to evaluate the relationship between AN and 1) easily extractable glomalin-related soil proteins; 2) abundance of arbuscular mycorrhizal fungi measured by the number of arbuscular mycorrhizal fungi spores, and 3) arbuscular mycorrhizal fungi activity (root colonization). Soil samples were taken at depths of 0-5 and 5-20 cm from cultivated and uncultivated plots throughout the southeastern province of Buenos Aires. Anaerobically mineralized nitrogen, soil organic carbon, particulate organic carbon, aggregate stability, easily extracted glomalin-related soil proteins and the logarithm of the number of arbuscular mycorrhizal fungi spores (log spores) at 0-5, 5-20 and 0-20 cm depths were determined. In wheat roots, the percentages of total infection and arbuscules at 0-20 cm were measured. At all depths, AN was positively correlated to easily extractable glomalin-related soil proteins (r=0.34-0.65), which is an indicator of arbuscular mycorrhizal fungi activity and abundance. Likewise, AN was positively related to log-spores (r=0.58-0.78), which is an indicator of arbuscular mycorrhizal fungi abundance. However, AN was not related to root colonization (the percentages of total infection and arbuscules) that manifests the activity of arbuscular mycorrhizal fungi at a specific moment. Thus, anaerobically mineralized nitrogen would be an indicator of mid- to long-term changes in arbuscular mycorrhizal fungi abundance and activity (easily extractable glomalin-related soil proteins and log-spores) resulting from soil use. Consequently, the AN would allow monitoring an important aspect of soil microbiological health associated with arbuscular mycorrhizal fungi. However, it is necessary to evaluate the relationships studied in this work in a wider range of soil situations. [ABSTRACT FROM AUTHOR]

Background: Stem cell-derived therapies hold the potential for treatment of regenerative clinical indications. Static culture has a limited ability to scale up thus restricting its use. Suspension culturing can be used to produce target cells in large quantities, but also presents challenges related to stress and aggregation stability. Methods: Utilizing a design of experiments (DoE) approach in vertical wheel bioreactors, we evaluated media additives that have versatile properties. The additives evaluated are Heparin sodium salt (HS), polyethylene glycol (PEG), poly (vinyl alcohol) (PVA), Pluronic F68 and dextran sulfate (DS). Multiple response variables were chosen to assess cell growth, pluripotency maintenance and aggregate stability in response to the additive inputs, and mathematical models were generated and tuned for maximal predictive power. Results: Expansion of iPSCs using 100 ml vertical wheel bioreactor assay for 4 days on 19 different media combinations resulted in models that can optimize pluripotency, stability, and expansion. The expansion optimization resulted in the combination of PA, PVA and PEG with E8. This mixture resulted in an expansion doubling time that was 40% shorter than that of E8 alone. Pluripotency optimizer highlighted the importance of adding 1% PEG to the E8 medium. Aggregate stability optimization that minimizes aggregate fusion in 3D culture indicated that the interaction of both Heparin and PEG can limit aggregation as well as increase the maintenance capacity and expansion of hiPSCs, suggesting that controlling fusion is a critical parameter for expansion and maintenance. Validation of optimized solution on two cell lines in bioreactors with decreased speed of 40 RPM, showed consistency and prolonged control over aggregates that have high frequency of pluripotency markers of OCT4 and SOX2 (> 90%). A doubling time of around 1–1.4 days was maintained after passaging as clumps in the optimized medium. Controlling aggregate fusion allowed for a decrease in bioreactor speed and therefore shear stress exerted on the cells in a large-scale expansion. Conclusion: This study resulted in a control of aggregate size within suspension cultures, while informing about concomitant state control of the iPSC state. Wider application of this approach can address media optimization complexity and bioreactor scale-up challenges. [ABSTRACT FROM AUTHOR]

Soil nutrient cycling, the distribution of soil aggregates, and their stability are directly influenced by soil texture. Different sizes of soil aggregates provide microhabitats for microorganisms and therefore influence soil carbon (C) and nitrogen (N) mineralization. The purpose of the present study was to assess the aggregate stability and dynamics of carbon and nitrogen in macroaggregate size fractions (1-8 mm) with different clay content from meadow soils. Surface soil samples (0-15 cm) were collected from 4- to 5-year-old forage crops. Four macroaggregate size classes were isolated by dry sieving and analyzed for their mass proportions: fine macroaggregates (FM) (less than 1 mm), medium-fine macroaggregates (MFM) (1-2 mm), mediumcoarse macroaggregates (MCM) (2-4 mm), and large-coarse macroaggregates (LCM) (4-8 mm). The dry mean weight diameter (MWD), organic carbon (OC), total nitrogen (TN), carbon and nitrogen of microbial biomass (C-MB, N-MB) were determined. CO2 emission and net nitrogen mineralized (NM) were measured after 14 weeks of incubation. The amounts of FM were significantly lower than those of intermediate macroaggregates (MCM and MFM) and decreased markedly with increasing clay content within soil macroaggregates. In general, the amounts of macroaggregate size fractions were lowest in soils with high clay content. MWD exhibited a significant correlation with particle size distribution, OC, and MB-C. OC, TN, MB-C, and MB-N contents within macroaggregates increased with decreasing macroaggregate size and increasing clay content of macroaggregate fractions. The CO2 emission and NM content increased with increasing macroaggregate size, indicating higher organic C and N mineralization activity in larger macroaggregates. Mineralization of OC was lowest in macroaggregate fractions with the highest clay content. We conclude that clay content can increase the protection of microbial biomass in meadow soils. Small macroaggregates tend to contain more recalcitrant organic matter compared to larger macroaggregates. [ABSTRACT FROM AUTHOR]

Geological hazards such as gully erosion, collapse and slope failure occur frequently in loess areas, which are closely related to the soil disintegration characteristics. Understanding the impact of freeze–thaw and wet–dry action on soil disintegration in the context of climate change is essential to establish effective soil and water conservation strategies and prevent engineering geological hazards in loess areas. In this study, sodic–saline loessial soils with different clay content were subjected to freeze–thaw and wet–dry cycles, followed by aggregate durability tests, direct shear tests and disintegration tests to investigate the effects of the two natural processes on soil disintegration characteristics. The results showed that the samples subjected to freeze–thaw cycles primarily exhibited rapid and stable disintegration, followed by slow disintegration, whereas the samples subjected to wet–dry cycles revealed weight gain, continuous slow disintegration and eventual sudden disintegration. Freeze–thaw action continuously deteriorated the disintegration resistance of soil, while wet–dry action improved the disintegration resistance of soil after the first cycle, and gradually weakened it in subsequent cycles. Statistical analysis showed that, for samples undergoing freeze–thaw cycles, the number of cycles and clay content were positively correlated with the disintegration rate, while the aggregate durability was negatively correlated with the disintegration rate. For samples undergoing wet–dry cycles, the number of cycles had a positive effect on the disintegration rate, while the clay content, shear strength and cohesion had a negative correlation with the disintegration rate. At a certain clay content, there was a positive correlation observed between the surface crack ratio, crack length and width with the disintegration rate of the wet–dry samples, while shear strength and cohesion had a negative correlation with the disintegration rate of both freeze–thaw and wet–dry samples. Furthermore, the study outlined the disintegration mechanism of loessial soils based on internal factors, driving factors, resistance factors and evolutionary factors. This study contributes to the in‐depth understanding of the catastrophic mechanism of geological hazards in cold and arid areas and provides experimental evidence for its control and management. [ABSTRACT FROM AUTHOR]

[Objective]The aims of this study are to explore the effect of arbuscular mycorrhizal fungi AMF on the stability of plant roots and soil aggregates, and to provide a theoretical basis for the ecological restoration of open pit dump. [Methods]Soil physicochemical properties, soil enzyme activities, plant root morphology, soil aggregate stability and other indexes of 3 species of Amorpha fruticosa, Hippophae rhamnoides, Caragana korshinskii were sampled and measured in the control and inoculated plots. Correlation analysis was conducted for each index. [Results]The average root diameter of the three plants could be significantly increased by inoculation, and the inoculation plot was 1. 33～2. 24 times that of the control. Under the condition of compacted soil, mycelia to some extent provided water and nutrients for plants instead of fine roots, which reduced the total root length of root system. Inoculation significantly increased soil enzyme activity and soil organic matter content, alkaline phosphatase activity increased by 335. 62％, urease activity increased by 44. 73％, extractable balloon amycin content increased by 82. 56％, soil organic matter content increased by 64. 74％. By increasing soil organic matter content and soil enzyme activity, inoculation significantly enhanced the stability of soil aggregates, increased the average weight diameter by 24. 14％～34. 29％, and reduced the failure rate of aggregates by 18. 25％～24. 35％. [Conclusion]Inoculation of AMF in open pit dump can significantly improve soil biological activity, increase nutrient content, promote plant root development, and thus improve the stability of soil aggreg [ABSTRACT FROM AUTHOR]

[Objective]The aim of this study is to elucidate the altitude distribution pattern and its impact mechanism of soil aggregate stability, which is imperative for evaluating the stability of ecological functional in mountain ecosystems. [Methods]Soil samples were collected in different soil depths under the elevation gradient of 900～2 100 m in Fanjing Mountain. The relationship between soil environmental factors and the stability of soil aggregates were discussed by means of wet-dry screening and redundancy analysis(RDA). [Results]The content of macroaggregates(＞0. 25 mm)constituted the largest proportion(86. 78％)of aggregate sizes across all elevations in mountain forest ecosystem in 0-60 cm soil layer. In 0-20 cm soil layer, the altitude gradient was significantly different, and the middle altitude 1 500～1 800 m was significantly higher than 1 800～2 100 m(p＜0. 05). There was a significant correlation between the MWD, GMD, and D of soil aggregates and altitude. As altitude increased, the MWD and GMD of soil aggregates showed a single peak distribution pattern of first increasing and then decreasing, reaching a peak at 1 500～1 800 m at mid altitude. In the 0-20 cm soil layer, the MWD and GMD of 1 500～1 800 m were 5. 03, 3. 64 and 4. 79, 3. 52, respectively, significantly higher than 900～1 200 m and 1 800～2 100 m(p＜0. 05). Redundancy analysis(RDA)showed that the stability of soil aggregates along the altitude gradient was mainly affected by soil organic carbon and pH, and the explanations for the stability of soil aggregates were 76. 3％and 1. 3％, respectively. [Conclusion]In the forest ecosystem of Fanjing Mountain, the stability of soil aggregates varies significantly along the elevation gradient, and soil chemical properties are important factors affecting the stability of aggregates. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Keduang Sub-Watershed area has faced multiple natural disasters like landslides, erosion, and flooding because of the poorly managed terrain in the area. This study examines the distribution of the slaking index on agricultural land in the Keduang Sub-Watershed, analyzes the impact of soil type on it, and identifies the soil physical elements that have the most significant influence on it. The study took place in the Keduang Sub-Watershed, Indonesia, utilizing agricultural land from woods, plantations, drylands, and paddy fields with Andisols, Alfisols, Inceptisols, and Entisols soil types. This survey research was supported by laboratory analysis of the soil's physical and chemical properties and used GIS for data interpretation. Soil samples were collected from 22 Land Map Units (LMUs) with 3 replications each, resulting in 66 samples. The SLAKES software assesses the primary parameter, the slaking index. The supporting parameters analyzed were aggregate stability, bulk density, texture, structure, pH, organic C, and Cation Exchange Capacity (CEC). The research showed that soil types in the Keduang Sub-Watershed significantly affect the slaking index value. The slaking index ranged from 0.13-11.63, with the highest values for Andisols in a forest, while the lowest values were Inceptisols in a plantation. The allophane mineral in Andisols was causing the high slaking index. The soil factors determining the slaking index were bulk density and exchangeable K. The lower the bulk density, the higher the slaking index. Meanwhile, the lower the exchangeable K, the lower the slaking index. The land management recommendations based on determinant factors are adding organic material and reducing soil cultivation practices. [ABSTRACT FROM AUTHOR]

Pre-harvest burning of sugarcane is a major management system globally and could have a significant effect on soil organic carbon (SOC) fractions, aggregates stability and nutrient cycling, while green cane harvest system can be more beneficial to soil quality and environmental sustainability. The current study examined the effects of sugarcane harvest systems on SOC fractions and aggregate stability of sandy loam Umbric Rhodic Ferralsols, with relatively high SOC. Soil aggregate stability was determined using the wet-sieving method. SOC fractions were determined using the physical and chemical separation method, thereafter the SOC content in different fractions was determined by the wet oxidation method. Pre-harvest burning reduced soil aggregate stability by >100 and 64.3% when compared to green cane in the top 0–5 and 5–10 cm depths, respectively. The carbon in the macro-aggregates fraction constituted more than 60% of total SOC, making it the primary C storage fraction for both green cane and pre-harvest burning. Pre-harvest burning had 20.4 and 45.2% lower SOC content in macro- and micro-aggregate fractions, respectively, when compared to green cane. Also, coarse particulate organic matter carbon and fine particulate organic matter carbon were lower in pre-harvest burning management after the dispersion of macro-aggregates when compared to green cane. Pre-harvest burning increased mineral-associated C in µSilt + µClay from bulk soil fractionation by 23.7% when compared to green cane. All the C fractions decreased with an increase in soil depth in both green cane and pre-harvest burning, except for the mineral-associated C. These findings demonstrate that green cane production increases aggregate stability and SOC storage in different soil fractions, with a potential reduction in greenhouse gas emission and sustainable sugarcane production when compared with the pre-harvest burning on sandy loam Umbric Rhodic Ferralsols. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agricultural soil contamination is increasing day-by-day and becoming a major problem over the globe. Trace elements accumulation in the bulk soil is frequently documented, however, there is no precise mechanism of their distribution in the different soil aggregates level. We collected twelve composite soil samples from banana fields, fallow land, rice cultivated with pond water (rice field-I), and rice cultivated with rain water (rice field-II). We separated soil samples into four different size of aggregates (4-2, 2–0.25, 0.25–0.053, 0.05). Moreover, macroaggregate acted as an accumulator for Fe, Mn, and As, while all the aggregate fractions acted as accumulators for Cu and Zn. Our study indicated that MWD, SOC, aggregate size and composition, and metal species were the controlling factors of trace elements accumulation and distribution in the various sizes of soil aggregates.

Aggregate stability strongly affects many soil processes and is critical to maintain sustainable agriculture. Aggregate breakdown is controlled by the interaction between soil intrinsic properties and solution characteristics. Nitrogen fertilization including different forms is well known to influence aggregate stability; however, relative to their long-term effects, there is little recognition on the rapid response of aggregate breakdown to nitrogen solutions. This study aimed to examine the effects of nitrogen form and concentration on aggregate stability for different types of soils. Aggregate breakdown against slaking of three soil types (Phaeozem, Luvisol, and Acrisol) and three horizons (organo-mineral (A), illuvium (B), and parent material horizons (C)) was determined subjected to nitrogen solutions of three forms (CO(NH2)2, NH4+, NO3–) and five concentrations (0.05 ∼ 1.0 mol/L). Among nitrogen forms, urea solution almost had non-significant effect irrespective of soil type and horizon (p > 0.05); for NH4+ and NO3– solutions, aggregate stability showed little variations (MWD of 0.19 ∼ 0.26 mm) with electrolyte concentration for Phaeozem in B and C horizons, overall increased for Luvisol and Phaeozem in A horizon, and decreased first and then reached a steady state for Acrisol. The effects of nitrogen forms on aggregate breakdown were dependent on soil aggregation status or cementing agents (mainly organic matter, clay mineralogy). Electrolyte nitrogen solutions (NH4+ and NO3–) inhibited aggregate breakdown mainly through reducing electrostatic repulsive forces for moderately developed soils rich in swelling clays, and promoted aggregate breakdown by both weakening particle cohesion and enhancing compression pressure of entrapped air for highly developed soils rich in non-swelling clays and Fe/Al oxides. These results facilitate an improvement of fertilizer management and irrigation to improve soil quality on different soil types.

The assessment of soil health and the determination of carbon stability in soils are current challenges that have gained momentum through initiatives at national as well as international scales. However, inferring universally valid soil health parameters that are directly linked to carbon permanence remains challenging. Our aim was to evaluate the potential of simultaneous thermal analysis (STA) for an improved monitoring of soil health advances in the context of carbon farming strategies. For this purpose, an on-farm comparison of soil health in ten conservation agricultural systems with adjacent conventional farms was performed based on STA and thermal measures were related to key biological and physical indicators for monitoring soil functions. Using an autocorrelation-based approach, we identified independent thermal indicators, revealing that carbon farming efforts predominantly increased labile soil organic matter fractions in the range of 300–400 °C, while thermally more recalcitrant fractions did not respond to farming system transformation. Similarly, most soil health indicators revealed highest correlation with temperature ranges of mass loss of labile organic matter fractions. The relation of STA with commonly used soil health indicators was highest for soil organic carbon (SOC, r=0.971) and total nitrogen (TN, r=0.981). However, also inference on microbial activity parameters such as dimethylsulfoxid reduction, microbial biomass carbon and substrate-induced respiration could be demonstrated with r>0.663. The results thus highlight key temperature ranges of organic matter stability for future soil monitoring tasks of climate change mitigation potentials of carbon farming and related advances in soil health.

Aims: To demonstrate how intensive management practices affect the belowground productivity of Moso bamboo, we examined the spatial distribution of fine root traits under three stands with high-intensity (T1, tillage plus biennial fertilization), low-intensity (T2, tillage plus quadrennial fertilization), and extensive (CK, no-tillage plus no fertilization) management, and evaluated the relationships among root traits and soil properties, aggregate stability (MWD). Methods: Bamboo fine root and soil samples were collected from three depths (0–10, 10–20, 20–30 cm) and three horizontal distances (20, 40, 60 cm) under three management strategies. Root biomass, root morphology, soil properties, and aggregate composition were determined. Results: Compared with CK, T1 and T2 had higher fine root biomass (FRB), and the largest FRB in the 10–20 cm soil layer. T1 had significantly higher allocation proportion of D1–2 class FRB and root length density (RLD) and significantly lower specific root length (SRL) and specific surface area (SSA). Vertically, intensive management led to an increase in FRB in the 10–20-cm soil layer and MWD in the 20–30-cm soil layer. Horizontally, FRB was highest at a distance of 20 cm from bamboo culm. A strong positive correlation was identified among FRB, RLD, and TP in each soil layer as well as among MWD, TP, and RLD. Conclusions: Intensive management promotes fine root growth with high length in response to more soil P content, and high-intensity management shifts the expression of root functional traits toward transport fine roots proportion and 10–20-cm soil layer, and facilitates aboveground productivity of Moso bamboo. TOC, TP, and RLD are the main three drivers correlated with soil aggregate stability. [ABSTRACT FROM AUTHOR]

Background and aims: Straw incorporation and optimized fertilization application are considered as effective strategies for agricultural sustainable development. However, the interaction of straw incorporation and N fertilization on labile carbon fraction, soil aggregate stability and microbial community composition are less known, especially in saline-alkali soil. Methods: A 4-year experiment was conducted in the Yellow River Delta with two factors: straw incorporation (0, 4 500 and 9 000 kg ha−1; C0, C1 and C2, respectively) and N fertilization (255 and 400 kg N ha−1; N1 and N2). Results: Soil organic carbon (SOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC) and particulate organic carbon (POC) contents were also increased. Meanwhile, the proportion of macroaggregate was enhanced with straw incorporation through the increase of MBC and POC. Compared with N2 level, DOC:SOC ratio was decreased with straw application under N1 level, reflecting the improvement of SOC adsorption capacity. Additionally, the proportion of straw-C converted to SOC under N1 level was about 21–25%, 15–20% under N2 level, and the highest conversion rate was in N1C1 treatment. We also found DOC and SOC were the most important factors to affect the abundance of bacteria (Firmicutes) and fungi (Ascomycota) involved in straw-C degrading, which were lower under N1 level. Conclusions: It is feasible to achieve higher carbon content while increasing soil aggregate stability by optimizing straw incorporation and N fertilizer in saline-alkali soil. These findings provide important insights for improving saline-alkali soil. [ABSTRACT FROM AUTHOR]

Organic amendment has proven to improve soil quality and crop production, in addition to reduce resource waste. However, the effect of organic amendment on soil water-stable aggregates and soil organic carbon is unclear. A two-year field experiment with four organic amendment treatments, biochar, organic fertilizer, microbial agents and polyacrylamide (PAM), was conducted to investigate the effect of different soil organic amendments on Loess Plateau. The results revealed that organic amendments significantly influenced the mean weight diameter (MWD) and geometric mean diameter (GMD) of water-stable aggregates, particularly in the case of PAM treatment. The MWD and GMD values increased significantly by 33.7% and 29.8% in the PAM treatment. The proportion of macroaggregates (2-0.25 mm) showed a remarkable 52.9% increase compared to the control (CK) treatment in the PAM-treated soil. Biochar-amended treatments increased soil organic carbon (SOC) in all aggregate fractions compared to CK treatment. Soil organic amendments also decreased soil bulk density and increased total nitrogen (TN) and available phosphorus (AP). Compared to CK treatment, the maize yields in the organic fertilizer and biochar treated soil increased by 19.8 and 30.3%, respectively. These findings suggest that biochar and PAM amendments are particularly suitable for loessal soil in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Altered rainfall caused by climate change affects soil cations and aggregate stability and thus affecting the soil productivity of ecosystems. However, little is known regarding the changes of soil nutrients and aggregate stability with rainfall change in desert grassland. To investigate the effect of rainfall on the soil nutrients and aggregate stability, cations of Ca2+, Mg2+, K+, Na+ and Al3+ and micronutrients of Fe2+, Mn2+, Cu2+ and Zn2+ in bulk soil and three soil aggregate sizes classes (microaggregate, < 0.25 mm; small macroaggregate, 0.25–2 mm; large macroaggregate, > 2 mm) from rainfall manipulation (i.e., ambient rainfall amount as a control, ± 20% and ± 40% of ambient rainfall) were examined in a desert grassland of the western Loess Plateau. The Na+ content under extreme drought (− 40%) was significantly increased in all aggregate size classes and bulk soil and further increased effective cation exchange capacity (ECEC) in the microaggregate. Fe2+ in microaggregate under + 20% treatment was significantly increased compared to ± 40% and CK (ambient rainfall). Although the significant differences in Mg2+, Ca2+, Mn2+, Cu2+ and Zn2+ in aggregates and bulk soil were not found among rainfall treatments, more micronutrients tended to accumulate in the small macroaggregate. Extreme drought reduced soil aggregate stability resulting from the increased soil fractal dimension (D) due to the accumulation of Na+. The contribution of large macroaggregate to cations and micronutrients in bulk soil, soil mean weight diameter (MWD) and geometric mean diameter (GMD) significantly increased with increased rainfall. In contrast, D, erodibility (K) as well as the contribution of microaggregate to nutrients in bulk soil increased with the decreased rainfall. This work highlights the importance of cations for aggregate stabilization under altered rainfall regimes in a desert grassland. Moreover, the response of micronutrients to rainfall alteration needs to be investigated in the aspect of aggregate and bulk soil. [ABSTRACT FROM AUTHOR]

Coagulation of polydisperse detonation nanodiamond (DND) hydrosol containing primary aggregates with a prevailing average size in a range of 20–200 nm has been studied experimentally and theoretically within the framework of the classical and extended DLVO theory as depending on the concentrations of an indifferent electrolyte (NaCl) and potential-determining ions (pH). It has been shown that the surface of DND particles is charged due to the ionization of ionogenic amphoteric hydroxyl and acidic carboxyl groups located on it. The isoelectric point of the detonation nanodiamond particles has been found to correspond to pH 7.5. It has been revealed that the main stabilizing factor of the DND hydrosol is electrostatic. It has been shown that the stability and coagulation of the sol can be described within the framework of the extended DLVO theory using the effective Hamaker constant for primary porous aggregates and taking into account the initial polydispersity of the DND particles. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to investigate the effects of cropland fallowing on soil structure and stability in the development areas of yellow and calcareous soils in Qianzhong Karst Region, and to provide theoretical basis for the prevention and control of soil erosion and evaluation of the benefits of revegetation of fallowed cropland in karst region. [Methods] Differential characteristics of soil aggregate composition and stability in shallow (0—30 cm) soil layers of cropland (YM) and different stages of vegetation restoration after fallow [grassland (CD), scrubland (GC), and woodland (LD) ] were investigated based on the wet-dry sieve method. [Results] The contents of soil mechanical aggregates in the two types of soil development areas decreased with the decrease of particle size, and the content of water stable aggregates decreased at first and then increased with the decrease of particle size, and the main content of soil mechanical aggregates was ＞1 mm aggregate, and the proportions of yellow loam and lime soil were 82.45% and 84.01%, respectively. The water stable aggregates were mainly ＞2 mm aggregate, accounting for 53.53% and 54.61%, respectively. The mean weight diameter (MWD) and geometric mean diameter (GMD) of aggregates in yellow soil decreased with the increase of soil depth, while the opposite trend in calcareous soil to that in yellow soil was found. Cluster stability of yellow soil fallow land was better compared to calcareous soils. In general, the MWD and GMD of the two soils were the lowest in YM, and the soil structure damage rate (PAD) was the highest, the stability of soil aggregates in YM was the lowest, and the stability of soil aggregates in different stages of vegetation restoration was improved compared with that in YM. MWD of yellow soil was significantly positively correlated with organic matter content (SOM) and total nitrogen (TN), GMD was significantly positively correlated with SOM, and PAD was significantly positively correlated with silt (p＜0.05) . MWD and GMD of calcareous soil were significantly positively correlated with sand and total potassium (TK) (p＜0.05), and negatively correlated with total phosphorus (TP) . PAD was significantly negatively correlated with sand and TK, positively correlated with TP (p＜0.01), and positively correlated with clay (p＜0.05) . The results of multivariate analysis of variance showed that vegetation type, soil depth and soil type had significant effects on soil aggregate stability (p＜0.05) . [Conclusion] In the two soil development areas, the soil aggregate stability indexes of different vegetation recovery stages after fallow are higher than those of cultivated land, which shows that fallow returning forest to grass effectively improves the stability of soil aggregate and strengthens the ability of soil to resist erosion, and the results of this study can provide theoretical basis for the deployment of soil and water conservation measures and the evaluation of the benefits of fallow land in the karst area. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: The objective of this research was to examine the influence of olive kernel biochar on silty clay soil that is susceptible to erosion. The hypothesis proposed that the effectiveness of biochar in improving soil physical properties and mitigating soil erosion depends on factors such as application rate, particle size as well as placement method. Materials and methods: Three application rates (0, 1, and 2%) and two particle size ranges (53–250 and 250–500 µm) of biochar were tested, along with two placement methods (commixing and slurry). Effects of biochar application on soil aggregate stability and water repellency were investigated after a 10-month incubation period. Effectiveness of biochar to reduce soil loss and runoff generation was also assessed. Results and discussion: The biochar application resulted in a reduction of soil water repellency. Notably, regarding particle size, application rate, and placement method, no statistically significant difference was observed. The slurry method resulted in about 30% higher mean weight diameter of aggregate (MWD) compared to the commixing. The reduced soil disturbance in the slurry method may allow for greater enhancement of soil aggregation by biochar. The relative decrease in runoff (462 vs. 356%) and soil loss (52 vs. 23%) in biochar-treated soils compared to the control treatment were considerably higher in the slurry than commix method. The results also demonstrated a significant interaction between the biochar placement method and treatment type regarding soil loss characteristics in both commixing and slurry methods. Larger biochar particles at higher rates effectively reduced runoff and soil loss using the slurry method, while smaller biochar particles at lower rates were more effective with commixing method. Conclusion: Overall, the slurry method proved effective in incorporating biochar into erosion-prone areas. Furthermore, the selection of appropriate biochar particle sizes and application rates is crucial for optimizing desired outcomes. [ABSTRACT FROM AUTHOR]

Sewage sludge is a valuable source of nutrients when applied to the soil. Research on its agricultural use has been focused on chemical parameters to prevent heavy metal buildup. However, soil quality includes a wider spectrum of indicators. Our aim was to evaluate the impacts of sludge application on the biological and physical soil properties of calcareous soil when sludge is applied in maize monoculture using fertilization dosage criteria determined by N input or soil P thresholds. A control based on mineral fertilization was also included. After 20 years, no differences were found in the biological indicators: earthworm and soil oribatid mite abundances. Five oribatid species were identified, but three predominated: Acrotritia ardua americana, Oribatula (Zygoribatula) excavata and Tectocepheus sarekensis. The latter two showed a maximum number of individuals five months after maize stalks were buried in soil, independent of fertilization treatment. Sludge significantly increased water-stable aggregates (up to 30%), but there was no difference in macroporosity (apparent pore diameter > 30 μm). Under irrigated calcareous soil, sewage sludge applied as fertilizer is a sustainable option, independent of the threshold criterion (N or P) used. Nevertheless, as the P threshold criterion allows for reduced P inputs, it is more sustainable over the long term. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Humic acid can improve water absorption by plants by improving soil structure and water retention in soil. These characteristics have caused the use of humic acid in the soils of dry areas to be considered. This study aimed to investigate the simultaneous effect of humic acid and deficit irrigation on soil physical and biological properties under the cultivation of bell pepper. A factorial-based experiment in a randomized complete design was carried out with three levels of humic-acid (0 (HA0), 2 (HA20), and 4 (HA40) g per pot) and four irrigation levels (60 (L60), 80 (L80), 100 (L100), 120 (L120), (percent of soil moisture depletion) with three replications in the research greenhouse of Payam Noor Bojnourd University. The results showed that the best treatments for improving soil physical properties, AS (aggregate stability), and decreasing PAD (percentage of aggregate destruction)), were L80HA40, L100HA40, and L120HA40 treatments. Also, by increasing the dose of HA and increasing the irrigation level up to L80, the activity of urease, alkaline phosphatase, and acid phosphatase enzymes increased and then decreased in L100 and L120.Therefor the highest amount of urease, alkaline phosphatase, and acid phosphatase enzymes (μg NH4+-N g-1 dry soil 2h-1) 678.98, 845.54 671.30 (μg PNP g−1 dry soil h -) were observed in L80L40, which were to be 4.6, 5.9, 2.8 and 0.6 times more than L60HA0 treatment, respectively. By increasing the amount of humic acid and increasing the irrigation levels up to L100, respiration rates increased and then decreased at L120, however, microbial activity followed by respiration at L80 and L100 were not significantly different.Introduction Humic substances are formed through the mineralization of plant and animal residues and through the biological activities of microorganisms. The humic acid (coloured recalcitrant organic compounds) application increases the soil porosity and the water use efficiency and reduces the moisture stress conditions for plant growth (Hal et al. 2021). Humic substances directly and indirectly have significant effects on plant growth. It also improves water and nutrient absorption (Moghbeli and Arvin, 2014). Humic substances are eco-friendly and they reduce the application of chemical fertilizers. On the other hand, drought is one of the most important abiotic stress factors that have a negative effect on the growth, metabolism, and performance of plants (Bhati et al. 2015). The first reaction of a plant to drought stress is growth reduction, during drought stress. This research aims to determine the effect of different amounts of humic acid to reduce the destructive effects of deficit irrigation on bell pepper production in greenhouse conditions. Materials and Methods A factorial-based experiment in a randomized complete design was carried out with three levels of humic-acid (0 (HA0), 2 (HA20), and 4 (HA40) g per pot) and four irrigation levels (60 (L60), 80 (L80), 100 (L100), 120 (L120), (percent of soil moisture depletion) with three replications in the research greenhouse of Payam Noor Bojnourd University. To prepare the pots, the soil sample was passed through a 2 mm sieve and humic was added to the soil sample according to the experimental treatments. Two bell pepper seedlings were transferred to each pot and all pots were irrigated according to the experimental treatments. Eighty days after cultivation, plants were harvested and soil samples were air dried. Soil texture, soil pH, electrical conductivity (ECe), soil organic carbon, total nitrogen, available phosphorus, soil urease, acidic and alkaline phosphatase, and soil microbial respiration were determined by conventional methods. Results and Discussion The aggregate stability (AS) increased with the increase of humic acid application and the irrigation level up to (L100) and then decreased at the irrigation level of 120% (L120) .The highest AS was observed in the L100H40 treatment, which was 2.04 percent higher than the L60HA0 treatment. In contrast, the maximum value of the aggregate destruction percentage (PAD) was observed in the L60HA0 treatment compared to the L100HA40 treatment. By increasing the amount of humic acid application and increasing the irrigation levels (up to L80), the soil urease activity and alkaline and acid phosphatase increased and then their values decreased at L100 and L120 treatment, however, the activity of these enzymes was not significantly different. The highest soil urease and alkaline and acid phosphatase was observed with 678.98 (μg NH4+-N g-1 dry soil 2h-1, 845.54 and 30.671g-1 dry soil h-1) µg PNP) in L80 HA0 treatment which were respectively 5.9, 2.8 and 6 times higher than the L60HA0) treatment. Based on the results, with increasing the humic acid application and the increase in irrigation levels up to L100, respiration rates increased and then decreased in L120, however, microbial activity and respiration in L80 and L100 were not significantly different. Therefore, the highest amount of respiration (3.77-2.74) was observed in L100HA40, which was on average 2.5 times higher than the L60HA0 treatment. Also, the comparison of the main effect of humic acid on total soil nitrogen concentration showed that due to the use of humic acid in the soil, the concentration of total soil nitrogen increased significantly. The results also showed the positive effect of the humic acid application on the soil's available phosphorus concentration. Thus, at all levels of irrigation water, the concentration of soil available phosphorus in the treatments containing humic acid was significantly higher than in the treatment without humic acid. Also, available potassium increased in treatments containing humic acid. These results can be attributed to the relatively high concentration of potassium in humic acid (25.7 mg/kg) by adding humic acid to the soil. Conclusion The highest activity of soil urease, alkaline and acid phosphatase enzymes was observed in the L80H40 treatment. Nevertheless, the amount of moisture required for maximum stability of soil accumulation (AS) and minimum PAD was obtained in the L100 treatment. In general, better absorption of nutrients and plant growth and crop production were observed in HA40 treatment with an 80% soil moisture level. It seems that the use of humic acid can be very effective in reducing the water requirement and it helps to improve the activity of microorganisms and increase the soil stability indexes. [ABSTRACT FROM AUTHOR]

Background and Objectives: The formation of soil surface seal caused by rain can have destructive agricultural, hydrological and environmental effects. Seal formation is a complex mechanism that is controlled by a wide range of factors such as soil properties, rainfall characteristics, and flow conditions. The present study aims to identify the relationship between soil sensitivity to surface seal formation, characteristics affecting the stability of soil structure, comparison of indicators of soil sensitivity to the surface seal formation, and introduction of the best indicator of surface sealing in the soils of Kowar plain in Fars province by using descriptive statistics and modeling of It was done through ridge multivariate linear regression with backward stepwise method. Methodology: In the present research work, firstly, a land use map, geology and topography of Dasht Kovar of Fars province was prepared and by carrying out field activities in different seasons and matching the features and shapes in the maps with the environmental conditions, based on the extend of the studied area according to the systematic grid method in first, 160 specific sampling points were selected and according to the characteristics of the area and the type of land use, finally 80 composite soil samples were taken from a depth of 0-20 cm. Then the parameters of soil particle size distribution, mass moisture, organic matter, electrical conductivity and pH of saturated past extract were measured. Also, the mean weight diameter (MWD) of soil aggregates, geometric mean diameter (GMD), calcium carbonate equivalent (CCE), fractal dimension, saturation percentage, sodium, calcium, magnesium, sodium absorption ratio (SAR), saturated hydraulic conductivity (Ks) and bulk density of soil were determined. Assessing the sensitivity of soil to the formation of surface sealing by comparing the regression equations of seven different indices, including the soil structural stability index (SSI), crusting index (CI), water aggregate stability (WAS), crusting susceptibility index (CSI), consistency index (C5-C10), penetration resistance (PR) and relative sealing index (RSI) were performed. In data pre-processing, descriptive statistics of variables such as mean, maximum, minimum and variance of each characteristic, data distribution diagram and data distribution using Minitab-19 software are specified and if there are outliers or wrong data, appropriate measures were taken in entering the data and a table of descriptive information was prepared. Also, the normality of the frequency distribution of these characteristics was evaluated using the significance test of skewness. In order to explain the capability of indices and statistics in predicting the seal formation, the linear correlation between the variables was determined by SPSS-22 software, and by using the Pearson's correlation coefficient (r), the correlation between the indices and early soil characteristics was obtained and to analyze the data. Pearson's correlation method and ridge multiple linear regression were used in the backward stepwise method and using Statistic, SPSS-26 and Minitab-19 softwares. Findings: In terms of the soil structural stability index, the studied area was in the risk range of aggregate destruction, which can be related to the high percentage of silt in the area. The ratio of sodium surface absorption in most of the examined soil samples is low and 95% of the samples with agricultural use are in the weak to medium group in terms of organic matter and structure stability. The relatively low value of the standard deviation in the soil structure stability index also indicates the greater accuracy of this model in estimating the coefficients. Also, clay is a common variable in the five regression equations of the indices, and it points to the importance and dual role of clay in the stability of soil aggregates and reducing sensitivity to compaction. In most of the samples, clay is more than 20% and most of the measured variables have a low coefficient of variation and in terms of data distribution and dispersion, they have a relatively favorable situation. In the present study, the best fitted regression models to describe the sensitivity of soil to the formation of surface seal belong to the indicators of soil aggregates stability and FAO crusting indices. Conclusion: Based on the obtained results, the soil aggregate stability index with a modified coefficient of explanation R²=0.92 has a high capability in predicting the sensitivity of soil to the seal formation and is the most effective index in expressing changes in soil aggregate stability and the formation of surface sealing. The results of the data analysis also indicate the severe limitation class of the mean weight diameter of the soil aggregate in the region. [ABSTRACT FROM AUTHOR]

Soil aggregate mechanical properties are of vital importance for plant growth, tillage and soil erosion, and strongly conditioned by the amount and type of cementing agents that differ with soils. As most research focus at the site scale, how aggregate mechanical stability vary across different types of soils at regional scales and underlying mechanisms remain poorly understood. Herein, seven typical zonal soils in heavy textures with an increased status of soil development were collected under two land uses (arable and forest) and at three pedogenic horizons along the mid-temperate to south-subtropical climatic gradient in the East Asian monsoon region. Aggregate tensile strength (Y), specific rupture energy (Esp) and friability (FI) were measured on air-dried aggregates in a compression test, as well as soil cementing agents related to particle size distribution, organic matter and its components, metal oxides, phyllosilicates and exchangeable cations. Y and Esp were most affected by soil type (F = 37.7 and 21.4, p 0.01), suggesting the predominant roles of the inorganic cementing agents in aggregate mechanical stability across soil types. Aggregate mechanical stability was increased by exchangeable polyvalent cations and vermiculite (r = 0.71 ∼ 0.81, p

Sodic soil formation, following irrigation with saline-sodic water has become a major concern due to its negative impact on soil structure, crop growth and yield. However, specifically in orchards, little knowledge exists regarding the reclamation of sodic soils. Our objective was to examine the effects of different amendments on soil reclamation and crop performance of olive grove. The study was conducted in a 14 years old olive grove, grown in a clayey soil, in which irrigation started in 2008 using saline-sodic water resulting in sodium adsorption ratio (SAR) ranging from 22 to 40 (mmolc L−1)0.5. Six treatments were studied: control (no amendments applied), CaCl2, MgCl2 and H2SO4 that were added to the irrigation water, and gypsiferous material (GM) that was added to the soil surface prior to the rainy season and either left spread or tilled into the upper soil layer. Soil samples were analyzed for selected saturated extract properties and for aggregate stability. Additionally, plant parameters including yield, trunk expansion, fruit oil content, and tree nutritional status were measured. The results showed that the lowest SARs were observed in the GM and GM till treatments at 0–30 cm [5.0 and 3.3 (mmolc L−1)0.5, respectively], while CaCl2 and MgCl2 treatments had the lowest SARs at 30–90 cm [16.2 and 17.1 (mmolc L−1)0.5, respectively]. GM and CaCl2 application raised the electrical conductivity (EC) levels to 6.9 and 7.6 dS m−1 respectively. GM addition resulted in the most stable aggregates which was associated with a significant improvement in average tree productivity of 33 kg/tree. Conversely, MgCl2 had the lowest average yield, of 21.3 kg/tree, which was attributed to the high concentration of Mg that led to some nutrient imbalances. In conclusion, the current study showed the efficacy of different amendments based on Ca for remediating sodic soil in drip-irrigated orchards.

Study area: Karst region in Guangxi Province, Southwest China. Study focus: Both soil properties and rainfall characteristics have a critical influence on splash erosion and aggregate stability. However, the impact of electrolytes on splash erosion has received less attention. In this study, soils from 4 typical land use types (cropland, orchard, artificial forest and secondary forest) in karst region were utilized as the research objects. NaCl, KCl, and MgCl2 solutions of different concentrations were used to determine the stability of the aggregates via fast wetting (FW) treatment of Le Bissonnais (LB) method and the characteristics of splash erosion via simulated rainfall experiments. New hydrological insights for the region: Results revealed that both the land use types and electrolyte significantly influenced the soil aggregate stability and splash characteristics. Specifically, the change in land use from cropland to orchard, artificial forest and secondary forest significantly increased the aggregate stability, thus decreasing soil erodibility. The aggregate stability decreased and the total splash rate increased as the electrolyte concentration increased. The total splash erosion rate of the 4 soils was positively correlated with the

IntroductionIn most arid and semi-arid areas, the soils have a compact surface layer that is denser and less permeable than the underlying layers. These layers are referred to as surface coating when they are wet, and when they dry, they are referred to as surface crust. Surface crust can be divided into physical, chemical, and biological crusts depending on the nature of formation. Physical and biological soil crusts are the most significant types of soil crusts in arid and semi-arid regions. Two types of the physical crust are structural and depositional. Natural events, such as raindrops and the drying process, are the primary causes of the formation of surface crust. The process involves the creation of hard, thin layers on the surface of the soil. The thickness of the surface crusts is typically between 1 mm and 5 cm. Many researches have described different theoretical mechanisms for the formation of surface crusts in soil and reported their effective role in controlling wind erosion. The formation of crust in soil involves multiple stages, and the reaction of the soil surface to raindrop energy is divided into two main parts, as it was demonstrated. The first part involves the splashing of soil particles by raindrops' impact. A layer with a thickness of approximately 0. 1 mm is produced in this instance. The second component is composed of fine soil particles that penetrate the soil pores with water and cause the formation of a layer that is 2 mm thick. According to a study, soil loss control is not affected by the crust cover beyond 30%. There is a linear relationship between soil loss and surface crust coverage, as the surface crust cover develops gradually, soil loss differs between soil types. Material and MethodsDuring field surveys of dust storm sources in Khuzestan, it was observed that there are surface crusts that are strong enough to act as a barrier against wind erosion in certain locations. The suggestion was made to investigate the type and general characteristics of these surface crusts. The purpose of this study is to examine the general characteristics of these surface crusts and their effect on wind erosion control. The study was conducted by randomly obtaining 18 surface crust samples, each containing three sub-samples from a depth of 0 to 5 cm from the dust storm sources of Khuzestan province. After being air dried, they were then passed through a sieve of 2 mm. The factors of pH, EC, CaCo3, CEC, ESP, Ca, Mg, Po3-4 texture, initial moisture, and apparent density of the surface crusts were measured. The soil's sensitivity to crust formation was assessed by using soil stability index, Crusting Index, pressure resistance, and shear resistance. The stability of soil aggregates was assessed using the mean weight diameter and geometric mean diameter indices. Soil samples were collected and tested in a wind tunnel to examine the impact of these surface crusts on wind erosion control and the amount of soil loss and the speed of wind erosion were assessed. An orbital wind tunnel device was utilized for this purpose. Trays with soil were placed on the bottom of the tunnel in this manner. After the wind blew (speeds of 15, 10, 25 m/s) by measuring the difference in the weight of the tray before and after the wind blowing, the amount of erosion was calculated from a certain surface. Then, the threshold speed for wind erosion was determined. Statistical analysis was carried out using SPSS 26 software. The Kolmogorov-Smirnov test was used to verify data normality. Then, the data sets were entered into a step-by-step regression as independent components to determine their relationship with the index of crust formation and stability of soil aggregates, as well as the effect of crusts and stability of soil aggregates on the amount of wind erosion. The accuracy of the regression models was verified by using RMSE, RSE, MAE, and R2 statistics. The morphology of the crusts was finally determined by using a scanning electron microscope. Results and DiscussionThe results showed that the lowest amount of RMSE, and RSE statistics, and the lowest absolute error for evaluating the sensitivity of soil to crust formation in the dust storm sources of East Ahvaz, Southeast Ahvaz and Omidieh, Mahshahr and Hendijan, respectively belong to the index of compressive strength, soil stability and shear resistance. The scanning electron microscope images taken of the crusts of three dust storm sources indicated that small foreign matter is present in the soil's pores. The features of the sedimentary crust are displayed in all the images. The external materials in the crust structure reflect the different washing processes in soil particles, which cause adhesion and connection between the soil particles and make the crusts resistant to wind erosion. Based on the given explanations, it is possible that the crusts found in Khuzestan's dust storm sources are usually sedimentary crusts. Results also showed that the wind erosion threshold speed in the dust storm sources of East Ahvaz, South East Ahvaz and the sources of Mahshahr, Omidiye and Hendijan are 1. 44, 1. 62 and 2. 1 time their powdered state, respectively. These sources experience a soil loss of 3. 55, 2. 09, and 3. 01 times the intact crusts, respectively.

Amendment significantly improves soil structure and promotes crop growth. To combat soil degradation and low crop yields in facility agriculture, it is crucial to study the optimal application rate of amendments. This study analyzed the effects of biochar, vermicompost, and mineral-source potassium fulvic acid on the stability of aggregate structure, soil nutrient content, and tomato yield in cambisols, providing a theoretical basis for improving the soil quality of plastic greenhouses in Southern China. A pot experiment on tomato cultivation was carried out in yellow-brown soil in plastic greenhouses. The experiment included eight treatments: 1% biochar (B1); 3% biochar (B3); 5% biochar (B5); 3% vermicompost (V3); 5% vermicompost (V5); 0.1% mineral-source potassium fulvic acid (F1); 0.2% mineral-source potassium fulvic acid (F2); and the control condition without adding soil amendments (CK). The results showed that the biochar and vermicompost treatments effectively reduced soil bulk density and increased total soil porosity. Compared to the control, treatments with soil amendments significantly increased soil pH and had different effects on soil nutrients: F2 showed the most significant improvement in the content of available nitrogen, available phosphorus, and available potassium, with an increase of 133.33%, 834.59%, and 74.34%, respectively; B3 treatment had the highest increase in dissolved organic carbon (DOC), while B5 treatment had the highest organic matter content. Compared to the CK, the particle size of the biochar treatment was mainly 0.053~0.25 mm, while the V3, F1, and F2 mainly occurred with a particle size > 0.25 mm; and V3 has the best aggregate stability. Biochar, vermicompost, and mineral potassium fulvic acid can all promote tomato yield, with the F2 and V3 treatments having a yield increase effect of over 30%. Furthermore, Pearson’s correlation analysis showed a highly significant positive correlation between geometric mean diameter (GMD) and mean weight diameter (MWD), water-stable macroaggregate content (R0.25), and a positive correlation between alkaline-dissolved nitrogen, available phosphorus, dissolved organic carbon content, and aggregate stability indicators. Adding 0.2% mineral-source potassium fulvic acid optimizes cambisols’ properties, enhances aggregate formation and stability, boosts tomato yield, and shows great application potential.

Fenced enclosures, a proven strategy for restoring degraded grassland, have been widely implemented. However, recent climate trends of warming and drying, accompanied by increased extreme rainfall, have heightened soil erosion risks. It is crucial to assess the long-term effectiveness of fenced enclosures on grassland restoration and their impact on soil physicochemical properties and water infiltration capacity. This study investigated the effects of enclosure duration on soil organic matter, aggregate composition and stability, and infiltration capacity in Yunwu Mountain Grassland Nature Reserve, comparing grasslands with enclosure durations of 2, 14, 30, and 39 years. Results showed that grasslands enclosed for 14, 30, and 39 years had infiltration rates increased by 20.66%, 152.03%, and 61.19%, respectively, compared to those enclosed for only 2 years. After 30 years of enclosure, soil quality reached its optimum, with the highest root biomass, soil organic matter, aggregate stability, and a notably superior infiltration rate. The findings suggest that long-term fenced enclosures facilitate grassland vegetation restoration and enhance soil infiltration capacity, with the most significant improvement observed at the 30-year enclosure milestone, followed by a gradual decline in this effect.

Earthworm incubation combined with organic fertilization is promoted as an amended measure to improve soil properties in the ecological restoration of various degraded soils. However, the impacts of earthworms on the soil aggregate size under different organic fertilization in salt‐affected soils have not yet been fully revealed. This hinders our ability to develop policies by which to alleviate soil salinization. In this study, under mesocosm experiments, we investigate the effects of earthworm (Aporrectodea trapezoides) and organic fertilization on the soil aggregate size after 16 weeks of incubation. The soil treated with clover residues showed lower earthworm survival rates and biomass compared to that treated with sheep manure. However, the soil macropores and large macroaggregate were higher in the soils treated with clover residue when earthworms were present. In addition, earthworm burrowing activities form pathways toward food patches improve the characteristics of soil macropores, and the properties of the residue itself play a decisive role. Moreover, whether earthworms are present or not significantly influences the soil macroporosity, macropore number, and soil electrical conductivity. This demonstrates that earthworms exhibit a key feature of soil physical functioning in salt‐affected soil. In conclusion, we propose that the application of earthworms with organic residues in salt‐affected soils is a priority in producing and maintaining favorable soil structure. [ABSTRACT FROM AUTHOR]

This study aims to investigate the impact of vegetation restoration on soil humus and aggregate stability within the karst region of Southwest China. This study focused on soils at five vegetation succession stages (abandoned land, grassland, shrub rangeland, shrubland, and secondary forest) in the typical karst region, and the aggregate stability was determined using wet sieving and the Le Bissonnais method. Simultaneously, the Pallo method and separation extraction were used to determine the humus composition, aiming to analyze the distribution of humus content in the soil aggregates and its effect on aggregate stability. The results revealed the following: (1) The mean weight diameter of soil aggregates significantly increased with vegetation restoration stages. Soil water-stable aggregates at each vegetation stage mainly included particles over 2 mm in size. (2) The humic acid and fulvic acid contents consistently increased with vegetation restoration, and the precipitation quotient value of the humification degree showed an increasing trend. At each vegetation restoration stage, the percentage of each humus component was, from highest to lowest, as follows: insoluble HM, fulvic acid, humic acid, clay-bound HM, and iron-bound HM. (3) Through stepwise regression analysis, humic acid content in >2 mm aggregates, fulvic acid and clay-bound HM contents in 1–2 mm aggregates, and insoluble HM content in <0.25 mm aggregates were the dominant factors affecting soil aggregate stability in the karst region. These results aim to provide novel insights for a more in-depth comprehension of the restoration and rehabilitation of vegetation within the karst region of Southwest China, thereby laying a robust foundation for scientific theories and further investigations. [ABSTRACT FROM AUTHOR]

Background: Vegetation roots are considered to play an effective role in controlling soil erosion by benefiting soil hydrology and mechanical properties. However, the correlation between soil hydrology and the mechanical features associated with the variation root system under different vegetation types remains poorly understood. Methods: We conducted dye-tracer infiltration to classify water flow behavior and indoor experiments (including tests on soil bulk density, soil organic carbon, mean weight diameter, soil cohesion, root density, etc.) to interpret variation patterns in three forest systems (coniferous and broad-leaved mixed forest, CBF; coniferous forest, CF; Phyllostachys edulis, PF) and fallow land (FL). Results: Based on the soil dye-tracer infiltration results, the largest dyeing area was observed in CF (36.96%), but CF also had the lowest infiltration rate (60.3 mm·min−1). The soil under CBF had the highest shear strength, approximately 25% higher than other vegetation types. CF exhibited the highest aggregate stability, surpassing CBF by 98.55%, PF by 34.31%, and FL by 407.41%, respectively. Additionally, PF forests showed the greatest root biomass and length. The results of correlation analysis and PCA reveal complex relationships among hydrological and mechanical soil traits. Specifically, soil cohesion does not exhibit significant correlations with hydrological traits such as the dyeing area, while traits like MWD and PAD show either positive or negative associations with hydrological traits. Root traits generally exhibit positive relationships with soil mechanical traits, with limited significant correlations observed with hydrological traits. Conversely, we found that root biomass contributes significantly to the dyeing area (accounting for 51.48%). Conclusions: Our findings indicate that the reforestation system is a successful approach for conserving water and reducing erosion by increasing soil-aggregated stability and shear strength, causing water redistribution to be more homogenized across the whole soil profile. [ABSTRACT FROM AUTHOR]