Dry Sieving Method Research Articles

Grass species and mycorrhizal fungi improved aggregate stability of compacted and vegetated soils

Abstract Aim Compaction of slope soils can substantially hinder root penetration of grass cover, which may be alleviated through the colonisation of arbuscular mycorrhizal (AM) fungi and aggregate stabilisation. We investigated aggregate stabilisation and breakdown mechanisms in compacted dense mycorrhizal soils. Methods A pot-culture experiment with seven treatments (five replicates per treatment) was implemented. In a local decomposed granitic soil, we inoculated two grass species (Chrysopogon ziaanioides and Cynodon dactylon) with AM fungi. We used loose soil to grow C. dactylon to compare it with compacted dense soil, as well as pots without a plant and/or fungal inoculation for comparison. After 20 weeks of cultivation, we measured root and AM fungal characteristics, soil organic matter and aggregate properties by dry sieving, wet sieving and Le Bissonnais methods. Results Compaction led to the formation of macro-aggregates (> 0.25 mm) but had a negative influence on the aggregate stability. The fungal inoculation increased polysaccharide production and aggregate stability in the compacted soil vegetated with C. dactylon. The inoculated C. ziaanioides showed a similar level of aggregate stability as the inoculated C. dactylon, but the uninoculated group demonstrated higher aggregate stability compared with the inoculated group owing to root decomposition. The aggregate stability against various breakdown mechanisms was related to the established aggregate hierarchy and qualitative organic matter inputs. Conclusion Soil organic matter supplied by grass species together with the mediation of AM fungal hyphae played a crucial role in the systemic enhancement of aggregate stability in the compacted soil.

The stoichiometric characteristics of carbon, nitrogen, and phosphorus in soil aggregates of Cryptomeria japonica plantation with stand ages in the Rainy Area of Western China.

Understanding the variations in soil aggregate composition, as well as the contents and stoichiometry of organic carbon (C), total nitrogen (N) and total phosphorus (P), in the surface layer of Cryptomeria japonica plantations with different stand ages can provide a theoretical basis for the optimized management of plantations and the improvement of soil fertility in the Rainy Area of West China. With the dry-sieving method, we measured the contents of soil aggregates with different sizes in the 0-15 and 15-30 cm soil layers across C. japonica plantations with five distinct developmental stages at Hongya Forestry Farm, Sichuan Province, including young stands (7 years old), middle-aged stands (13 years old), nearly mature stands (24 years old), mature stands (33 years old), and over-mature stands (53 years old). We further analyzed the C, N and P contents and ecological stoichiometric characteristics of soil aggregates. The results showed that the particle size composition of soil aggregates in C. japonica plantations varied among stand ages. The nearly mature and mature stands had higher proportion of large aggregates (0.5-1 and 1-2 mm), whereas the nearly mature stand had a lower proportion of micro-aggregates (0.053-0.25 mm) and the silt-plus-clay fraction (<0.053 mm). Moreover, the C, N and P contents and stoichiometric ratios in soil aggregate showed a unimodal pattern, which increased initially and then decreased with stand age, with peak values in the nearly mature and mature plantations. Furthermore, the C, N and P contents in aggregates in 0-15 cm soil layer were higher than that in the 15-30 cm soil layer. The highest C and N contents were found in the aggregates with particle sizes of 0.5-1 and 0.25-0.5 mm. In conclusion, the near-mature and mature stands of C. japonica plantations have higher nutrient content in soil aggregate, underscoring these stages was critical for maintaining soil fertility and advancing sustainable management practices.

Research on the enhancement material and culture method of soil aggregates composed of feldspathic sandstone and sand

The Mu Us Sandy Land is a region characterized by wind-blown sand and soil erosion in northern China. To enhance the soil quality of this area, various organic materials were incorporated into the mixed soil at a volume ratio of 1:2 for feldspathic sandstone to sand. Culture was conducted in the field and under constant temperature conditions in laboratory culture chambers. Four treatments were established in the experiment, each calculated based on weight ratio and controlled (with no organic material added, CK); single application of straw (5% straw, P1); single application of biochar (5% biochar, P2); combined application of biochar and straw (5% biochar + 5% straw, P3). After 90 days of culture, soil samples were collected for analysis of various indicators such as soil aggregate particle size distribution, water stability of soil aggregates, mean weight diameter, mean geometric diameter, and fractal dimension using dry sieving and wet sieving methods. The objective is to establish a scientific basis and provide technical support for addressing the challenges associated with compound soil and implementing rational fertilization measures. The research results indicate that: (1) The quantity of aggregates > 0.25 mm under different treatments follows the order CK < P1 < P2 < P3, and the differences between treatments are significant (P < 0.05); (2) Soil water stability, mean weight diameter (MWD), mean geometric diameter (GMD), and fractal dimension of soil aggregates in compound soil with different organic material additions are superior to the control, and the effect of biochar on improving soil aggregates is better than that of corn straw. The combined application of both significantly improves the effect compared to single applications. In both culture modes, under wet sieving, the P3 treatment shows the highest MWD and GMD of soil aggregates, with an increase ranging from 3.45% to 85% and 4.55% to 38.46%, respectively, compared to other treatments. (3) The trend of fractal dimension among treatments is consistent: P3 < P2 < P1 < CK, and the differences between treatments are significant (P < 0.05). Moreover, there is a good negative correlation linear equation relationship between the fractal dimension (y) and WR > 0.25 (x) of compound soil, with a correlation coefficient of up to 0.9851. In conclusion, the incorporation of organic materials can effectively enhance the proportion of macroaggregates in compound soil consisting of Feldspathic sandstone and sand, thereby improving soil stability and erosion resistance. The optimal outcome is achieved through the combined application of biochar and straw. Indoor culture proves to be more effective than field culture, while wet sieving accurately reflects the structural characteristics of compound soil under both dry and wet sieving treatments.

Mechanical Analysis of Sand Ripples Deposits in the Lower Basin of Wadi Tilal "Geomorphological study"

The current study is set to determine the volumes of sand ripple deposits in the lower basin of Wadi Tilal in micro depositional environments by mechanical analysis. To do so, the present study analyzed samples of sediment in the laboratory using an electric sieve and the dry sieving method. The results were then calculated in the Phi unit to be processed using the Fraction V.3 program combined with the Folk &amp; Ward equations in order to find out an estimation of the volume coefficients, and categories of statistical coefficients for the volumes of sediment sand. The study’s main findings was that the medium-sized sand category (1-2ø) constitutes about 44.75% of the weight of the ripple sand samples, and that the average sand size is about (1.698ø) and it falls within the medium-sized sand category. Moreover, the average value of the sorting coefficient was (0.873ø), which falls within the medium sorting category. In addition, most of the distribution curves fell within the high positive skewness category with an average of (0.336ø), and the value of the flattening coefficient was (1.265ø). The shape of the distribution curve falls within the category of flattened and sharpen end.

Structure and stability characteristics of zonal soil aggregates in the Three Rivers Source of the Qinghai‐Tibetan Plateau

AbstractThis study aimed to explore the structure and stability characteristics of zonal soil aggregates in cold high‐altitude regions and reveal the variation patterns of alpine soil aggregates, using the Three Rivers Source of the Qinghai‐Tibetan Plateau as an example. Zonal soils representing the local vegetation types (alpine meadow soil, alpine grassland soil) were collected, and soil aggregates were separated using wet and dry sieving methods. Random forest modeling was used with climate data from 2011 to 2019 as variables in order to generate multifactor digital maps of water‐stable and mechanically stable aggregates. The composition and differences of zone‐specific soil aggregates were compared and analyzed using the evaluation indices of macroaggregate content (R &gt; 0.25), mean weight diameter (MWD), geometric mean diameter, and fractal dimensions. Their controlling factors were also explored. The study results showed that the model's explanatory power for soil aggregates was over 68%. In the random forest model, elevation and sunshine duration contributed more to soil water‐stable aggregates, whereas precipitation contributed more to soil mechanically stable aggregates. The content of large aggregates with particle size greater than 0.5 mm was higher in alpine meadow soils than in alpine grassland soils. In contrast, the content of large aggregates with particle size less than 0.5 mm was lower than that of alpine grassland soils. There are also some differences in the distribution of water‐stable aggregates and mechanically stable aggregates between alpine meadow soils and alpine grassland soils in each particle size, and these differences are most pronounced in the particle sizes &gt;2 and &lt;0.25 mm. In addition, the stability of alpine meadow soil aggregates is higher than that of alpine grassland soil aggregates. Finally, the mapping results show that the stability of soil aggregates in the study area has similar zonal characteristics to the zonal variation of vegetation cover and climate and other factors.

Phosphatase activities and available nutrients in soil aggregates affected by straw returning to a calcareous soil under the maize–wheat cropping system

The objective of this study was to investigate the effects of different rates of straw returning on soil aggregate stability, phosphatase activities, and the available nitrogen (N) and phosphorus (P) within different soil aggregate sizes. The experiment included five treatments: 1) no straw returning and no chemical fertilizer, 2) chemical fertilizer only (150 kg N ha-1, 75 kg P ha-1, and 75 kg K ha-1), 3) 20% straw returning with chemical fertilizer, 4) 60% straw returning with chemical fertilizer, and 5) 100% straw returning with chemical fertilizer. Soil samples were collected 3.5 years after the start of the experiment and separated into four aggregate sizes (&amp;lt;0.25 mm, 0.25–1 mm, 1–2 mm, and 2–7 mm) using the dry sieving method. Soil acid phosphomonoesterase (AcP) and alkaline phosphomonoesterase (AlP); phosphodiesterase (PD); pyrophosphatase (PrA) activities; and soil NO3−−N, NH4+−N, and resin-P were determined within soil aggregates. The results showed that straw returning rates did not significantly impact soil aggregate distribution. However, straw returning increased soil AcP, AlP, and PD in &amp;lt;2 mm aggregates, and high rates of straw returning led to high enzyme activities. Soil phosphatase activities were also higher in 1–2 mm aggregates. All straw returning and chemical fertilization treatments increased soil NO3−−N and resin-P concentrations but had much less effect on soil NH4+−N concentrations. Additionally, the study revealed that soil pH, the concentrations of NH4+−N, NO3−−N, resin-P, and CaCO3 significantly influenced soil phosphatase activities, but their impact varied across different sizes of aggregates.

Grain size distribution of modern beach sediments in Sri Lanka

Grain size distributions are widely used to describe sedimentary geochemistry, depositional environment, and sediment transportation. The objective of this study is to analyze grain size distributions of modern sandy beach sediments in Sri Lanka. Sediment samples (n = 90) were collected from beach berm, representing the entire coastline of Sri Lanka. Grain sizes were determined by the dry-sieving method. Statistical parameters such as mean size, sorting, skewness, and kurtosis were calculated using GRADISTATV9.1 software for all the sieved sediment samples. Grain size variations (108.2 – 609.8 µm) show that Sri Lanka mainly consists of medium sand, whereas the northeast part of the country mixes with fine sand due to the influence of Bengal fan sediments. The variations of skewness (-0.229 – 0.446) and sorting (1.305 – 2.436) indicate symmetrical distributed moderately sorted samples. These variations specify a moderate energy depositional environment/wave action around the coastline of Sri Lanka. In addition, grain size analysis confirmed relatively high and low energy deposition environments on the west and east coasts, respectively. Accordingly, the west coast is more vulnerable to coastal erosion compared to the east coast of Sri Lanka. Therefore, this study provides the baseline grain size distribution data that can be used in decision-making for coastal zone management by mitigating beach erosion.

Soil Aggregates and Aggregate-Associated Carbon and Nitrogen in Farmland in Relation to Long-Term Fertilization on the Loess Plateau, China

Soil aggregation plays a critical role in the maintenance of soil structure and crop productivity. Fertilization influences soil aggregation, especially by regulating soil organic carbon (SOC) and total nitrogen (TN) contents in aggregate fractions. Here, we conducted a fixed-site field experiment to quantify the effect of five N application rates: 0, 75, 150, 225, and 300 kg·N·ha−1, denoted as N0, N75, N150, N225, and N300, respectively, on soil aggregate stability, aggregate-associated SOC and TN sequestration and crop productivity. Soil aggregates were divided into &gt;0.25 (&gt;5, 5–2, 2–1, 1–0.5, 0.5–0.25) and &lt;0.25 mm through wet and dry sieving methods. The results showed that long-term fertilization increased the proportion of macro-aggregates (&gt;0.25 mm), decreased the proportion of micro-aggregates (&lt;0.25 mm), and improved the aggregates stability. Compared with N0, the proportion of micro-aggregates in N225 was significantly decreased by 66.45% under wet sieving, while the proportion of &gt;5 mm macro-aggregates in N225 was significantly increased by 19.24% under dry sieving (p &lt; 0.05). With the increase in N application rate, the bulk SOC and TN contents first increased and then decreased, and the SOC and TN of N225 were significantly increased by 17.75% and 72.33% compared with N0 (p &lt; 0.05). More specifically, fertilization promoted the distribution and enrichment of SOC and TN in macro-aggregates and reduced the C/N of the micro-aggregates and the contribution of SOC and TN in the micro-aggregates. Compared with N0, the contribution rate of macro-aggregates to SOC and TN of N225 under wet sieving was significantly increased by 84.13 and 17.18%, respectively, while the C/N of micro-aggregates of N225 under wet and dry sieving methods was significantly decreased by 45.95 and 31.74%, respectively (p &lt; 0.05). Moreover, fertilization improved the yield, and N225 significantly increased the total yield by 80.68% compared with N0 (p &lt; 0.05). In conclusion, N225 was the suitable N application for improving soil aggregate stability, carbon and nitrogen sequestration, and crop productivity on the Loess Plateau, China.

Long‐term fertilization and plastic film mulching modify temporal incorporation of 13C/15N‐labelled particulate organic matter

AbstractPlastic film mulching (PFM) is critical for agricultural planting and maximizing production in semiarid and arid areas. Particulate organic matter (POM) is assumed to be a sensitive indicator for evaluating the effects of different agricultural practices on soil fertility and the soil organic carbon (SOC) pool. Soil aggregates have the function of ‘wrap’ and protect the POM stored in them. However, there is limited information regarding how PFM and fertilization jointly influence the dynamic changes of newly added stalk‐derived POM in brown earth. Consequently, an in‐depth study of the fate of carbon (C) and nitrogen (N) derived from maize stalk residues within the particulate organic carbon (POC) and particulate organic nitrogen (PON) fractions in soil aggregates was undertaken. Its outcome would contribute to better predictions on the active organic matter components sequestered in the soil. The dynamics and accumulation of newly added maize stalk C and N as POC and PON in different soil aggregates (using the dry sieving method divided into &gt;2, 1–2, 0.25–1 and &lt;0.25 mm) were analysed by an in situ 13C/15N‐tracing technique under PFM and different fertilization treatments. Over 360 days of cultivation, the POC and PON contents were significantly (p &lt; 0.05) larger in the nitrogen (N) and organic manure (M) treatments than in the MN (manure combined with nitrogen) and Control treatments. The PFM treatment accelerated the decomposition of maize stalk C in the N fertilizer treatment, with an increase of 64% in stalk‐derived POC after the 1‐day cultivation period. Stalk‐derived POM tended to accumulate in &lt;0.25 mm microaggregates in the early cultivation period and then decreased rapidly with the extension of the cultivation period affected by PFM coupled with fertilization. However, stalk‐derived POM accumulation in macroaggregates (&gt;0.25 mm) fluctuated over the 360‐day cultivation period. Accordingly, PFM application and fertilization practices had important effects on the accumulation of newly added stalk‐derived POM in soil aggregates. We conclude that the accumulation of maize residue POM was primarily affected by soil fertilization type, rather than by the presence or absence of PFM. These results provide new insights into agricultural management strategies for improving soil carbon sequestration capacity.

Particle size distribution of growing media constituents using dynamic image analysis: Parametrization and comparison to sieving

AbstractGrowing media constituents have heterogeneous particle size and shape, and their physical properties are partly related to them. Particle size distribution is usually analyzed through sieving process, segregating the particles by their width. However, sieving techniques are best describing more granular shapes and are not as reliable for materials exhibiting large varieties of shapes, like growing media constituents. A dynamic image analysis has been conducted for a multidimensional characterization of particle size distribution of several growing media constituents (white and black peats, pine bark, coir, wood fiber, and perlite), from particles that were segregated and dispersed in water. Diameters describing individual particle width and length were analyzed, then compared to particle size distribution obtained by dry and wet sieving methods. This work suggests the relevance of two parameters, FeretMAXand ChordMINdiameters for assessing particle length and width, respectively. They largely varied among the growing media constituents, confirming their non‐spherical (i.e., elongated) shapes, demonstrating the advantages of using dynamic image analysis tools over traditional sieving methods. Furthermore, large differences in particle size distribution were also observed between dynamic image analysis and sieving procedures, with a finer distribution for dynamic image analysis. The discrepancies observed between methodologies were discussed (particle segregation, distribution weighing, etc.), while describing in details methodological limitations of dynamic image analysis.

Relationship between sediment type, total organic matter, and water quality on mangrove density on Tunda Island, Serang Banten

Environmental conditions that are quite important in the growth of mangroves are the type of sediment, organic matter, and water quality because the organic matter produced can be useful for mangrove fertility. This study aims to determine the type of sediment, the percentage of total organic matter, water quality, mangrove density, and determine the relationship between sediment types, total organic matter, and water quality on mangrove density on Tunda Island, Serang, Banten. This study used a survey method while collecting data using a purposive sampling method. Mangrove density was obtained through the line transect plot method. The sediment type test used the dry sieving method, the total organic matter (BOT) test used the loss on ignition (LOI) method, the statistical test used the multiple correlation method. All data was then analyzed in a quantitative descriptive manner. The results of the study are that the type of sediment in Tunda Island mangroves is dominated by silty sand and sand. The total organic matter contained in mangrove sediments ranges from 2.40% - 3.62% which is included in the moderate to high category. Salinity values ranged from 31 - 34.33 ppt included in the high category. The pH value ranges from 7.33 - 7.70 which is included in the good category for mangrove growth. Temperature values ranging from 27.37oC - 31.63oC are included in the good category for mangrove growth because they can still grow and develop normally. The mangrove density level is dominated by the dense category, which is 2,400 ind/Ha at station 1 and 1,700 ind/Ha at station 2, and the rare category is 1,000 ind/Ha at station 3 and 900 ind/Ha at station 4. There is a significant relationship between sediment type, total organic matter, water quality with mangrove density.Keywords: BOT; Mangroves; Sediment; Water Quality

Relationship between sediment type, total organic matter, and water quality on mangrove density on Tunda Island, Serang Banten

Environmental conditions that are quite important in the growth of mangroves are the type of sediment, organic matter, and water quality because the organic matter produced can be useful for mangrove fertility. This study aims to determine the type of sediment, the percentage of total organic matter, water quality, mangrove density, and determine the relationship between sediment types, total organic matter, and water quality on mangrove density on Tunda Island, Serang, Banten. This study used a survey method while collecting data using a purposive sampling method. Mangrove density was obtained through the line transect plot method. The sediment type test used the dry sieving method, the total organic matter (BOT) test used the loss on ignition (LOI) method, the statistical test used the multiple correlation method. All data was then analyzed in a quantitative descriptive manner. The results of the study are that the type of sediment in Tunda Island mangroves is dominated by silty sand and sand. The total organic matter contained in mangrove sediments ranges from 2.40% - 3.62% which is included in the moderate to high category. Salinity values ranged from 31 - 34.33 ppt included in the high category. The pH value ranges from 7.33 - 7.70 which is included in the good category for mangrove growth. Temperature values ranging from 27.37oC - 31.63oC are included in the good category for mangrove growth because they can still grow and develop normally. The mangrove density level is dominated by the dense category, which is 2,400 ind/Ha at station 1 and 1,700 ind/Ha at station 2, and the rare category is 1,000 ind/Ha at station 3 and 900 ind/Ha at station 4. There is a significant relationship between sediment type, total organic matter, water quality with mangrove density.Keywords: BOT; Mangroves; Sediment; Water Quality

Effects of management intensities on soil aggregate stability and carbon, nitrogen, phosphorus distribution in Phyllostachys edulis forests.

Soil aggregates are the main sites for the decomposition of soil organic matter and the formation of humus. The composition characteristics of aggregates with different particle sizes are one of the indicators for soil fertility. We explored the effects of management intensity (frequency of fertilization and reclamation) on soil aggregates in moso bamboo forests, including mid-intensity management (T1, fertilization and reclamation every 4 years), high-intensity management (T2, fertilization and reclamation every 2 years), and extensive management (CK). The water-stable soil aggregates (0-10, 10-20, and 20-30 cm layers) from moso bamboo forest were separated by a combination of dry and wet sieving method and the distribution of soil organic carbon (SOC), total nitrogen (TN) and available phosphorus (AP) across different soil layers were determined. The results showed that management intensities had significant effects on soil aggregate composition and stability, and SOC, TN, AP distribution of moso bamboo forests. Compared with CK, T1 and T2 decreased the proportion and stability of macroaggregates in 0-10 cm soil layer, but increased that in 20-30 cm soil layer, while reduced the content of organic carbon in macroaggregates, the contents of organic carbon, TN and AP in microaggregates. Such results indicated that the intensified management was not conducive to formation of macroaggregates in 0-10 cm soil layer and carbon sequestration in macroaggregates. It was beneficial to the accumulation of organic carbon in soil aggregates and nitrogen and phosphorus in microaggregates with lower human disturbance. Mass fraction of macroaggregates and organic carbon content of macroaggregates was significantly positively correlated with aggregate stability, which best explained the variations of aggregate stability. Therefore, macroaggregates and organic carbon content of macroaggregates were the most important factors affecting the formation and stability of aggregates. Appropriate reduction of disturbance was beneficial to the accumulation of macroaggregates in the topsoil, the sequestration of organic carbon by macro-aggregates, and the sequestration of TN and AP by microaggregates, and improving soil quality and sustainable management in moso bamboo forest from the point of view of soil aggregate stability.

Key soil properties influencing infiltration capacity after long-term straw incorporation in a wheat (Triticum aestivum L.)–maize (Zea mays L.) rotation system

Straw incorporation is increasingly being adopted in wheat (Triticum aestivum L.)–maize (Zea mays L.) rotation systems to improve soil physiochemical properties. To identify the main soil properties influencing infiltration capacity under long-term straw incorporation in a wheat–maize rotation system, the study set four treatments: no straw incorporation and fertilizer application, wheat straw incorporation with 276 kg nitrogen/ha, wheat and maize straw incorporation with 276 kg N/ha, and wheat and maize straw incorporation. The initial, average, and final infiltration rates were calculated to represent soil infiltration capacity. Compared with other treatments, wheat straw incorporation with 276 kg nitrogen/ha treatment significantly decreased soil bulk density, soil aggregate (DMWD) mean weight diameter measured using the dry sieving method, and weight rate of soil aggregates with diameters greater than 0.25 mm measured using the wet sieving method, and significantly increased total soil porosity, soil capillary porosity, field capacity, and weight rate of soil aggregates with diameters less than 0.25 mm measured using the wet sieving method. In contrast, wheat and maize straw incorporation treatment significantly increased soil bulk density and noncapillary porosity, but decreased total soil porosity, capillary porosity, and field capacity. The results of partial least squares regression indicated that the soil moisture content and DMWD were the primary factors influencing initial infiltration rate with positive regression coefficient. Higher total soil porosity, capillary porosity, field capacity, and DMWD contributed to higher final infiltration rate, while higher soil bulk density and noncapillary porosity were correlated with a lower final infiltration rate. The key influencing factors of average infiltration rate were soil bulk density, soil moisture content, total soil porosity, capillary porosity, and DMWD. The wheat straw incorporation with 276 kg nitrogen/ha treatment had higher infiltration rates than no straw incorporation and fertilizer application treatment. However, with an increase in straw amount, the influence of straw on infiltration showed a law of diminishing marginal returns. Therefore, wheat and maize straw incorporation with 276 kg nitrogen/ha treatments had a lower infiltration rate than wheat straw incorporation with 276 kg nitrogen/ha treatment. In addition, wheat and maize straw incorporation treatment had the lowest average and final infiltration rates of all treatments, indicating that excessive straw incorporation without nitrogen fertilizer had adverse effects on infiltration rates. This study furthers understanding of the influence of long-term straw incorporation on soil hydrological processes and helps rationally use straw resources in wheat–maize rotation systems.

Effects of Shelterbelt Transformation on Soil Aggregates Characterization and Erodibility in China Black Soil Farmland

Farmland shelterbelts are widely used to reduce wind erosion, maintaining the ecological and food security of the black soil plain region of northeast China. In recent years, the protective effect of shelterbelts has been reduced due to tree degeneration. Efforts have been made to transform the construction of shelterbelts to conserve the stability of soil aggregates and enhance protection against erosion, however, the results are not well understood. To evaluate the impact of shelterbelt transformation on the stability of farmland soil aggregates and soil erodibility, three transformation modes of shelterbelts were selected, including pure Pinus sylvestris var. mongolica (ZC), pure Picea asperata (YS), and mixed Populus × xiaohei–Pinus sylvestris var.mongolica (ZY), with a degraded Populus × xiaohei shelterbelt (TYC) used as a control. We set up soil sampling points at 0.5H, 1H, 1.5H, 3H, 5H, 7H, and 9H from the shelterbelts and analyzed aggregate composition, mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D), soil erodibility (K-value), and their relationships to soil properties of the 0–10 cm, 10–20 cm and 20–40 cm soil layers and the shelterbelt structure by using dry and wet sieving and equation estimation methods. The results show that dry (d) sieved soil samples from the transformed shelterbelt-protected farmlands are mainly composed of 2–5 mm and &gt;5 mm grain size aggregates; the sum of the two particle sizes ranged from 48.67% to 51.27%, significantly larger than in the degraded shelterbelts (15.37%), decreasing with increasing distance from the shelterbelts. The effect is most obvious in the 0–10 cm soil layer. Wet (w) sieved soil samples are all dominated by &lt;0.25 mm and 0.25–0.5 mm grain size aggregates; the sum of the two particle sizes ranged from 78.25% to 80.82%, which do not vary significantly with the mode of shelterbelts. The dMWD and dGMD show significantly higher mean values in samples from transformed shelterbelt-protected farmland than in soil from degraded shelterbelt-protected farmland; their magnitudes differ depending on the transformation mode, showing a pattern of ZC &gt; ZY &gt; YS and decreasing with increasing distance from shelterbelts, while the opposite is true for D and K. The difference between wMWD and wGMD for different shelterbelts protected farmland is not significant and is significantly lower than that between dMWD and dGMD. Clay and silt content was highly significantly positively correlated with aggregates dMWD and dGMD, weakly positively correlated with wMWD, wGMD and wD, and highly significantly negatively correlated with dD and K values. This shows that particle composition parameters can be used to reflect the sensitivity of agricultural soils to wind erosion. Farmland shelterbelt porosity is the main factor driving changes in soil aggregates stability, soil erodibility, and other soil properties. The transformation of degraded farmland shelterbelts can decrease the porosity and reduce wind speed, resulting in improved stability and erosion resistance of the farmland soil aggregates by increasing the clay content of the farmland soils. These results are useful in renovating degraded shelterbelts, providing novel insights into how to regulate the stability of soil aggregates and soil erodibility characteristics at the shelterbelt network scale.

Trichoderma Bio-Fertilizer Decreased C Mineralization in Aggregates on the Southern North China Plain

Trichoderma bio-fertilizer is widely used to improve soil fertility and carbon (C) sequestration, but the mechanism for increasing C accumulation remains unclear. In this study, effects of Trichoderma bio-fertilizer on the mineralization of aggregate-associated organic C were investigated in a field experiment with five treatments (bio-fertilizer substitute 0 (CF), 10% (BF10), 20% (BF20), 30% (BF30) and 50% (BF50) chemical fertilizer nitrogen (N)). Aggregate fractions collected by the dry sieving method were used to determine mineralization dynamics of aggregate-associated organic C. The microbial community across aggregate fractions was detected by the phospholipid fatty acid (PLFA) method. The results indicated that Trichoderma bio-fertilizer increased organic C stock across aggregate fractions and bulk soil compared with CF. Cumulative mineralization of aggregate-associated organic C increased with the increasing bio-fertilizer application rate. However, the proportion of organic mineralized C was lower in the BF20 treatment except for &lt;0.053 mm aggregate. Moreover, the PLFAs and fungal PLFA/bacterial PLFA first increased and then decreased with increasing bio-fertilizer application rates. Compared with CF, the increases of bacteria PLFA in &gt;2 mm aggregate were 79.7%, 130.0%, 141.0% and 148.5% in BF10, BF20, BF30 and BF50, respectively. Similarly, the PLFAs in 0.25–2, 0.053–0.25 and &lt;0.053 mm aggregates showed a similar trend to that in &gt;2 mm aggregate. Bio-fertilizer increased the value of fungi PLFA/bacteria PLFA but decreased G+ PLFA/G− PLFA, and BF20 shared the greatest changes. Therefore, appropriate Trichoderma bio-fertilizer application was beneficial to improving soil micro-environment and minimizing risks of soil degradation.

3D Printing of Diatomite Incorporated Composite Scaffolds for Skin Repair of Deep Burn Wounds.

Deep burn injury always causes severe damage of vascular network and collagen matrix followed by delayed wound healing process. In this study, natural diatomite (DE) microparticles with porous nanostructure were separated based on the particles size through a dry sieving method and combined with gelatin methacryloyl (GelMA) hydrogel to form a bioactive composite ink. The DE-containing inorganic/organic composite scaffolds, which were successfully prepared through three-dimensional (3D) printing technology, were used as functional burn wound dressings. The scaffolds incorporated with DE are of great benefit to several cellular activities, including cell spreading, proliferation, and angiogenesis-related gene expression in vitro, which can mainly be attributed to the positive effect of bioactive silicon (Si) ions released from the embedded DE. Moreover, due to establishment of bioactive ionic environment, the deep burn wounds treated with 3D-printed DE incorporated scaffolds exhibited rapid wound healing rate, enhanced collagen deposition, and dense blood vessel formation in vivo. Therefore, the present study demonstrates that the cost-effective DE can be used as biocompatible Si source to significantly promote the bioactivities of wound dressings for effective tissue regeneration.

Effect of Soil Aggregate Separation Methods on the Occurrence Characteristics of Typical Pollutants

To study the distribution characteristics of typical pollutants in soil aggregates using different sieving methods, urban and arable soils were collected from Beijing and separated to different sizes by dry and wet sieving methods, to analyze present concentrations of inorganic chlorine and nine typical heavy metals (Cr, Mn, Co, Ni, Cu, Zn, Cd, As, and Pb). Results revealed that the distribution of wet-sieved aggregates was biased towards microaggregates (&lt;250 μm), while the contrary result was found for the dry sieving method. Inorganic chlorine was more likely to be enriched in &lt;53 μm fractions attained by both sieving methods. However, the content of inorganic chlorine in wet-sieved aggregates was significantly lower than in those that were dry sieved, which means the water’s effect on soluble ions was more pronounced. Heavy metals in urban soils were preferentially enriched in microaggregates no matter what kind of sieving method was applied. As for Mn and As found in agricultural soils using the dry sieving method, they were preferentially enriched in the fractions of 1000–2000 μm and 250–1000 μm, while the other seven heavy metals were preferentially enriched in &lt;53 μm fractions, indicating that Mn and As in agricultural soils were easily transferred in aggregates with different particle sizes. Samples with particle sizes &lt;53 μm showed the highest distribution factors for all heavy metals when the wet sieving method was applied. The dry sieving method resulted in a higher mass loading of heavy metals in coarser fractions and lower proportions in finer fractions. Results of a potential ecological risk analysis showed that the ecological risk (Eri) value of Cd found in aggregates by the different sieving methods was significantly different (p &lt; 0.05). The findings suggest that different sieving methods could result in different occurrence patterns of pollutants in the soil aggregates of different land use types.

Archaeobotanical evidence of agricultural products in the southern Mediterranean part of Turkey during the Bronze Ages from Tatarlı Höyük

In this study, archaeobotanical data were gathered from the Early, Middle, and Late Bronze Age layers (2400-1200 BC) of the Tatarlı Höyük exposed in the 2011?2012 excavation seasons in the Ceyhan district of Adana Province were evaluated. In 8 trenches relating to these periods, archaeological contexts such as inside areas, hearths, ovens, middens, ceramic pots, etc., as well as contexts with carbonized plant remains were recovered by using dry and wet sieving methods, corresponding in total to 90 soil samples. The major agricultural plants identified were Triticum monococcum (einkorn wheat), Triticum dicoccum (emmer wheat), Triticum aestivum (bread wheat), Hordeum vulgare (barley), and Lens culinaris (lentil) species. Identified Vitis sylvestris (wild vine), Vitis vinifera (vine), and Olea europaea (olive) species show that fruit cultivation and accordingly wine and olive oil production were carried out during these periods. Archaeobotanical data revealed the changes in the cultivated species during the different Bronze Ages, showing which species were preferred in different periods and whether changes in the climate affected those preferences.

Particle size distribution of hammer-milled maize and soybean meal, its nutrient composition and in vitro digestion characteristics

The mean particle size of ground grains influences both pig growth performance and gastric health although this effect is not consistent and the underlying reasons are not fully understood. The inhomogeneous nutrient content distribution in particles of different sizes and the characteristics of particles may be reasons for inconsistent findings. The objective of the present study was to determine the nutrient content and physical characteristics of individual size fractions of hammer-milled maize and soybean meal (SBM), and to relate it to in vitro digestibility. Maize and SBM were hammer-milled over a 6- and 2-mm size screen, respectively, and were sieved into seven fractions. Particle characteristics of the hammer-milled material were determined by dry sieving, wet sieving and image analysis methods; the nutrient composition including dry matter, ash, crude fibre (CF), crude fat (CFat), crude protein (CP), starch and in vitro digestibility of organic matter (OM), CP (SBM) and starch (maize) were measured and nitrogen-free-extract was calculated. The results show that the nutrient composition differed among fractions of ground maize and SBM (P < 0.001). A large difference in starch levels (754.2 vs 578.9 g/kg) of maize was observed between the various sieve size fractions whereas the CP content of SBM increased with larger sieve sizes. The in vitro digestibility of OM and CP was different (P < 0.001) among the various particle size fractions for both ingredients. However, the in vitro digestibility of starch did not differ between each size fraction in maize (P = 0.060). The regression models relating the nutrient composition and in vitro digestibility show that the digestibility of OM was positively related to the starch level (P < 0.001). As for SBM, CF (negatively) and CFat (positively) were correlated with OM digestibility (P < 0.001); ash and CF had a negative effect on the digestibility of CP, though CFat had a positive relation with the CP digestibility (P < 0.05). Using image analysis, the OM digestibility of different fractions of maize and SBM could be related to the projected perimeter (R2 = 0.933) and solidity (R2 = 0.704) of particles in a linear model. The presented data show that the nutrient composition and physical characteristics of materials among various size fractions of hammer-milled maize and SBM differ and may explain pig growth performance differences observed in commercial production.