Wet Sieving Research Articles

Does biochar application improve soil aggregation? A meta-analysis

Biochar as a potential soil amendment has been widely used in agricultural soils for improving soil physical properties. However, the effects of biochar addition on soil aggregation are inconsistent in many individual studies. Therefore, we conducted a meta-analysis of 641 comparisons from 119 published studies to assess the combined effects of biochar application on soil aggregation through biochar attributes, initial soil properties, and experimental conditions. Overall, our results indicate that biochar application significantly improved soil aggregation by 16.4 ± 2.5 %, regardless of biochar/experimental/soil conditions. The response ratio (lnR) of biochar-induced soil aggregation had significant variability across different studies. In the context of biochar attributes, there was a higher favorable influence of wood biochar with higher pyrolysis temperature (> 600 °C). With the amount of biochar increased, the effects of biochar on soil aggregation significantly improved (P < 0.001). Considering experimental conditions, the advancement of soil aggregation was more significant over a longer period of time (> 3 years). In particular, the wet sieving method (18.2 %) is better than the dry sieving method (4.05 %) for assessing soil aggregation. Moreover, soil aggregation intensified in neutral and acidic soil, while alkaline soil was not significantly changed. Also, biochar amendment strengthened soil aggregation in the loam-textured (19.9 %) soils relative to sandy soils (13.4 %). Our meta-analysis demonstrates that biochar as a soil amendment can improve soil aggregation through the combination of experimental conditions with specific biochar, and soil properties.

Étude de l’habitat et des exigences écologiques du Vertigo geyeri Lindholm, 1925 dans le Massif jurassien

Le Vertigo septentrional (Vertigo geyeri Lindholm, 1925) est un Mollusque millimétrique inscrit à l’annexe II de la Directive Habitat-Faune-Flore. La Franche-Comté, qui constitue la limite occidentale de son aire de répartition continentale, abrite le principal bastion de cette espèce au niveau national, ce qui lui confère des responsabilités particulièrement élevées pour le maintien de cette espèce en France. Dans le cadre d’un stage de deuxième année de master, une étude a été conduite afin de caractériser l’habitat et les exigences écologiques du Vertigo geyeri en Franche-Comté, par l’analyse des cortèges botaniques et malacologiques associés, ainsi que les composantes environnementales clés pour cette espèce. Ainsi, 32 sites ont été échantillonnés en 2016 et 2018 dans le Massif jurassien, sur lesquels un relevé malacologique utilisant la méthode du wet sieving a été effectué, en complément d’un relevé botanique phytosociologique comprenant les trachéophytes et les bryophytes. La connaissance de la distribution du Vertigo geyeri dans le Massif jurassien a pu être améliorée, avec à ce jour 62 stations connues en Franche-Comté. Suite à cette étude, nous pouvons estimer que Vertigo geyeri est associé aux tourbières basses neutroclines minétrophes à trèfle d’eau et amblystégiacées (Caricenion lasiocarpae), avec comme espèces structurantes Menyanthes trifoliata L. et Scorpidium cossonii Hedenä. Ces zones humides sont généralement ouvertes, situées au sein de réseaux hydrologiques importants avec une végétation éparse et un sol constamment humide et limité en nutriments.

Sahilkent (Bafra, Samsun) yöresindeki alüvyal zeminlerin sıvılaşma potansiyelinin CPT verileri kullanılarak araştırılması

In this study, liquefaction potential of the alluvial soils consisting of clay, silt, and sand sized materials in Sahilkent (Bafra, Samsun) area was investigated using CPT data. Within the scope of the study, 20 boreholes each having a depth of 15 meters were drilled throughout Bafra district, and one undisturbed soil sample were obtained per meter from 5 of these boreholes located in Sahilkent area. Wet sieve, hydrometer, plastic limit, liquid limit, and natural water content determinations were conducted on 20 samples with high silt and sand content. In the preliminary evaluation, it was determined that there is a liquefaction potential in some regions at different depths, and in order to perform detailed liquefaction analyses, 15-meter-deep CPTu were carried out in 1 meter distance from those 5 borehole locations. In CPTu tests, data including cone tip resistance, sleeve friction, effective stress, relative stiffness, etc. were recorded every 5 cm, and average values of these data for each meter depth were used in the liquefaction analysis. Liquefaction analyses was conducted for an earthquake scenario of Mw = 7.2 and the liquefaction potential of the 15-meter soil layer in the study area was determined. As a result of the analyses, it was determined that no liquefaction will occur for an earthquake scenario of Mw = 7.2 in Sahilkent region. It is thought that high fine-grained content of the alluvium, and the fact that existing clean sand levels are located between fine-grained soil layers increase the resistance of the soil against liquefaction.

Modified Humic Substances as Soil Conditioners: Laboratory and Field Trials

The paper is devoted to the development and performance testing of a soil conditioner based on leonardite humic substances (LHS) modified with 3-aminopropyltriethoxysilane (APTES). The modified HS were obtained by adding APTES to LHS solution at different mass ratios of LHS and APTES, followed by the investigation of siloxane structures using 31Si NMR spectroscopy. The Urbic Technosol was used as a model soil. The size and amount of water-stable soil aggregates were estimated using wet sieving and laser diffraction, respectively. Toxicity was evaluated by monitoring microbial substrate-induced respiration (SIR) and seedling bioassay. Laboratory column experiments demonstrated an increase in water-stability of the 3–5 mm soil aggregates after LHS-APTES application. Field tests showed an increase in the average weighted diameter of micro aggregates (from 59 to 73 μm) and water-stable macroaggregates (from 1.6 to 2.9 mm) due to the LHS-APTES amendment. A substantial increase in SIR from 5 to 9 mg CO2 (kg h)−1 was detected. Better survival of seedlings was observed. The obtained beneficial results indicate that APTES-modified HS can be successfully used as a soil conditioner. The formation of extended siloxane networks was suggested as the main mechanism of the observed improvement in the structure of the amended soils.

Risks and phyto-uptake of micro-nano size particulates bound with potentially toxic metals in Pb-contaminated alkaline soil (NW China): The role of particle size fractions

The fate and risk in the environment of potentially toxic metals (PTMs) pollutants depends on the size-fractions of contaminated soil. In this study, the variable micro-nano size-fractions of 50–250 μm, 5–50 μm, 1–5 μm, <1 μm in long-term Pb-contaminated alkaline soil (NW China) were obtained by Sequential Wet Sieving Separation Procedure (SWSSP). The chemical speciation, mobility and risk of PTMs in micro-nano particle fractions as well as their uptaken and translocation in Maize (Zea mays L.) plant were systematically determined. The results demonstrated that higher accumulation of both investigated PTMs was observed in the fine fractions of <1 μm. The metallic Pb predominantly occurred in all size-fractions (65%–86%) identified by XPS, and the reducible forms of lead oxide (Ⅱ,Ⅳ) would also likely preferred to enrich in the fine fraction of <1 μm. The mobility and bioaccessibility of PTMs in fine fraction of <1 μm were higher than other fractions, which were identified by the multi-indices, enrichment factor (EF), accumulation factor (AF), mobility factor (MF), potential ecological risk index of single metal (Eri) and the comprehensive potential ecological risk index (RI). The scenario for phyto-uptake of Pb and Cu in <1 μm soil nanoparticles under pot tests indicated that the Pb and Cu enriched in <1 μm with high ecological risk were inclined to translocate into the Maize roots and shoots with nano size fractions. The results implied that further environmental management should be needed in order to prevent the risk of PTMs from Pb-bearing micro-nano size fractions in the industrial contaminated alkaline soil.

Processing of Iraqi Attapulgite For Using as Drilling Muds: A Comparison Study

Clay mineral processing is in charge on quality, quantity and functional properties of final produced clay. In this work, Iraqi attapulgite (Palygorskite) clay was processed with dry sieving, dispersing agent and wet sieving processes to make it suitable in oil and gas wells drilling fluids preparation. Yield of clay (quality) and yield of process (quantity) were taken as preferring criteria in choosing the proper process of Iraqi attapulgite clay preparation. XRD and FESEM tests were used for mineralogical and morphological identification respectively. OFITE viscometer was used to measure the rheological properties of the drilling fluids prepared with the produced attapulgite from the investigated processes. The results of this work showed that dry sieving process was failed in attapulgite separation. Moreover, dry grinding was a destructive process of the attapulgite crystalline structure which reduced the rheological properties up to 80%. The results showed that the dispersing agents process produces attapulgite clay with higher quality (101.94 and 89.87 barrle/ton) with fresh and salt water respectively and at low quantity of about 7%. While wet sieving process produces attapulgite clay with quality equals to (94.21 and 79.93barrel/ton) with fresh and salt water respectively and quantity reaching 40%. It follows that wet sieving was the recommended process in preparing Iraqi attapulgite to be suitable for oil and gas wells drilling fluid

Processing of Iraqi Attapulgite For Using as Drilling Muds: A Comparison Study

Clay mineral processing is in charge on quality, quantity and functional properties of final produced clay. In this work, Iraqi attapulgite (Palygorskite) clay was processed with dry sieving, dispersing agent and wet sieving processes to make it suitable in oil and gas wells drilling fluids preparation. Yield of clay (quality) and yield of process (quantity) were taken as preferring criteria in choosing the proper process of Iraqi attapulgite clay preparation. XRD and FESEM tests were used for mineralogical and morphological identification respectively. OFITE viscometer was used to measure the rheological properties of the drilling fluids prepared with the produced attapulgite from the investigated processes. The results of this work showed that dry sieving process was failed in attapulgite separation. Moreover, dry grinding was a destructive process of the attapulgite crystalline structure which reduced the rheological properties up to 80%. The results showed that the dispersing agents process produces attapulgite clay with higher quality (101.94 and 89.87 barrle/ton) with fresh and salt water respectively and at low quantity of about 7%. While wet sieving process produces attapulgite clay with quality equals to (94.21 and 79.93barrel/ton) with fresh and salt water respectively and quantity reaching 40%. It follows that wet sieving was the recommended process in preparing Iraqi attapulgite to be suitable for oil and gas wells drilling fluid

Palaeoethnobotanical analysis of plant remains discovered in the graveyard of the Haihun Marquis, Nanchang, China

Analysis of plant remains of 73 taxa obtained from the graveyard of the Haihun Marquis (circa 59 bc) at Nanchang, China, is presented. Chronology was confirmed by direct AMS radiocarbon dating of both a seed and wood, while plant seeds were collected by wet sieving. Detailed composition of the samples suggests that the fundamental landscape of the graveyard was composed of Platycladus orientalis, a symbol of solemnity and compatible with the high status of the tomb owner Liu He. Furthermore, seeds of Sapium sebiferum, Castanopsis sclerophylla and Lauraceae, among other high-status plants were also discovered and thus could be included in the landscaping of the graveyard of the Haihun Marquis. In addition, plants like Poaceae, Santalaceae, Cyperaceae and Broussonetia sp., among others, represented a considerable share of the graveyard growth. Fruit stones of Amygdalus persica, Armeniaca mume and Cerasus pseudocerasus discovered in the well may have been included as fruit trees, but grew outside the graveyard. In the main tomb (M1), remains of five plant were discovered, i.e. Oryza sativa (rice), Cannabis sativa (hemp), Setaria italica (foxtail millet) and Cucumis melo (sweet melon), as well as Armeniaca mume (Japanese apricot) and had been placed in the tomb for further use as cereals and fruit by the deceased in the world beyond, thus also demonstrating diversified plant use in the Western Han Dynasty.

Production of High-Purity Silica Sand from Ivorian Sedimentary Basin by Attrition without Acid Leaching Process for Windows Glass Making

To produce high-purity silica sand usable for glass making, the present study was carried out. The objective of this work was to increase the silicon dioxide (SiO2) content to at least 99% using a simple process without chemical input. The raw sand samples were taken from the Ivorian sedimentary basin, from Maféré and Assinie areas, Côte d’Ivoire. Wet sieving and attrition technique were used for the purification process. The results from the energy dispersive spectrometer (EDS) analyses of the raw and treated samples show a significant increase of silica content and a significant reduction of impurities. The silica content (SiO2) of the sand of Maféré increases from 98.73% ± 0.15% to 99.92% ± 0.05%. And the sand of Assinie increased from 98.82% ± 0.67% in the raw samples to 99.44% ± 0.27% after treatment. The rate of iron oxide and alumina is reduced in these sands. Moreover, the sand of Maféré contains 53.2% of grains of size lower than 500 microns and that of Assinie contains 29.30%. Regarding the chemical composition of these purified sands, they meet the standard BS2975s, the American Ceramic Society and the National Bureau of Standards for window glass making.

黄土高原天然次生林植被演替过程中土壤团聚体有机碳动态变化

土壤团聚体物理保护是促进有机碳积累主要机制之一。以黄土高原子午岭林区天然次生林植被演替群落为对象，研究从农田、草地（白羊草，Bothriochloa ischaemum）、灌木林（沙棘，Hippophae rhamnoides）、先锋林（山杨，Populus davidiana）到顶级林（辽东栎，Quercus liaotungensis）5个植被演替阶段0-20 cm土壤团聚体稳定性和团聚体有机碳的动态变化，并分析团聚体有机碳的影响因素。结果表明：土壤团聚体稳定性随着植被演替显著提高（P<0.05），顶级林的团聚体稳定性最高；土壤有机碳含量和各粒径土壤团聚体（> 2 mm、2-0.25 mm、0.25-0.053 mm、<0.053 mm）有机碳含量均随着植被演替而增加。除草地0.25-0.053 mm团聚体有机碳含量最高外，其他演替阶段均为0.25-2 mm粒径最高。根系生物量、凋落物生物量、微生物生物量碳、团聚体稳定性均与团聚体有机碳含量呈显著正相关关系（P<0.05）。总体而言，长期植被演替有助于团聚体稳定性和团聚体有机碳累积。;Vegetation restoration plays an important role in soil structure and nutrients. The effects of vegetation restoration on the aggregate stability and soil carbon storage have been widely studied, but the distribution of aggregate associated organic carbon and the effects of plants on aggregate associated organic carbon in the secondary forest succession are still unclear. This paper studied the stability of soil aggregates and the changes of soil aggregate-associated organic carbon under the succession sequence of the secondary forests in Ziwuling forest region of the Loess Plateau, China. We discussed the dynamics of aggregate-associated organic carbon and its influencing factors following the secondary forest succession. In the field investigation, five vegetation succession stages were selected:farmland (CL), grassland (GL), shrub (S), pioneer forest (PF), and climax forest (CF). Soil samples in 0-20 cm were collected and the aggregates were separated by wet sieving. The stability of aggregates was characterized by mean weight diameter (MWD), geometric mean diameter (GMD), and percentage of water stable aggregates (WAS). The organic carbon, root biomass, litter biomass and microbial biomass carbon (MBC) of soil and aggregates were measured. The dynamics of soil aggregate-associated organic carbon and its influencing factors were analyzed. The results showed that soil organic carbon contents increased with vegetation succession, which showed that CF>PF>S>CL, and the organic carbon contents of aggregates increased more significantly from grassland to pioneer arbor stage. The succession of vegetation communities significantly increased the content of soil organic carbon. The stability of soil aggregate increased significantly with vegetation succession (P<0.05). The stability of soil aggregate in climax forest was the highest, and the contents of macroaggregate>0.25 mm in pioneer forest and climax forest were higher than that in farmland. The organic carbon contents of soil aggregates with different particle sizes increased with vegetation succession, and the organic carbon content of 2-0.25 mm was the highest in each succession stage. The stability of aggregates was positively correlated with the soil organic carbon. Root biomass, litter biomass and the MBC were significantly positively correlated with aggregate-associated organic carbon content. The main factors affecting soil organic carbon contents of aggregates were different in different particle sizes. Except the stages of vegetation succession, soil total organic carbon, litter biomass and soil aggregate stability were the main factors affecting the organic carbon content in the macroaggregates (> 0.25 mm), middle aggregates (0.25-0.053 mm), and microaggregates (<0.053 mm). The study suggests that vegetation succession plays an important role in the stability of aggregates and the fixation of organic carbon in aggregates.

马尾松人工林土壤各粒径团聚体湿筛后的有机碳分配

选取25a、45a和65a马尾松人工林为研究对象，采用湿筛法对各粒径土壤团聚体分别湿筛。探究了马尾松人工林各粒径团聚体湿筛后的团聚体有机碳分配，以探讨各粒径团聚体湿筛后分配到同一粒级团聚体有机碳含量及其对团聚体水稳性的贡献差异。结果表明：种植年限增加显著降低土壤团聚体水稳性（P<0.05）；各粒径团聚体湿筛后分配的有机碳随粒级减小含量呈先降后增趋势，以保持原粒级团聚体有机碳（12.96-32.01 g/kg）含量最高，其次是<0.25 mm粒级（8.08-23.53 g/kg）。各粒径团聚体湿筛分配到同一粒级的有机碳以保持原粒级的含量最高（P<0.05）；土壤团聚体水稳性与各粒径团聚体湿筛后保持原粒径的有机碳呈显著或极显著正相关（P<0.05或0.01），分配到越小的粒级正相关性越不显著。此外，团聚体水稳性与各粒径团聚体湿筛分配到同一粒级的有机碳呈正相关，以保持原粒级相关性最高（P<0.01或0.05）；回归方程及相关性系数表明，有机碳与保持原粒径团聚体呈显著呈或极显著正相关（P<0.05或0.01），与消散到其他粒级的团聚体呈负相关或极显著负相关（P>0.05或<0.01）。本研究得出有机碳含量增加促进更大粒径团聚体形成。反之，促使大粒径团聚体向较小粒径团聚体转化。同一粒级团聚体间，保持原粒级团聚体比易转化形成更大粒级团聚体有更高的有机碳含量和更强的水稳性，这对团聚体的固碳提供了新的认识。;Compared with the traditional Elliott wet screen method, the modified wet screen method can be used to analyze the difference in organic carbon for the wet sieving of each particle size aggregate to the same size. This study selected 25a, 45a and 65a Masson Pine plantations as the research objects. Soil aggregates with different particle sizes were wet-screened by wet screening method. The organic carbon distribution of soil aggregates with different particle sizes in Masson Pine plantation was investigated after wet screening. The purpose is to explore the difference of the organic carbon distribution to the same size after wet screening of aggregates of various particle sizes and its influence on the water stability of aggregates. The results showed that the increase of planting years significantly decreased the water stability of soil aggregates (P<0.05); After wet screening, the organic carbon content of each particle size aggregates decreased firstly and then increased with the decrease of grain size, so as to maintain the highest organic carbon content of the original particle size aggregates (12.96-32.01 g/kg), followed by <0.25 mm particle size aggregates (8.08-23.53 g/kg). Wet sieve agglomerates of various particle sizes allocated to the same size of organic carbon to maintain the highest content of the original size (P<0.05); There was significantly or extremely significantly positive correlation between the water stability of soil aggregates and the organic carbon of the aggregates with the original particle size after wet screening (P<0.05 or 0.01). The smaller the particle size was allocated, the less significant the positive correlation was. In addition, the water stability of aggregates was positively correlated with the organic carbon allocated to the same grain size in the wet screen of aggregates with different particle sizes, and it had the strongest correlation with the organic carbon that maintained the original grain size (P<0.01 or 0.05). The regression equation and correlation coefficient showed that the organic carbon had a significantly or extremely significantly positive correlation with the aggregates with original particle size (P<0.05 or 0.01), and an extremely significantly negative correlation with the aggregates dispersed to other particle sizes (P>0.05 or <0.01). This study concludes that organic carbon is an important cementing material for the formation of aggregates, and the increase of organic carbon content can promote the formation of larger size aggregates. On the contrary, it promotes the conversion of large particle size aggregates to small particle size aggregates. In addition, comparison among aggregates of the same grain size, maintaining the original particle size aggregates have higher organic carbon content and stronger water stability than easily transforming into larger particle size aggregates, which provides a new understanding for the carbon sequestration of aggregates.

Effects of fertilization and planting patterns on soil aggregate and carbon distribution in farmland of the Loess Plateau, Northwest China

Based on a long-term experiment in the Changwu Agro-ecological Experimental Station in Xianyang, Shaanxi, China, we examined the effects of fertilization and planting patterns on soil aggregate quantity, aggregate stability and total carbon and organic carbon distribution in different aggregate fractions through dry and wet sieving methods, as well as the TOC combustion method. There were ten treatments, including uncultivated (R), wheat continuous cropping (CK/W), wheat-corn rotation (L), and nitrogen fertilizer (N), phosphorus fertilizer (P), nitrogen and phosphorus fertilizer (NP), organic fertilizer (M), nitrogen and organic fertilizer (NM), phosphorus and organic fertilizer (PM), nitrogen and phosphorus and organic fertilizer (NPM) for CK/W. The results showed that fertilizer application and planting patterns affected soil aggregate distribution and stability, the contents and contribution rates of total C and organic C. Force-stable aggregate was mainly constituted by >0.25 mm aggregate (>67%), which was reduced by fertilization. Continuous cropping decreased micro-aggregate while rotation facilitated it and the effect was larger than fertilization. Water-stable aggregate was mainly comprised of micro-aggregate (<0.25 mm), the contribution of which was larger than 61%. Both fertilizer application and planting pattern reduced water-stable micro-aggregate. Fertilizer application and planting pattern decreased the percentage of aggregate destruction rate (PAD) and increased macro-aggregate (>0.25 mm, R0.25) content. Organic fertilizer significantly improved total C and organic C concentrations in all the fractions of force-stable aggregates. Continuous cropping and rotation cropping increased total C concentration in all the aggregate fractions while rotation cropping significantly decreased organic C concentration. Single N and P fertilization decreased soil total C concentration, while mixed application of N and P fertilizers, and organic fertilizer significantly increased soil total C concentration. The effect of planting patterns on soil total C was lower than that of fertilization. Both continuous cropping and rotation cropping increased soil total C. Mixed application of N and P fertilizers, and organic fertilizer signifi-cantly increased soil organic C concentration while single N and P fertilization decreased it. The effect of planting patterns on soil organic C was lower than that of fertilization, while rotation cropping did not facilitate soil organic C. Micro-aggregate was the most notable size fraction to total carbon and organic C, with the contribution being 21.2%-33.6%. Fertilization and planting pattern increased the contribution rate of micro-aggregate in soil total C. NP and NPM significantly increased the contribution rate of micro-aggregate in soil total C and soil organic C. The effect of rotation cropping was most obvious in driving the contribution rate of micro-aggregate in soil total C and soil organic C.

A novel approach to improve the energy and cost efficiency of feedstock drying for pellet production

The success of the pellet industry depends on internal and external factors, comprising pellet quality, pellet production parameters and market variables. This study investigated the pellet production process from the raw material properties to the economic production parameters in order to quantify the feasibility of a new production concept. The proposed concept includes the sieving of the wet feedstock and successive selective drying of the fine fraction, while the coarse fraction is not dried. The impact of this energy saving measure is evaluated in terms of pellet quality, combustion emissions, and production / transport costs and energy consumption. Three sieve sizes were investigated (1.4 mm, 2.0 mm, 2.8 mm). The feedstock was separated and the fine and coarse fraction were equilibrated at 12 and 24% water content, respectively and mixed again for pelletization in a semi-industrial ring dye press. The pellets showed an improved durability and a higher water content, which had both positive and negative impacts on the combustion emissions. The bulk density decreased, which affected the transport parameters negatively. The economic benefit for medium and large scale production was high, mainly depending on the feedstock water content and the thermal efficiency of the dryer. The 2.0 mm sieve caused the best combination of improved durability, reduced emissions, increasing transport costs and thermal energy savings. A post-press reduction of the pellet water content can further improve the pellet quality and reduce combustion emissions, while the process of wet sieving has to be evaluated on industrial scale.

Isolation and Characterization Of Arbuscular Mychorhiza Fungi from Gaharu Wood (Aquilaria spp.) Rhizosphere

In the last 30 years there have been increasing demand of agarwood. Unlimited hunting of agarwood causing it become threatened species. Aquilaria spp. is the main genus producing agarwood that considered as threathened species. Conserving Aquilaria spp. as germ plasm needs is essential against destruction. Arbuscular mycorrhizal fungi (AMF) have been used as inoculant to increase the growth of Aquilaria spp., but information about the existence of AMF in Aquilaria spp. rhizosphere has not been reported. This research was carried out with objective to identify AMF from Aquilaria spp. rhizosphere. Soil and root samples from rhizosphere of Aquilaria spp. taken from four location that is: Carita (A. malaccensis), Ciapus (A. filaria), Cifor (A. crasna &amp; A. malaccensis), and Bantar Kemang (A. beccariana, A. crasna, &amp; A. malaccensis). Roots staining was conducted with modified Phillips and Hayman procedure (1970). Soils sample was run dry wed and placed in pot culture with Pueraria javanica as the host plant. Spore was separated from pot culture using wet sieving and decanting method continued with centrifugation. The result showed the occurrences of AMF in Aquilaria spp. roots i.e. external hypha, internal hypha, coiled hypha, arbuscules, and vesicles. All AMF colony structure found in Aquilaria spp. roots show asosiation bettwen the plant and AMF. Four species of AMF were found i.e. Glomus sp.1, Glomus sp.2, Gigaspora albida, and Dentiscutata sp.&#x0D; Key Words: Isolation, Arbuscule Mycorrhizae Fungi, Rhizosfer, Agarwood

Cropping diversity with rice influences soil aggregate formation and nutrient storage under different tillage systems

AbstractBackground: The soils under continuous rice monocropping are currently facing a serious threat of accelerated soil and environmental quality degradation.Aims: Examining the impact of tillage and cropping diversity on soil aggregate stability and associated nutrients in a sub‐tropical rice ecosystem.Methods: A split‐plot experiment with tillage (minimum, MT vs. conventional, CT) as a main plot and cropping diversity [mustard (Brassica napus)–rice (Oryza sativa)–rice (M–R–R), wheat (Triticum aestivum)–rice–rice (W–R–R), and lentil (Lens esculenta)–rice–rice (L–R–R)] as a sub‐plot was repeated for four years. Soil aggregate properties were measured using wet sieving techniques. Soil organic carbon (SOC) and nutrients were measured in different aggregate size groups as well as in the bulk soil samples.Results: Results show that all the aggregate size groups were similar in both MT and CT, except in 0.85–0.30 mm. Likewise, cropping diversities increased soil aggregation, being higher aggregate size of &lt; 0.053 mm in M–R–R relative to the W–R–R and L–R–R, where the latter two were alike. By contrast, &gt; 2 mm aggregates were higher in L–R–R than in M–R–R and W–R–R, where the latter two were similar. The MT increased aggregate mean weight diameter (MWD) by 14% in W–R–R, and by 29% in L–R–R. Soil organic carbon (SOC), total N (TN), and available P were higher in MT than in CT, while it was alike for exchangeable K and available S. While W–R–R had a higher aggregate‐associated SOC, available P, and available S, L–R–R had a higher TN, and M–R–R had a higher exchangeable K. While SOC, TN, and exchangeable K accumulated more in the &gt; 0.85 mm size aggregates, the available P, in contrast, accumulated more in &lt; 0.85 mm size aggregates.Conclusion: Wheat–rice–rice diversity, coupled with minimum tillage, has a higher potential for soil fertility sustenance and crop productivity through better nutrient protection.

Effect of particle size on the microstructure and distribution of fly ash for metal matrix composite applications

Particle size is an important parameter in the processing of reinforcement particles utilized as particulate metal matrix composites. These particulate reinforcements provide advantages such as high stiffness, high strength, wear resistance properties, corrosion and thermal resistance to metal matrix composites (MMCs). This work attempts to study the effects of ball milling on the density, microstructure and morphology of fly ash. The milling times were varied as 0 mins, 15 mins, 30 mins, 45 mins, 60 mins and 180 mins. The density of the fly ash samples was measured as 2.44 g/cm3 using Le Châtelier's principle. The microstructural analysis showed a change in morphology with increasing milling time. The SEM micrographs showed an agglomeration of the fly ash particles due to the dry milling conditions. The EDS analysis showed the presence of oxygen, aluminium, silicon and iron as the major elements common to all the fly ash samples at the different milling times. The XRD analysis identified mullite (3Al2O3SiO2), silica (SiO2), alumina (Al2O3), wustite (FeO) and hematite (Fe2O3) as the major phases. The particle size distribution obtained via wet sieve analysis showed that 16.3%, 3.9%, 1.76%, 0.43%, 0.1%, and 0% were retained for the 0mins, 15 mins, 30 mins, 45 mins, 60 mins and 180 mins milled fly ash samples respectively.

Comparison of digital image analysis methods for morphometric characterization of soil aggregates in thin sections

The purpose of this study was to investigate the applicability of semiautomatic segmentation methods for obtaining and evaluating morphometric parameters of soil aggregates in artificially prepared loose samples in soil thin sections. The object of the research is typical arable Chernozem. The aggregates were separated by wet sieving method from loose sample of upper 10 cm of the plowing horizon after erosion by a model shallow water flow on a large erosion tray. The aggregates, loosely scattered on the glass and fixed with polyester resin, were used to produce the thin sections. Images of the thin sections were taken under a polarizing microscope and then were processed using two methods compared: Adobe Photoshop + CTan and Thixomet Pro. Data on morphometric parameters of aggregates were obtained: the shape factor, the degree of roundness and the coefficient of aggregate surface roughness. The convergence of the results obtained using Photoshop + CTan by three researchers was evaluated by comparing samples using the Student's test and the Mann-Whitney test. The convergence of the averaged results obtained using Photoshop + CTan and the results obtained using Thixomet Pro was evaluated using the Mann - Whitney test. No significant differences were found between the parameters of the same aggregates obtained using a combination of Adobe Photoshop and CTan programs by different researchers. No significant differences were found between the parameters of the same aggregates obtained by the compared methods. So, one can conclude that the reliability of determining the morphometric parameters of soil aggregates using Thixomet Pro is comparable to the reliability of results when working with images of sectionsin CTan after binarization in Adobe Photoshop. The method of obtaining data on morphometric parameters of soil aggregates using Thixomet Pro completely eliminates the possibility of subjective error, shows a high degree of automation, reproducibility and reliability of the results obtained, and is faster.

Comparison of different methods for assessing effects of soil interparticle forces on aggregate stability

Soil interparticle forces, involving in van der Waalsattractive force, and surface hydration and electrostatic repulsive forces, greatly influence the soil aggregate stability. However, current studies on methods for evaluating the impact of soil interparticle forces in aggregate stability are scarce. This research was aimed to examine the impact of soil interparticle forces on aggregate stability using diverse methods for different soil types. Soil aggregate stability was tested through the pipette method, wet sieving, and rainfall simulation, respectively characterized by aggregate stability index (ASI), mean weight diameter (MWD), and splash erosion mass (SE). Soil interparticle forces were adjusted by the changing concentrations of NaCl solution. The results showed that all three approaches can be applied to study the impact of soil interparticle forces on aggregate stability. The ASI, MWD, and SE showed little change below 10−2 mol L−1 NaCl concentration and then ASI and MWD increased at a high rate above 10−2 mol L−1 concentration of NaCl, while the SE showed the opposite trend. These results were as expected for soil interparticle forces. Moreover, for a single soil, a substantial correlation existed between the aggregate stability indicators obtained from three methods. However, the order of soil aggregate stability, measured by three methods were varied among soil types. Our results suggest that a single method cannot be applied to determine the aggregate stability of all soil types even if the breakdown mechanism was identical, because organic matter content and particle size distribution of soil are important factors influencing aggregate stability. Hence, in order to compare the difference in aggregate stability between various soils, multiple methods should be considered to investigate the impact of interparticle forces of soil on its aggregate stability. If a single method was to be chosen, wet sieving may be a good choice as it was not only relatively simple and time-saving but also reflected more comprehensive information about sizes and amount of fragments released from soil aggregates.

Comparison of Arbuscular Mycorrhizal Spores Abundance Under Sengon (Falcataria moluccana (Miq.) Barneby &amp; Grimes) Planted on Deep Peat and Mineral Soils

Mycorrhizae are known as soil fungi because of their habitat in the rooting area (rhizosphere). Nearly 97% of terrestrial plant species interact or symbiotic with mycorrhizae. Symbiosis is formed in the form of an exchange between nutrients and carbohydrates and helps plants absorb P. elements. In Kalimantan, sengon often used as industrial material because it is fast-growing species and widely cultivated by the community. Sengon is a common species planted in mineral soils; however, due to the rising demand of sengon timber, it has been planted on peatlands. This study aims to compare the abundance of arbuscular mycorrhizal spores and identify the morphology of arbuscular mycorrhizal spores associated with Sengon planted on peatlands and mineral soils. This study used a wet sieving method and root staining from the modification of Vierherling et al. 1996 and calculation of root mycorrhizal colonization with gridline techniques. The research used the normality test of data distribution and the T test (Independent sample T test) to determine trends and comparison of differences in the abundance of FMA spores. The study results showed a significant difference in the abundance of AMF in the form of colonization by calculating the percentage of AMF colonization in the sengon root in mineral soils and peatlands of 23.56% 41.67%, respectively. The spore density on mineral soils and peatlands were 18.05 / 50gr and 1.09 / 50gr, respectively. Identification results showed that there were four genera found in peat soil locations, namely the genus Glomus, Gigaspora, Scutellospora, and Acaulospora, while in the mineral soil were found three generas namely genus Glomus, Scutellospora, and Acaulospora. Out of the four generas, the most abundant in both soil types was Glomus.

Temperature dependence of volcanic ash soil aggregate stability: Effects of fertilizer application

Soil structures and associated physical properties are strongly affected by soil wetness and temperature, especially when physically treated for sterilization. Effect of soil temperature on soil aggregate stability under wet condition is, however, still not well understood. This study aimed to investigate the effect of temperature on aggregate stability of soils treated with chemical fertilizers (F plot) and organic fertilizers (M plot) originating from cattle manure. We proposed a two-step wet sieving method in which samples were wet sieved at 20 °C and then at an increased constant temperature during the second wet sieving step in a water column. Macro-aggregates (≥250 μm) collected from the M plot disaggregated less compared to those from the F plot, indicating that they were more stable. As opposed to the macro-aggregates, micro-aggregates (<250 μm) were generally stable against temperature regardless of the fertilizer type. The polysaccharide content in the suspension in the soil column after the second wet sieving increased more than twofold when the temperature was increased from 20 to 80 °C for the macro aggregates of the F plot, suggesting the importance of polysaccharides in aggregate stability against temperature.