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Due to large areas of abandoned land in Russia, it is necessary to identify indicators that allow to determine evolutionary direction of properties and composition of post-agrogenic soils. This is necessary for the rational use of abandoned areas. One of these indicators is the mineralogical composition of fraction <1μm, which define the stocks of plant nutrients and a number of physical properties and soil fertility.The aim of the study is to identify changes in mineralogical composition of the upper horizons of postagrogenic soils.We've selected two plant communities in the South of the Arkhangelsk region, Russia (middle taiga zone) which are at different stages of succession: young (18-years old) and old spruce forests (70-years old). Both soil profiles are characterized by the presence of morphological features of the arable horizon. Sub-horizons of arable part were identified for more detailed study.To separate <1 micron (clay) fractions samples were rubbed into a thick paste and sedimented. Oriented preparations of fractions were examined by XRD method. The clay fraction of the studied sub-horizons is represented by the following components: mixed-layer formation, trioctahedral illite, chlorite and kaolinite. There is a high amount of fine quartz and small admixture of K-feldspar and plagioclase.Under old spruce forest the content of clay fraction in the micro-profile of the upper horizon does not change with depth (4.0%). Mixed-layer minerals dominate both in the fraction (49%-56%) and in the soil (2.0-2.3%) in samples from all depths. There is a relative increase in the content of mixed-layer minerals in the fraction to the bottom of micro-profile. The content of illite and kaolinite slightly decreases to the lower part of profile. The amount of mixed-layer minerals and illite in the upper part is higher than in the lower part recalculating to the whole soil sample.Content of clay fraction under young spruce forest is higher (6.3-7.2%) comparing to the old forest profile. The amount of clay is slightly reduced towards the bottom of the microprofile. Mixed-layer minerals are also dominant (50-57%). Distribution of minerals in the fraction is different: the amount of mixed-layer minerals in the upper part of the profile is higher than in the lower part what corresponds to fraction distribution. Content of kaolinite increases to the bottom, while chlorite does not change significantly. The highest amount of illite is observed at a depth of 10-15 cm.Both microprofiles under spruce forests are homogeneous, what does not allow to differentiate the sub-horizons on the macromorphological level. Podzolic process under 70-years spruce forest led to a bleaching of the upper horizon and to a light grain size distribution. There are trends in changing the mineralogical composition in the young spruce forest. The destruction of some minerals is at the initial stage, as can be seen on the XRD patterns of the clay fraction. The crystallinity of minerals is improving to the bottom of the micro-profile (based on the shape of the peaks). [ABSTRACT FROM AUTHOR]

It is well known the increasing difficulty of finding out clay deposits adequate both in quality and size, able to supply the traditional pottery industry existent in the District of Évora, Portugal. To overcome such difficulty one project was planned aiming at the use as pottery raw materials of the clay-rich "terra rossa" that overlies the marble deposits that occur in the region of the Anticlinal of Estremoz, as well as other local clay-rich non residual soils, and fine grained carbonate-rich (around 99% of CaCO3) wastes (sludges) derived from the sawing and polishing of marble stone in local processing industrial plants. In such context "terra rossa" samples (Lagoa and Borba VV) and clay soils (sample Biblio VV) have been studied. The textural, mineralogical and chemical characteristics of the sludge materials referred to have been studied too. Along this study, the raw materials had suffered some improvement which included drying, breakdown, cutting and granulometric partition to 0.250 mm. Afterwards, some sample portions were removed for tests of physical, mineralogical and technological characterization. From the results obtained, five ceramic paste were formulated and, subsequently, subject to technological tests in the laboratory of Cencal – training centre for the ceramic industry of Caldas da Rainha. The research culminated with an industrial test on Olaria XT (traditional pottery), with the shaping of some pieces on Potter's wheel, and subsequent evaluation. From the technological results, it was concluded that all the studied samples showed an excellent plasticity and workability, having obtained great results during extrusion and conformation of the test pieces. Despite the low values of mechanical resistance to bending in raw, it was possible to handle the ceramic pieces without causing defects, with a substantial increase of the values with the rising temperatures of cooking up to 950 °C. The lower values of dry/cooked retraction and total retraction in this study are associated with the use of the carbonated mud. The industrial test revealed that all ceramic pastes showed excellent workability, resembling the industrial pastes, traditionally used. After the industrial test, it was also found that almost all pottery pieces were flawless with high toughness, with special highlight for the raw material Biblio VV. After all the work, it was possible to prove that technically it is feasible to apply these raw materials in traditional pottery, and the values obtained are promising, with some of them capable to compete with the results corresponding to the commercial pastes typically used.References:[1] Alves, T. 2015. Formulação de Pastas Cerâmicas a partir de Matérias-Primas Argilosas dos Concelhos de Vila Viçosa e Redondo para a Produção de Olaria Tradicional. Unpublished Master's thesis in Geological Engineering, University of Évora. Portugal, pp. 251. AcknowledgmentThe authors acknowledge the funding provided by ICT, under contract with FCT (the Portuguese Science and Technology Foundation). Trabalho co-financiado pela União Europeia através do Fundo Europeu de Desenvolvimento Regional, enquadrado no COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização) através do projeto ICT (UID/GEO/04683/2013) com a referência POCI-01-0145-FEDER-007690. [ABSTRACT FROM AUTHOR]

The volatile organic compounds (VOCs) in soils stem from a large variety of different sources within soils as soils act as both sources and sinks for these compounds. Many of the VOCs formed in soils are produced by soil microorganisms living within them. There have been many efforts to fingerprint the VOC profiles from these complex microbial habitats, most of which are based on the use of solid phase microextraction (SPME). This automated extraction method allows the monitoring of the community structure, physiological state, and activity of any microbial community in a soil without the need of manual extraction or cultivation procedures.SPME is a fast, economical and solvent-free methodology widely used for the environmental analysis of soils in combination with GC-MS. The methodology using SPME in headspace (HS-SPME) analysis has been used to determine VOCs in a wide range of different soils of varying textures, organic matrices from manures and composts from different origins.In this presentation we discuss an innovative mode of extending the sensitivity of SPME extraction called SPME-trap in which a refocussing cold trap is used to further pre-concentrate analytes released from a SPME fibre used on soil samples before the analytes are injected into the GC-MS system. Other techniques commonly used to monitor the VOC fingerprints from soils are static headspace, headspace- or immersive- high capacity sorptive extraction or thermal desorption using sorbent-packed tubes for active or passive, in situ sampling of soil. The focusing trap technology used in this study allows the combination of all these techniques to be run on a single analytical system without the change of hardware; it also allows single and multiple extractions to be carried out automatically on a single sample to increase the analytical sensitivity, thus achieving a comprehensive VOC profile. To illustrate the enhanced capabilities of SPME-trap we investigate the fingerprints of VOCs for a 50 cm soil profile of a loamy and clayey floodplain soils with naturally high groundwater around Llantrisant, UK with a variety of different VOC sample preparation methods showing the benefits of adding high-performance trapping technology to the VOC analysis of soils. [ABSTRACT FROM AUTHOR]

Organic carbon is a key component in soil, which influences important soil physical properties such as soil structure. It has been hypothesized that an association between clay and soil organic carbon (SOC) can increase soil porosity and structural stability. This association can also enhance the storage of SOC itself through physico-chemical stabilization. If SOC has an impact on soil structure, SOC should also influence water flow and solute transport in soil; however, the knowledge regarding SOC effect on these soil physical processes is still limited. The purpose of this research was (1) to quantify the amount of stable SOC associated with silt and clay and (2) to reveal how total SOC and the stable SOC fraction influence soil structure and preferential transport.We sampled two different sizes of undisturbed soil cores (n=35) from a conventionally tilled arable field with large variation in clay (9–45%) and total SOC (1.1–2.7%) contents. Large cores (height 200 mm, diameter 125 mm) were used to quantify the degree of preferential transport by conducting non-reactive solute transport experiments and to analyze macropore networks (pores > 0.12 mm) using X-ray tomography. The small cores (100 mm height, 68 mm diameter) were used to determine soil water retention at -30, -100, -300 and -600 cm pressure potential and thus pore volumes corresponding to these pressure potentials. Additionally, we conducted SOC fractionation to obtain the SOC fraction associated with clay and silt sized particles (< 0.063 mm).On average, about 81.7% of total SOC was found in the clay and silt fraction. Regression analysis showed that the degree of preferential transport was positively correlated to the clay content (R2 = 0.56, p < 0.0001) whereas it was negatively correlated to the SOC content (R2 = 0.11, p = 0.0335). The mesoporosity (0.03–0.1 mm) was also negatively correlated to the degree of preferential transport (R2 = 0.55, p < 0.0001), suggesting that increased mesoporosity prevents the activation of macropore flow. A negative correlation between SOC and clay content makes it difficult to isolate effects of SOC on the degree of preferential transport. Therefore, we analyzed a subgroup (n=19) of the data in which there was no correlation between SOC (1.1–2.7%) and clay (16–29%) content. For this dataset, there were no significant correlations between the degree of preferential transport and clay (p = 0.0916) or SOC (p = 0.1945) contents. Instead, the SOC content in the silt and clay fraction was negatively correlated with the degree of preferential transport (R2 = 0.26, p = 0.0146), suggesting that a higher degree of association between clay + silt and SOC reduced the degree of preferential transport. The SOC concentration in the silt and clay fraction was also positively correlated with mesoporosity (R2 = 0.73, p < 0.0001). Overall, our preliminary results indicate that, although the clay content has a strong effect on the degree of preferential transport in this field, SOC reduces preferential transport through its effect on soil structure, particularly the existence of better-developed networks of mesopores. [ABSTRACT FROM AUTHOR]

The physical protection of carbon (C) within aggregates contributes to the total C storage capability of soils. Changes in land use may have an immense effect especially in the topsoil where most of the disturbances (e.g. organic matter input, soil cultivation, surface temperature) intertwine. In strongly weathered and acidic tropical soils, pedogenic metal oxides and low-activity clay minerals should be the most important determinants of aggregation in addition to organic matter. However, it is unknown how different contents of these oxides and clay minerals affect the storage of organic C in aggregates. Moreover, we do not know whether effects of land use change on aggregate related C storage depend on the content of pedogenic oxides and clay in these tropical soils. To answer these questions, we selected an area located in the East Usambara Mountains, Tanzania, with abundant highly leached, acidic Acrisols. We selected each six sites under natural forest and annual cropping, having a similar plant species composition at each land use. Site selection at each land use was done based on strongly different ratios between the contents of pedogenic Fe oxides and oxide-free clay. The long soil development (East Usambara Mountains formed more than 25 million years ago) under these tropical climate conditions resulted in a similar mineral composition, consisting mainly of hematite, gibbsite, and kaolinite. Topsoil material was sampled (0-5 and 5-10 cm) at three slope positions and subjected to an aggregate fractionation by dry sieving. Bulk soils were analyzed for total element contents as well as contents of pedogenic metal oxides, soil texture (including oxide-free clay), pH, soil organic C, and total N. The obtained five aggregate size fractions (>4000 to <250 µm) were analyzed for their C and N contents. The unique characteristics of our gradient enable us to elucidate the influence of contrasting contents in pedogenic oxides and clay minerals on soil aggregation and the related C storage. Forest topsoils contained significantly more C than topsoils under cropland (4.4 vs. 3.1 kg/m²), whereas C storage under cropland was better related to mineralogical proxies. Therefore, we assume that mineral-organic associations are relatively more important for C storage under croplands, whereas labile particulate C contributes more to C storage in forest topsoils. Using all of our results, we will be able to estimate the impact of human disturbance on soil organic C storage along the gradient of pedogenic metal oxides and clay mineral contents. Thus, we will be able to identify the combination of these two factors resulting in the largest aggregate stability and the smallest land use-induced loss in organic C. [ABSTRACT FROM AUTHOR]

While it is generally understood that conservation tillage in heavy soils under a cool, wet climate increases N2O fluxes compared with inversion tillage, the interaction between tillage and manure type on soil N2O fluxes in different textured soils is not well understood. To investigate how long-term applications of different manures interact with tillage effects on N2O fluxes, we established a long-term trial in 2009 in eastern Canada, using two tillage (conventional: inversion at 25 cm in autumn; conservation: harrow at 5 cm in spring) and three fertilizer types (liquid swine manure, liquid dairy manure and a 0-N control) arranged in a split-plot design with 3 replications. The experiment is reproduced on two contrasting soil textures (silty clay and sandy loam) located approximately 800m apart in a wheat-maize-soybean rotation. During 2016 (wheat – Triticum aestivum), 2017 (maize – Zea mays) and 2018 (soybean – Glycine max), we measured the N2O fluxes from each plot using standard non-flow through, non-steady state, manual chambers for the snow-free period (1 April through 30 November). Cumulative fluxes for the snow free periods ranged from 0.4 kg N2O-N ha-1 for the inversion tillage on the sandy loam soil during the third year when soybean was grown without fertilizer, to 7.6 kg N2O-N ha-1 for the cattle manure/conservation tillage on the silty clay soil. Conservation tillage increased soil N2O fluxes for both manure types and the 0-N control in the clay soil (mean flux for all fertilizer treatments over all three seasons were 4.7 and 2.3 kg N2O-N ha-1 season-1 for the conservation and inversion tillage, respectively); while on the sandy loam the N2O flux was similar between the conservation and inversion tillage systems (mean flux for all fertilizer treatments over both seasons were 1.1 kg N2O-N ha-1 season-1 for both the conservation and inversion tillage). Considering that soil organic C may not increase in fine-textured soils under conservation tillage in temperate, humid areas such as eastern Canada, our findings suggest that conservation tillage in fine-textured soils in the region may lead to a net decrease in the GHG balance. [ABSTRACT FROM AUTHOR]

The southeast region subsoil of Mexican Republic is make up of alluvial deposits transported by the different rivers flowing to the Gulf of Mexico (Usumacinta and Grijalva), which deposit along their riverbed different materials including sands, compressible fine soils such as clays and silts, organic soils, peats and their mixtures, producing a very heterogeneous and erratic stratigraphy as in vertical direction as horizontal. From Geotechnical point of view these alluvial soils are materials of low shear resistance and high compressibility; in addition due to the flat morphology of the terrain and the intense rains, the soil remains saturated most of the year. Structures or buildings built on this type of ground, including bridges, buildings, housing units, storage tanks, platforms and drilling towers, road embankments and viaducts, among others, may experience large settlements or differential subsidence causing the inclination of structures (angular distortions) which exceed the permissible values in their service limit state specified in the building codes. The aforementioned can cause serious damages to structures or even the collapse of these constructions which represents a Threat and Potential Georisk for people and their properties. In this article a historic case of one housing buildings at Villahermosa city, in Tabasco México is presented, where there have been differential settlements up to 25.8 cm in 10 m long (building width). The subsoil stratigraphic profile and its physical and mechanical properties are characterized from the geotechnical point of view. Furthermore also the constructive works used to solve the inclination buildings problems are described, including under-excavation and hydrofracturing cement grout injection into the subsoil; the same procedures as they were used to reduce the inclination of Metropolitan Cathedral in México's city and the Leaning Tower of Pisa in Italy in order to preserve both monuments of the world heritage. The first procedure consist in extract small volumes of material into the subsoil of the higher part of the area in order to reduce the differential settlements and level the structures; and the second one consist in the differential cement grout injection into the subsoil to equal the additional settlements that the ground will suffer in the future due to the different strata thickness and the different consolidation degree of the soft soil. [ABSTRACT FROM AUTHOR]

Management strategies aiming to increase SOC stocks in agricultural soils have mainly focused on topsoil layers (0-30 cm), despite increasing research suggests that subsoil is pivotal for SOC storage and stabilization. As a result, there is a knowledge gap between prospects of deep SOC accumulation, and evidence from experimental studies–especially conducted in the long term–that highlight benefits and drawbacks of different management practices.With this work, we studied the SOC stock change in long-term experiments (> 40 years) of northeastern Italy that compare different agricultural systems and soil types. Three long-term experiments were established between early 60s and 70s at the experimental farm of the University of Padova: 1) a crop rotation experiment (starting year 1962), that compares rotations (2, 4, 6 years) and monocultures (maize, wheat, permanent meadow) with different rates of N fertilizer and types of organic amendments in a silty loam alluvial Cambisol, which is the most widespread in the northern plain of Italy (288, 46.8-m2 plots); 2) a soil type and fertilization experiment (starting year 1964), that compares mineral N fertilizer and organic amendment inputs in three contrasting soil types, namely a sandy (Calcaric Arenosol), a clay (Gleyic-Vertic Chernozem), and a peaty (typic sulfisaprists euic, mesic) soil (18, 4-m2 open lysimeters); 3) a soil type and residue experiment (starting year 1970), that combines six mineral N fertilization rates with crop residue incorporation, or removal, in clay, sandy loam and sandy soils (108, 4-m2 open lysimeters). A hydraulic sampler was used to take in each plot undisturbed soil columns (length > 0.7 m), and measure bulk density, SOC content and stock at different layers according to the equivalent soil mass approach. Results showed that agricultural management acted differently among soil types, increasing the SOC layering in naturally poor OC soils. Sandy (22.7 t ha-1) and silty loam (65.5 t SOC ha-1) soils were less efficient to stock SOC than the clay-rich ones in the soil type and fertilization experiment top 70 cm. Clay soil was also associated with the highest SOC distribution in the deepest layer (50-70 cm), 30% vs 26% (sandy) vs 22% (silty loam) of the total SOC stock. In this context, a combination of minimum tillage and organic inputs with high humification coefficient may increase the SOC storage, despite some C saturation capacity occurred, especially in the sandy topsoil layers. Permanent meadow was the most impactful strategy to stock SOC in the long term along the soil profile. Promising strategies were also highlighted by high input farmyard manure (ca. 7 Mg ha-1 yr-1) in maize monoculture systems with deep roots that stocked as much as the meadow, despite being characterized by yearly deep tillage. [ABSTRACT FROM AUTHOR]

Most of our knowledge about the aggregation of soil components into larger structures is derived from analyzing wet-sieved samples, which impedes the quantification of mechanical aggregate stability. Here, we present a dry method to isolate soil microaggregates (< 250 µm) by uniaxial crushing with the goal to preserve their natural structure. To understand how soil texture governs soil microaggregation, we investigated topsoil samples of an agricultural plot in Scheyern (Germany) with clay contents of 19, 24, and 34 %. Microscopic and tomographic observations revealed fine particle microaggregates in the clayey soils, whereas the dry-crushed aggregates in the sandy loam soil included sand grains. These dry-crushed sandy microaggregates showed a high variability when measuring their uniaxial mechanical stability in a loading frame. We compared the dry-crushed microaggregates with wet-sieved ones and found that wet-sieved aggregates had a lower and less variable mechanical stability indicating a more homogeneous structure and fewer occluded sand grains. The more heterogeneous arrangements of dry-crushed aggregates also revealed a higher microbial diversity than the wet-sieved ones. In the dry-crushed aggregates the microbial community composition differed between clay contents, whereas it was similar between small (20-53 µm) and large (53-250 µm) microaggregates. When dispersing the dry-crushed aggregates in water we found mostly aggregates sized approximately 25 µm in diameter. The distribution of such fine particle microaggregates was related with higher concentrations of organic matter in aggregates. Within the dry-crushed microaggregates, the larger size fraction retained more organic matter that was less decomposed than in the smaller size fractions. Our study reveals that dry-crushing enables the isolation of sandy microaggregates, whereas water-stable fine particle microaggregates governed the distribution of organic matter. [ABSTRACT FROM AUTHOR]

Sugarcane fields in Brazil are increasing every year as consequence of biofuel raising demand. Low-intensity pastures are the main sites giving place to the sugarcane crop. As consequence, the pressure to improve the grazing fields' productivity will lead to the pastures intensification, which usually includes practices that were not applied before, such as fertilizer use and soil tillage. Despite their similarities, sugarcane and brachiaria have their peculiarities and their management differs as well. For instances, nitrogen (N) yield might be higher than its input for both crops due to N fixation. Spontaneous brachiaria might inhibits nitrification driven by Bacteria (AOB). This phenomenon would result in the predominance of ammonia oxidizing Archaea (AOA). In sugarcane fields fertilizer is concentrated in bands and liming is performed, what could favor AOB over AOA. Nitrification driven by either one of these two groups of nitrifiers would yield different ratios of N-N2O. In this research we are examining how land use change between pasture to sugarcane affects greenhouse gases (GHGs) emissions; and its relation with shifts in the N cycling functional genes and nitrification and immobilization potentials. The experimental design includes three scenarios: low-intensity pasture (LIP), with no soil management practices; LIP to high-intensity pasture (HIP), in which soil tillage, planting and fertilizer are used; and LIP to sugarcane field. In a thematic project, the land use change was simulated in three experimental sites (n=5; plots 2,500 m2) in regions that represent the expansion of sugarcane in São Paulo State, which produces around 50% of the sugarcane in Brazil. GHG fluxes measurements began with soil tillage, in spring. Sugarcane and pasture were planted in the first week of December 2018. Fields growing sugarcane in the same catena than the one from the experiments were used as reference for long term effects of land use change. Soils in these three sites present a textural gradient, from sandy to clay soil. Despite contrasting soil characteristics, soil use (pasture or sugarcane) significantly affected ammonia oxidizers, being AOA more abundant in pastures and AOB in sugarcane fields (p<0.05). The other quantified functional genes related to N cycling (nifH, nirS, nirK) shifted among sites (p<0.05) but not among soil uses. We are now analyzing the GHG data along with the functional genes upon soil tillage as well the effects of land use change on N immobilization and mineralization potentials. For this purpose we are using an N isotope tracing method. [ABSTRACT FROM AUTHOR]

Сlay soil form on river terraces in Siberia under cold environments with seasonal and perennial frost action, which gives the specific appearance of the soil. We studied the cryogenic structure of clay soil in middle taiga zone of Western and Eastern Siberia.The climate of Western Siberia is moderately cold with mean annual temperature -4 -2°C, mean January temperature -20°C and mean July temperature +18°C. The annual precipitation is 580 mm. The area has insular permafrost. The climate of Central Yakutia (Eastern Siberia) is more continental with mean annual temperature -10.2°C, mean January temperature -38,6°C, and mean July temperature +19,5°C. The annual precipitation is 238 mm. The area has continuous permafrost. Both are covered with taiga forests with larch, pine and Siberian pine. The parent materials of the studied soils are loams, sandy loams, sands of alluvial and ancient alluvial origin.Soils have brownish and pale colors. They have specific caviar structure in B horizons and сryogenic platy structure consolidated with ice in lower horizons. The latter feature is typical for permafrost-affected soils. Micromorphological study of soil thin sections in transmitted and reflected light showed the presence of numerous rounded aggregates with and without Fe-Mn nodules in the center. Mercury porosity showed the presence of a large number of pores of different confiruations, predominantly of small and medium size. The mineralogical composition of clays is characterized by the presence of сhlorite-vermiculite, kaolinite and smectite. There are some types of coatings: clay, humus-clay and carbonate. The West Siberian soils are strongly acid and Eastern Siberia soils are neutral-alkaline. Soils were identified as Cambisols, Alisols, Cryosols, and Planosols according to the WRB.We hypothesized that the specific caviar structure may be ascribed to the frost action.Financial Support: This work was supported by the grant of Russian Science Foundation No. 17-17-01293. [ABSTRACT FROM AUTHOR]

Aggregation confounds soil particles of different sizes into a larger architecture. Such mixtureimpedes resolving which particles build aggregates and how these control the accumulationof soil organic matter (OM). We used a novel method to differentiate microaggregates(&#x003C;250 μm) from dispersed particles based on a dynamic image analysis in water. To identifythe impact of soil texture, we analyzed 25 topsoil samples of an arable site in Scheyern(Germany) with a gradient in clay content of 16-37 % clay and organic carbonconcentrations of 10-15 g kg1. We found that soils with a higher clay content containedlarger microaggregates and more occluded ones. The soils with lower clay contents consistedof less occluded microaggregates while the &#x003C;53 μm aggregates contained higher OMconcentrations. This shows that in the low clay soils a similar amount of OM couldbe held despite containing fewer fine particles and less occluded aggregates. Theadditional OM in the low clay soils was decoupled from the BET specific mineralsurface area which remained constant across the clay gradient. Soils with a highercontent of fine particles were related with the increased preservation of OM throughaggregation and occlusion. Our data reveal that a higher fine particle content buildslarger soil microaggregates and allocates more OM into occluded aggregate units. [ABSTRACT FROM AUTHOR]

DNA-tagged particle tracers have been the subject of several researches as a new tracer for hydrological applications. This tracer potentially permits the production of a large number of identically transported but distinguishable tracers. Such technique facilitates multi-point and multi-time tracer experiments in a specific location without confounding the signal of the different tracers. All of those potential benefits of DNA-tagged particles can effectively improve our understanding on contamination flow origin and its pathways in the subsurface environment.In this study the effect of soil size on the transport of DNA-tagged silica particles is evaluated. We assumed that the presence of preferential flow pathways or dual porosity in a clayey soil can lead to negligible mass recovery rate of tracer in comparison to matrix flow in sandy soil. Thereto, a series of soil column laboratory tests under saturated conditions were conducted. The columns are custom-designed with a diameter of 25 cm and a height of 25 - 28 cm. The columns were in-situ excavated from a clayey Holocene soil from West of the Netherlands; and from a sandy Pleistocene soil from the East of the Netherlands. We not only determined mass recovery rates and advective-dispersive transport parameters of the colloidal DNA-tagged silica particle tracer, but also compared DNA tracer data with deuterium tracer data, applied to the same columns. Finally, we defined the role of preferential flow paths in the columns. [ABSTRACT FROM AUTHOR]

The estimation of adsorption isotherm data is essential to predict adsorption mechanisms that characterise the interactions between soils and solutes in soil aggregates, columns and profiles. Such mechanisms will affect soil filtration function with respect to the transport of reactive solutes. Dye tracer experiments are often used to reflect the transfer of reactive solutes. For soils sensitivity analysis of dye tracer experiments the Ultraviolet-Visible (UV-vis) spectrophotometry is a commonly used method in biochemical and water research field. The linear and non-linear models of Henry, Freundlich, Langmuir, and Dubinin-Radushkevich were used to obtain the adsorption isotherms from batch experiments with Brilliant Blue (E133) for three differently textured soils (glacial till, loess, sand) with (i) mixed bulk soil samples which includes soil organic matter (SOM) and clay-organic coatings, (ii) mixed soil samples in which SOM is destroyed and (iii) clay-organic coatings that are separated from the respective soils. The results indicate that the non-linear Langmuir model (r²: >0.97) reflects the experimental data better and to a larger extent than the three other models (r²: 0.89−0.95). The values of maximum adsorption capacities estimated from the non-linear Langmuir model decrease in the following order: glacial till > loess > sand with iii) > i) > ii). The authors can conclude that a) more clayey soils show a higher adsorption capacity than sandy soils and b) clay-organic coatings are key factors affecting the adsorption capacity of differently textured soils. [ABSTRACT FROM AUTHOR]

Recent literature suggests that soil features can strongly influence the grape, and then wine, characters not only within a wine district, but also within a farm or a vineyard. Although the role of soil hydrology played a basic role for grape features, soil chemistry and microbiology can also have important effects. This multidisciplinary work wants to assess, through a multivariate approach, the possible role of soil microbial communities on winegrape features. Indeed, the study investigated the multivariate relationships among soil features, soil microbial communities and grape quality (Sangiovese cv.) in 8 sites (4 vineyards) of Chianti Classico DOCG districts (Tuscany, central Italy), during three years (2012-13-14). The sites represent four typical terroir of Chianti Classico, which are: i) CALC- stony clayey soils, strongly calcareous, developed on clay-calcareous flysch; ii) SAND – stony sandy soils, non calcareous, developed on feldspathic sandstone; iii) MAR- loamy soils, with medium calcium carbonate, developed on marine sands of Pliocene period; IV) FLUV – loamy soils, with medium calcium carbonate, developed on ancient fluvial terrace. The vineyards have similar age (12-16 years) and belong to the same winery, which uses the same cultivar (Sangiovese cv.) and the same vine and soil management. The overall results of the three years highlighted some significant relationships between grape quality and soil features, in particular gravel content, calcium carbonate, and rooting distribution. On the other hand, microbial richness seems to play a role on grape anthocyanins content, one of the most important index of red grape quality. [ABSTRACT FROM AUTHOR]

Tillage aims at optimizing the soil environment for crop growth and involves alteration of the topsoil structure by mechanical agitation. However, freshly tilled soil is unstable. The tilled layer of soil therefore undergoes slumping, largely caused by climatic forces such as wetting-drying cycles. Slumping is associated with changes in soil structure and associated functions, e.g. fluid transport properties. Although the processes involved in post-tillage soil structure dynamics are generally well established, their quantitative and predictive representation remain limited. The current research project aims at advancing the quantitative description of post-tillage soil structure evolution. A novel small-scale experiment was set up inside an industrial microCT scanner device to study the effects of wetting and drying on soil structural changes within a seedbed. Air-dry soil aggregates were loosely packed up to 35 mm into an aluminium ring (inner diameter: 22 mm; height 59 mm) and placed on a sand bed inside the CT scanner. Next, the sample was wetted from below at a constant pressure head (-1 cm). After 6 hours when the supplied water had reached the top of the sample, the wetting phase was terminated, and air-drying from the top of the column was started and maintained for up to 17 hours. During the wetting-drying cycle, the sample was scanned multiple times (varying time steps). Here, we present results from one clay soil and one loam soil. The onset and termination of different slumping mechanisms (micro-cracking due to differential swelling and coalescence under plastic conditions) were quantified from the temporal images taken at the different time steps. We propose a method for quantification of the degree of coalescence and the initiation and termination of coalescence based on the contact area between aggregates. In addition micro-crack evolution due to swelling and shrinkage of aggregates will be analysed based on crack volume and distribution. During wetting, rheological flow was more prominent in the loam soil while micro-cracking played the major role in aggregate fragmentation in the clay soil. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPS) are the most important constituents of bacterial biofilms. EPS impart several functions for microbial life, e.g. promoting microbial adhesion to surfaces and increasing the tolerance to harsh environmental conditions. Together with the respective soil properties, EPS produced by soil bacteria are also supposed to contribute to soil aggregation. However, there is little knowledge about the relations among the composition of the soil and the residing bacterial community, the amount of bacterial EPS produced and the extent of its influence on soil aggregation. Therefore, the interrelationships between the amount of fine-sized particles (clay content), the decomposability of organic matter and the bacterial community composition were studied. It was hypothesized that an increased microbial activity, induced by organic matter input (starch or cellulose) will stimulate EPS production depending on the clay content in the soil. We conducted an incubation experiment (20°C and 50% WHC) with a sandy arable topsoil spiked with either starch or cellulose as substrate source over 80 days. Different amounts of montmorillonite were added to the soils to build a gradient of clay contents (+0, 0.1, 1, 10%). The CO2 respiration, microbial biomass, EPS content and soil aggregation were measured over the incubation time. In addition, the composition of the bacterial communities was assessed by denaturing gradient gel electrophoresis (DGGE) and Illumina high-throughput sequencing of bacterial 16S rRNA genes amplified from total community DNA. DGGE fingerprinting showed that the bacterial community changed over the incubation time. Pronounced shifts in the microbial community composition have been found for the soil with highest clay mineral addition after 10 and 20 days of incubation compared to soils without clay addition. In contrast, the different organic matter substrates had no strong influence on microbial community composition. 16S rRNA gene sequencing revealed that the relative abundance of the phylum Firmicutes was enhanced by spiking of starch to the soil. However, this effect was depending on the amount of clay added. On lower taxonomic rank, a number of different bacterial genera enriched in response to the different treatments were identified. The EPS contents were shaped by the clay mineral contents with distinct dynamics in EPS concentrations over time. These results will especially provide insights into how shifts in the soil bacterial community composition may affect EPS production and their consequences for soil aggregation. [ABSTRACT FROM AUTHOR]

Management of croplands affects the soil organic carbon content in the soil. Thus, changes in the management might increase the SOC content. However, changes in the management go along with a risk of decreased yield. Therefore, these two aspects needs to be analysed together. Emission factors (EF) are an easy approach to calculate the impact of the changes and they are widely applied in different studies. These emission factors are generic and estimated for actual climatic conditions. The values might vary among countries or for changed climatic conditions. Therefore, this study presents computer simulation based calculations for EF in UK on six croplands (all wheat). The EF are calculated by using simulation results of the biogeochemical models LandscapeDNDC and DAYCENT. The considered management practises included changes in fertilizer amounts, residue management and tillage. Additional, fertilizer plots were tested for manure application instead of mineral fertilizer. The results show varying impacts through the different test sites, but with a general trend of highest SOC increases for changes in residue management (residues left on the field) and manure application. The scale of the impacts is different on the different soil types, with higher impacts of residue management on clayey soils and higher tillage effects on sandy soils. An additional analysis of impacts on yield showed that mitigation options resulted in a greater reduction in yield under a future climate than under the current climate. The calculated EF is not in entirely in agreement with IPCC values, especially for some values for manure and residue management that exceed IPCC values for the UK. The results of the study show that the IPCC values need to be adapted for a country specific analysis. Additionally, the EF might change for future climate conditions, which needs to be considered in future estimates. [ABSTRACT FROM AUTHOR]

Organo-mineral associations are considered to be an effective mechanism in the long-term preservation of organic matter (OM) in soil, which is of great importance for the global carbon cycle. However, organo-mineral associations are rarely studied in peat soils. These soils are rich in OM, and the main mechanism of OM preservation is reduced decomposition rates due to anoxic conditions. Yet the soils can contain also clay minerals, so that organo-mineral associations may also contribute to the characteristics and preservation of OM in the soils. In this study, we investigate the peat core in Dajiuhu peatland in Hubei Province, central China. The soil profiles at the study site is characterized by horizons with varying clay mineral content. By comparing OM characteristics between clay and bulk soil samples from different soil horizons, we aimed at gaining a first insight into how the formation of organo-mineral associations affects the cycling of OM at the site. We used 13C-NMR, gas chromatography–mass spectrometry (GC–MS), trace GC instrument coupled to isotope ratio mass spectrometer (GC-IRMS) and thermo-gravimetry (TG) to demonstrate the dynamics of OM in peat soil.Using NMR we found smaller O-alkyl C to alkyl C ratios in clay fractions than in bulk soil samples, suggesting that OM components rich in alkyl C preferentially contribute to organo-mineral associations, and thus may preferentially be preserved via sorptive protection in peat. Evaluation of the other results is currently underway and will be presented at the conference. [ABSTRACT FROM AUTHOR]

Soil microbiome play very important role in development of soil profile and implementation of soilbiochemical processes, especially for initial stages of soil regeneration after strong antropogenic impact. The developing soils of postmining landscape of Central Yamal (Russia, Yamal demi-island) and soil microbiome composition was investigated for the first time by use metagenomic approaches.The study includes sampling from heaps of abandoned mines of chromatic ore and sand quarries, reclaimed sand heap and mature larch forest as a reference. We analyzed several agrochemical parameters (pH, C- and N-content, basal respiration and other) and microbial community structure, measured quantitatively by RT-PCR and qualitatively by use high-throughput sequencing of 16s rRNA gene sequence libraries.Investigated soils showed low content of organic carbon and total nitrogen. Soil regeneration and soil basal respiration rate were considered as slow for tundra and forest tundra zones, which indicates the low level of soil microbiological activity. The highest total content of bacteria, acrchaea and fungi was revealed for soils of sandy and clay texture heaps and reclaimed soils. Reclamation practice result in sharp increasing of bacteria, archaea and fungi counts. At the same time, reclaimed soils showed the lower values diversity indexes in comparison with soils of abandoned mines.In taxonomic analysis composition of microbiomes that were revealed, many taxa was described previously as dominant groups in different cold environments, including alpine soils. Among them are Chthoniobacteraceae, bacteria from order Ellin 6513, Koribacteriaceae, Gaiellaceae and other.This work was supported by the Russian Scientific Foundation projects 17-16-01030, 'Soil biota dynamics in chronoseries of post-technogenic landscapes: analyses of soil ecological effectiveness of ecosystems restoration'. [ABSTRACT FROM AUTHOR]