Undisturbed Soil Research Articles

Strong Dispersal Limitation of Microbial Communities at Shackleton Glacier, Antarctica.

Microbial communities can be structured by both deterministic and stochastic processes, but the relative importance of these processes remains unknown. The ambiguity partly arises from an inability to disentangle soil microbial processes from confounding factors, such as aboveground plant communities or anthropogenic disturbance. In this study, we characterized the relative contributions of determinism and stochasticity to assembly processes of soil bacterial communities across a large environmental gradient of undisturbed Antarctic soils. We hypothesized that harsh soils would impose a strong environmental selection on microbial communities, whereas communities in benign soils would be structured largely by dispersal. Contrary to our expectations, dispersal was the dominant assembly mechanism across the entire soil environmental gradient, including benign environments. The microbial community composition reflects slowly changing soil conditions and dispersal limitation of isolated sites. Thus, stochastic processes, as opposed to deterministic, are primary drivers of soil ecosystem assembly across space at our study site. This is especially surprising given the strong environmental constraints on soil microorganisms in one of the harshest environments on the planet, suggesting that dispersal could be a driving force in microbial community assembly in soils worldwide. IMPORTANCE Because of their diversity and ubiquity, microbes provide an excellent means to tease apart how natural communities are structured. In general, ecologists believe that stochastic assembly processes, like random drift and dispersal, should dominate in benign environments while deterministic processes, like environmental filtering, should be prevalent in harsh environments. To help resolve this debate, we analyzed microbial community composition in pristine Antarctic soils devoid of human influence or plant communities for eons. Our results demonstrate that dispersal limitation is a surprisingly potent force of community limitation throughout all soil conditions. Thus, dispersal appears to be a driving force of microbial community assembly, even in the harshest of conditions.

Ecological consequences of a single introduced species to the Antarctic: terrestrial impacts of the invasive midge Eretmoptera murphyi on Signy Island

The nutrient-poor soils of Antarctica are sensitive to change. Recent increases in the number of anthropogenic introductions mean that understanding the impact of non-native species on Antarctic soils is pertinent, and essential for developing future risk assessments and management strategies. Through comparative baseline assessments of vegetation, microbes, soil chemistry, substrate composition and micro-arthropod abundance, this study explored if there are detectable terrestrial ecosystem impacts resulting from the introduction of the chironomid midge Eretmoptera murphyi to Signy Island in maritime Antarctica. The key finding was that E. murphyi is the likely driver of an increase in inorganic nitrogen availability within the nutrient-poor soils in which it occurs. When compared with the levels of inorganic nitrogen present in soils influenced by native vertebrate wildlife aggregations, the increase in local nitrate availability associated with E. murphyi was similar to that caused by deposits from seals and giant petrel colonies. Overall, available nitrate has increased by three- to five-fold in soils colonised by the midge, relative to undisturbed soils. This may ultimately impact rates of decomposition as well as the native plant and micro-arthropod communities of Signy Island.

Raindrop-impact-induced ejection characteristics of surface particles for soils with a textural gradient

The ejection of surface soil particles caused by raindrops is an important stage of water erosion. Generally, surface soil is typically comprised of more complex structural units (e.g. crumb, block, or platy structures) rather than single granular structures (e.g. aggregate), especially on surface soil influenced by the different arrangement mode between soil particles. Thus, soil aggregate samples as a selected test material cannot properly characterise the particle ejection characteristics of surface soil with more complex structural units during rainfall. Considering this issue, undisturbed soil samples with a textural gradient were collected as test materials for this study and a needle-type raindrop simulator was used to simulate rainfall experiments. Our results demonstrate that, the first 6 min of rainfall is the key period for particle ejection. During this phase of the experiment, the clay-sized and fine-silt-sized particles were preferentially ejected, and the enrichment ratio (ER) of those particles decreased progressively from sandy loam to silty clay loam. With increased rainfall duration, the soils with a low clay content (e.g. sandy loam, silty loam and loam) were found to develop surface crusts more easily compared with clay loam and silty clay loam. Although the formation of soil crust reduced the size-selectivity of the splash-detached particles, the percentage of sand-sized particles in splash-detachment particles showed an increasing trend, while the percentage of clay-sized and fine-silt-sized particles showed a decreasing trend. The finding of this study suggests that identifying changes in the soil surface condition, as determined by soil texture, is the key factor affecting the ejection characteristics of surface soil particles during splash erosion.

Comparing two methods to perform a beerkan infiltration run in a loam soil at different dates

Performing beerkan infiltration runs with different heights of water pouring could help to obtain saturated soil sorptivity, S, and hydraulic conductivity, Ks, data usable to explain and simulate hydrological processes. However, most of the available information on the L (low height of water pouring, nearly 3 cm) – H (high height, 1–2 m) methodology refers to runs making use of a relatively limited number of water volumes and there is some sign that a few water volumes could yield an incomplete description of soil alteration phenomena induced by wetting. For a loam soil, the objective of this investigation was to determine water pouring height effects on the S and Ks values obtained in different sampling dates with more than usual amounts of applied water. Soil alteration due to the mechanical impact of the applied water appeared almost completed by the end of the runs in all cases but in a more advanced stage when the soil was initially more sorptive and conductive. Overall, the H runs yielded 2.3–2.8 times smaller S values and 8.5–14.5 times smaller Ks values than the L runs but differences between the L and H methodologies varied during the sampling period. In particular, these differences were smallest when the soil was initially relatively wet and little sorptive and conductive (S and Ks values differing with the experiment by no more than two times) and largest in the opposite conditions (S and Ks values differing by 3 and 17–21 times, respectively). The L runs yielded coefficients of variations, CV, of 14–60 % for S and 45–171 % for Ks, depending on the sampling date, and a ratio between the highest and the lowest mean of 2.5 for S and 11.8 for Ks. With the H runs, the corresponding CV values were 14–38 % for S and 35–107 % for Ks and two means differed at the most by 1.3 times for S and 2.2 times for Ks. Therefore, the H runs described a soil that was less sorptive, less conductive, more spatially homogeneous and more temporally stable than the L runs. Less runs could be enough to parameterize the soil in a disturbed condition as compared with the undisturbed one. Further testing the L-H methodology in other environmental conditions is recommended in the perspective to develop simple field methods to determine the hydrodynamic properties of both a nearly undisturbed soil and an intensively disturbed soil.

Effect of sterile rice spikelets derived biochar amendment on nutrient leaching and availability in paddy soil under continuous standing water

ABSTRACT Undisturbed soil columns were used to study the effect of sterile rice spikelets-derived biochar (SRSB) on NH4 +-N, available P, and available K leaching and nutrients availability in a paddy soil under continuous standing water (CSW) condition. The experiment was conducted for two crop cycles and comprised of three treatments: recommended dose of sole chemical fertilizers (CF), CF+SRSB (2 t ha−1), and control. In both crop cycles, incorporation of SRSB reduced the leachate NH4 +-N and available K concentrations, while increased the available P concentration compared to sole CF. The SRSB amendment reduced the cumulative losses of NH4 +-N by 35–38% and available K by 23–25% than CF only. However, there was no significant variation in cumulative available P loss between SRSB and CF only. The reduced leaching loss of NH4 +-N and available K could be attributed to the better nutrient adsorption capacity of SRSB. After completion of two crop cycles, the soil pH, soil organic carbon, soil total N, available P, and available K increased with SRSB amended soils than sole CF. This study showed positive effects of SRSB on retaining nutrients and increasing their availability in the soil which could benefit efficient fertilizer management in paddy soil under CSW.

Hydraulic properties of fine-textured soils in lowland ecosystems of Western Serbia vary depending on land use

Land use in agriculture can alter the physical, chemical and biological properties of soils, but little is known how it affects the hydraulic properties of the fine-textured soils of lowland agroecosystems in continental climates. This research assesses the impact of long-term (>100 years) continuous use of natural meadows and arable land, after conversion of native mixed deciduous forests, on hydraulic properties such as water retention, pore-size distribution, saturated hydraulic conductivity, and bulk density. The research was conducted on Fluvic Phaeozems in the valley of the Kolubara River, western Serbia. Disturbed and undisturbed soil samples from three different land use systems (forest, meadow, and arable land) and three different locations were collected at 0–15, 15–30, and 30–45 cm soil depth. Significant effects of different land uses were observed for bulk density, total porosity, macroporosity, mesoporosity, microporosity, air-filled porosity, field water capacity, plant available water capacity and saturated hydraulic conductivity at 0–15 cm soil depth, but a much smaller effect was observed at 15–30 cm. The water content estimated by the van Genuchten model was similar to the measured water content (R2 = 0.932–0.972). At 30–45 cm soil depth, land use only significantly affected a few of the examined variables. Dexter's soil physical quality index (S-index) also detected degradation of soil physical quality after conversion from forest to agroecosystems. In summary, the conversion of native forests into agricultural land tends to cause considerable change in the hydraulic properties and soil physical quality of fine-textured soils in lowland continental agroecosystems, which could have an adverse effect on crop yield and the environment.

Weathering rates of Ca and Mg related to granitic and gabbro mineralogy in boreal forest soils and the effect of mechanical soil disturbance on weathering release

This study’s aim was to calculate the weathering rates of Ca and Mg for five boreal forest soils in southern Finland on granitic and gabbro containing bedrock. The effect of mineralogy on the total concentrations of Ca and Mg in soil and weathering rates was evaluated. The aim was also to estimate the effect of mechanical soil disturbance related to ploughing on the weathering in the gabbro area. The total concentrations of SiO2, CaO, MgO, and Zr were determined by XRF, and weathering rates of Ca and Mg were determined based on the changes in the CaO, MgO, and Zr concentrations. The weathering rates of Ca+Mg varied 5–38 mmolc m–2 year–1 in the E+B/BC horizons among the plots. Soil disturbance related to ploughing increased the weathering of Ca and Mg largely in the disturbed part of the topmost mineral soil as indicated by the decreasing concentrations of Ca and Mg after mechanical soil disturbance. The weathering input of Ca in the undisturbed soil did not fully replace the Ca output in final whole-tree cutting. The weathering input of Mg in the undisturbed soil was sufficient to replace the lost Mg in stemwood harvesting but not on all the plots the lost Mg in whole-tree harvesting. Weathering rates were higher in the gabbro than the granitic areas.

Pores distribution influences the soil microorganism's response to changes in temperature and moisture

Microorganisms are an essential fraction of soil organic matter, which presence and activity depend directly on soil physical conditions. This study aimed to address the effect of soil temperature and moisture under contrasting macroporosity conditions on soil biological properties. Soil physical-chemical characterization implicated the collection of composite samples and undisturbed surface soil samples (0 to 10 cm). Also, samples of undisturbed surface soil were extracted in 40 polyvinyl chloride cylinders of 18 cm diameter and 20 cm height for the arrangement of soil mesocosm as the experimental units of a completely randomized experiment with a 2x2x3 factorial arrangement. The experiment duration was 21 days, and the soil biological properties measured were microbial biomass (MB) and soil respiration (SR). Macroporosity showed a significant effect on MB, which indicates that aeration pore influences the number of microorganisms in the soil; for the SR, the macroporosity had a not significant effect. The temperature at the ranges established in the experiment did not significantly affect MB, whereas a highly significant effect of temperature over SR was observed. A highly significant effect of soil moisture was observed on MB and SR. Macroporosity, moisture, and temperature are determining factors in the presence of soil microorganisms, both directly and through the interaction between them. Herein the microorganisms have a wide range of thermal adaptation, and the effect of soil temperature can boost soil microorganisms. In turn, it was observed that the microorganisms present are significantly sensitive to the moisture deficit in soil.

Characterising earth scent

Environmental context Everyone is familiar with the earth odour that comes from digging in the soil. We measured the chemicals comprising this odour and studied how the environment influences how much of these chemicals are released from disturbed soils. Understanding what conditions affect emission of these compounds from soils could provide new technologies for remotely assessing soil health and what people are doing to soils. Rationale Earth scent is the odour emitted from soils. This scent, primarily comprising the alcohols geosmin and 2-methylisoborneol (MIB), has not been fully characterised, but offers high potential for use as an environmental interrogation tool. Methodology We utilised our field-based, solid-phase microextraction fibre method to test the hypothesis that soil activity and soil property variation can be detected in situ by comparing biogenic volatile emissions. Results We eliminated sources of error utilising field-based sampling with these fibres, concluding that room temperature storage for up to 7 days is acceptable with minimal loss. Variation in individual fibre affinity for both compounds was higher than expected but no measured concentrations were observed to constitute outliers. Disturbance of minor soil volumes led to significantly higher emission of both compounds over background levels. Soil texture and soil cover had a significant effect on the emission of both compounds. Simulated rainfall, producing the characteristic odour known as petrichor, initiates elevated emission of geosmin. Background (undisturbed soil) concentrations of MIB were occasionally detectable during some sampling events, but geosmin concentrations in the air were always below detection limits without soil disturbance. Virtually all background and disturbed soil samples contained much higher concentrations of MIB compared to geosmin, but geosmin variation between replicates and experimental units was much lower. Discussion Soil disturbance and soil property variation can be remotely detected using emission of volatile compounds. Correlating emission from the soil with respect to disturbance events and environmental properties could yield a powerful new tool for acquiring soil information.

Modified inderbitzen equipment for simulation of water erosion in undeformed soil samples

Several devices have been developed to assess soil losses by water erosion. However, they rarely assess the combined effects of raindrop impact and surface runoff together with vegetation cover on varying slopes. This study aimed to design and validate an equipment, on laboratory scale, to evaluate the effect of water erosion on undisturbed soil samples with and without plant cover, as well as to assess the kinetic energy of simulated rain and the resultant shear stress at varying runoff intensities. The equipment is composed of a rainfall simulator, an adjustable stand for different slopes and falling heights, and a runoff ramp for testing undisturbed soil samples measuring 15 x 20 x 40 cm (height, width, and length). In this study, the equipment simulated and evaluated the effect of precipitation and runoff on soil losses, allowing to obtain different values of the kinetic energy of precipitation and runoff. For a f low rate of 12 L min-1 and slope of 35%, the shear stress could reach up to 8 Pa. Furthermore, the equipment showed the effect of vegetation cover and slope on soil losses in different granulometric fractions (< 0.106 mm, 0.106 to 0.25 mm, 0.25 to 0.5 mm, 0.5 to 1.0 mm, 1.0 to 2.0 mm, and > 2.0 mm), revealing the potential of its use in several erosion studies on a laboratory scale.

Spatial distribution of 137Cs, 40K, 226Ra, 232Th in soils of Olenegorsk city (Murmansk region)

The goal of the study is obtain original data and identify the main patterns of spatial distribution of radionuclides in the soils of Olenegorsk, depending on zoning and urban development, focusing one specific activity of 137Cs and natural radionuclides, namely 232Th, 226Ra, 40K, in soils. Such studies of urban soils in Olenegorsk have not been carried out earlier. Location and time of the study. Soil samples in the city of Olenegorsk, Murmansk region, were collected in the summer of 2018. Methods. Soil samples were collected at 24 study sites on the territory of the Olenegorsk city from the upper 0-5 cm layer. Under laboratory conditions, the samples were dried at 105° C to constant mass. Then soil aliquots were placed in a Marinelli vessel to measure isotope specific activity using gamma spectrometry. Registration of gamma radiation from a countable soil sample, as well as processing of spectra, was carried out using the Progress-gamma software and hardware complex FVKM.412131.002-03. Calibration of the gamma spectrometer by energy to monitor the safety of the installation parameters was carried out after each measurement using a combined control source OISN-137-1 in a 1-liter Marinelli vessel. The minimum exposure time for the counting sample was 3600 seconds. However, depending on the activity of a sample, the exposure time in individual samples with weak activity was increased. Main results: The maximal specific activity of 137Cs in urban soils of Olenegorsk was 47.5 Bq/kg in the northwestern part of the city in the undisturbed soils of the natural landscape. Maximal values of 40K specific activity reached 293.8 Bq/kg in the central and south-eastern parts of the city within the boundaries of multi-storey residential district. The maximal specific activity of 226Ra in soils reached 14.6, and that of 232Th reached 12.2 Bq/kg, being confined to soils in the area of high-rise and mid-rise buildings, most likely, due to the differential vegetation density since the latter easily involves 40K into the biotic turnover. Maximal values of soil 226Ra and 232Th specific activity (14.6 and 12.2, respectively) were determined in areas with multi-storey and mid-rise buildings. The correlation analysis between the radionuclides and soil skeleton particles (≥2 mm) and finer (≤ 1 mm) fractions showed rather close association of radionuclides with soil skeleton and <45 µm particles, as well as a moderately strong correlation with the 45 µm fraction. Moderately strong correlation was found between 232Th and 226Ra, and between 40K and soil skeleton particles. Conclusion. The obtained data about the accumulation of 137Cs and natural radionuclides (232Th, 226Ra, 40K) in the soils of Olenegorsk do not exceed the maximum permissible concentrations, characteristic of the urbanized areas of the Murmansk region.

Physical Soil Parameter and Resistivity Profile in the Vadose Zone: Preliminary Result of Groundwater Recharge Study

In tropical-volcanic-dominated areas, such as Java Island in Indonesia, aquifer recharge is highly impacted by rainfall intensity and soil characteristics. The first stage of recharge begins with the soil surface's response to rainwater until it percolates to the deep layer. The primary objective of this research was to study groundwater recharge processes from the soil surface to deep percolation in the volcanic deposit at the northwest flank of Mount Pangrango, West Java, Indonesia. The present study also includes the 2D geoelectrical survey results combined with the soil core drilling. A vertical undisturbed soil profile 4 to 4.5 meters deep was drilled to determine parameters such as soil water content, total porosity, permeability, organic content, and soil texture. Results from core drilling activities confirmed that resistivity values are in the range of 80 to 360 ohm.m, which is related to wet soil layers at 1 to 4 meters below the surface. It is found that the most significant difference between organic and mineral soils in terms of resistivity value is that of organic content. Depth and radius of Pinus merkusii and Melia azedarach tree according to resistivity and soil drilling result confirmed at 2.5; 4.5 meter and 0.9; 2.2 meters respectively. By profiling these factors, the behavior of water movement may be better described, allowing the net recharge rate from rainwater to the water table in the unsaturated zone to be estimated.

Calibration of a granular matrix sensor for suction measurements in partially saturated pyroclastic soil

Field monitoring of soil moisture and matrix suction is a useful tool for the implementation of a reliable early warning system against rainfall-induced landslide occurrence. Several test fields have been set up in Campania region (southern Italy), frequently affected by flow-like landslides involving pyroclastic soil cover. In particular, at the Mount Faito test site (Lattari Mountains, southeast of Naples), field matric suctions were measured over two years by conventional jet-fill tensiometers and granular matrix sensors (Watermark, Irrometer®) at different depths. Granular matrix sensor is a resistive device that is more and more spread in agriculture applications and that may also be used for geotechnical purposes thanks to a suitable calibration. In order to gain the calibration curve of the Watermark sensor, two small tip tensiometers (STT) and one High Capacity Tensiometer (HCT) were installed at the same depth of the Watermark sensor in the partially saturated pyroclastic soil sampled at the topsoil of the Mount Faito test site. Tests were carried out in the laboratory by performing drying and wetting phases on undisturbed soil sample. By coupling resistance measurements by Watermark and matrix suction provided by the reference tensiometers, it was possible to derive the non-linear relationship between these two quantities. The soil retention curve was also determined thanks to the installation in the soil sample of a decagon probe previously calibrated in the same pyroclastic soil.

Redoxtrons – An experimental system to study redox processes within the capillary fringe

AbstractSpatiotemporal characterisation of the soil redox status within the capillary fringe (CF) is a challenging task. Air‐filled porosities (ε), oxygen concentration (O2) and soil redox potential (EH) are interrelated soil variables within active biogeochemical domains such as the CF. We investigated the impact of water table (WT) rise and drainage in an undisturbed topsoil and subsoil sample taken from a Calcaric Gleysol for a period of 46 days. We merged 1D (EH and matric potential) and 2D (O2) systems to monitor at high spatiotemporal resolution redox dynamics within self‐constructed redoxtron housings and complemented the data set by a 3D pore network characterization using X‐ray microtomography (X‐ray μCT). Depletion of O2 was faster in the organic matter‐ and clay‐rich aggregated topsoil and the CF extended >10 cm above the artificial WT. The homogeneous and less‐aggregated subsoil extended only 4 cm above the WT as indicated by ε–O2–EH data during saturation. After drainage, 2D O2 imaging revealed a fast aeration towards the lower depths of the topsoil, which agrees with the connected ε derived by X‐ray μCT (εCT_conn) of 14.9% of the total porosity. However, small‐scaled anoxic domains with O2 saturation <5% were apparent even after lowering the WT (down to 0.25 cm2 in size) for 23 days. These domains remained a nucleus for reducing soil conditions (EH < −100 mV), which made it challenging to characterise the soil redox status in the CF. In contrast, the subsoil aeration reached O2 saturation after 8 days for the complete soil volume. Values of εCT_conn around zero in the subsoil highlighted that soil aeration was independent of this parameter suggesting that other variables such as microbial activity must be considered when predicting the soil redox status from ε alone. The use of redoxtrons in combination with localised redox‐measurements and image based pore space analysis resulted in a better 2D/3D characterisation of the pore system and related O2 transport properties. This allowed us to analyse the distribution and activity of microbiological niches highly associated with the spatiotemporal variable redox dynamics in soil environments.Highlights The time needed to turn from reducing to oxidising (period where all platinum electrodes feature EH > 300 mV) condition differ for two samples with contrasting soil structure. The subsoil with presumably low O2 consumption rates aerated considerably faster than the topsoil and exclusively by O2 diffusion through medium‐ and fine‐sized pores. To derive the soil redox status based upon the triplet ε–O2–EH is challenging at present in heterogeneous soil domains and larger soil volumes than 250 cm3. Undisturbed soil sampling along with 2D/3D redox measurement systems (e.g., redoxtrons) improve our understanding of redox dynamics within the capillary fringe.

Prilog poznavanju nekih fizičkih i hemijskih osobina krečnjačkih zemljišta planinskog masiva Ozren

Soils formed on limestones occupy large area in Serbia, but there is not a lot of information about their properties. This paper presents physical and chemical properties of the Brownized Calcomelanosols and Moderately-deep Calcocambisols of the Ozren Mountain. Brownized Calcomelanosols under natural grassy vegetation were investigated at the Vlasina pass, whereas Calcocambisols under mixed forests were investigated near the site "Ozrenske livade". Soil profiles were excavated up to the parent material, and disturbed and undisturbed soil samples were collected from soil genetic horizons. Following soil characteristics were determined: particle size distribution, soil structure and water resistance of structural aggregates, bulk density, total porosity, air capacity, water-holding capacity, water conductivity, pH, content of humus, available phosphorus (P2O5) and potassium (K2O), hydrolytic acidity, cation exchange capacity (CEC), sum of exchangeable base cations, and base saturation. Humus-accumulative horizon (Amo) of the Brownized Calcomelanosols has silty clay texture, whereas the cambic (B)rz horizon of both soils has a clay texture. The Amo horizon of Calcomelanosols is characterized by fine to medium granular structure (0.5-5 mm) of very high water resistance. The total porosity, air capacity and water permeability of both soils is high. Their water-holding capacity is high. Amo horizon of Calcomelanosols is characterized by a high humus content (>10%). Soil reaction in water of Amo horizon is neutral, whereas in (B)rz horizons both soils are moderately acid. Both soils have high CEC (>58 cmol kg-1 ) and base saturatation (>95%). Brownized Calcomelanosol is moderately to highly supplied with available K2O, whereas Calcocambisol is moderately supplied; while both soils are very poor in available P2O5. Since this study presents quite favorable physical and chemical properties of the investigated soils due to the conservation of natural forests and grasslands, the results can help in a deeper understanding of soil ecology and the preservation of natural plant cover.

Determination of physical properties of undisturbed soil samples according to V. Novák

The methodology described here presents the procedures for determining physical soil properties of undisturbed soil samples. Besides describing the methods for determining bulk and particle density, moisture content and porosity of the soil in detail, it also offers a way of determining soil's water holding properties when there is no pressure membrane apparatus available. This method is based on a capillary water saturation experiment and gravimetric measurements performed in different time intervals after the saturation (30 minutes, 2 hours, and 24 hours). With a few, simple to follow steps, and not using complicated and space-consuming equipment, it can be replicated in almost any laboratory, and the results are easily interpreted. The method was, and still is, widely used in the Czech Republic, and some parts of it are used as standard soil testing methods. To a lesser or greater detail, this method is described in Rejšek (1999), Valla et al. (2011), Pospíšilová et al. (2016) and ÚKZÚZ (2016), and this methodology is compiled from those publications, mainly focusing (and using the same abbreviations) on the procedures described by Valla et al. (2011). The methodology described does not essentially differ from the original, but the steps here have been described to a greater detail, based on the practical experiences obtained over the years, in order to make some common mistakes less likely to happen. The methodology is further complemented with graphical illustrations for each step described in the process, making it clearer, more easily understood, and easier to replicate. Since this methodology has not been available in English so far, this guide offers a great opportunity of its replication on an international level.•Simple, cost-effective and environmentally friendly method for determining physical soil properties•Easy replication and results interpretation•Results can be obtained even in non-highly specialized soil laboratories

Effects of Selected Manure Sources on Runoff, Soil Loss, and Nutrient Transport

Highlights Surface water runoff was reduced following manure additions. Sediment yield was reduced following manure additions. Nutrient loss was increased following manure additions. Abstract. Soil erosion models are becoming increasingly accurate and now can simulate a variety of surface covers which can lessen erosion by reducing detachment and movement of soil particles. Currently, there is limited data on the effects of animal manure on soil erosion. Most process-based models credit animal manure as crop residue cover. Thus, there is a need for bench studies under laboratory conditions, as well as field studies to determine the effects manure applications have on runoff and sediment loss. Rainfall simulation studies were conducted to evaluate the influence of different animal manures on runoff, sediment yield, and nutrient loss using undisturbed soil monoliths placed in perforated trays. The soil was collected from fields managed under long-term no-till and a conventional till for over 15 years. Poultry litter, solid dairy manure, liquid swine manure, liquid dairy manure applied to the experimental units were compared to a no manure treatment. Generally, sediment yield and runoff amounts were reduced following manure application regardless of source (averaged across all rainfall events and manure rates), with reductions generally occurring with increasing rates of manure. When evaluating each rainfall event separately, runoff increased with increasing rates of manure for the liquid dairy manure only in the initial rainfall simulation events due to surface sealing. However, the effects of surface sealing decreased from the first rainfall simulation event to the third event. Sediment yield tended to be higher in conventional till versus no-till (only evaluated with liquid dairy manure); however, the addition of manure tended to be more effective at reducing sediment loss with conventional till. Dissolved reactive P, NH4-N, and NO3-N levels in the runoff effluent increased for all of the manure sources with increasing rates of manure. These results suggest that manure applications can reduce soil loss, especially from the conventionally-tilled treatment. Keywords: Manure, Rainfall simulation, Runoff, Soil erosion.

Effectiveness of narrow tyne and double-discs openers to overcome shallow compaction and improve soybean yield in long-term no-tillage soil

Compaction adversely affects the soil physical quality and crop yields in no-tillage (NT) systems. No-tillage seeders equipped with narrow tyne openers may be a cost-effective option to overcome shallow compaction in NT soil and reduce the reliance on tillage for seedbed preparation and crop establishment. This study was conducted to: (1) quantify changes in soil physical quality indicators and determine the crop response to the use of a NT seeder equipped with either narrow tyne or double-disc openers, and (2) evaluate the potential of seeding tynes to overcome shallow compaction in NT soils of southern Brazil. Soil compaction was induced by applying 0, 3, 6, and 9 tractor passes equivalent to 84 %, 89 %, 94 %, and 99 % of the degree of compactness. In each treatment, a narrow tyne opener was used for the deposition of fertilizers compared to double discs. Undisturbed soil samples were taken from the 0–0.10 and 0.10–0.20 m depths and used to measure soil bulk density, soil water and air storage capacity, and the Least Limiting Water Range (LLWR). Soil penetration resistance and soybean (Glycine max L., Merr.) yield were also measured during the 2014/2015 cropping season. Soil bulk density and soil water storage capacity increased while air storage capacity and the LLWR decreased with an increase in the degree of compactness. The use of narrow tyne openers reduced soil penetration resistance in the 0.0–0.10 m layer by up to 66 % compared with the use of discs, and increased soybean yield by an average of 600 kg ha-1 (or US$ 227 per ha). By contrast, the use of double-discs on previously compacted soil resulted in yield penalties of up to 1200 kg ha-1. Soybean yield was more strongly correlated with LLWR (r = 0.97) than with any other measured soil physical quality indicator. Overall, these results supported the hypothesis that the use of NT seeders equipped with narrow tyne openers was effective in overcoming shallow compaction in NT soil.

The Soil Environment of Abandoned Charcoal Kiln Platforms in a Low-Altitude Central European Forest

This study examines the soil environment of eight charcoal kiln platforms and the neighboring soil in Czech and Bohemian low-altitude forest stands. Both mixed and undisturbed soil samples were used to assess the hydrophysical soil properties, nutrient content, cation exchange capacity, enzyme activity, and soil active carbon content, while soil color, stoniness, root density, and horizon thickness were estimated in the field. Charcoal-rich horizons had high total organic carbon concentrations and total nitrogen content (about 150% and 40% higher than in the organomineral horizons of the control plot, respectively), with total carbon stocks being higher than those in neighboring forest soils. Fine root density was highest in the charcoal-rich horizons, encouraged by high soil porosity, aeration, and favorable chemical properties. Enzyme group activity differed between individual soil horizons and kiln and control plots, with depolymerization enzyme activity highest in charcoal-rich horizons and humification enzyme activity highest in mineral horizons. Phosphatase, chitinase, and phenoloxidase activity were highest in charcoal-rich horizons, while β-glucosidase activity remained similar across horizons. After long-term abandonment, kiln sites shift from inhospitable sites to localized hotspots for plant and microbial growth, having more favorable physical, enzymatic, and chemical soil properties than the surrounding areas. This study confirmed that kiln production platforms act as microhabitat hotspots, also providing information on a wide spectrum of soil properties linked with soil microorganisms and root growth.

An empirical model for prediction of topsoil deformation in field traffic

Agricultural topsoils are characterized by a heterogeneous mixture of structural units with a considerable difference in soil mechanical properties. Mechanistic modeling of compaction for this layer is challenging because of the need to parameterize model input parameters. This study quantified soil deformation during loading in semi-confined conditions and searched for drivers decisive for observed strains with no a priori assumptions of material properties. Undisturbed soil samples were collected in the plough layer of eleven sandy and loamy soils in Denmark. The samples were adjusted to either of the following matric potentials: − 30, − 50, − 75, − 100, − 160 and − 300 hPa (pF from ∼1.5 to ∼2.5). Cores at each water condition were loaded with an annulus covering one third of the soil surface at either of the following normal loads: 30, 60, 90, 120, 150, 180 kPa. Multiple regression was performed to estimate the best model describing the variation in soil compressibility. Measured strain, ε, decreased with increase in soil organic matter, bulk density and pF, but the effect of pF was affected by soil clay content. The model explained ∼84 % of the variation in data and predicted well measured strain for two independent data sets. The regression model is suggested for prediction of soil deformation of arable topsoils in field traffic. A procedure is described for the prediction, including calculation of the relevant stress based on loading characteristics.