Searching below thresholds: Tracing the origins of preferential flow within undisturbed soil samples

2002 ◽  
pp. 265-274 ◽  
Author(s):  
Milena Císlerová ◽  
Tomáš Vogel ◽  
Jana Votrubová ◽  
Alice Robovská
Keyword(s):  
Preferential Flow ◽  
Soil Samples ◽  
Undisturbed Soil

The relation between soil structure and solute transport under raised bed cropping and conventional cultivation in south-western Victoria

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 577 ◽  
Author(s):  
J. E. Holland ◽  
R. E. White ◽  
R. Edis
Keyword(s):  
Solute Transport ◽  
Soil Structure ◽  
Preferential Flow ◽  
Soil Samples ◽  
Water Volume ◽  
Undisturbed Soil ◽  
Resin Impregnation ◽  
Cultivated Soil ◽  
Raised Bed ◽  
Western Victoria

This study examined the relationship between soil structure and solute transport in a texture contrast soil under 2 different tillage treatments—raised beds and conventional cultivation—in south-western Victoria. Undisturbed soil samples were collected for resin-impregnation and image analysis. This enabled several descriptive parameters of macropore structure to be calculated. Large, undisturbed soil samples were also collected for a solute transport experiment using a KCl solution. A convective log-normal transfer function was used to model Cl– movement. The assessment of soil structure showed that the raised beds contained a better connected pore network than the conventionally cultivated soil. Solute transport was faster through the raised bed soil when close to saturation (at –5 mm tension). Under these conditions, the solute transport parameters showed a smaller ratio of transport volume to soil water volume in the raised bed than the conventionally cultivated soil. Together, these data strongly indicate that the raised beds had greater pore connectivity and were able to transmit solute faster and more efficiently than the conventionally cultivated soil. It is concluded that raised bed soils are better structured and provide less risk from waterlogging than conventionally cultivated soils. However, there is greater potential for preferential flow of pesticides and solutes in raised bed soils.

Re-colonization of sterile soil samples during long term field exposure

2020 ◽  
Author(s):  
Michael Herre ◽  
Bernd Marschner ◽  
Sven Marhan
Keyword(s):  
Microbial Activity ◽  
Preferential Flow ◽  
Soil Samples ◽  
Bulk Soil ◽  
Forest Site ◽  
Field Exposure ◽  
Flow Paths ◽  
Undisturbed Soil ◽  
Preferential Flow Paths ◽  
Colonization Potential

<p>The distribution of soil organic matter and microbial biomass in subsoils is much more heterogeneous than in the topsoil due to a more localized input of fresh substrate and nutrients from rhizodeposition and preferential flow paths forming hotspots of microbial activity. However, the remaining bulk soil also contains substantial amounts of labile substrates that are readily mineralized during lab incubation experiments. We therefore hypothesized that one reason for this is that potential consumers are spatially separated from these substrates due to the low microbial densities in subsoils. Consequently, hotspots are not only formed through high substrate inputs but also through a higher abundance and diversity of microorganisms compared to the bulk soil due to inputs of cells and spores with the soil solution or through hyphal growth. However, little is known about the colonization potential or dynamics of microorganisms in the subsoil.</p><p>In November 2018, we started a field experiment to investigate the re-colonization potential of microorganisms by exposing 24-well microplates containing sterilized soil samples in the field at two different depths (topsoil: 10 cm, subsoil 60 cm) at a beech forest site in northern Germany. After 6 and 12 months, samples from each well and from the intact soil compartments above each well were analyzed for enzyme activities (hydrolytic enzymes using MUF and AMC substrates), microbial activity parameters (soil respiration and SIR using the MicroResp®) and the microbial community structure (quantitative PCR).</p><p>We expect (1) different temporal dynamics of re-colonization between top- and subsoil samples; (2) that the recolonization potential is related to the microbial activity in the soil compartments above the exposed samples and (3) that the heterogeneous re-colonization is maintained throughout the field exposure and thus indicates the relevance of preferential flow paths for microbial transport especially in subsoils.</p><p>First results of the SIR assays after 6 months of field exposure show that in the topsoil microbial activity has been re-established in all of the wells, but is still below the mean activity in the undisturbed soil above the sterilized samples. In all subsoil samples, the re-established microbial activity was much lower and even below detection limit in some of the wells. In both depths, the SIR assays show a very patchy distribution of wells with higher microbial activities indicating that the influx of organisms is limited to small areas from the soil above the exposed containers.</p>

scholarly journals Least limiting water range of Udox soil under degraded pastures on different sun-exposed faces

2017 ◽  
Vol 31 (3) ◽  
pp. 393-400 ◽  
Author(s):  
Renato Ribeiro Passos ◽  
Liovando Marciano da Costa ◽  
Igor Rodrigues de Assis ◽  
Danilo Andrade Santos ◽  
Hugo Alberto Ruiz ◽  
...  
Keyword(s):  
Soil Management ◽  
Sun Exposure ◽  
Soil Samples ◽  
The South ◽  
Undisturbed Soil ◽  
North West ◽  
The North ◽  
Pasture Degradation ◽  
Least Limiting Water Range ◽  
Degraded Pastures

AbstractThe efficient use of water is increasingly important and proper soil management, within the specificities of each region of the country, allows achieving greater efficiency. The South and Caparaó regions of Espírito Santo, Brazil are characterized by relief of ‘hill seas’ with differences in the degree of pasture degradation due to sun exposure. The objective of this study was to evaluate the least limiting water range in Udox soil under degraded pastures with two faces of exposure to the sun and three pedoenvironments. In each pedoenvironment, namely Alegre, Celina, and Café, two areas were selected, one with exposure on the North/West face and the other on the South/East face. In each of these areas, undisturbed soil samples were collected at 0-10 cm depth to determine the least limiting water range. The exposed face of the pasture that received the highest solar incidence (North/West) presented the lowest values in least limiting water range. The least limiting water range proved to be a physical quality indicator for Udox soil under degraded pastures.

scholarly journals DEGRADASI LAHAN PADA KEBUN CAMPURAN DAN TEGALAN DI KABUPATEN DHARMASRAYA

Jurnal Solum ◽  
2007 ◽  
Vol 4 (1) ◽  
pp. 5
Author(s):  
Syafrimen Yasin ◽  
Gusnidar Gusnidar ◽  
Dedy Iskandar
Keyword(s):  
Land Use ◽  
Soil Depth ◽  
Soil Surface ◽  
Soil Samples ◽  
Imperata Cylindrica ◽  
Undisturbed Soil ◽  
Fertility Status ◽  
Land Use Types ◽  
Bulk Volume ◽  
Soil Fertility Status

A research conducted in Sungai Rumbai, Dharmasraya Regency and in Soil Laboratory Andalas university was aimed to evaluate soil fertility status on the depth below 0-20 cm from several land use types , especially under Mixed Garden and annual cultivated dryland soil.  Soil samples were taken on Ultisol at 0-8% slope (late-waving soil surface).  Land use types evaluated were forest, annual cultivated dryland, bush land, rangeland covered by Imperata cylindrica and mixed garden.  Composite soil samples for soil chemical analysis were taken on the 0-20 cm soil depth with four replications, and 5 drillings for each replication.  Undisturbed soil samples by using sample ring were used to analyze sol bulk volume.  The data resulted were compared to the criteria and were statistically tested using Analysis of Variance and then were continued by LSD at 5% level.  From the results of analyses could be concluded that land use  for mixed garden had the higher Organic Carbon (OC) content and the lower bulk volume (BV) than those for annual cultivated dryland soil.Key Words: Degradasi Lahan, Kebun Campuran, Tegalan

scholarly journals Alternative method for volumetric core removal in hardsetting soils

2005 ◽  
Vol 62 (5) ◽  
pp. 493-497 ◽  
Author(s):  
Herdjania Veras de Lima ◽  
Álvaro Pires da Silva ◽  
Sílvia Imhoff ◽  
Afrânio Ferreira Neves Junior
Keyword(s):  
Soil Bulk Density ◽  
Field Method ◽  
Laboratory Method ◽  
Soil Samples ◽  
Soil Core ◽  
Hydraulic Pump ◽  
Undisturbed Soil ◽  
Alternative Method ◽  
Moisture Conditions ◽  
Large Soil

Due to the narrow window of ideal moisture conditions required for collecting undisturbed soil samples from hardsetting horizons in the field, this study compared the efficiency of an alternative method of soil core removal in the laboratory with that of the traditional field method by using measurements of soil bulk density data (Db). In a first sampling, cylinders were removed with a soil sampler in the field. In a second sampling, large soil blocks were removed with Kubiena-type zinc (brass) boxes in the field. Volumetric core cylinder samples were removed from these blocks in the laboratory with a manual hydraulic pump. There were no differences between the Db values determined from the laboratory and the field coring method. The laboratory method was considered more efficient than the field method because it allowed reductions in the errors made by operators in the field, and those caused by differences in soil water content. The laboratory method allows sampling in hardsetting horizons throughout the year, and collecting soil core samples under conditions of controlled moisture and applied force.

scholarly journals Field and numerical study of chlorotoluron transport in the soil profile

2011 ◽  
Vol 50 (No. 8) ◽  
pp. 333-338 ◽  
Author(s):  
R. Kodešová ◽  
J. Kozák ◽  
O. Vacek
Keyword(s):  
Adsorption Isotherm ◽  
Solute Transport ◽  
Soil Water ◽  
Soil Profile ◽  
Preferential Flow ◽  
Water Movement ◽  
Numerical Study ◽  
Soil Samples ◽  
Transport Parameters ◽  
Four Square

The transport of chlorotoluron in the soil profile under field conditions was studied. The herbicide Syncuran was applied on a four square meter plot using an application rate of 2.5 kg/ha active ingredient. Soil samples were taken after 119 days to study the residual chlorotoluron distribution in the soil profile. HYDRUS-1D (Šimůnek et al. 1998) was used to simulate water movement and herbicide transport in the soil profile. Soil hydraulic properties and their variability were studied previously by Kutílek et al. (1989). The solute transport parameters, like the adsorption isotherm and the degradation rate, were determined in the laboratory. The Freundlich and Langmuir equations were used to fit the experimental data points of the adsorption isotherm, and the affect of each type of adsorption isotherm equation on the solute transport was studied. The chlorotoluron concentrations in soil water tended to be higher for the simulation performed with the Freundlich isotherm then that of the model using the Langmuir isotherm. In both cases, the solution did not pass a depth of8 cm. The simulated chlorotoluron concentrations in soil samples were higher then the observed concentrations when the chlorotoluron degradation was assumed to be in soil water only. Assumption of the solute degradation in both in the solid and the liquid phase significantly improved the accuracy of the solution. The different characters of the simulated and observed chlorotoluron distributions can probably be attributed to the preferential flow of water and solute in the soil profile and by variability of the transport parameters.

scholarly journals Calibration of a soil moisture sensor with disturbed and undisturbed soil samples from Bahia

2018 ◽  
Vol 22 (10) ◽  
pp. 696-701
Author(s):  
João G. A. Lima ◽  
Aureo S. de Oliveira ◽  
Luciano da S. Souza ◽  
Neilon D. da Silva ◽  
Paula C. Viana
Keyword(s):  
Soil Moisture ◽  
Soil Samples ◽  
Calibration Data ◽  
Undisturbed Soil ◽  
Moisture Sensor ◽  
Soil Moisture Sensor ◽  
Disturbed Soil ◽  
Undisturbed Samples ◽  
Three Samples ◽  
Quadratic Models

ABSTRACT The objective of this study was to evaluate the models proposed by manufacturers and in the literature with respect to soil moisture measurement and to evaluate the performance of the CS616 sensor in the calibration of disturbed and undisturbed soil samples. These calibrations were performed using linear and quadratic models. Disturbed samples were collected in São Gabriel/BA, six samples placed in pots, whereas undisturbed samples were collected in Cruz das Almas/BA, three samples directly collected in the area and placed in a container. A calibration was performed between 21/12/2016 and 08/01/2017. The models proposed in the literature and by manufacturers differed in the estimation of volumetric soil moisture. Disturbed soil samples had higher data dispersion than undisturbed samples, due to factors such as grain size and bulk density, which influence the calibration data. The CS616 sensor had satisfactory performance in the calibration of disturbed and undisturbed samples, with excellent fit of the soil moisture data. Using soil moisture contents obtained by the CS616 sensor, without a previous calibration, may lead to errors in the results, confirming the need for a specific calibration for each type of soil.

A SOIL SAMPLING PROCEDURE FOR MICROMORPHOLOGICAL STUDIES

1987 ◽  
Vol 67 (3) ◽  
pp. 693-695 ◽  
Author(s):  
K. C. WIRES ◽  
B. H. SHELDRICK
Keyword(s):  
Key Words ◽  
Thin Section ◽  
Mineral Soil ◽  
Sampling Procedure ◽  
Soil Samples ◽  
Soil Sampling ◽  
Sampling System ◽  
Undisturbed Soil

An inexpensive, lightweight adjustable hydraulic sampling system is described for obtaining "undisturbed" Kubiena box samples, in relatively stone-free mineral soil, for thin-section preparation. Key words: Hydraulic sampling, undisturbed soil samples, thin section

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