Solute Diffusivity in Undisturbed Soil: Effects of Soil Water Content and Matric Potential

2012 ◽  
Vol 76 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Mette Laegdsmand ◽  
Per Moldrup ◽  
Per Schjønning
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Matric Potential ◽  
Undisturbed Soil ◽  
Solute Diffusivity ◽  
Soil Effects

scholarly journals Soil Structure and Texture Effects on the Precision of Soil Water Content Measurements with a Capacitance- Based Electromagnetic Sensor

2020 ◽  
Vol 63 (1) ◽  
pp. 141-152
Author(s):  
Jasreman Singh ◽  
Derek M. Heeren ◽  
Daran R. Rudnick ◽  
Wayne E. Woldt ◽  
Geng Bai ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Sensor Calibration ◽  
Soil Water Depletion ◽  
Undisturbed Soil ◽  
Water Depletion ◽  
Soil Moisture Sensors ◽  
Electromagnetic Sensor

HighlightsCapacitance-based electromagnetic soil moisture sensors were tested in disturbed and undisturbed soils.The uncertainty in estimation of soil water depth was lower using the undisturbed soil sample calibrations.The uncertainty in estimation of soil water depletion was lower than the uncertainty in volumetric water content.Undisturbed calibration of water depletion quantifies water demand with better precision and avoids over-watering.Abstract. The physical properties of soil, such as structure and texture, can affect the performance of an electromagnetic sensor in measuring soil water content. Historically, calibrations have been performed on repacked samples in the laboratory and on soils in the field, but little research has been done on laboratory calibrations with intact (undisturbed) soil cores. In this study, three replications each of disturbed and undisturbed soil samples were collected from two soil texture classes (Yutan silty clay loam and Fillmore silt loam) at a field site in eastern Nebraska to investigate the effects of soil structure and texture on the precision of a METER Group GS-1 capacitance-based sensor calibration. In addition, GS-1 sensors were installed in the field near the soil collection sites at three depths (0.15, 0.46, and 0.76 m). The soil moisture sensor had higher precision in the undisturbed laboratory setup, as the undisturbed calibration had a better correlation [slope closer to one, R2undisturbed (0.89) > R2disturbed (0.73)] than the disturbed calibrations for the Yutan and Fillmore texture classes, and the root mean square difference using the laboratory calibration (RMSDL) was higher for pooled disturbed samples (0.053 m3 m-3) in comparison to pooled undisturbed samples (0.023 m3 m-3). The uncertainty in determination of volumetric water content (?v) was higher using the factory calibration (RMSDF) in comparison to the laboratory calibration (RMSDL) for the different soil structures and texture classes. In general, the uncertainty in estimation of soil water depth was greater than the uncertainty in estimation of soil water depletion by the sensors installed in the field, and the uncertainties in estimation of depth and depletion were lower using the calibration developed from the undisturbed soil samples. The undisturbed calibration of soil water depletion would determine water demand with better precision and potentially avoid over-watering, offering relief from water shortages. Further investigation of sensor calibration techniques is required to enhance the applicability of soil moisture sensors for efficient irrigation management. Keywords: Calibration, Capacitance, Depletion, Irrigation, Precision, Sensor, Soil water content, Structure, Uncertainty.

Determination of critical soil water content and matric potential for wind erosion

2010 ◽  
Vol 11 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Kristine Bolte ◽  
Peter Hartmann ◽  
Heiner Fleige ◽  
Rainer Horn
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Wind Erosion ◽  
Matric Potential

scholarly journals Drought stress tolerance of two wheat genotypes

2008 ◽  
Vol 3 (Special Issue No. 1) ◽  
pp. S95-S104 ◽  
Author(s):  
A. Lukács ◽  
G. Pártay ◽  
T. Németh ◽  
S. Csorba ◽  
C. Farkas
Keyword(s):  
Soil Moisture ◽  
Drought Stress ◽  
Water Balance ◽  
Water Content ◽  
Stress Tolerance ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Columns ◽  
Undisturbed Soil ◽  
Wheat Genotypes

Biotic and abiotic stress effects can limit the productivity of plants to great extent. In Hungary, drought is one of the most important constrains of biomass production, even at the present climatic conditions. The climate change scenarios, developed for the Carpathian basin for the nearest future predict further decrease in surface water resources. Consequently, it is essential to develop drought stress tolerant wheat genotypes to ensure sustainable and productive wheat production under changed climate conditions. The aim of the present study was to compare the stress tolerance of two winter wheat genotypes at two different scales. Soil water regime and development of plants, grown in a pot experiment and in large undisturbed soil columns were evaluated. The pot experiments were carried out in a climatic room in three replicates. GK Élet wheat genotype was planted in six, and Mv Emese in other six pots. Two pots were left without plant for evaporation studies. Based on the mass of the soil columns without plant the evaporation from the bare soil surface was calculated in order to distinguish the evaporation and the transpiration with appropriate precision. A complex stress diagnosis system was developed to monitor the water balance elements. ECH<sub>2</sub>O type capacitive soil moisture probes were installed in each of the pots to perform soil water content measurements four times a day. The irrigation demand was determined according to the hydrolimits, derived from soil hydrophysical properties. In case of both genotypes three plants were provided with the optimum water supply, while the other three ones were drought-stressed. In the undisturbed soil columns, the same wheat genotypes were sawn in one replicate. Similar watering strategy was applied. TDR soil moisture probes were installed in the soil at various depths to monitor changes in soil water content. In order to study the drought stress reaction of the wheat plants, microsensors of 1.6 mm diameter were implanted into the stems and connected to a quadrupole mass spectrometer for gas analysis. The stress status was indicated in the plants grown on partly non-irrigated soil columns by the lower CO<sub>2</sub> level at both genotypes. It was concluded that the developed stress diagnosis system could be used for soil water balance elements calculations. This enables more precise estimation of plant water consumption in order to evaluate the drought sensitivity of different wheat genotypes.

scholarly journals Field scale variability of solute transport parameters and related soil properties

1997 ◽  
Vol 1 (4) ◽  
pp. 801-811 ◽  
Author(s):  
B. Lennartz ◽  
S. K. Kamra ◽  
S. Meyer-Windel
Keyword(s):  
Soil Properties ◽  
Solute Transport ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Preferential Flow ◽  
Type I ◽  
Transport Parameters ◽  
Undisturbed Soil ◽  
Soil Hydraulic

Abstract. The spatial variability of transport parameters has to be taken into account for a reliable assessment of solute behaviour in natural field soils. Two field sites were studied by collecting 24 and 36 small undisturbed soil columns at an uniform grid of 15 m spacing. Displacement experiments were conducted in these columns with bromide traced water under unsaturated steady state transport conditions. Measured breakthrough curves (BTCs) were evaluated with the simple convective-dispersive equation (CDE). The solute mobility index (MI) calculated as the ratio of measured to fitted pore water velocity and the dispersion coefficient (D) were used to classify bromide breakthrough behaviour. Experimental BTCs were classified into two groups: type I curves expressed classical solute behaviour while type II curves were characterised by the occurrence of a bromide concentration maximum before 0.35 pore volumes of effluent (MI<0.35) resulting from preferential flow conditions. Six columns from site A and 8 from site B were identified as preferential. Frequency distributions of the transport parameters (MI and D) of both sites were either extremely skewed or bimodal. Log-transformation did not lead to a normal distribution in any case. Contour maps of bromide mass flux at certain time steps indicated the clustering of preferential flow regions at both sites. Differences in the extent of preferential flow between sites seemed to be governed by soil structure. Linear cross correlations among transport parameters and independently measured soil properties revealed relations between solute mobility and volumetric soil water content at time of sampling, texture and organic carbon content. The volumetric field soil water content, a simple measure characterising the soil hydraulic behaviour at the sampling location, was found to be a highly sensitive parameter with respect to solute mobility and preferential flow situations. Almost no relation was found between solute transport parameters and independently determined soil properties when non-preferential and preferential samples were considered separately in regression analyses. Future work should concentrate to relate integrated parameters such as the infiltration rate or the soil hydraulic functions to solute mobility under different flow situations.

Soil carbon dioxide efflux determined from large undisturbed soil cores collected in different soil management systems

Biologia ◽  
2009 ◽  
Vol 64 (3) ◽  
Author(s):  
Eszter Tóth ◽  
Sándor Koós ◽  
Csilla Farkas
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Management ◽  
Measuring Method ◽  
Soil Co2 Efflux ◽  
Management Systems ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Undisturbed Soil

AbstractThe aim of this study was to evaluate a measuring technique for determining soil CO2 efflux from large soil samples having undisturbed structure under controlled laboratory conditions. Further objectives were to use the developed measuring method for comparing soil CO2 efflux from samples, collected in three different soil management systems at various soil water content values. The experimental technique was tested and optimised for timing of sampling by taking air samples after 1, 3 and 6 hours of incubation. Based on the results, the incubation time was set to three hours. The CO2 efflux measured for different soil management systems was the highest in the no-till and the lowest in the ploughing treatment, which was in accordance with measurements on accessible organic carbon for microbes. An increase in CO2 efflux with increasing soil water content was found in the studied soil water content range. Our results indicate that soil respiration rates, measured directly after tillage operations, can highly differ from those measured long after.

scholarly journals Soil penetration resistance in a rhodic eutrudox affected by machinery traffic and soil water content

2013 ◽  
Vol 33 (4) ◽  
pp. 748-757 ◽  
Author(s):  
Moacir T. de Moraes ◽  
Henrique Debiasi ◽  
Julio C. Franchini ◽  
Vanderlei R. da Silva
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Compaction ◽  
Crop Yields ◽  
Penetration Resistance ◽  
Soil Bulk Density ◽  
Front Axle ◽  
Undisturbed Soil ◽  
Soil Penetration Resistance

Soil compaction caused by machinery traffic reduces crop yields. This study aimed to evaluate the effects of intensive traffic, and the soil water content, on the soil penetration resistance (PR) of a Rhodic Eutrudox (Distroferric Red Latosol, Brazilian Classification), managed under no-tillage (NT). The experiment consisted of six treatments: NT with recent chiseling, NT without additional compaction, and NT with additional compaction by 4, 8, 10 and 20 passes of a harvester with a weight of 100 kN (70 kN on the front axle). Undisturbed soil samples were collected at 5.5-10.5 cm and 13.5-18.5 cm depth to quantify the soil bulk density (BD). The PR was assessed in four periods, using an impact penetrometer, inserted in the soil to a depth of 46 cm. The effect of traffic intensities on the PR was small when this variable was assessed with the soil in the plastic consistency. Differences in PR among treatments increased as the soil water content decreased. The increase in the values of PR and BD was higher in the first passes, but the increase in the number of traffics resulted in deeper soil compaction. The machinery traffic effects on PR are better characterized in the friable soil consistency.

scholarly journals Correction of resistance to penetration by pedofunctions and a reference soil water content

2012 ◽  
Vol 36 (6) ◽  
pp. 1704-1713 ◽  
Author(s):  
Moacir Tuzzin de Moraes ◽  
Henrique Debiasi ◽  
Julio Cezar Franchini ◽  
Vanderlei Rodrigues da Silva
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Compaction ◽  
Soil Layer ◽  
Penetration Resistance ◽  
Pedotransfer Functions ◽  
Undisturbed Soil ◽  
Important Indicator ◽  
Soil Penetration Resistance

The soil penetration resistance is an important indicator of soil compaction and is strongly influenced by soil water content. The objective of this study was to develop mathematical models to normalize soil penetration resistance (SPR), using a reference value of gravimetric soil water content (U). For this purpose, SPR was determined with an impact penetrometer, in an experiment on a Dystroferric Red Latossol (Rhodic Eutrudox), at six levels of soil compaction, induced by mechanical chiseling and additional compaction by the traffic of a harvester (four, eight, 10, and 20 passes); in addition to a control treatment under no-tillage, without chiseling or additional compaction. To broaden the range of U values, SPR was evaluated in different periods. Undisturbed soil cores were sampled to quantify the soil bulk density (BD). Pedotransfer functions were generated correlating the values of U and BD to the SPR values. By these functions, the SPR was adequately corrected for all U and BD data ranges. The method requires only SPR and U as input variables in the models. However, different pedofunctions are needed according to the soil layer evaluated. After adjusting the pedotransfer functions, the differences in the soil compaction levels among the treatments, previously masked by variations of U, became detectable.

scholarly journals Soil moisture and matric potential – an open field comparison of sensor systems

2020 ◽  
Vol 12 (1) ◽  
pp. 683-697 ◽  
Author(s):  
Conrad Jackisch ◽  
Kai Germer ◽  
Thomas Graeff ◽  
Ines Andrä ◽  
Katrin Schulz ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Best Practice ◽  
Calibration Procedure ◽  
Sensor Systems ◽  
State Variables ◽  
Matric Potential ◽  
Cross Correlation Analysis

Abstract. Soil water content and matric potential are central hydrological state variables. A large variety of automated probes and sensor systems for state monitoring exist and are frequently applied. Most applications solely rely on the calibration by the manufacturers. Until now, there has been no commonly agreed-upon calibration procedure. Moreover, several opinions about the capabilities and reliabilities of specific sensing methods or sensor systems exist and compete. A consortium of several institutions conducted a comparison study of currently available sensor systems for soil water content and matric potential under field conditions. All probes were installed at 0.2 m b.s. (metres below surface), following best-practice procedures. We present the set-up and the recorded data of 58 probes of 15 different systems measuring soil moisture and 50 further probes of 14 different systems for matric potential. We briefly discuss the limited coherence of the measurements in a cross-correlation analysis. The measuring campaign was conducted during the growing period of 2016. The monitoring data, results from pedophysical analyses of the soil and laboratory reference measurements for calibration are published in Jackisch et al. (2018, https://doi.org/10.1594/PANGAEA.892319).

Soil tillage systems to reduce the harmful effect of extreme weather and hydrological situations

Biologia ◽  
2009 ◽  
Vol 64 (3) ◽  
Author(s):  
Csilla Farkas ◽  
Márta Birkás ◽  
György Várallyay
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Structure ◽  
Water Regime ◽  
Harmful Effect ◽  
Soil Tillage ◽  
Catch Crop ◽  
Undisturbed Soil

AbstractSoil as the largest potential natural water reservoir in the Carpathian Basin has increasing importance under conditions of predicted climate change resulting in increase of probability of extreme hydrological events. Soil management changes soil structure and has a major effect on soil water, heat and nutrition regimes. In this study the effect of four tillage treatments in combination with catch crop management was studied on soil hydraulic properties and water regime under semi-arid conditions. Investigations were carried out in a long-term soil tillage experiment established on Calcic Chernozem soil in Hungary. Tillage variants comprised mouldboard ploughing, disking, loosening combined with disking and direct drilling. The crop sequence between September 2003 and September 2004 comprised maize (main crop), rye (catch crop) and pea (forage). In May 2004, disturbed samples and undisturbed soil cores were collected from each tillage treatment/catch crop combination. The main soil physical and hydrophysical properties were determined in laboratory. In each treatment, capacitive soil moisture probes were installed up to 80 cm depth to ensure continuous measurement of soil water content. Total soil water amounts of chosen soil layers and soil water content dynamics as a function of depth were evaluated for selected periods in order to quantify the effect of the studied management systems on soil water regime. The main conclusion from the experiment is that under such (or similar) ecological conditions, the uniform, „over-standardized“ adaptation of tillage methods for soil moisture conservation is rather risky, their application needs special care and the future is for site-specific precision technologies. These are, in combination with catch crop application can be efficient measures of environmental protection and soil structure and water conservation.

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