scholarly journals Spatial Relationships Between Soil Water Content and Hydraulic Conductivity in a Highly Structured Clay Soils

2014 ◽  
pp. 75-90 ◽  
Author(s):  
Sidney Rosa Vieira ◽  
Célia Regina Grego ◽  
George Clarke Topp ◽  
Willian Daniel Reynolds
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Clay Soils ◽  
Spatial Relationships ◽  
Structured Clay

scholarly journals Effect of Biochar Application and Re-Application on Soil Bulk Density, Porosity, Saturated Hydraulic Conductivity, Water Content and Soil Water Availability in a Silty Loam Haplic Luvisol

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1005 ◽  
Author(s):  
Lucia Toková ◽  
Dušan Igaz ◽  
Ján Horák ◽  
Elena Aydin
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Bulk Density ◽  
Relative Increase ◽  
Saturated Hydraulic Conductivity ◽  
Soil Drought ◽  
Silty Loam

Due to climate change the productive agricultural sectors have started to face various challenges, such as soil drought. Biochar is studied as a promising soil amendment. We studied the effect of a former biochar application (in 2014) and re-application (in 2018) on bulk density, porosity, saturated hydraulic conductivity, soil water content and selected soil water constants at the experimental site in Dolná Malanta (Slovakia) in 2019. Biochar was applied and re-applied at the rates of 0, 10 and 20 t ha−1. Nitrogen fertilizer was applied annually at application levels N0, N1 and N2. In 2019, these levels were represented by the doses of 0, 108 and 162 kg N ha−1, respectively. We found that biochar applied at 20 t ha−1 without fertilizer significantly reduced bulk density by 12% and increased porosity by 12%. During the dry period, a relative increase in soil water content was observed at all biochar treatments—the largest after re-application of biochar at a dose of 20 t ha−1 at all fertilization levels. The biochar application also significantly increased plant available water. We suppose that change in the soil structure following a biochar amendment was one of the main reasons of our observations.

Modelling leaching and recharge in a bare transitional red-brown earth ponded with low salinity water in summer

1994 ◽  
Vol 34 (7) ◽  
pp. 1085 ◽  
Author(s):  
L Cai ◽  
SA Prathapar ◽  
HG Beecher
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Soil Surface ◽  
Saturated Hydraulic Conductivity ◽  
Rate Dependent ◽  
Water And Salt Movement ◽  
Winter Fallow

A modelling study was conducted to evaluate water and salt movement within a transitional red-brown earth with saline B horizon soil when such waters are used for ponding in summer. The model was calibrated using previously published experimental data. The calibrated model was used to evaluate the effect of depth to watertable, saturated hydraulic conductivity, and ponding water salinity on infiltration, water and salt movement within the soil profile, and recharge. The study showed that when initial soil water content and the saturated hydraulic conductivity (Ks) are low, infiltrating water will be stored within the soil profile even in the absence of a shallow watertable. Once the soil water content is high, however, recharge will be significant in winter, even if there is no net infiltration at the soil surface. Infiltration rates depend more on Ks than the depth to watertable if it is at, or below, 1.5 m from the soil surface. When Ks is high, recharge under ponding will be higher than that under winter fallow. Subsequent ponding in summer and fallow in winter tend to leach salts from the soil profile, the leaching rate dependent on Ks. During winter fallow, due to net evaporation, salts tend to move upwards and concentrate near the soil surface. In the presence of shallow watertables, leached salts tend to concentrate at, or near, the watertable.

Field calibration of ThetaProbe (ML2x) and ECHO probe (EC-20) soil water sensors in a Black Vertosol

Soil Research ◽  
2007 ◽  
Vol 45 (3) ◽  
pp. 233 ◽  
Author(s):  
J. L. Foley ◽  
E. Harris
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Clay Soils ◽  
Deep Drainage ◽  
Swelling Clay ◽  
Field Calibration ◽  
Volumetric Measurements

Past studies have shown that soil-specific calibrations are required to attain a higher level of accuracy when measuring soil water content with ThetaProbe and ECHO probe soil water sensors, particularly in swelling clay soils. Both probes were assessed for their capacity to accurately monitor soil water in a deep drainage study on a Black Vertosol. Probes were trialled in situ and calibrated against hand-sampled volumetric measurements. The generic calibrations given by the manufacturers resulted in significant errors in water content estimates for both probes. Using the generic calibration, ECHO probes under-estimated water content by 0.10–0.2 m3/m3, whereas ThetaProbes under-estimated by 0.04 m3/m3 at the wet end and over-estimated by 0.08 m3/m3 at the dry end. The soil-specific calibrations significantly improved the accuracy of both probes. ThetaProbes were chosen for the drainage study. The calibration allowed for accuracy across the full wet–dry range to within 0.001–0.004 m3/m3 of volumetric measurements. ECHO probes were less accurate at the wet end, but still determined soil water content to within 0.02–0.05 m3/m3 of volumetric measurements.

scholarly journals Numerical Modeling of Water Movement from Buried Vertical Ceramic Pipes through Soils

2018 ◽  
Vol 24 (6) ◽  
pp. 72
Author(s):  
Zena Kamil Rasheed ◽  
Maysoon Basheer Abid
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Transient Flow ◽  
Initial Conditions ◽  
Irrigation System ◽  
Pipe Length ◽  
Ceramic Pipe ◽  
Initial Soil

The problem of water scarcity is becoming common in many parts of the world, to overcome part of this problem proper management of water and an efficient irrigation system are needed.  Irrigation with a buried vertical ceramic pipe is known as a very effective in the management of irrigation water.  The two- dimensional transient flow of water from a buried vertical ceramic pipe through homogenous porous media is simulated numerically using the HYDRUS/2D software.  Different values of pipe lengths and hydraulic conductivity were selected.  In addition, different values of initial volumetric soil water content were assumed in this simulation as initial conditions.  Different values of the applied head were assumed in this simulation as boundary conditions.  The results of this research showed that greater spreading occurs in the horizontal direction.  Increasing applied heads, initial soil water contents and pipe hydraulic conductivities, cause increasing the size of wetting patterns but in a few increases.  Also, the results showed that the empirical formulas which can be used for expressing the wetted width and depth in terms of applied head, initial soil water content, application time, pipe hydraulic conductivity, and pipe length, are good and can be used as design equations.        

scholarly journals Numerical Modeling of Water Movement from Buried Vertical Ceramic Pipes through Coarse Soils

2018 ◽  
Vol 13 (4) ◽  
pp. 164-173
Author(s):  
Zena Kamil Rasheed ◽  
Maysoon Basheer Abid
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Transient Flow ◽  
Vertical Direction ◽  
Empirical Formulas ◽  
Pipe Length ◽  
Ceramic Pipe ◽  
Initial Soil

Problem of water scarcity is becoming common in many parts of the world.  Thus to overcome this problem proper management of water and an efficient irrigation systems are needed.  Irrigation with buried vertical ceramic pipe is known as a very effective in management of irrigation water.  The two- dimensional transient flow of water from a buried vertical ceramic pipe through homogenous porous media is simulated numerically using the software HYDRUS/2D to predict empirical formulas that describe the predicted results accurately.   Different values of pipe lengths and hydraulic conductivity were selected.  In addition, different values of initial volumetric soil water content were assumed in this simulation as initial conditions.  Different values of applied head were assumed in this simulation as a boundary conditions.  In general, a good agreement was obtained when comparing the predicted results with available measured values.  The results of this research showed that greater spreading occur in vertical direction.  Increasing applied heads, initial soil water contents, pipe hydraulic conductivities, cause increasing the size of wetting patterns.  Also the results showed that the empirical formulas which can be used for expressing the wetted width and depth in terms of applied head, initial soil water content, application time, pipe hydraulic conductivity, and pipe length, are good and can be used as a designing equations.  

USE OF TEMPE CELL, MODIFIED TO RESTRAIN SWELLING, FOR DETERMINATION OF HYDRAULIC CONDUCTIVITY AND SOIL WATER CONTENT

1984 ◽  
Vol 64 (2) ◽  
pp. 265-272 ◽  
Author(s):  
T. G. SOMMERFELDT ◽  
G. B. SCHAALJE ◽  
W. HULSTEIN
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Movement ◽  
Clay Content ◽  
Core Sample ◽  
Soil Samples ◽  
The Core ◽  
Silty Loam

The Tempe cell, modified by others to determine saturated hydraulic conductivity (K), was further modified to restrain swelling of the soil and to facilitate air and water movement across the top and bottom of the sample. An apparatus was developed whereby K and water content (θ) could be determined for several soil samples concurrently and suction levels could be varied without disturbing the sample. K and θ were determined for several prepared soil samples by the constant head permeameter method and by the Tempe cell with and without swelling restrained, and for soil cores by the Tempe cell with swelling restrained. With swelling restrained, the K results from the prepared samples did not differ significantly from those of the core samples. For the sandy to silty loam soils at suction levels 0, 10, and 20 kPa, θ of the core sample was less than that from the other samples, whereas for the clay loam soils, θ of the core sample was less than that from the others at suction levels of 0 and 10 kPa. For all methods, θ was correlated to clay content of the soil. These results indicate that the Tempe cell, as finally modified with swelling restraints, can be used to determine K and θ for characterizing the drainability of a nonstructured to weakly structured soil, using either prepared samples or cores. Key words: Hydraulic conductivity, pore volume, soil water content, Tempe cell

The dielectric behaviour of clay soils and its application to time domain reflectometry

Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 825 ◽  
Author(s):  
BJ Bridge ◽  
J Sabburg ◽  
KO Habash ◽  
JAR Ball ◽  
NH Hancock
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Clay Soils ◽  
Dielectric Behaviour ◽  
Swelling Clay ◽  
Network Analyser ◽  
Water Contents

The dielectric behaviour of 3 soils, a sandy loam (Red Chromosol), a highly structured non-swelling clay (Red Ferrosol), and a self-mulching swelling clay (Black Vertosol), was investigated using a waveguide and network analyser technique in the frequency range 3.0 GHz to 4.5 GHz. Curves relating the real part of the relative permittivity to water content are presented and compared with the general Topp curve. The Chromosol generally followed the Topp curve, but the Ferrosol and Vertosol both had curves below the Topp curve. The Ferrosol showed a maximum horizontal offset of 0.05 m3/m3 from the Topp curve in the mid soil-water content range of 0.2–0.3 m3/m3 offset from the Topp curve of 0.10 m3/m3, with a maximum of 0.12 m3/m3 occurring at a soil water content of 0.4 m3/m3. Similar dielectric curves were obtained for the Chromosol and Vertosol using time domain reflectometry (TDR). With this method, the Chromosol showed very close agreement with the Topp curve, but the Vertosol again gave a curve below the Topp curve, similar to the one obtained using the waveguide and network analyser, but with a smaller maximum horizontal offset of 0.08 m3/m3. The difference between the waveguide and TDR Vertosol curves was mainly attributed to low bulk densities in the waveguide where packing was difficult. Some was also attributed to the wider spectrum of frequencies used by TDR. Use of the Topp curve for TDR measurements in the Vertosol would underestimate its water content by at least 0.06 m3/m3. These results are in good agreement with others obtained from similar soils. Deviations from the Topp curve are attributed to bound water associated with the clay particles and this depends on clay mineralogy and clay content. The presented calibration curves improve the accuracy of TDR measurements in these types of clay soils. A field comparison between water contents measured by TDR and gravimetric sampling in a similar Black Vertosol is presented. This calibration showed that soil water contents can be severely overestimated by using TDR with long probes and cables. This unexpected and opposite result is discussed in terms of attenuated high frequencies in the 15-m-long connecting cable used, errors in depth of probe placement, and changes in bulk density and DC conductivity.

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