scholarly journals A Novel Frequency Domain Impedance Sensor with a Perforated Cylinder Coaxial Design for In-Situ Measuring Soil Matric Potential

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2626 ◽  
Author(s):  
Chao Chen ◽  
Xiaofei Yan ◽  
Qiang Xu ◽  
Song Yu ◽  
Yihan Ma ◽  
...  
Keyword(s):  
Water Content ◽  
Water Retention ◽  
Soil Samples ◽  
Environmental Research ◽  
Water Retention Curve ◽  
The Novel ◽  
Soil Matric Potential ◽  
Matric Potential ◽  
Retention Curve

Soil matric potential is an important parameter for agricultural and environmental research and applications. In this study, we developed a novel sensor to determine fast and in-situ the soil matric potential. The probe of the soil matric potential sensor comprises a perforated coaxial stainless steel cylinder filled with a porous material (gypsum). With a pre-determined gypsum water retention curve, the probe can determine the gypsum matric potential through measuring its water content. The matric potential of soil surrounding the probe is inferred by the reading of the sensor after the soil reaches a hydraulic equilibrium with the gypsum. The sensor was calibrated by determining the gypsum water retention curve using a pressure plate method and tested in three soil samples with different textures. The results showed that the novel sensor can determine the water retention curves of the three soil samples from saturated to dry when combined with a soil water content sensor. The novel sensor can respond fast to the changes of the soil matric potential due to its small volume. Future research could explore the application for agriculture field crop irrigation.

scholarly journals Influence of the wetting process on estimation of the water-retention curve of tilled soils

Soil Research ◽  
2016 ◽  
Vol 54 (7) ◽  
pp. 840 ◽  
Author(s):  
D. Moret-Fernández ◽  
C. Peña-Sancho ◽  
M. V. López
Keyword(s):  
Water Content ◽  
Water Retention ◽  
Capillary Rise ◽  
Time Domain Reflectometry ◽  
Soil Samples ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Hydraulic Behaviour ◽  
Soil Wetting ◽  
Wetting Process

Correct estimation of the soil-water retention curve (WRC) is of paramount importance to characterise the hydraulic behaviour of soils. This paper studies the influence of two different soil-wetting processes (waterlogging soil, WP; capillary rise to saturation, CRP) on the estimate of the WRC. The two procedures were applied on undisturbed loam soil samples with three degrees of soil structure: (i) consolidated soils under conventional tillage (CT), reduced tillage (RT) and no tillage (NT); (ii) freshly tilled soil under CT and RT; and (iii) CT and RT after secondary tillage plus some intense rainfalls events. WRCs were estimated with time-domain reflectometry (TDR) pressure cells and volumetric water content was measured at saturation conditions (for the WP method) and at pressure heads of 0.5, 1.5, 3, 5, 10, 50, 100, 500 and 1500 kPa. The same cores were used to determine the soil bulk density (ρb), which was subsequently used to estimate the saturated water content under CRP. The ρb value of the consolidated soil under NT was significantly higher (P < 0.001) than under CT and RT. No effect of the wetting process on the WRC of consolidated soils was observed. Only the freshly tilled soil samples under RT were significantly affected by the wetting process. In these cases, the water draining after WP collapsed the more unstable soil macropores and increased the volume of the smaller ones. However, this effect was minimised by the CRP method, which prevented the collapse of the more unstable soil pores. This work demonstrates that the soil-wetting process may have an important effect on the characterisation of the water-holding capacity on freshly tilled soils.

Determination of the tensile strength of unsaturated tailings using bending tests

2015 ◽  
Vol 52 (11) ◽  
pp. 1874-1885 ◽  
Author(s):  
Bibiana Narvaez ◽  
Michel Aubertin ◽  
Faustin Saleh-Mbemba
Keyword(s):  
Tensile Strength ◽  
Water Content ◽  
Water Retention ◽  
Water Retention Curve ◽  
Initial Water Content ◽  
Ambient Conditions ◽  
Initial Water ◽  
Bending Tests ◽  
Retention Curve ◽  
Apparent Cohesion

Bending tests were conducted on specimens of unsaturated tailings from three hard rock mines to evaluate their tensile strength. Saturated samples were prepared at an initial water content, w0, of 40% and then naturally dried under ambient conditions to pre-selected degrees of saturation, Sr, which can be related to the corresponding suction using the water retention curve. The basic interpretation of the bending tests results is based on an elastic–brittle behavior. The results show how the tensile strength, σt, of unsaturated tailings varies with water content, w (and Sr). The experimental data are also used to evaluate Young’s modulus in tension, Et, and to estimate the apparent cohesion, capp, as a function of Sr. Predictive equations are also applied to estimate the values of σt of unsaturated tailings using the water retention curve.

Retrieving soil-water retention curve at the wet part by remote sensing

2020 ◽  
Author(s):  
Zampela Pittaki-Chrysodonta ◽  
Per Moldrup ◽  
Bo V. Iversen ◽  
Maria Knadel ◽  
Lis W. de Jonge
Keyword(s):  
Remote Sensing ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Spectral Data ◽  
Water Retention ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve

&lt;p&gt;The soil water retention curve (SWRC) at the wet part is important for understanding and modeling the water flow and solute transport in the vadose zone. However, direct measurements of SWRC is often laborious and time consuming processes. The Campbell function is a simple method to fit the measured data. The parameters of the Campbell function have been recently proven that can be predicted using visible-near-infrared spectroscopy. However, predicting the SWRC using image spectral data could be an inexpensive and fast method. In this study, 100-cm&lt;sup&gt;3&lt;/sup&gt; soil samples from Denmark were included and the soil water content was measured at a soil-water matric potential from pF 1 [log(10)= pF 1] up to pF 3. The anchored Campbell soil-water retention function was selected instead of the original. Specifically, in this function the equation is anchored at the soil-water content at pF 3 (&amp;#952;&lt;sub&gt;pF3&lt;/sub&gt;) instead at the saturated water content. The image spectral data were correlated with the Campbell parameters [&amp;#952;&lt;sub&gt;pF3&lt;/sub&gt;, and the pore size distribution index (Campbell b). The results showed the potential of remote sensing to be used as a fast and alternative method for predicting the SWRC in a large-scale.&lt;/p&gt;

scholarly journals Estimating the van Genuchten retention curve parameters of undisturbed soil from a single upward infiltration measurement

Soil Research ◽  
2017 ◽  
Vol 55 (7) ◽  
pp. 682 ◽  
Author(s):  
D. Moret-Fernández ◽  
C. Peña-Sancho ◽  
B. Latorre ◽  
Y. Pueyo ◽  
M. V. López
Keyword(s):  
Water Retention ◽  
Time Domain Reflectometry ◽  
Soil Samples ◽  
Water Retention Curve ◽  
Internal Diameter ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Retention Curve ◽  
Loam Soil ◽  
Undisturbed Soil Cores

Estimation of the soil–water retention curve, θ(h), on undisturbed soil samples is of paramount importance to characterise the hydraulic behaviour of soils. Although a method of determining parameters of the water retention curve (α, a scale parameter inversely proportional to mean pore diameter and n, a measure of pore size distribution) from saturated hydraulic conductivity (Ks), sorptivity (S) and the β parameter, using S and β calculated from the inverse analysis of upward infiltration (UI) has been satisfactorily applied to sieved soil samples, its applicability to undisturbed soils has not been tested. The aim of the present study was to show that the method can be applied to undisturbed soil cores representing a range of textures and structures. Undisturbed soil cores were collected using stainless steel cylinders (5cm internal diameter×5cm high) from structured soils located in two different places: (1) an agricultural loam soil under conventional, reduced and no tillage systems; and (2) a loam soil under grazed and ungrazed natural shrubland. The α and n values estimated for the different soils using the UI method were compared with those calculated using time domain reflectometry (TDR) pressure cells (PC) for pressure heads of –0.5, –1.5, –3, –5, –10 and –50kPa. To compare the two methods, α values measured with UI were calculated to the drying branch of θ(h). For each treatment, three replicates of UI and PC calculations were performed. The results showed that the 5-cm high cylinders used in all experiments provided accurate estimates of S and β. Overall, the α and n values estimated with UI were larger than those measured with PC. These differences could be attributed, in part, to limitations of the PC method. On average, the n values calculated from the optimised S and β data were 5% larger than those obtained with PC. A relationship with a slope close to 1 fitted the n values estimated using both methods (nPC=0.73 nUI+0.49; R2=0.78, P<0.05). The results show that the UI method is a promising technique to estimate the hydraulic properties of undisturbed soil samples.

scholarly journals ESTUDO COMPARATIVO DE MÉTODOS PARA A DETERMINAÇÃO DA CURVA DE RETENÇÃO DE ÁGUA NO SOLO

Irriga ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 193-207 ◽  
Author(s):  
Patricia Dos Santos Nascimento ◽  
Luis Henrique Bassoi ◽  
Vital Pedro da Silva Paz ◽  
Carlos Manoel Pedro Vaz ◽  
João De Mendonça Naime ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Soil Layer ◽  
Irrigation Scheduling ◽  
Soil Samples ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Disturbed Soil

A curva de retenção de água no solo pode ser estimada por diversos métodos, e alguns deles demandam maior tempo para a sua determinação. Assim, o objetivo desse trabalho foi a comparação da curva de retenção de água no solo, determinada pelos métodos de Arya & Paris, câmara de Richards e centrífuga, em um Neossolo Quartzarênico em Petrolina - PE. Nas camadas de 0,00-0,20, 0,20-0,40 e 0,40-0,60 m de profundidade, foram coletadas amostras deformadas em 3 pontos de uma área cultivada com videiras irrigadas, as quais foram homogeneizadas por camada, formando assim uma amostra composta para cada camada; em seguida, tais amostras foram subdividas em três subamostras e cada uma foi encaminhada para a determinação da curva de retenção de água no solo pelos métodos testados. Os resultados obtidos pelo método de Arya & Paris não apresentaram correspondência com os obtidos pelos métodos da centrífuga e da câmara de Richards. No entanto, o desenvolvimento de calibrações específicas do método de Arya & Paris para os solos irrigados do Submédio São Francisco é recomendada, tanto pela possibilidade de uso da curva de retenção de água no solo para o manejo de irrigação, como pelo potencial do método quanto à determinação rápida.   UNITERMOS: retenção de água do solo, analisador granulométrico, método.     NASCIMENTO, P. dos S.; BASSOI, L. H.; PAZ, V. P. da S.; VAZ, C. M. P.; NAIME, J. de M.; MANIERI, J. M. COMPARATIVE STUDY OF DETERMINING METHODS OF SOIL WATER RETENTION CURVE     2 ABSTRACT   Soil water retention curve can be estimated by different methods, and some of them are time consuming. Hence, this research aimed to determine and compare the soil water retention curve, obtained by the methods proposed by Arya & Paris, Richards (pressure membrane apparatus) and centrifuge, of a Typic Quartzipisamment from Petrolina, State of Pernambuco, Brazil. To determine the soil water retention curve in the layers of 0.00-0.20; 0.20-0.40 and 0.40-0.60 m depths, disturbed soil samples were collected in three points of an irrigated vineyard area. The disturbed soil samples were homogenized by layer, thus forming a composed sample for each soil layer. These samples were subdivided into three sub samples, and each one was used to determination of soil water retention curve by the methods tested. The results from method proposed by Arya & Paris did not present similarity with those obtained by Richards´chamber and centrifuge methods. Nevertheless, the development of specific calibration to irrigated soils from Lower-middle São Francisco region is recommended due to the application of soil water retention curve to irrigation scheduling as well as the quickness of the method.   KEYWORDS: soil water retention, granulometry analyzer, method.  

scholarly journals Filter Paper Method for the Determination of the Soil Water Retention Curve

2015 ◽  
Vol 39 (5) ◽  
pp. 1344-1352 ◽  
Author(s):  
Eurileny Lucas de Almeida ◽  
Adunias dos Santos Teixeira ◽  
Francisco Chagas da Silva Filho ◽  
Raimundo Nonato de Assis Júnior ◽  
Raimundo Alípio de Oliveira Leão
Keyword(s):  
Filter Paper ◽  
Water Retention ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Matric Potential ◽  
Retention Curve ◽  
Filter Paper Method ◽  
Van Genuchten Model ◽  
Paper Method

ABSTRACT High cost and long time required to determine a retention curve by the conventional methods of the Richards Chamber and Haines Funnel limit its use; therefore, alternative methods to facilitate this routine are needed. The filter paper method to determine the soil water retention curve was evaluated and compared to the conventional method. Undisturbed samples were collected from five different soils. Using a Haines Funnel and Richards Chamber, moisture content was obtained for tensions of 2; 4; 6; 8; 10; 33; 100; 300; 700; and 1,500 kPa. In the filter paper test, the soil matric potential was obtained from the filter-paper calibration equation, and the moisture subsequently determined based on the gravimetric difference. The van Genuchten model was fitted to the observed data of soil matric potential versus moisture. Moisture values of the conventional and the filter paper methods, estimated by the van Genuchten model, were compared. The filter paper method, with R2 of 0.99, can be used to determine water retention curves of agricultural soils as an alternative to the conventional method.

scholarly journals New Soil Property Database Improves Oklahoma Mesonet Soil Moisture Estimates*

2013 ◽  
Vol 30 (11) ◽  
pp. 2585-2595 ◽  
Author(s):  
Bethany L. Scott ◽  
Tyson E. Ochsner ◽  
Bradley G. Illston ◽  
Christopher A. Fiebrich ◽  
Jeffery B. Basara ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Large Scale ◽  
Water Retention ◽  
Soil Property ◽  
Volumetric Water Content ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Soil Moisture Data ◽  
Oklahoma Mesonet

Abstract Soil moisture data from the Oklahoma Mesonet are widely used in research efforts spanning many disciplines within Earth sciences. These soil moisture estimates are derived by translating measurements of matric potential into volumetric water content through site- and depth-specific water retention curves. The objective of this research was to increase the accuracy of the Oklahoma Mesonet soil moisture data through improved estimates of the water retention curve parameters. A comprehensive field sampling and laboratory measurement effort was conducted that resulted in new measurements of the percent of sand, silt, and clay; bulk density; and volumetric water content at −33 and −1500 kPa. These inputs were provided to the Rosetta pedotransfer function, and parameters for the water retention curve and hydraulic conductivity functions were obtained. The resulting soil property database, MesoSoil, includes 13 soil physical properties for 545 individual soil layers across 117 Oklahoma Mesonet sites. The root-mean-square difference (RMSD) between the resulting soil moisture estimates and those obtained by direct sampling was reduced from 0.078 to 0.053 cm3 cm−3 by use of the new water retention curve parameters, a 32% improvement. A &gt;0.15 cm3 cm−3 high bias on the dry end was also largely eliminated by using the new parameters. Reanalysis of prior studies that used Oklahoma Mesonet soil moisture data may be warranted given these improvements. No other large-scale soil moisture monitoring network has a comparable published soil property database or has undergone such comprehensive in situ validation.

scholarly journals Watertable fluctuation-induced variability in the water retention curve: Sand column experiments

2020 ◽  
Author(s):  
Zhaoyang Luo ◽  
Jun Kong ◽  
Zhiling Ji ◽  
Chengji Shen ◽  
Chunhui Lu ◽  
...  
Keyword(s):  
Water Content ◽  
Capillary Pressure ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Retention ◽  
Water Retention Curve ◽  
Water Flow Velocity ◽  
Retention Curve ◽  
Wide Range ◽  
Static Conditions

&lt;p&gt;The soil water retention curve (WRC), describing the relation between the soil water content and its corresponding capillary pressure, relies not only on whether drying or wetting occurs but also on the pore scale water flow velocity. Here, we investigated the effects of the watertable fluctuations on the WRC through 28 laboratory experiments covering a wide range of fluctuation amplitudes and periods. Results show that both the response of the capillary pressure and soil water content lag behind the watertable fluctuation, and the vertical capillary pressure distribution in the unsaturated zone is non-hydrostatic, especially for the fluctuations with shorter period. As a consequence of watertable fluctuation, the measured WRC deviates from that under static conditions, depending on both the fluctuation amplitude and period. Moreover, the air-entry pressure under dynamic conditions is considerably larger than that under static conditions, and it first increases and then decreases as the fluctuation period decreases. The effects of the watertable fluctuations on the dynamic capillary coefficient was further examined. It is found that the relation between the dynamic capillary coefficient and saturation is nonunique even for the drying and wetting of a given sand and watertable fluctuation, suggesting a hysteretic dynamic capillary coefficient, and the dynamic capillary coefficient is rate-dependent, decreasing with an increase of fluctuation rate.&lt;/p&gt;

Root bio-hydro-mechanical reinforcement of unsaturated vegetated soil: experiments and modelling

2021 ◽  
Author(s):  
Anthony Leung ◽  
Davide Boldrin ◽  
Ali Akbar Karimzadeh ◽  
Zhaoyi Wu ◽  
Suriya Ganesan
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Water Retention ◽  
Water Regime ◽  
Biomechanical Properties ◽  
Root Water Uptake ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Soil Bioengineering ◽  
Induced Changes

&lt;p&gt;Plant roots affect soil water regime through root-water uptake upon transpiration. This process induces soil matric suction, which affects soil hydraulic conductivity, soil shear strength and hence shallow soil stability. This is referred to as plant hydrological reinforcement in the soil bioengineering application. Recent experimental evidence put forward by the authors has demonstrated that plant hydrological reinforcement should not be exclusively limited to the effects of root-water uptake and plant transpiration. The presentation will provide some new evidence of other potential aspects of plant hydrological reinforcement, namely (1) root-induced changes in soil hydraulic properties, (2) root water-dependent bio-hydro-mechanical properties. In aspect (1), laboratory test results on how root growth dynamic alter the soil pore size distribution and hence affect both the soil water retention curve and hydraulic conductivity will be presented. To highlight the effects of these root-induced changes in soil properties on slope water regime and slope stability, numerical simulation employing a dual-permeability water transport model in unsaturated rooted soil will be discussed. In aspect (2), a new concept, hysteretic root water retention curve (relationship between root water content and root water potential), will be introduced with support of some preliminary data. How root water retention affects the root biomechanical properties including not only tensile strength and Young&amp;#8217;s modulus that have received wide attention in the soil bioengineering literature but also breakage strain will be presented. New data will be provided in order to attempt to use root water content to explain the large variability of biomechanical properties observed in the literature.&lt;/p&gt;

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