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 >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.

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.

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.

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

<p>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<sup>3</sup> 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 (θ<sub>pF3</sub>) instead at the saturated water content. The image spectral data were correlated with the Campbell parameters [θ<sub>pF3</sub>, 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.</p>

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.

scholarly journals Water retention and shrinkage curves of weathered pyroclastic soil

2020 ◽  
Vol 195 ◽  
pp. 03003
Author(s):  
Ana Sofia Dias ◽  
Abhijith Kamath ◽  
Marianna Pirone ◽  
Gianfranco Urciuoli
Keyword(s):  
Stress State ◽  
Water Content ◽  
Water Retention ◽  
Accurate Determination ◽  
Volumetric Water Content ◽  
Water Retention Curve ◽  
Correct Estimation ◽  
Pyroclastic Soil

The modelling of the triggering mechanism of rainfall-induced landslides in slopes covered by pyroclastic soil (as the area surrounding Mount Vesuvius in Campania, Italy) requires the hydraulic characterization of soil in unsaturated conditions in order to analyse the slope response to rainfalls. In previous studies carried out on Campanian pyroclastic soils, the volumetric soil changes due to suction changes have been disregarded, being them negligible in soils characterized by low plasticity and low clay contents. However, a more accurate determination of the water retention curve (WRC) in terms of volumetric water content requires a correct estimation of the total soil volume, which is affected by the soil stress-state. The proper approach would require the estimation of both WRC in terms of gravimetric water content and the shrinkage curve (SC). In the present study, a relation between void ratio and suction was determined for a pyroclastic soil sampled at Mount Faito in Southern Italy. Therefore, a correction of the volumetric water content was carried out resulting in updated water retention curves. Here, the matric suction was the only factor affecting the stress-state of the soil.

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;

Relating soil structure and hydrophysical characteristics to aerobic and anaerobic soil respiration

2020 ◽  
Author(s):  
Teamrat Ghezzehei ◽  
Jennifer Alvarez ◽  
Yocelyn Villa ◽  
Rebecca Ryals
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Soil Water ◽  
Soil Structure ◽  
Water Retention ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Aerobic And Anaerobic

&lt;p&gt;The dynamics of soil organic matter is strongly controlled by the hydrophysical environmental factors, including motility, aqueous diffusivity of substrates, gaseous diffusivity, and energetic constraints on microbial physiology. The relationships among these physical factors depend on soil moisture and the architecture of the soil pores. In this regard, the soil water retention curve can serve as a macroscopic signature of pore-size distribution. Therefore, the sensitivity of aerobic and anaerobic microbial activity must be closely associated with the shape of the soil water retention curve. The soil water retention curve is, in turn, strongly dependent on soil texture and structure. Here, we present a physically-based model of aerobic and anaerobic microbial respiration rates. We also present a novel experimental technique for the characterization of the soil-moisture sensitivity of soil microbial activity. The proposed experimental and modeling approaches allow direct coupling of the fate soil organic matter with the nature of soil structure.&lt;/p&gt;

scholarly journals DEVELOPMENT EXPERIENCE AND WAYS OF IMPROVEMENT OF IRRIGATION MANAGEMENT SYSTEMS

2019 ◽  
pp. 17-30
Author(s):  
M. I. Romashchenko ◽  
T. V. Matіash ◽  
V. O. Bohaienko ◽  
V. P. Kovalchuk ◽  
O. P. Voitovich ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Retention ◽  
Moisture Transfer ◽  
Irrigation Management ◽  
Management Systems ◽  
Water Retention Curve ◽  
Suction Pressure ◽  
Winter Rape ◽  
Retention Curve ◽  
Irrigation Control

The paper provides an overview of models and software used in decision support systems in irrigation. The models of biomass accumulation or evapotranspiration are the base of decision support systems in irrigation. The overview of the most famous systems is given, as well as an innovative irrigation control system "Irrigation online" is presented. The objective of the work is to share the experience of development and implementation of irrigation management systems and outline the ways of their improvement. The "Irrigation online" system consists of hardware and software components. The part of the system's hardware is located in the field consisting of iMetos or Davis weather stations, as well as of own-developed equipment. The software part, intended for storing, processing and providing recommendations, is hosted and run on a server. It sends the recommendations about start watering and necessary irrigation rates to a user’s computer or mobile device. The system is based on modelling of moisture transfer, automated measurements of soil moisture and meteorological indicators in the field and weather data from automated forecast web-sites. Water retention curve of  soil and the dependence of the moisture transfer coefficient on the head, which are the input parameters of the model, are given  for every layer according to the van Genuchten-Mualem Model. The application of the system took place in 2019 in SE EF“Askaniiske” Kherson region and LLC “APC “Mais” in Cherkasy region. The system "Irrigation Online" provided the recommendations on watering winter rape, wheat, corn, soybeans, alfalfa and potatoes. The system provided the recommendations on watering winter rape, wheat, corn, soybeans, alfalfa and potatoes. It was specified that the use of the system "Irrigation Online" enables to schedule irrigation regimes, the implementation of which requires watering with less (by 15-25%) in comparison with the current irrigation rates, due to which  more favourable conditions for the maximum realization of crop varieties and hybrids potential  are created. It is accompanied by enhancing the environmental safety of irrigation as a result of minimization of irrigation water losses for infiltration. Irrigation control system "Irrigation Online" uses a range of soil moisture suction pressure rather than a soil moisture range as an optimum moisture supply range for plants. For setting up irrigation terms and rates, the value of suction pressure, which corresponds to the part of water field capacity when it is determined by water retention curve of soil, is taken. The pre-irrigation threshold of suction pressure is the value, which at non-irrigation for some short period will not cause water stress for plants Monitoring of meteorological parameters and soil moisture level in the "Irrigation Online" system allows daily adjusting irrigation terms and rates for next 5 day period and significantly improves the accuracy of their forecasting.

Sign in / Sign up

Export Citation Format

Share Document