The Petrophysical Relationship between the Dielectric Permittivity and Water Content of Peat Soil Moisture Measurements

Author(s):  
Nurul Izzati Abd Karim ◽  
Samira Albati Kamaruddin ◽  
Rozaimi Che Hasan
2018 ◽  
Vol 7 (2.29) ◽  
pp. 815
Author(s):  
Nurul Izzati Abd Karim ◽  
Samira Albati Kamaruddin ◽  
Rozaimi Che Hasan

Accurate measurements of Soil Water Content (SWC) with applicable and relevant support are essential in many fields of earth and soil engineering research. Ground Penetrating Radar (GPR) is a geophysical tool that measures and provides accurate results for determination of the SWC. To prove the accuracy of SWC measurement using GPR, a field survey was performed in peat soil. This paper presents a fieldwork survey with the aim of assessing the SWC measurement using GPR. The survey work was conducted at Johor Bharu using different antenna frequencies (250 and 700 MHz). Five profiles, which is 5m by 5m in length, were scanned along an east-west direction with a common offset at an equal spacing of 1m.  To measure the SWC using GPR, the researchers used the velocity from the GPR’s signal from the receiving antenna to the soil. Statistical analysis was carried out based on the dielectric permittivity and SWC. Schaap’s equation and Roth’s equation were used to distinguish the relative dielectric permittivity of the soil to SWC. The results of this study show the linear function,  for the measured SWC. The validation graph shows that at a frequency of 250 MHz, the depth of penetration was greater compared to the frequency of 750 MHz. These results, suggest that a higher frequency will give higher resolution but lower depth penetration.  


2013 ◽  
Vol 50 (3) ◽  
pp. 407-425 ◽  
Author(s):  
T. SAMPATHKUMAR ◽  
B. J. PANDIAN ◽  
P. JEYAKUMAR ◽  
P. MANICKASUNDARAM

SUMMARYWater stress induces some physiological changes in plants and has cumulative effects on crop growth and yield. Field experiments were conducted to study the effect of deficit irrigation (DI) on yield and some physiological parameters in cotton and maize in a sequential cropping system. Creation of soil moisture gradient is indispensable to explore the beneficial effects of partial root zone drying (PRD) irrigation and it could be possible only through alternate deficit irrigation (ADI) practice in paired row system of drip layout that is commonly practiced in India. In the present study, PRD and DI concepts (creation of soil moisture gradient) were implemented through ADI at two levels of irrigation using drip system. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Relative leaf water content (RLWC) and chlorophyll stability index (CSI) of cotton and maize were reduced under water stress. A higher level of leaf proline content was observed under severe water-stressed treatments in cotton and maize. RLWC and CSI were highest and leaf proline content was lowest in mild water deficit (ADI at 100% crop evapotranspiration once in three days) irrigation in cotton and maize. The same treatments registered higher values for crop yields, net income and benefit cost ratio for both the crops.


2021 ◽  
Vol 253 ◽  
pp. 112233
Author(s):  
Drew S. Lyons ◽  
Solomon Z. Dobrowski ◽  
Zachary A. Holden ◽  
Marco P. Maneta ◽  
Anna Sala

2012 ◽  
Vol 29 (7) ◽  
pp. 933-943 ◽  
Author(s):  
Weinan Pan ◽  
R. P. Boyles ◽  
J. G. White ◽  
J. L. Heitman

Abstract Soil moisture has important implications for meteorology, climatology, hydrology, and agriculture. This has led to growing interest in development of in situ soil moisture monitoring networks. Measurement interpretation is severely limited without soil property data. In North Carolina, soil moisture has been monitored since 1999 as a routine parameter in the statewide Environment and Climate Observing Network (ECONet), but with little soils information available for ECONet sites. The objective of this paper is to provide soils data for ECONet development. The authors studied soil physical properties at 27 ECONet sites and generated a database with 13 soil physical parameters, including sand, silt, and clay contents; bulk density; total porosity; saturated hydraulic conductivity; air-dried water content; and water retention at six pressures. Soil properties were highly variable among individual ECONet sites [coefficients of variation (CVs) ranging from 12% to 80%]. This wide range of properties suggests very different behavior among sites with respect to soil moisture. A principal component analysis indicated parameter groupings associated primarily with soil texture, bulk density, and air-dried water content accounted for 80% of the total variance in the dataset. These results suggested that a few specific soil properties could be measured to provide an understanding of differences in sites with respect to major soil properties. The authors also illustrate how the measured soil properties have been used to develop new soil moisture products and data screening for the North Carolina ECONet. The methods, analysis, and results presented here have applications to North Carolina and for other regions with heterogeneous soils where soil moisture monitoring is valuable.


2012 ◽  
Vol 16 (2) ◽  
pp. 501-515 ◽  
Author(s):  
R. M. Nagare ◽  
R. A. Schincariol ◽  
W. L. Quinton ◽  
M. Hayashi

Abstract. There are not many studies that report water movement in freezing peat. Soil column studies under controlled laboratory settings can help isolate and understand the effects of different factors controlling freezing of the active layer in organic covered permafrost terrain. In this study, four peat Mesocosms were subjected to temperature gradients by bringing the Mesocosm tops in contact with sub-zero air temperature while maintaining a continuously frozen layer at the bottom (proxy permafrost). Soil water movement towards the freezing front (from warmer to colder regions) was inferred from soil freezing curves, liquid water content time series and from the total water content of frozen core samples collected at the end of freezing cycle. A substantial amount of water, enough to raise the upper surface of frozen saturated soil within 15 cm of the soil surface at the end of freezing period appeared to have moved upwards during freezing. Diffusion under moisture gradients and effects of temperature on soil matric potential, at least in the initial period, appear to drive such movement as seen from analysis of freezing curves. Freezing front (separation front between soil zones containing and free of ice) propagation is controlled by latent heat for a long time during freezing. A simple conceptual model describing freezing of an organic active layer initially resembling a variable moisture landscape is proposed based upon the results of this study. The results of this study will help in understanding, and ultimately forecasting, the hydrologic response of wetland-dominated terrain underlain by discontinuous permafrost.


2015 ◽  
Vol 10 (4) ◽  
pp. 208 ◽  
Author(s):  
Lorenzo Barbanti ◽  
Ahmad Sher ◽  
Giuseppe Di Girolamo ◽  
Elio Cirillo ◽  
Muhammad Ansar

A better understanding of plant mechanisms in response to drought is a strong premise to achieving high yields while saving unnecessary water. This is especially true in the case of biomass crops for non-food uses (energy, fibre and forage), grown with limited water supply. In this frame, we investigated growth and physiological response of two genotypes of biomass sorghum (<em>Sorghum bicolor</em> (L.) Moench) to contrasting levels of soil moisture in a pot experiment carried out in a greenhouse. Two water regimes (high and low water, corresponding to 70% and 30% field capacity) were applied to JS-2002 and Trudan-8 sorghum genotypes, respectively bred for dry sub-tropical and mild temperate conditions. Two harvests were carried out at 73 and 105 days after seeding. Physiological traits (transpiration, photosynthesis and stomatal conductance) were assessed in four dates during growth. Leaf water potential, its components and relative water content were determined at the two harvests. Low watering curbed plant height and aboveground biomass to a similar extent (ca. 􀀀70%) in both genotypes. JS-2002 exhibited a higher proportion of belowground to aboveground biomass, <em>i.e</em>., a morphology better suited to withstand drought. Despite this, JS-2002 was more affected by low water in terms of physiology: during the growing season, the average ratio in transpiration, photosynthesis and stomatal conductance between droughty and well watered plants was, respectively, 0.82, 0.80 and 0.79 in JS-2002; 1.05, 1.08 and 1.03 in Trudan-8. Hence Trudan-8 evidenced a ca. 20% advantage in the three traits. In addition, Trudan-8 could better exploit abundant moisture (70% field capacity), increasing aboveground biomass and water use efficiency. In both genotypes, drought led to very low levels of leaf water potential and relative water content, still supporting photosynthesis. Hence, both morphological and physiological characteristics of sorghum were involved in plant adaptation to drought, in accordance with previous results. Conversely, the common assumption that genotypes best performing under wet conditions are less suited to face drought was contradicted by the results of the two genotypes in our experiment. This discloses a potential to be further exploited in programmes of biomass utilization for various end uses, although further evidence at greenhouse and field level is needed to corroborate this finding.


2020 ◽  
Vol 1 (1) ◽  
pp. 23-32
Author(s):  
Sampurna Dadi Riskiono ◽  
Roy Harry Syidiq Pamungkas ◽  
Yudha Arya

Development at this time is increasing, people expect a tool or technology that can help human work, so technology becomes a necessity for humans. This final task is made a device that can do the job of watering tomato plants automatically. This tool aims to replace the manual work becomes automatic. The benefit of this tool is that it can facilitate the work of humans in watering chili plants. This tool uses a soil moisture sensor which acts as a soil moisture detector and sends an order to Arduino Uno to turn on the relay driver so that the wiper motor can splash water according to the needs of the soil automatically. The making of this final project is done by designing, making and implementing system components which include Arduino uno as a controller, driver relay to blow on and off the wiper motor, LCD (Linquit Cristal Display) to display the percentage value of water content


2021 ◽  
Vol 3 ◽  
Author(s):  
Andres Patrignani ◽  
Tyson E. Ochsner ◽  
Benjamin Montag ◽  
Steven Bellinger

During the past decade, cosmic-ray neutron sensing technology has enabled researchers to reveal soil moisture spatial patterns and to estimate landscape-average soil moisture for hydrological and agricultural applications. However, reliance on rare materials such as helium-3 increases the cost of cosmic-ray neutron probes (CRNPs) and limits the adoption of this unique technology beyond the realm of academic research. In this study, we evaluated a novel lower cost CRNP based on moderated ultra-thin lithium-6 foil (Li foil system) technology against a commercially-available CRNP based on BF3 (boron trifluoride, BF-3 system). The study was conducted in a cropped field located in the Konza Prairie Biological Station near Manhattan, Kansas, USA (325 m a.s.l.) from 10 April 2020 to 18 June 2020. During this period the mean atmospheric pressure was 977 kPa, the mean air relative humidity was 70%, and the average volumetric soil water content was 0.277 m3 m−3. Raw fast neutron counts were corrected for atmospheric pressure, atmospheric water vapor, and incoming neutron flux. Calibration of the CRNPs was conducted using four intensive field surveys (n &gt; 120), in combination with continuous observations from an existing array of in situ soil moisture sensors. The time series of uncorrected neutron counts of the Li foil system was highly correlated (r2 = 0.91) to that of the BF-3 system. The Li foil system had an average of 2,250 corrected neutron counts per hour with an uncertainty of 2.25%, values that are specific to the instrument size, detector configuration, and atmospheric conditions. The estimated volumetric water content from the Li foil system had a mean absolute difference of 0.022 m3 m−3 compared to the value from the array of in situ sensors. The new Li foil detector offers a promising lower cost alternative to existing cosmic-ray neutron detection devices used for hectometer-scale soil moisture monitoring.


Author(s):  
Yanwei Fan ◽  
Liangjun Ma ◽  
Hujun Wei ◽  
Pengcheng Zhu

Abstract Vertical line source irrigation (VLSI) is an underground irrigation method suitable for deep-rooted plants. Understanding the characteristics of the soil wetting body of the VLSI was the key to designing this irrigation system. On the basis of experimental verification of the reliability of the HYDRUS simulation results of VLSI under the conditions of soil texture (ST), initial water content (θi), line source buried depth (B), line source diameter (D) and line source length (L), numerical studies of the migration law of the wetting front of VLSI and the distribution characteristics of soil moisture were performed. The wetting front migration (WFM) was mainly influenced by ST, θi, D and L (P &lt; 0.05), while B had little effect on WFM (P &gt; 0.05). The shape of the soil wetting body changed little under different influencing factors. The water content contour was approximately ‘ellipsoidal’ around the line source. The soil moisture near the line source was close to the saturated moisture content. The moisture content around the line source gradually decreased outward, and the contour lines gradually became dense. According to the simulation results, a prediction model of multiple factors influencing the migration process of the VLSI wetting front was established. The predicted value was in good agreement with the measured value. The results of this research could provide a theoretical basis for further optimizing the combination of VLSI and irrigation elements.


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