Evaluation of Various Soil Moisture Sensors in Four Different Soil Types

Abstract.Accurate measurements of soil moisture content can contribute to resource conservation in irrigated systems. The objective of this study was to evaluate various soil moisture sensors (a porous cup tensiometer, Diviner 2000, PR2, XH300, PM100, and ML3; the mention of model names does not constitute an implied endorsement) used in four different soil types. The experiment was conducted inside a greenhouse using a specially constructed box that contained the soil samples. The soil samples were first saturated and subsequently drained before starting the measurements. The soil moisture content was determined by the oven-drying method. Using the standard deviation of the sensor readings, regression analyses were performed, resulting in calibration equations and coefficient of determination (R2) values for each sensor and soil type combination. The porous cup tensiometer, Diviner 2000, PR2, and ML3 measurements resulted in excellent R2 values that exceeded 0.95 for the four soils. However, measurements with the XH300 and PM100 sensors resulted in R2 values of 0.37 to 0.86 and 0.61 to 0.94, respectively, limiting their scientific applicability for the studied soils. Therefore, the porous cup tensiometer, Diviner 2000, PR2, and ML3 estimated the soil moisture content with greater confidence than did the other sensors and with an error of less than 5%. Keywords: Calibration, Tensiometer, Volumetric water content.

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Draft Requirement of Two Animal - Drawn Institute for Agricultural Research (IAR) Weeders

Journal of Engineering Research and Reports ◽

10.9734/jerr/2020/v10i317039 ◽

2020 ◽

pp. 14-20

Author(s):

Y. A. Unguwanrimi ◽

A. M. Sada ◽

G. N. Ugama ◽

H. S. Garuba ◽

A. Ugoani

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Bulk Density ◽

Soil Moisture Content ◽

Agricultural Research ◽

Soil Samples ◽

Soil Conditions ◽

Experimental Plot ◽

Moisture Contents ◽

Loam Soil

Draft requirements of two animal – drawn (IAR) weeders operating on loam soil were determined in the study. The implements include a straddle row weeder and an emcot attached rotary weeder evaluated under the same soil conditions, using a pair of white Fulani breed of oxen. The animal draft requirement was first estimated from the animal ergonomics measurements. Using area of 0.054 hectare as experimental plot for each implement the draft requirement of each implement was investigated after taking soil samples for soil moisture content and bulk density determinations. The implements tested showed variation in their average draft requirement. The straddle row weeder had the highest value of 338.15 N respectively while the emcot attached rotary weeder had the lowest value of 188.12 N with 47.03%, respectively. The average soil moisture contents and bulk density were 13.0% and 1.46%/cm3, respectively.

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Soil moisture content estimation using water absorption bands

GEOMATICA ◽

10.1139/geomat-2018-0020 ◽

2019 ◽

Vol 73 (3) ◽

pp. 63-73 ◽

Cited By ~ 1

Author(s):

Mohammad Reza Mobasheri ◽

Meisam Amani ◽

Mahin Beikpour ◽

Sahel Mahdavi

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Water Absorption ◽

Soil Moisture Content ◽

Mean Squared Error ◽

Sandy Loam ◽

Soil Types ◽

Accurate Estimation ◽

Absorption Bands ◽

New Models

Soil moisture content (SMC) is a crucial component in various environmental studies. Although many models have been proposed for SMC estimation, developing new models for accurate estimation of SMC is still an interesting subject. This study aimed to develop new models for SMC estimation using the water absorption bands in the spectral signatures of three different soil types: loam, silty loam, and sandy loam. Based on the three absorption bands (i.e., 1400, 1900, and 2200 nm) and regression analyses, six approaches were considered. These scenarios were generally based on the reflectance value and its logarithm, as well as the difference between the wet and dry reflectance values for the absorption bands. Finally, 24 models were developed for SMC estimation from the three different soil types, as well as the entire soil samples. The most accurate SMC, as indicated by the lowest root mean squared error (RMSE) and the highest correlation coefficient (r), was obtained from the model developed using the logarithm of the average values reflectance in the three water absorption bands for sandy loam (RMSE = 0.31 g/kg, r = 0.99). Overall, using the spectrometry data derived in the lab, the results of the proposed models were promising and demonstrate great potential for SMC estimation using spectral data collected by satellites in the future studies.

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Continuous field soil moisture content mapping by means of apparent electrical conductivity (ECa) measurement

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2013-0039 ◽

2013 ◽

Vol 61 (4) ◽

pp. 305-312 ◽

Cited By ~ 4

Author(s):

Viliam Nagy ◽

Gábor Milics ◽

Norbert Smuk ◽

Attila József Kovács ◽

István Balla ◽

...

Keyword(s):

Electrical Conductivity ◽

Soil Moisture ◽

Moisture Content ◽

Soil Moisture Content ◽

Interpolation Method ◽

Moisture Distribution ◽

Coefficient Of Determination ◽

Volumetric Moisture Content ◽

Sampling Points ◽

Apparent Electrical Conductivity

Abstract A soil moisture content map is important for providing information about the distribution of moisture in a given area. Moisture content directly influences agricultural yield thus it is crucial to have accurate and reliable information about moisture distribution and content in the field. Since soil is a porous medium modified generalized Archie’s equation provides the basic formula to calculate moisture content data based on measured ECa. In this study we aimed to find a more accurate and cost effective method for measuring moisture content than manual field sampling. Locations of 25 sampling points were chosen from our research field as a reference. We assumed that soil moisture content could be calculated by measuring apparent electrical conductivity (ECa) using the Veris-3100 on-the-go soil mapping tool. Statistical analysis was carried out on the 10.791 ECa raw data in order to filter the outliers. The applied statistical method was ±1.5 interquartile (IRQ) distance approach. The visualization of soil moisture distribution within the experimental field was carried out by means of ArcGIS/ArcMAP using the inverse distance weighting interpolation method. In the investigated 25 sampling points, coefficient of determination between calculated volumetric moisture content data and measured ECa was R2 = 0.87. According to our results, volumetric moisture content can be mapped by applying ECa measurements in these particular soil types.

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Methodology adaptation and development to assess salt content dynamics and salt balance of soils under secondary salinization

Acta Agraria Debreceniensis ◽

10.34101/actaagrar/1/8326 ◽

2021 ◽

pp. 199-206

Author(s):

Arzu Rivera Garcia ◽

Géza Tuba ◽

Györgyi Kovács ◽

Lúcia Sinka ◽

József Zsembeli

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Soil Moisture Content ◽

Saline Water ◽

Salt Content ◽

Soil Layer ◽

Soil Samples ◽

Irrigation Season ◽

Salt Balance ◽

Secondary Salinization

The effect of irrigation with saline water (above 500 mg L-1) is considered a problem of small-scale farmers growing vegetable crops with high water demand in the hobby gardens characteristic of the Hungarian Great Plain. In order to simulate the circumstances of such hobby garden, we set up an experiment including five simple drainage lysimeters irrigated with saline water in the Research Institute of Karcag IAREF UD in 2019. We regularly measured the electric conductivity (EC) of the soil referring to its salt content and the soil moisture content with mobile sensors. Before and after the irrigation season, soil samples from the upper soil layer (0-0.6 m) were taken for laboratory analysis and the soil salt balance (SB) was calculated. The actual salt balance (SBact) was calculated of the upper soil layer (0-0.6 m) based on the salt content of the obtained soil samples. The theoretical salt balance (SBth) was calculated by the total soluble salt content of the irrigation water and leachates. During the irrigation season, we experienced fluctuating EC in the topsoil in close correlation with the soil moisture content. Based on the performed in-situ EC measurements, salts were leached from the upper soil layer resulting in a negative SB. Combining SBact and SBth of the soil columns of the lysimeters, we estimated the SB of the deeper (0.6-1.0 m) soil layer. We quantified 12% increase of the initial salt mass due to accumulation. We consider this methodology to be suitable for deeper understanding secondary salinization, which can contribute to mitigating its harmful effect. By repeating our measurements, we expect similar results proving that saline irrigation waters gained from the aquifers through drilled wells in Karcag are potentially suitable for irrigation if proper irrigation and soil management are applied.

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Field calibration of DFM capacitance probes for continuous soil moisture monitoring

Water SA ◽

10.17159/wsa/2021.v47.i1.9448 ◽

2021 ◽

Vol 47 (1 January) ◽

Author(s):

L Myeni ◽

ME Moeletsi ◽

AD Clulow

Keyword(s):

Soil Moisture ◽

Soil Depth ◽

Regression Function ◽

Linear Functions ◽

Soil Types ◽

Coefficient Of Determination ◽

Site Specific ◽

Calibration Equations ◽

Soil Moisture Monitoring

This study was undertaken to derive textural and lumped site-specific calibration equations for Dirk Friedhelm Mercker (DFM) capacitance probes and evaluate the accuracy levels of the developed calibration equations for continuous soil moisture monitoring in three selected soil types. At each site, 9 probes (3 per plot) were installed in 2 m2 plots, for continuous soil moisture measurements at 5 different depths (viz. 10, 20, 30, 40 and 60 cm) under dry, moist and wet field conditions. Textural site-specific calibration equations were derived by grouping the same soil textural classes of each site regardless of soil depth, while lumped site-specific calibration equations were derived by grouping all datasets from each site, regardless of soil depth and textural classes. Sensor readings were plotted against gravimetrically measured volumetric soil moisture (θv) for different textural classes as a reference. The coefficient of determination (r2) was used to select the best fit of the regression function. The developed calibration equations were evaluated using an independent dataset. The results indicated that all developed textural and lumped site-specific calibration equations were linear functions, withr2 values ranging from 0.96 to 0.99. Relationships between the measured and estimated θv from calibration equations were reasonable at all sites, with r2 values greater than 0.91 and root mean square error (RMSE) values ranging from 0.010 to 0.020 m3∙m-3. The results also indicated that textural site-specific calibration equations (RMSE < 0.018 m3∙m-3) should be given preference over lumped site-specific calibrations (RMSE < 0.020 m3∙m-3) to attain more accurate θv measurements. The findings of this study suggest that once DFM capacitance probes are calibrated per site, they can be reliably used for accurate in-situ soil moisture measurements. The developed calibration equations can be applied with caution in other sites with similar soil types to attained reliable in-situ soil moisture measurements.

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The influence of the initial soil moisture content on the degree of water stable aggregation as determined by wet sieving

Agricultural and Food Science ◽

10.23986/afsci.71490 ◽

1959 ◽

Vol 31 (1) ◽

pp. 233-239

Author(s):

Mikko Sillanpää

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Soil Moisture Content ◽

Soil Samples ◽

Moisture Condition ◽

Initial Soil Moisture ◽

Initial Soil ◽

Pre Treatment ◽

A Minor ◽

Wet Sieving

The effect of the soil moisture content (varying from the field-moist to air-dry before re-wetting the muddy clay soil samples for aggregate analysis) on aggregation was studied. Two wetting procedures were used and compared: They were spraying samples with a fine mist and wetting them by immersion; aggregate analyses were made by wet sieving method. The results of the aggregate analyses proved to be practically independent of the initial moisture condition of the soil samples when the samples were wetted slowly with a spray. When wetting the samples by direct immersion the mean weight diameters of aggregates decrease with decreasing initial soil moisture content to values of less than half of those obtained from samples in their original field-moist condition (34.6—36.7 % dry wt.) or of those wetted with a spray. Air-drying seems to be a minor factor affecting the destruction of aggregates but the destruction effect of the sample pre-treatment may be very harmful if immersion wetting is used. This, however, can be eliminated almost completely if wetting with a fine mist is used.

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Measurement and prediction of permethrin persistence in six Malaysian agricultural soils

Soil Research ◽

10.1071/sr01097 ◽

2002 ◽

Vol 40 (5) ◽

pp. 817 ◽

Cited By ~ 5

Author(s):

B. S. Ismail ◽

Kalithasan Kailasam

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Half Life ◽

Dissipation Rate ◽

Degradation Rate ◽

Soil Moisture Content ◽

Rate Coefficient ◽

Agricultural Soils ◽

Field Capacity ◽

Soil Types

The effect of soil types, soil temperature, and soil moisture content on the degradation of permethrin was studied under controlled greenhouse conditions. Six soils were used in the study: Soil 1 (Teringkap series), Soil 2 (Ringlet series), Soil 3 (Teringkap 2), Soil 4 (Teringkap 3), Soil 5 (Gunung Berinchang), and Soil 6 (Lating series). Observed data showed that permethrin was more persistent in Soil 1 (23.3 days) and less persistent in Soil 5 (16.7 days). Similarly, the degradation rate coefficient (k) was greater in Soil 5 than Soil 1. The half-life and the dissipation patterns of permethrin between the observed and predicted data were not much different in all 6 soils studied, even though the predicted data were slightly higher. The half-life of permethrin in Soil 6 decreased as the temperature increased from 20°C (36.1 days) to 35°C (13.9 days). The degradation rate coefficient increased as the temperature increased. The predicted data derived from the model showed greater values than the observed data. The half-life of permethrin in Soil 6 decreased as the soil moisture increased from 30% (26.8 days) to 80% (20.1 days). The dissipation rate was not very different between the predicted and the observed data at 80% field capacity and at the temperature of 35°C, and it consequently became closer when the incubation period was prolonged.

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Laboratory calibration of different soil moisture sensors in various soil types

10.5194/egusphere-egu2020-5956 ◽

2020 ◽

Author(s):

Urša Pečan ◽

Damijana Kastelec ◽

Marina Pintar

Keyword(s):

Soil Moisture ◽

Water Content ◽

Bulk Density ◽

Soil Water ◽

Soil Water Content ◽

Soil Bulk Density ◽

Soil Samples ◽

Soil Types ◽

Soil Moisture Sensors ◽

Dry Soil

Measurements of soil water content are particularly useful for irrigation scheduling. In optimal conditions, field data are obtained through a dense grid of soil moisture sensors. Most of the currently used sensors for soil water content measurements, measure relative permittivity, a variable which is mostly dependant on water content in the soil. Spatial variability of soil characteristics, such as soil texture and mineralogy, organic matter content, dry soil bulk density and electric conductivity can also alter measurements with dielectric sensors. So the question arises, whether there is a need for a soil specific calibration of such sensors and is it dependant on the type of sensor? This study evaluated the performance of three soil water content sensors (SM150T, Delta-T Devices Ltd, UK; TRIME-Pico 32, IMKO micromodultechnik GmbH, DE; MVZ 100, Eltratec trade, production and services d.o.o., SI) in nine different soil types in laboratory conditions. Our calibration approach was based on calibration procedure developed for undisturbed soil samples (Holzman et al., 2017). Due to possible micro location variability of soil properties, we used disturbed and homogenized soil samples, which were packed to its original dry soil bulk density. We developed soil specific calibration functions for each sensor and soil type. They ranged from linear to 5th order polynomial. We calculated relative and actual differences in sensor derived and gravimetrically determined volumetric soil water content, to evaluate the errors of soil water content measured by sensors which were not calibrated for soil specific characteristics. We observed differences in performance of different sensor types in various soil types. Our results showed measurements conducted with SM150T sensors were within the range of manufacturer specified measuring error in three soil types for which calibration is not necessary but still advisable for improving data quality. In all other cases, soil specific calibration is required to obtain relevant soil moisture data in the field.

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Retrieving Photometric Properties and Soil Moisture Content of Tidal Flats Using Bidirectional Spectral Reflectance

Remote Sensing ◽

10.3390/rs13071402 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1402

Author(s):

Chen Gao ◽

Min Xu ◽

Hanzeyu Xu ◽

Wei Zhou

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Soil Moisture Content ◽

Roughness Parameter ◽

Soil Surface ◽

Pso Algorithm ◽

Tidal Flats ◽

Soil Samples ◽

Asymmetry Factor ◽

Equivalent Water Thickness

Moisture content in tidal flats changes frequently and spatially on account of tidal fluctuations, which greatly influence the reflectance of the tidal flat surface. Precise prediction of the spatial-temporal variation of tidal flats’ moisture content is an important foundation of surface bio-geophysical information research by remote sensing. In this paper, we first measured the multi-angle reflectance of soil samples obtained from tidal flats in the northeastern Dongtai, Jiangsu Province, China, in the laboratory. Then, based on the particle swarm optimization (PSO) algorithm, we retrieved the photometric characteristics of the soil surface by employing the SOILSPECT bidirectional reflectance model. Finally, the soil moisture content was retrieved by introducing the equivalent water thickness of the soil. The results showed that: (i) A significant correlation existed between the retrieved equivalent water thickness and the measured soil moisture content. The SOILSPECT model is capable of estimating soil moisture with high precision by using multi-angle reflectance. (ii) Retrieved values of single scattering albedo (ω) were consistent with the variation of soil moisture content. The roughness parameter (h) and the asymmetry factor (Θ) were consistent with the structure and particle composition of the soil surface in dry soil samples. (iii) When the soil samples were soaked with water, the roughness parameter (h) and the type of scattering on the soil surface both showed irregular changes. These results support the importance of using the measured soil particle size as one of the parameters for the retrieval of soil moisture content, which is a method that should be used cautiously, especially in tidal flats.

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Persisting effects of ligneous organic soil amendments on CO2, N2O and CH4 emissions in relation to moisture content in northern agricultural clay soil

10.5194/egusphere-egu2020-7464 ◽

2020 ◽

Author(s):

Kenneth Peltokangas ◽

Jimi Havisalmi ◽

Jussi Heinonsalo ◽

Kristiina Karhu ◽

Liisa Kulmala ◽

...

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Soil Moisture Content ◽

Soil Amendments ◽

Ghg Emissions ◽

Organic Amendments ◽

Organic Soil ◽

Soil Samples ◽

Climate Effect ◽

Organic Soil Amendments

In agriculture, organic soil amendments are envisioned to mitigate climate change through carbon sequestration. However, the full impact of the organic amendments on soil physico-chemical dynamics is still poorly understood. We conducted a laboratory incubation to assess the net climate effect of four ligneous organic amendments: two biochars (willow and spruce) and two fiber byproducts of paper and pulp industry. Soil samples were collected from a soil-amendment field experiment at Qvidja farm, South-West of Finland. Soil samples were sieved, air-dried and adjusted to 30%, 50%, 80% and 110% of water holding capacity (WHC), and incubated for 32 days in standard laboratory conditions. Greenhouse gas (GHG) emissions were measured after 1, 5, 12, 20 and 33 days.&#160;The carbon dioxide (CO2) emissions were highest at 80% WHC, and lowest at severely water stressed conditions at 30% WHC. The organic amendments did not have an observable effect on CO2 dynamics. The CO2 emissions correlated linearly with soil moisture and microbial biomass nitrogen. Nitrous oxide (N2O) emissions were systematically lower in the amended soils compared to the control soil, and independent of soil nitrate concentrations. Without organic amendments, N2O emissions increased exponentially with soil moisture content. Methane (CH4) emissions fluctuated throughout the incubation, exhibiting mostly negative values. Consequently, CH4 emissions played only a minor role in the GHG budget.CO2, N2O and CH4 emissions, calculated as&#160;CO2 equivalent,&#160;exhibited a&#160;linear correlation with the moisture gradient. CO2 dominated the GHG budget up to a moisture of 80% WHC, but was superseded by N2O emissions at 110% WHC. The results indicate that soil moisture content is critically affecting the GHG emissions and that while organic soil amendments may have persisting effects on GHG exchange, they primarily occur through N2O dynamics.

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