Calibration of a Capacitance System for Measuring Water Content of Tropical Soil

Polyakov, Viktor O.; Fares, Ali; Ryder, Micah

doi:10.2136/vzj2005.0028

Cited by 51 publications

(29 citation statements)

References 25 publications

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“…Due to this dependency, it was not possible to transfer findings of calibration functions established under laboratory conditions to field conditions. These two aspects conform to different studies, which evaluated other capacitance‐based soil moisture sensors [ Veldkamp and O'Brien , 2000; Polyakov et al , 2005]. The manufacturer's function was found not to be appropriate above 30–40 Vol.%.…”

Section: Discussionsupporting

confidence: 72%

Soil moisture monitoring for climate research: Evaluation of a low-cost sensor in the framework of the Swiss Soil Moisture Experiment (SwissSMEX) campaign

et al. 2011

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[1] Soil moisture measurements are essential to understand land surface-atmosphere interactions. In this paper we evaluate the performance of the low-cost 10HS capacitance sensor (Decagon Devices, United States) using laboratory and field measurements. Measurements with 10HS sensors of volumetric water content (VWC, Vol.%), integrated absolute soil moisture (millimeters) over the measured soil column, and the loss of soil moisture (millimeters) for rainless days are compared with corresponding measurements from gravimetric samples and time domain reflectometry (TDR) sensors. The field measurements were performed at two sites with different soil texture in Switzerland, and they cover more than a year of parallel measurements in several depths down to 120 cm. For low VWC, both sensor types present good agreement for laboratory and field measurements. Nevertheless, the measurement accuracy of the 10HS sensor reading (millivolts) considerably decreases with increasing VWC: the 10HS sensors tend to become insensitive to variations of VWC above 40 Vol.%. The field measurements reveal a soil type dependency of the 10HS sensor performance, and thus limited applicability of laboratory calibrations. However, with site-specific exponential calibration functions derived from parallel 10HS and TDR measurements, the error of the 10HS compared to the TDR measurements can be decreased for soil moisture contents up to 30 Vol.%, and the day-to-day variability of soil moisture is captured. We conclude that the 10HS sensor is appropriate for setting up dense soil moisture networks when focusing on medium to low VWC and using an established site-specific calibration function. This measurement range is appropriate for several applications in climate research, but the identified performance limitations should be considered in investigations focusing on humid conditions and absolute soil moisture.

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Section: Discussionsupporting

confidence: 72%

Soil moisture monitoring for climate research: Evaluation of a low-cost sensor in the framework of the Swiss Soil Moisture Experiment (SwissSMEX) campaign

et al. 2011

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“…The calibration equation for the capacitance probe was derived from regression analysis of sensor measurements of scale frequency (SF) against volumetric soil water content (θ v ) for each soil depth (10,20,30,40,50,70 and 90 cm) with SF = aθ v b . For calibration purposes, six probes were installed at the site covering a wide range of soil water contents following the procedure recommended by the manufacturer (Sentek, 2001;Polyakov et al, 2005).…”

Section: Soil Water Measurementmentioning

confidence: 99%

Effect of incorporated or mulched compost on leaf nutrient concentrations and performance of Vitis vinifera cv. Merlot

Nguyen

Fuentes

Marschner

2013

J. Soil Sci. Plant Nutr.

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Compost can reduce evaporation and increase nutrient uptake by plants, but it is not clear if it can increase soil water holding capacity or stimulate leaf gas exchange, water use efficiency and yield of vines. To study these effects, compost from garden and food waste was incorporated or mulched in a vineyard at a rate of 100 m 3 ha -1 , three months before the measurements. The vineyard received irrigation during spring and summer. Soil water content was monitored regularly with a capacitance probe. Photosynthesis, transpiration, stem water potential and leaf area index were measured several times during the vegetation period. At harvest, yield, berry weight and quality as well as chlorophyll, N, P and K concentrations in leaves were determined. Only mulched compost increased soil water content at 10 cm depth, but the water content in the deeper layers was not affected by compost addition. Compost also did not affect transpiration rate and stomatal conductance during the vegetation period, but mulched compost increased the photosynthesis per plant at flowering, pea size and maturity periods. Compost amendment, particularly mulching, increased yield, specific berry weight, and leaf N and P concentrations, and reduced the number of chlorotic leaves at harvest. Berry quality was not affected by compost amendment. It can be concluded that mulched compost has a positive effect on grapevine yield and can be an alternative fertiliser source for vines with no adverse effect on berry quality.

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“…The correlation coefficient between the readings and actual soil water content based on field calibration was 89.39%, with a resolution of 0.008%, and a precision of ±0.06%. The temperature effects on readings of MCP (Multi-sensor Capacitance Probe) were conducted in the lab with the standard procedures described in detail by Polyakov (2005) and Fares (2007). The temperature effects for the capacitance sensors were 14.4% of readings from 12 • C to 45 • C at 10 cm, 13.9% from 11 • C to 50 • C at 20 cm, 14 % from 9 • C to 51 • C at 30 cm, 13% from 9 • C to 55 • C at 40 cm, and 15 % of readings from 8 • C to 55 • C at 50 cm, respectively.…”

Section: Experimental Design and Data Collectionmentioning

confidence: 99%

Diurnal pattern of the drying front in desert and its application for determining the effective infiltration

Zeng

Wan

et al. 2009

Hydrol. Earth Syst. Sci.

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Abstract. Located in western Inner Mongolia, the Badain Jaran Desert is the second largest desert in China and consists of a regular series of stable megadunes, among which over 70 permanent lakes exist. The unexpected lakes in desert attracted research interests on exploring the hydrological process under this particular landscape; however, a very few literatures exist on the diurnal and spatial variation of the drying front in this area, which is the main issue in the desert hydrological process to characterize the movement of water in soil. In order to understand the drying front in the Badain Jaran Desert, a field campaign was conducted by the observations of soil physical parameters and micrometeorological parameters. With the field data, the performance of a vadose zone soil water balance model, the HYDRUS, was verified and calibrated. Then, the HYDRUS was used to produce the spatial and temporal information of coupled water, water vapour and heat transport in sand to characterize the variation pattern of the drying front before, during and after the rainfall. Finally, the deepest drying front was applied to determine the effective infiltration, which is defined as the amount of soil water captured by the sand beneath the deepest drying front by infiltrating water of an incident rainfall event.

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Calibration of a Capacitance System for Measuring Water Content of Tropical Soil

Cited by 51 publications

References 25 publications

Soil moisture monitoring for climate research: Evaluation of a low-cost sensor in the framework of the Swiss Soil Moisture Experiment (SwissSMEX) campaign

Soil moisture monitoring for climate research: Evaluation of a low-cost sensor in the framework of the Swiss Soil Moisture Experiment (SwissSMEX) campaign

Effect of incorporated or mulched compost on leaf nutrient concentrations and performance of Vitis vinifera cv. Merlot

Diurnal pattern of the drying front in desert and its application for determining the effective infiltration

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