scholarly journals Approaches to calibrate in-situ capacitance soil moisture sensors and some of their implications

2016 ◽  
Author(s):  
N. A. L. Archer ◽  
B. R. Rawlins ◽  
B. P. Machant ◽  
J. D. Mackay ◽  
P. I. Meldrum
Keyword(s):  
Soil Moisture ◽  
Field Measurements ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Soil Moisture Sensors ◽  
Soil Sensors ◽  
Laboratory Calibration ◽  
Rain Events ◽  
Undisturbed Soil Cores

Abstract. Capacitance probes are increasingly being used to monitor volumetric water content (VWC) in field conditions and are provided with in-built factory calibrations so they can be deployed at a field site without the requirement for local calibration. These calibrations may not always have acceptable accuracy and therefore to improve the accuracy of such calibrations soil-specific laboratory or field calibrations are required. In some cases, manufacturers suggest calibration is undertaken on soil in which the structure has been removed (through sieving or grinding), whilst in other cases manufacturers suggest structure may be retained. The objectives of this investigation were to (i) demonstrate the differences in laboratory calibration of the sensors using both structured and unstructured soils, (ii) compare moisture contents at a range of suctions with those predicted from soil moisture release curves for their texture classes (iii) compare the magnitude of errors for field measurements of soil moisture based on the original factory calibrations and the laboratory-based calibrations using structured soil. Grinding and sieving clay soils to  50 % water to the ground and sieved soil samples, dielectric values to VWC > 50 % were observed to be significantly lower than using undisturbed soil cores taken from the field and therefore undisturbed soil cores were considered to be better to calibrate capacitance probes. Generic factory calibrations for most soil sensors have a range of measurement from 0 to 50 %, which is not appropriate for the studied clay-rich soil, where ponding can occur during persistent rain events, which are common in temperate regions.

Carbon kinetics in a Black Chernozem with roots in situ

1995 ◽  
Vol 75 (3) ◽  
pp. 299-305 ◽  
Author(s):  
J. G. Xu ◽  
N. G. Juma
Keyword(s):  
Decomposition Rate ◽  
Microbial Respiration ◽  
Root Decomposition ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Barley Cultivars ◽  
The Difference ◽  
Kinetics Of ◽  
Undisturbed Soil Cores

The rates of decomposition of roots and root-derived materials are needed to assess the contribution of these materials to sequestration of organic carbon in soil. The objective of this study was to examine the kinetics of different forms of C in a Black Chernozem, with roots in situ under two barley cultivars, using 14C pulse-labeling and incubation methods. Plants were pulse-labeled (1 d) with 14CO2 25 d after emergence. Shoots were excised, and undisturbed soil cores containing the roots of a single plant were incubated at 20 °C for 80 d. The experiment involved two barley cultivars, with six replications at six sampling dates (days 0, 5, 10, 25, 40 and 80). The percentage of the labile components in roots of Abee (48%) was greater than that of Samson (39%), but the half lives of the labile components (0.693 k−1) of the roots were not significantly different between the two barley cultivars. The decomposition-rate constants for the resistant components of the roots were also not significantly different between the two barley cultivars. This indicated that the difference between the two barley cultivars in root decomposition rate could be explained by the difference in the ratios of the labile components to the resistant components. The average half life of 14C in roots was 41 d for Abee and 71 d for Samson. The amount of root 14C + soil 14C under Samson was higher than under Abee during the incubation period. These results supported our hypothesis that the cultivar that translocated more 14C-labeled carbon into roots and root-derived material has greater microbial respiration and greater C stabilization because a portion of added C remains in the soil after being transformed by microorganisms. Key words: Carbon kinetics, carbon sequestration, roots in situ, 14C pulse-labeling, Black Chernozem

Isoproturon movement and dissipation in undisturbed soil cores from a grassed buffer strip

Agronomie ◽  
2000 ◽  
Vol 20 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Pierre Benoit ◽  
Enrique Barriuso ◽  
Philippe Vidon ◽  
Benoit Réal
Keyword(s):  
Soil Cores ◽  
Undisturbed Soil ◽  
Buffer Strip ◽  
Undisturbed Soil Cores

Relationship Between Soil Properties and Nitrogen Mineralization in Undisturbed Soil Cores from California Agroecosystems

2018 ◽  
Vol 50 (1) ◽  
pp. 77-92 ◽  
Author(s):  
Kenneth Miller ◽  
Brenna J. Aegerter ◽  
Nicholas E. Clark ◽  
Michelle Leinfelder-Miles ◽  
Eugene M. Miyao ◽  
...  
Keyword(s):  
Soil Properties ◽  
Nitrogen Mineralization ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Undisturbed Soil Cores

Effect of Soil Depth on the Quantification of Soil Moisture Content Value Estimated from NOAA Satellite Images

2014 ◽  
Vol 567 ◽  
pp. 705-710
Author(s):  
Abdalhaleem A. Hassaballa ◽  
Abdul Nasir Matori ◽  
Helmi Z.M. Shafri
Keyword(s):  
Soil Moisture ◽  
Critical Parameter ◽  
Satellite Images ◽  
Soil Moisture Content ◽  
Soil Depth ◽  
Vegetation Indices ◽  
Field Measurements ◽  
Spatial Estimation ◽  
Optical Images

Soil moisture (MC) is considered as the most significant boundary conditions controlling most of the hydrological cycle’s processes especially over humid areas. However, MC is very critical parameter to measure because of its variability in both space and time. The fluctuation of MC along the soil depth in turn, makes it so difficult to assess from optical satellite techniques. The study aims to produce a rectified satellite’s surface temperature (Ts) in order to enhance the spatial estimation of MC. The study also aims to produce MC estimates from three variable depths of the soil using optical images from NOAA 17 in order to examine the potential of satellite techniques in assessing the MC along the soil depths. The universal triangle (UT) algorithm was used for MC assessment based on Ts, vegetation Indices (VI) and field measurements of MC; which were conducted at variable depths. The study area was divided into three classes according to the nature of surface cover. The resultant MC extracted from the UT method with rectified Ts, produced accuracies of MC ranging from 0.65 to 0.89 when validated with in-situ measured MC at depths 5cm and 10 cm respectively.

scholarly journals Soil Structure and Texture Effects on the Precision of Soil Water Content Measurements with a Capacitance- Based Electromagnetic Sensor

2020 ◽  
Vol 63 (1) ◽  
pp. 141-152
Author(s):  
Jasreman Singh ◽  
Derek M. Heeren ◽  
Daran R. Rudnick ◽  
Wayne E. Woldt ◽  
Geng Bai ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Sensor Calibration ◽  
Soil Water Depletion ◽  
Undisturbed Soil ◽  
Water Depletion ◽  
Soil Moisture Sensors ◽  
Electromagnetic Sensor

HighlightsCapacitance-based electromagnetic soil moisture sensors were tested in disturbed and undisturbed soils.The uncertainty in estimation of soil water depth was lower using the undisturbed soil sample calibrations.The uncertainty in estimation of soil water depletion was lower than the uncertainty in volumetric water content.Undisturbed calibration of water depletion quantifies water demand with better precision and avoids over-watering.Abstract. The physical properties of soil, such as structure and texture, can affect the performance of an electromagnetic sensor in measuring soil water content. Historically, calibrations have been performed on repacked samples in the laboratory and on soils in the field, but little research has been done on laboratory calibrations with intact (undisturbed) soil cores. In this study, three replications each of disturbed and undisturbed soil samples were collected from two soil texture classes (Yutan silty clay loam and Fillmore silt loam) at a field site in eastern Nebraska to investigate the effects of soil structure and texture on the precision of a METER Group GS-1 capacitance-based sensor calibration. In addition, GS-1 sensors were installed in the field near the soil collection sites at three depths (0.15, 0.46, and 0.76 m). The soil moisture sensor had higher precision in the undisturbed laboratory setup, as the undisturbed calibration had a better correlation [slope closer to one, R2undisturbed (0.89) > R2disturbed (0.73)] than the disturbed calibrations for the Yutan and Fillmore texture classes, and the root mean square difference using the laboratory calibration (RMSDL) was higher for pooled disturbed samples (0.053 m3 m-3) in comparison to pooled undisturbed samples (0.023 m3 m-3). The uncertainty in determination of volumetric water content (?v) was higher using the factory calibration (RMSDF) in comparison to the laboratory calibration (RMSDL) for the different soil structures and texture classes. In general, the uncertainty in estimation of soil water depth was greater than the uncertainty in estimation of soil water depletion by the sensors installed in the field, and the uncertainties in estimation of depth and depletion were lower using the calibration developed from the undisturbed soil samples. The undisturbed calibration of soil water depletion would determine water demand with better precision and potentially avoid over-watering, offering relief from water shortages. Further investigation of sensor calibration techniques is required to enhance the applicability of soil moisture sensors for efficient irrigation management. Keywords: Calibration, Capacitance, Depletion, Irrigation, Precision, Sensor, Soil water content, Structure, Uncertainty.

Three-Dimensional Quantification of Macropore Networks in Undisturbed Soil Cores

1999 ◽  
Vol 63 (6) ◽  
pp. 1530-1543 ◽  
Author(s):  
Johan Perret ◽  
S. O. Prasher ◽  
A. Kantzas ◽  
C. Langford
Keyword(s):  
Three Dimensional ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Undisturbed Soil Cores
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