CALIBRATION OF A TDR INSTRUMENT FOR SIMULTANEOUS MEASUREMENTS OF SOIL WATER AND SOIL ELECTRICAL CONDUCTIVITY

2006 ◽  
Vol 49 (1) ◽  
pp. 75-82 ◽  
Author(s):  
N. Ebrahimi-Birang ◽  
C. P. Maulé ◽  
W. A. Morley
Keyword(s):  
Electrical Conductivity ◽  
Soil Water ◽  
Soil Electrical Conductivity ◽  
Simultaneous Measurements

scholarly journals Using Multivariate Geostatistics to Assess Patterns of Spatial Dependence of Apparent Soil Electrical Conductivity and Selected Soil Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Glécio Machado Siqueira ◽  
Jorge Dafonte Dafonte ◽  
Montserrat Valcárcel Armesto ◽  
Ênio Farias França e Silva
Keyword(s):  
Electrical Conductivity ◽  
Soil Properties ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Clay Content ◽  
Data Sets ◽  
Soil Electrical Conductivity ◽  
Multivariate Geostatistics ◽  
Northwestern Spain

The apparent soil electrical conductivity (ECa) was continuously recorded in three successive dates using electromagnetic induction in horizontal (ECa-H) and vertical (ECa-V) dipole modes at a 6 ha plot located in Northwestern Spain. One of the ECadata sets was used to devise an optimized sampling scheme consisting of 40 points. Soil was sampled at the 0.0–0.3 m depth, in these 40 points, and analyzed for sand, silt, and clay content; gravimetric water content; and electrical conductivity of saturated soil paste. Coefficients of correlation between ECaand gravimetric soil water content (0.685 for ECa-V and 0.649 for ECa-H) were higher than those between ECaand clay content (ranging from 0.197 to 0.495, when different ECarecording dates were taken into account). Ordinary and universal kriging have been used to assess the patterns of spatial variability of the ECadata sets recorded at successive dates and the analyzed soil properties. Ordinary and universal cokriging methods have improved the estimation of gravimetric soil water content using the data of ECaas secondary variable with respect to the use of ordinary kriging.

scholarly journals Assessment of soil and soil-water salinity in Ben Tre province by electromagnetic technology

2020 ◽  
Vol 19 (4) ◽  
pp. 507-516
Author(s):  
Le Ngoc Thanh ◽  
Nguyen Quang Dung ◽  
Luu Hai Tung
Keyword(s):  
Electrical Conductivity ◽  
Soil Water ◽  
Ground Surface ◽  
Fold Increase ◽  
Water Salinity ◽  
Current Status ◽  
Soil Electrical Conductivity ◽  
Geostatistical Techniques ◽  
Data Point ◽  
Total Dissolved Solid

Assessment of soil and soil-water salinity is essential in agricultural production, therefore it is necessary to find out the non-costly, effective, rapid and reliable integrated methodology for this purpose. The paper presents the results of using the electromagnetic induction instrument EM31-MK2Ô in combination with collecting and analyzing soil and soil-water samples, and applying GIS and geostatistical techniques to assess the current status of soil and soil-water salinity in Ben Tre province. Apparent soil electrical conductivity ECa measured from ground surface to 6 m in depth increases from inland to the sea in northwest - southeast direction; ECa is closely related to topsoil salinity to 30 cm deep and to soil-water salinity at depth of 10–100 cm. Current status of soil and soil-water salinity in 2018 was assessed with a 4-fold increase in information, from 16 km2/data point to 4 km2/data point. Consequently four maps were established, consisting of electrical conductivity ECe and total solube salt TSS distributions of soil; electrical conductivity σw and total dissolved solid TDS distributions of soil-water.

scholarly journals Evaluation of a Decision Support System for Variable-Rate Irrigation in a Humid Region

2020 ◽  
Vol 63 (5) ◽  
pp. 1207-1215
Author(s):  
Ruixiu Sui ◽  
Susan A. O’Shaughnessy ◽  
Steven R. Evett ◽  
Alejandro Andrade-Rodriguez ◽  
Jonnie Baggard
Keyword(s):  
Electrical Conductivity ◽  
Soil Water ◽  
Water Use ◽  
Irrigation Water ◽  
Canopy Temperature ◽  
Irrigation Scheduling ◽  
Variable Rate ◽  
Soil Electrical Conductivity ◽  
Irrigation Water Use ◽  
Variable Rate Irrigation

HighlightsAn Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system was tested against a soil electrical conductivity (EC) based method for variable-rate irrigation (VRI).Soil EC was used to create irrigation prescription in EC-based VRI.ISSCADA generated VRI prescriptions using canopy temperature, soil water content, and weather data.ISSCADA-based VRI reduced irrigation water use and increased irrigation water productivity.Abstract. Use of variable-rate irrigation (VRI) technology has the potential to improve irrigation water use efficiency (IWUE). VRI hardware is commercially available and can be implemented in any center pivot or lateral move irrigation system. However, practical methods and algorithms for creating VRI prescriptions have become the bottleneck in accelerating the adoption of VRI. An Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system for VRI was evaluated for two years in a humid region in the Mississippi Delta. The ISSCADA system was used to manage irrigation of soybeans for two seasons. In field practice, the ISSCADA system scanned the field for canopy temperature and collected soil water data from time domain reflectometers and weather data from a nearby weather station. The ISSCADA system automatically generated VRI prescription maps. The maps were modified to include plots managed using soil electrical conductivity (EC) based VRI prescriptions. Test results indicated that there was no difference in crop yield between EC-based VRI and ISSCADA-based VRI management. However, ISSCADA-based VRI management reduced irrigation water use and increased irrigation water productivity in comparison with EC-based VRI. There is great potential for the use of ISSCADA for VRI in humid regions. Keywords: Canopy temperature, Soil electrical conductivity, Soil moisture sensor, Soil water sensor, Soybean, Variable rate irrigation.

The effect of soil electrical conductivity on moisture determination using time-domain reflectometry in sandy soil

2000 ◽  
Vol 80 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Z. J. Sun ◽  
G. D. Young ◽  
R. A. McFarlane ◽  
B.M. Chambers
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Saline Soil ◽  
Time Domain Reflectometry ◽  
Propagation Time ◽  
Soil Electrical Conductivity ◽  
Volumetric Soil Water Content ◽  
Volumetric Soil Water

A series of laboratory experiments was conducted, in order to systematically explore the effect of soil electrical conductivity on soil moisture determination using time domain reflectometry (TDR). A Moisture Point MP-917 soil moisture instrument (E.S.I. Environmental Sensors Inc., Victoria, BC, Canada) was used to measure propagation time (time delay) of a step function along a probe imbedded in fine sand with different moisture and salinity. The volumetric soil water content was independently determined using a balance. With the help of the diode-switching technique, MP-917 could detect the reflection from the end of the probe as the electrical conductivity of saturated soil extract (ECe) increased to 15.29 dS m−1. However, the relationship between volumetric soil water content and propagation time expressed as T/Tair (the ratio of propagation time in soil to that in air over the same distance) deviated from a linear relationship as the conductivity exceeded 3.72 dS m−1. At the same water content, the time delay in a saline soil was longer than that in a non-saline soil. This leads to an over-estimation of volumetric soil water content when the linear calibration was applied. A logarithmic relationship between volumetric soil water content and T/Tair has been developed and this relation includes soil electrical conductivity as a parameter. With this new calibration, it is possible to precisely determine the volumetric water content of highly saline soil using TDR. Key words: Time domain reflectometry, time delay, bulk electrical conductivity (σ), volumetric soil water content (θ), relative permittivity or dielectric constant (εr), propagation velocity Vp

ESTIMATING SPATIAL VARIATIONS OF SOIL WATER CONTENT USING NONCONTACTING ELECTROMAGNETIC INDUCTIVE METHODS

1988 ◽  
Vol 68 (4) ◽  
pp. 715-722 ◽  
Author(s):  
R. G. KACHANOSKI ◽  
I. J. VAN WESENBEECK ◽  
E. G. GREGORICH
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Soil Texture ◽  
Spatial Variations ◽  
Bulk Soil ◽  
Soil Electrical Conductivity ◽  
Solution Conductivity

The relationships among the spatial variations of soil water content, soil texture, soil solution electrical conductivity, and bulk soil electrical conductivity were examined for a field characterized by net drainage and low concentrations of dissolved electrolytes. Bulk soil electrical conductivity was measured over various depths at 52 locations within a 1.8-ha field using noncontacting electromagnetic inductive meters. Soil water content (0–0.5 m depth) was measured at the same locations using the time domain reflectometry method. Measurements of soil texture and soil solution conductivity were obtained from core samples from 37 of the sampling locations. Soil water content at the site ranged from 0.06 to 0.36 m3 m−3. Clay content ranged from 2.5 to 44% percent and bulk soil electrical conductivity ranged from 0.0 to 0.21 S m−1. Significant correlation existed among almost all of the measured variables. Regression analysis indicated soil solution conductivity had no effect on measured bulk soil electrical conductivity for soil water contents less than 0.25 m3 m−3. Bulk soil electrical conductivity explained 96% of the spatial variation of soil water content independent of a wide range of soil texture. Autocorrelations of soil water content were similar to autocorrelations for bulk soil electrical conductivity. Under conditions similar to those in the study area, it should be possible to infer spatial variations in soil water content quickly by measuring bulk electrical conductivity using noncontacting electromagnetic inductive meters. Key words: Spatial variability, soil water, electrical conductivity, soil texture

scholarly journals Identifying Within-Field Spatial and Temporal Crop Water Stress to Conserve Irrigation Resources with Variable-Rate Irrigation

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1377
Author(s):  
Jeffrey D. Svedin ◽  
Ruth Kerry ◽  
Neil C. Hansen ◽  
Bryan G. Hopkins
Keyword(s):  
Electrical Conductivity ◽  
Water Stress ◽  
Soil Water ◽  
Variable Rate ◽  
Soil Electrical Conductivity ◽  
Soil Water Depletion ◽  
Crop Water ◽  
Water Depletion ◽  
Crop Water Stress ◽  
Variable Rate Irrigation

Addressing within-field and within-season variability of crop water stress is critical for spatially variable irrigation. This study measures interactions between spatially variable soil properties and temporally variable crop water dynamics; and whether modelling soil water depletion is an effective approach to guide variable-rate irrigation (VRI). Energy and water balance equations were used to model crop water stress at 85 locations within a 22 ha field of winter wheat (Triticum aestivum L.) under uniform and spatially variable irrigation. Significant within-field variability of soil water holding capacity (SWHC; 145–360 mm 1.2 m−1), soil electrical conductivity (0.22–49 mS m−1), spring soil water (314–471 mm 1.2 m−1), and the onset of crop water stress were observed. Topographic features and modelled onset of crop water stress were significant predictors of crop yield while soil moisture at spring green-up, elevation, and soil electrical conductivity were significant predictors of the onset of crop water stress. These results show that modelling soil water depletion can be an effective scheduling tool in VRI. Irrigation zones and scheduling efforts should consider expanding to include temporally dynamic factors, including spring soil water content and the onset of crop water stress.

Sign in / Sign up

Export Citation Format

Share Document