Use of time domain reflectometry for continuous monitoring of nitrate-nitrogen in soil and water

Payero, J. O., Tarkalson, D. D. and Irmak, S. (2006) Use of time domain reflectometry for continuous monitoring of nitrate-nitrogen in soil and water. Applied Engineering in Agriculture, 22 5: 689-700. doi:10.13031/2013.22002

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Author Payero, J. O.
Tarkalson, D. D.
Irmak, S.
Title Use of time domain reflectometry for continuous monitoring of nitrate-nitrogen in soil and water
Journal name Applied Engineering in Agriculture   Check publisher's open access policy
ISSN 0883-8542
Publication date 2006-09
Sub-type Article (original research)
DOI 10.13031/2013.22002
Open Access Status File (Publisher version)
Volume 22
Issue 5
Start page 689
End page 700
Total pages 12
Place of publication St Joseph, MI, United States
Publisher American Society of Agricultural and Biological Engineers
Language eng
Formatted abstract
Nitrate-Nitrogen (NO3-N) losses to ground and surface water are an environmental and agronomic concern in modern crop production systems in the Central Great Plains. Monitoring techniques for nitrogen use in agricultural production are needed to increase crop yield, optimize nitrogen use, and reduce NO3-N leaching. Time domain reflectometry (TDR) could potentially be calibrated to continuously measure NO3-N in soil and water. The objectives of this study were to: (1) evaluate the effect of different factors affecting the response of the bulk electrical conductivity (ECb) sensed by TDR, (2) compare the sensitivity and differences between vertically-installed and horizontally-installed probes for measuring NO3-N leaching in the soil profile, and (3) evaluate the feasibility of using TDR to measure changes in NO3-N concentration in an irrigated agricultural soil. Studies were conducted in the laboratory and in the field at the University of Nebraska West Central Research and Extension Center in North Platte, Nebraska. Temperature of the medium (Ts), solute concentration, TDR cable length, and volumetric soil water content (θv) all influenced and were linearly related to the bulk electrical conductivity (ECb) sensed by the TDR probes. In the field, measured soil NO3-N correlated well with values estimated using TDR measurements of ECb, corrected for changes in θv and Ts. These results indicated that TDR, if properly calibrated for a particular soil, could be used to continuously monitor NO3-N in soil, and should also be well-suited for monitoring NO3-N in groundwater and surface water. It is, however, important to perform the calibration over a long enough period of time to include the expected range of θv, Ts, and NO3-N values to obtain adequate accuracy.
Keyword Time domain reflectometry
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Queensland Alliance for Agriculture and Food Innovation
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Created: Wed, 10 Aug 2011, 08:46:24 EST by System User on behalf of Qld Alliance for Agriculture and Food Innovation