HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (12) Citing Articles via Google Scholar Google Scholar Articles by Das, B. S. Articles by Inskeep, W. P. Search for Related Content PubMed Articles by Das, B. S. Articles by Inskeep, W. P. GeoRef GeoRef Citation Agricola Articles by Das, B. S. Articles by Inskeep, W. P.

Nitrate Concentrations in the Root Zone Estimated Using Time Domain Reflectometry

^a Land Resources and Environmental Sciences Dep., Montana State Univ., P.O. Box 173120, Bozeman, MT 59717-3120 USA

View larger version (17K): [in a new window]   Fig. 1 Schematic of field experiment layout including approximate locations of time domain reflectometry (TDR) arrays (X), solution samplers (), and soil cores () in the four plots having differential KNO3 application. Soil cores were collected from five randomly selected locations in each plot at each sampling date

View larger version (34K): [in a new window]   Fig. 2 Volumetric soil water contents () measured using replicate soil cores (symbols) and TDR (lines), at 0.15- and 0.9-m depths in Plots II and IV. Abrupt increases in measured by TDR at 0.15-m depth are in response to rainfall and irrigation

View larger version (33K): [in a new window]   Fig. 3 Mean ± standard error of mean (SEM) soil solution electrical conductivities (dS m-1) measured using replicate soil cores , horizontal or vertical TDR probes , and solution samplers at 0.15-m depth in Plots II and IV. Horizontal probes were at 0.15-m depth, while vertical probes spanned 0–0.29 m depth

View larger version (38K): [in a new window]   Fig. 4 Mean ± standard error of mean (SEM) soil solution electrical conductivities (dS m-1) measured using replicate soil cores , solution samplers , and TDR probes at 0.45- and 0.9-m depths in Plots I and III

View larger version (32K): [in a new window]   Fig. 5 Mean ± standard error of mean (SEM) soil solution electrical conductivities (dS m-1) measured using replicate soil cores (circles, ), horizontal TDR probes (lines, ), and solution samplers (squares, ) at 0.15-m depth in Plots I, II, and III. Time domain reflectometry (TDR) estimates are based on in situ mass balance RRP model optimizations vs. applied KNO3 (Eq. [9]) using vertical surface probes, and applied to horizontal probes at 0.15 m depth

View larger version (24K): [in a new window]   Fig. 6 Linear calibration results for soil nitrate concentrations (ppm) vs. soil solution electrical conductivities (dS m-1) in soils collected at the Creston field site. Relationships were determined for cores from each measurement depth, for all depths pooled, and using a dilution series experiment with surface soil. Numbered calibration equations correspond to parenthetical numbers in the legend

View larger version (30K): [in a new window]   Fig. 7 Mean ± standard error of mean (SEM) soil nitrate concentrations (ppm) measured using replicate soil cores and estimated using horizontal TDR probes at 0.15 m depth in all field plots. Amount of N applied as KNO3 is indicated for each plot