Articles
TIME DOMAIN REFLECTOMETRY FOR MONITORING SOIL NITROGEN DYNAMICS
Article number
563_29
Pages
233 – 238
Language
English
Abstract
The study of soil nitrogen transformations, both under laboratory conditions and in situ, requires a large number of time consuming and expensive chemical analyses.
In this paper we present a possible alternative to chemical analysis when monitoring N dynamics.
Time domain reflectometry (TDR) allows simultaneous monitoring of soil moisture content and bulk soil electrical conductivity (EC). In non-saline soils the nitrate ion plays an important part in the changes of soil solution electrical conductivity over time.
We used the strong correlation between NO3–-N concentration and EC for on-line monitoring of the mineralization process in two soils with different mineralization potential.
Agreement between measured and TDR calculated NO3–-N concentrations were good.
The observed discrepancies between measured and calculated NO3–-N concentrations can be explained by the influence on the EC of other anions, mainly SO42- and HCO3–. In a second experiment we used TDR to monitor the immobilisation of native and added NO3–-N in soil with addition of glucose.
The TDR calculated NO3–-N concentrations showed a strong immobilisation of N in the first 2-3 days, followed by a gradual remineralization.
From the results presented here it can be concluded that TDR has potential to monitor soil N transformations, especially under controlled environmental conditions such as in laboratory incubation studies.
In this paper we present a possible alternative to chemical analysis when monitoring N dynamics.
Time domain reflectometry (TDR) allows simultaneous monitoring of soil moisture content and bulk soil electrical conductivity (EC). In non-saline soils the nitrate ion plays an important part in the changes of soil solution electrical conductivity over time.
We used the strong correlation between NO3–-N concentration and EC for on-line monitoring of the mineralization process in two soils with different mineralization potential.
Agreement between measured and TDR calculated NO3–-N concentrations were good.
The observed discrepancies between measured and calculated NO3–-N concentrations can be explained by the influence on the EC of other anions, mainly SO42- and HCO3–. In a second experiment we used TDR to monitor the immobilisation of native and added NO3–-N in soil with addition of glucose.
The TDR calculated NO3–-N concentrations showed a strong immobilisation of N in the first 2-3 days, followed by a gradual remineralization.
From the results presented here it can be concluded that TDR has potential to monitor soil N transformations, especially under controlled environmental conditions such as in laboratory incubation studies.
Authors
S. De Neve, G. Hofman
Keywords
N mineralization, N immobilisation, denitrification, electrical conductivity, incubation
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