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  • Can infrared spectroscopy be used to measure change in potassium nitrate concentration as a proxy for soil particle movement?

Can infrared spectroscopy be used to measure change in potassium nitrate concentration as a proxy for soil particle movement?

Sensors (Basel, Switzerland) (2011-12-14)
Mila Ivanova Luleva, Harald van der Werff, Victor Jetten, Freek van der Meer
ABSTRACT

Displacement of soil particles caused by erosion influences soil condition and fertility. To date, the cesium 137 isotope ((137)Cs) technique is most commonly used for soil particle tracing. However when large areas are considered, the expensive soil sampling and analysis present an obstacle. Infrared spectral measurements would provide a solution, however the small concentrations of the isotope do not influence the spectral signal sufficiently. Potassium (K) has similar electrical, chemical and physical properties as Cs. Our hypothesis is that it can be used as possible replacement in soil particle tracing. Soils differing in texture were sampled for the study. Laboratory soil chemical analyses and spectral sensitivity analyses were carried out to identify the wavelength range related to K concentration. Different concentrations of K fertilizer were added to soils with varying texture properties in order to establish spectral characteristics of the absorption feature associated with the element. Changes in position of absorption feature center were observed at wavelengths between 2,450 and 2,470 nm, depending on the amount of fertilizer applied. Other absorption feature parameters (absorption band depth, width and area) were also found to change with K concentration with coefficient of determination between 0.85 and 0.99. Tracing soil particles using K fertilizer and infrared spectral response is considered suitable for soils with sandy and sandy silt texture. It is a new approach that can potentially grow to a technique for rapid monitoring of soil particle movement over large areas.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Potassium nitrate, SAJ first grade, ≥99.0%
Sigma-Aldrich
Potassium nitrate, BioReagent, suitable for cell culture, suitable for plant cell culture
Sigma-Aldrich
Potassium nitrate, BioXtra, ≥99.0%
Sigma-Aldrich
Potassium nitrate, 99.99% trace metals basis
Sigma-Aldrich
Potassium nitrate, 99.999% trace metals basis
Sigma-Aldrich
Potassium nitrate, puriss., meets analytical specification of Ph Eur, BP, USP, FCC, E252, 99.0-100.5%
Sigma-Aldrich
Potassium nitrate, ReagentPlus®, ≥99.0%
Sigma-Aldrich
Potassium nitrate, ACS reagent, ≥99.0%
Sigma-Aldrich
Potassium nitrate, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥99%
Supelco
Mettler-Toledo Calibration substance ME 51143095, Potassium nitrate, traceable to primary standards (LGC)