Izboljšanje določitve močno vezane vode v postopku umerjanja merilnika vode v tleh, ki temelji na zaznavanju nevtronov

Improving the determination of lattice water in the calibration process of cosmic ray neutron sensor

Author(s):

Nejc Golob, Špela Srdoč, Žiga Švegelj, Vesna Zupanc, Rozalija Cvejić

Abstract:

In this paper, we discuss continuous proximity sensing of soil water content using cosmic ray neutron sensors for area of about 25 hectares. Acquiring reliable soil moisture data requires a demanding calibration process, which accounts for the area’s heterogeneity and identifies various water sources in the environment. We focus on a calibration procedure to determine lattice water in soils. We compared two variations of a sample combustion method to quantify lattice water. The first approach involves combusting and weighing samples at different temperatures; the second includes a pretreatment of samples with a 10% hydrochloric acid solution (HCl), which removes carbonates and enables more accurate determination of water content between 400 and 1000 °C. The difference between the two methods is statistically significant, with an average difference of 0.00140 cm³/cm³. The average measured lattice water content is higher when no HCl pretreatment is used. The highest values of lattice water were measured in deeper soil layers (20–25 cm, 30–35 cm), associated with higher bulk density. On carbonate soils, we recommend the method with HCl pretreatment, as it provides more reliable data on lattice water in the soil.

Keywords:

sensor, soil water content, neutron detection, lattice water

DOI: 10.15292/geodetski-vestnik.2025.04.538-553

Citation:

Nejc Golob, Špela Srdoč, Žiga Švegelj, Vesna Zupanc, Rozalija Cvejić (2025). Izboljšanje določitve močno vezane vode v postopku umerjanja merilnika vode v tleh, ki temelji na zaznavanju nevtronov. | Improving the determination of lattice water in the calibration process of cosmic ray neutron sensor. Geodetski vestnik, 69 (4), 538-553. DOI: 10.15292/geodetski-vestnik.2025.04.538-553