University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Philipp Ruemmele
(2010):
Kalibrierung von kapazitiven Bodensonden am Standort der BOKU-Versuchswirtschaft in Groß-Enzersdorf.
Master / Diploma Thesis - Institut für Hydraulik und landeskulturelle Wasserwirtschaft (IHLW),
BOKU-Universität für Bodenkultur,
pp XXVI, 187.
UB BOKU
obvsg
FullText
- Abstract:
- The accuracy of the default calibration of capacitance sensors at varying soil profiles in Groß-Enzersdorf was anaylised. Following null hypothesis (H0) is tested in a field experiment: The default calibration shows no significant differences at inhomogeneous soil conditions in relation to the actual prevailing water content Θ. We installed three plot's, each with two access-tubes, on a corn field in Groß-Enzersdorf. We used eight sensors at a distance of 10 cm in the depths of (10-80) cm per capacitance-probe. It should be applied a wet plot at about 30 %, a moist plot at about 20 % and a dry plot at about 10% water content. The default calibrated sensor measurements were compared to the actual Θ (determined by soil samples). Because of the high precipitation in summer 2010, a Θ-range of "only” (25.0-35.9) % was achieved. A plastic-film-construction to prevent precipitation on the plot's turned out to be insufficient. Therefore a field calibration, which also includes drier conditions, was not possible. Overall, 240 soil samples (five per Sensor) were taken to determine Θ and compare it to 48 default calibrated sensor measurements (44 representatives). H0 was rejected at a Θ-range of (25.7-35.9) %. For the upper soil layer at (10-30) cm H0 was accepted at a Θ-range of (25.7-35.9) %. For the lower layer ((10-30) cm) H0 was rejected again at a Θ-range of (26-35) %. The soil textures clay, sandy loam and loamy silt (group I) are mainly present in the upper layer, soil samples with silty clay were classified into group II. H0 was accepted for group I, but was rejected for group II. In the Austrian texture triangle the differences between group I and group II are small. Three calibration functions of the authors Paltineanu und Starr (1997), Geesing, Bachmaier und Schmidhalter (2004) and Morgan et al. (1999) were tested for those cases, where the default calibration was rejected. For all cases the functions of Geesing, Bachmaier und Schmidhalter and Morgan et al. (1999) were accepted, the one of Paltineanu und Starr was rejected. In mean, the deviations for the accepted functions to determine Θ in these wet conditions are small. They are closer to the actual Θ than the default calibration. The calibration function of Morgan et al. performed best.
- Beurteilende(r): Loiskandl Willibald
- 1.Mitwirkender: Kammerer Gerhard