University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Johanna Reiter
(2019):
Monitoring of silicon, soil pH, nitrogen and organic carbon in the Lower Austrian Chernozem/Phaeozem region.
Master / Diploma Thesis - Institut für Bodenforschung (IBF),
BOKU-Universität für Bodenkultur,
pp 86.
UB BOKU
obvsg
FullText
- Abstract:
- Recently, Silicon (Si) has been receiving increasing attention as a beneficial element for plants. Silicon bioavailability is an important factor for plant health and plant growth. To obtain information about Silicon and key soil factors like pH, nitrogen (N) and organic carbon (OC) in the Lower Austrian Chernozem region I collected 99 topsoils between Nov. 2016 and March 2017 from the same croplands where 20-30 years ago the Austrian soil mapping services had already sampled and archived soils. This approach is different to the soil monitoring on Austrian and European level which rarely compares soils from the exact same places. To obtain information on the Si status of soils I extracted potentially plant-available (0.01 M CaCl2 extraction) and amorphous Si fractions (0.2 M NaOH extraction) in the archived and the re-sampled soils. The Si concentrations in both extracts were measured using the molybdenum blue method and spectrophotometry. Furthermore, the OC concentration, the pH of the resampled and the archived soils and the N concentration of the resampled soils was measured. The initial hypothesis was that the amorphous Si concentrations might have decreased due to Si-depleting management practices. In contrast, our findings indicate no relevant change of amorphous Si (mean 2560 mg/kg) and potentially plant-available Si (mean 44 mg/kg), however, at both sampling times nearly half of the soils were below the upper limit of Si deficiency for rice (< 43 mg/kg). Similarly, no change was observed for soil pH (mean 7.2) while OC showed a substantial increase of nearly 40% from a mean of 19.6 g/kg to 29.3 g/kg during the monitoring period. Multiple regression analyses were run to observe the influence of soil texture, mean annual precipitation, mean annual temperature, pH and OC on the Si fractions. As the main influencing factors could be emphasized: Organic carbon and temperature showed a decreasing effect on the Si fractions, clay showed an increasing effect.
- Beurteilende(r): Wenzel Walter
- 1.Mitwirkender: Puschenreiter Markus