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Gewählte Master / Diploma Thesis:

Wilfred Teejay Kosi Adjadeh (2022): Is phosphorus solubility and extractability in Lower Austrian soils in line with textbook theory?.
Master / Diploma Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 44. UB BOKU obvsg

Data Source: ZID Abstracts
Two opposing theories suggest the optimum soil pH for maximum phosphate solubility. The classic theory suggests that this optimum pH is from pH 6 to 7, while the alternate theory suggests this optimum is below pH 6. This thesis aimed to investigate whether soils in Lower Austria conform to the classic or alternate theories. A series of soil tests were conducted on 118 archived Lower Austria soils, and these were: two phosphate solubility tests (water extraction, diffusive gradients in thin films (DGT) measurements), a phosphate chemical extraction test (Olsen method), total phosphorus determination, and measurement of iron and aluminum oxides. The archive database provided all other physiochemical soil characteristics. The soils were classified into three pH groups: pH < 6, pH 6 to 7 and pH > 7. Using one-way ANOVA or Welch’s test on log-transformed data, the significant differences in available phosphate, exchangeable calcium, iron oxides, and aluminum oxides were identified amongst the soil pH groups. It was revealed that soluble phosphate was significantly higher in the pH range of 6 to 7. Exchangeable calcium was significantly higher at pH > 7, and aluminum oxides were significantly higher at pH < 6. These findings suggest that Lower Austrian soils with a wide variation in soil properties have maximum phosphate solubility at pH 6 to 7. However, the insufficient time for thesis work prevents a conclusive stand on the two opposing theories. Results from the stepwise multiple regression indicate that building the soil’s organic matter likely increases soluble phosphate whiles reducing the number of aluminum oxides, which are the dominant phosphate-sorbing phase in soil.

Beurteilende*r: Wenzel Walter

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