Publication Date
1997
Description
This study showed that significant amounts of phosphorus (P) applied to grasslands in the Adelaide hills, South Australia move through kaolinitic clay subsoils. Large undisturbed soil cores were collected down a hillslope with soils and pasture typical of the Adelaide hills. Fertiliser was added to the surface of soil cores and catchment rainfall simulated. Leachate from the cores was measured daily and analysed for P. Results showed up to 34% of P applied to pastures on the upper-slopes, moves vertically through the subsoil clays mostly in the dissolved form. Elsewhere, < 1% of the applied P was lost. The subsoils where P movement was significant had high clay (44%) and iron oxide content (14%). These subsoils also had the greatest number of macropores (20% of pores > 5 mm). The results showed the importance of macropore flow in the loss of P from these grasslands.
Citation
Cox, J W.; Kirkby, C A.; and Chittleborough, D J., "Pathways for Losses of Phosphorus for Rainfed Pastures in South Australia" (2024). IGC Proceedings (1993-2023). 17.
https://uknowledge.uky.edu/igc/1997/session20/17
Included in
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Pathways for Losses of Phosphorus for Rainfed Pastures in South Australia
This study showed that significant amounts of phosphorus (P) applied to grasslands in the Adelaide hills, South Australia move through kaolinitic clay subsoils. Large undisturbed soil cores were collected down a hillslope with soils and pasture typical of the Adelaide hills. Fertiliser was added to the surface of soil cores and catchment rainfall simulated. Leachate from the cores was measured daily and analysed for P. Results showed up to 34% of P applied to pastures on the upper-slopes, moves vertically through the subsoil clays mostly in the dissolved form. Elsewhere, < 1% of the applied P was lost. The subsoils where P movement was significant had high clay (44%) and iron oxide content (14%). These subsoils also had the greatest number of macropores (20% of pores > 5 mm). The results showed the importance of macropore flow in the loss of P from these grasslands.
