Additionally, how to manage P fertilisation in such soils? Continuously apply P fertiliser even though there is a big chance it might be fixed by sesquioxides?
@ Portia, I think Olsen method is most suitable for P extraction in acidic soils even you have high Al and Fe oxides.
@ Portia, I think Olsen method is most suitable for P extraction in acidic soils even you have high Al and Fe oxides.
....maybe Brey II or Mehlich 3; see for more information:https://www.agriculturejournals.cz/publicFiles/932_2014-PSE.pdf.
Portia Phohlo We compared ten P-tests to extract P from acidic soils (Podzol) managed under forest and managed fields with different fertilizer application histories. Water, citric acid, ammonium bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA), Morgan, Olsen, Bray-1, Bray-2, Mehlich-1 and -3 solutions were used to extract and analysed with ICP and colorimetric techniques. The studied soils had a pH range from 3.4 to 6.9; clay contents ranged from 6% to 38%; SOM varied between 0.5% and 47%. We found that Water ≤ Morgan < AB < M1 < B1 < M3 ≤ Olsen
I think bray-II preferable for acidic soil to test p from acidic soil.
Hi Portia
This technical note from Hill Laboratories in New Zealand may help.
Best regards Nevan Ofsoski
Bray's and Kurtz method for estimation of P in Acid soils and Olsen' s method for Alkali soils.
The Bray-1 extractant (0.025 N HCl + 0.03 N NH4F) was developed for use in acid soils. Aluminum phosphate (AlPO4) is the primary P mineral controlling solution P concentrations in acid soils. The F complexes with Al3+ in solution, and as the Al3+ concentration in soil solution decreases, AlPO4 dissolves to buffer or resupply solution Al and releases P into the solution.
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