
%0 Journal Article
%A Percival, HJ 
%A Giddens, KM 
%A Lee, R 
%A Whitton, JS 
%T Relationships between soil solution aluminium and extractable aluminium in some moderately acid New Zealand soils
%J Soil Research
%D 1996/10/01
%V 34
%N 5
%P 769-779
%K aluminium speciation, aluminium toxicity, 0.02 M CaCl2-extractable Al, KCl-extractable Al, labile aluminium, soil solution.
%R https://doi.org/10.1071/SR9960769
%U https://www.publish.csiro.au/paper/SR9960769 
%X This work investigates the relationship between soil solution aluminium (Al) and extractable Al in some New Zealand soils giving high extractable Al levels, yet with pH(H2O) values &ge; 5.2. Total Al in 1 M KCl extracts ranged from 0.8 to 11.6 cmol(+)/kg, and in corresponding 0.02 M CaCl2 extracts from 0.002 to 0.39 cmol(+)/kg. Soil solutions had low total Al concentrations, ranging from < 0.5 to 12.5 &micro;M, with < 10% of the Al in the monomeric Al form as determined by the chromeazurol S colorimetric method. There was a poor correlation between Al in soil solution and that extracted by either 1 M KCl or 0.02 M CaCl2. The measured monomeric Al concentrations in the soil solutions did not exceed levels corresponding to Al toxicity threshold activities set at 10 or 2 &micro;M, related to a range of pasture plant tolerances, whether based on the activity of Al3+ species alone, or on the sum of the individual activities of Al3+, Al(OH)2+ and Al(OH)2+ species. The high 1 M KCl-extractable and 0.02 M CaCl2-extractable Al values provided a misleading indication of potential Al toxicity status, probably due to the generation of artificially high extracted Al concentrations from these particular types of soils. 
