Forms of aluminium in some acid permanent grassland soils

Publisher Website
Google Scholar
Abstract
SUMMARY: The more labile forms of aluminium in a range of soils from areas of permanent grassland were determined with a number of selective extractants. The amounts of exchangeable A1 extracted with molar KCl were dependent upon pH, while the amounts exchangeable with 0.3 M LaCl3, although much greater, were not well correlated with pH. There were good correlations between soil organic C content and A1 extracted by (i) 0.5 M EDTA and (ii) 0.1 M potassium pyrophosphate. Pyrophosphate extracted greater amounts than any of the other extractants (sodium citrate/dithionite, ammonium oxalate (dark), acid oxalate (UV radiation), as well as those already mentioned). It was concluded that much of the extractable A1 in soils was associated with organic matter. Addition of lime to one of the soils reduced the amount of A1 extracted by all reagents except dithionite and acid oxalate solutions. There were considerable differences between soils in their release of A1 to continuous leaching with 0.01 M CaCl2. Despite these differences between the soils in organically bound extractable Al, the differences in the amounts and patterns of release of A1 with CaCl2did not appear to be related to organic matter contents, nor to the other determined properties.