Moreover, in this case, ammonium oxalate
treatment could solubilize part of the cellulose polymers closely connected to the pectin.
High percentage of growth reduction were obtained with calcium chelate, iron sulfate, ammonium oxalate
, and EDTA disodium which have low pH values, but no complete reduction was observed for salts have a higher pH like sodium silicate.
Batch experiments that examined the mobilisation of As showed that 0.5M and 1 M HCl and a mixture containing ammonium oxalate
, oxalic acid, and ascorbic acid were most effective in extracting AS, while Mg[Cl.sub.2] (an extractant for ion-exchangeable AS) extracted only 0.1% of the total As loading in the soft.
Table 2 also shows that the ammonium oxalate
solution extracted greater amounts of Fe relative to 1 M HCl solution; whereas the reverse was true for Al.
The ratio of ammonium oxalate
extractable P to (Al + Fe), referred to as the "degree of P saturation" (DP[S.sub.ox]), was expressed as:
Iron and aluminium soluble in ammonium oxalate
were determined by a method similar to that of Schwertmann (1964).
(1991), now widely used in Western Australia; the pH of the soil measured in sodium fluoride as recently recommended by Gilkes and Hughes (1994); and the amount of Al and Fe extracted from the soil by ammonium oxalate
For many soils from the south-west of Australia, P sorption capacity of topsoils is closely related to clay content, dithionite-citrate-bicarbonate (DCB) extractable Fe and Al, ammonium oxalate
extractable Fe and Al, sodium pyrophosphate extractable Al, and pH(NaF).