The chemistry of aluminium in strongly acidified sandy soil in Poland

Abstract

SummaryOrganically‐bound Al in acidic, base‐poor sandy soils seems to be a major contributor to dissolved Al. This hypothesis has been tested under field conditions at two intensely acidified sites. The research was conducted at the agricultural trial fields at Lyczyn, Poland, which have been fertilized continuously for 30 yr with 130 kg ha−1 a−1 N (as NH4NO3 or urea). The effect of depletion of Al on its solubility was also studied.Field data confirmed that mobilized Al originates largely in the organically bound fraction of soil Al. Depletion of this fraction resulted in a considerable decrease in the mobility of Al such that, at pH = 3.0 and reaction times of a few weeks, small amounts of Al were mobilized. Apparently, the rate at which Al is dissolved from structural silicates, which are abundant in the soil investigated, is small. This suggests that at sites in Poland most exposed to acid deposition, where the rates of soil acidification and depletion of organically‐bound Al are greatest, both the concentration of Al and the soil solution pH are expected to decline with time.