The influence of increased NH4+ deposition rates on aluminium chemistry in the percolate of acid soils

Abstract

SummaryThe influence of different NH4+ loads on aluminium speciation in percolating water was studied on acid luvisols with similar soil‐pH values but with different soil adsorption surface characteristics. All of the applied NH4+ was nitrified and therefore led to proton production. Thus, Al displacement in the percolate was increased. The extent of this enhanced translocation was found to be chiefly a function of the amount of exchangeable base cations which buffered the protons produced by nitrification.The proportion of the different Al species in the percolate was altered at large NH4+ loads. Very large A13+ concentrations eliminated Al species bound to dissolved organic matter and particles, presumably because of flocculation and precipitation of organic ligands. Furthermore, increased NO3− and A13+ concentrations enhanced the desorption of F− giving rise to an additional increase in Al displacement by the formation of Al fluoro complexes in the aqueous phase.