The plant availability of sulphur from a sulphate-aluminium hydrous oxide complex

Ryegrass was grown in sand containing35S-labelled sulphate adsorbed onto the surface of Al-hydrous oxide. S from this source was available to ryegrass even at very low surface coverage; and maximum yield of ryegrass occurred at an equilibrium solution concentration of 2 μM S corresponding to about 10% coverage on the hydrous oxide.