ABSTRACT
Samples of rootzone materials were incubated anaerobically in the laboratory to investigate factors influencing the production of metal sulphide which is the cause of black layer. Treatments examined included the addition of different sources of oxidised S, the addition of an organic adjuvant, seaweed extract and a comparison between soils with different reserves of reducible Fe. Where the oxidised S source decreased soil pH (FeSO4) sulphide production did not occur. Seaweed extract concentrations greater than recommended caused sulphide production. Larger amounts of reducible iron compounds decreased sulphide production.
