Utilisation of previously cultivated land for Proteaceae crops is a viable alternative to using pristine land. However, cultivated lands have usually been fertilized and typically have soil [P] unsuitably high for Proteaceae, resulting in P toxicity. After establishing that the main effects of P toxicity on the shoot were increased leaf P and Mn, but reduced leaf Fe and Zn, it was hypothesized that binding soil P and providing additional Fe and Zn to leaves would ameliorate P toxicity. Various soil and leaf amendments were tested for their efficacy in reducing soil P in unplanted lands, or ameliorating or preventing P toxicity in lands or pots planted with Protea 'Sylvia'. In an unplanted field, deep ploughing to 50 cm reduced available P from 16213 to 8.82.6 mg P kg -1 soil, i.e. by 95%. Sowing two seasons of the cover crops oat and lupin also greatly reduced available P (80%) whilst Al 2(SO 4) 3 application (278 g m -2) reduced available soil P by 80-65% depending on initial soil [P]. Ploughing was associated with disadvantages such as reduced cations and possible disruption of microbial populations. Thus use of cover crops or, for more immediate reduction in available soil P, aluminium application may be preferable. Application of Al 2(SO 4) 3 was also shown to be effective in prevention and amelioration of P toxicity symptoms in Protea 'Sylvia' in the field, while a Fe-containing compound 'OX' and a Fe/Zn containing foliar spray were only effective in preventing P toxicity in a pot experiment. Calcium sulphate was not effective as a P-binder in the field. Different agents may be used for different requirements but Al 2(SO 4) 3 application was effective in both prevention and amelioration of P toxicity.
