The Phosphorus Response of Eucalyptus Seedlings Grown in a Pallid Zone Clay Treated With Three Levels of Lime

Abstract

The responses of five Eucalyptus species (E. calophylla, E. globulus, E. maculata, E. marginata and E. resinifera) to four levels of calcium phosphate and three levels of lime (CaCO₃) on a granitic pallid zone clay of pH 4.0 from a jarrah forest soil were examined in a glasshouse trial. In the presence of a complete fertilizer, except for lime and phosphate, seedlings made poor growth and had weak root systems with few fine roots. Application of calcium phosphate promoted shoot and root growth in all species. Application of lime had no effect on plant growth except at very high levels (7.1 g per kg soil), where it induced iron deficiency chlorosis in some species.

All species achieved maximum yield with an application of calcium phosphate of between 30 and 300 mg per kg soil. Phosphorus concentrations in individual leaves and shoots were low (0.1-0.3%) and responded weakly to phosphate treatments. Phosphorus concentrations in stems responded strongly to increasing phosphate applications over the whole range of phosphate supply. We suggest that stem tissues may be used to indicate the phosphorus status of eucalypts.