The effect of fertilizer application on the growth of Eucalyptus globulus

Blue Gum (Eucalyptus globulus Labill.) fertilizer trials in Gippsland, Victoria were used to relate tree growth to soil chemical parameters and foliar nutrient concentrations. The effects of combinations of N, P, K and trace elements, on selected chemical characteristics of soils and foliage nutrients were compared across three sites covering a range of soil types and climates. The effect of site on soil chemical parameters; soil pH, oxidizable carbon, available phosphorus, available nitrogen, total soil nitrogen, carbon to nitrogen ratio and soil nitrate, was highly significant (p < 0.001). Similarly, the effect of site on foliar phosphorus and potassium was highly significant (p <0 001). Site did not significantly (p < 0.05) influence foliar nitrogen concentration. Height, diameter and basal area were significantly (p < 0.001) influenced by site. Fertilizer addition significantly (p < 0.05) increased available phosphorus in the topsoil of gradational clay loam soils but not in coarse sandy soils. N and P fertilizer addition significantly (p< 0.001) increased foliar nitrogen at all the three sites. Foliar N concentrations are useful in prescribing NP fertilizer requirement across the range of sites studied. Foliar K concentrations were significantly (p < 0.01) increased by NPK fertilizer addition in one of the sites only (Maryvale). Height and diameters of individual trees were significantly (p < 0.001) increased by NP and NPK fertilizer addition in all sites. There was a trend for the response in absolute terms to increase with site quality. Overall, foliar nutrient concentrations were better correlated with growth than soil chemical parameters, and showed great potential for predicting E. globulus response to fertilization at 29 months of age