Nutrient levels of threeEucalyptusspecies/provenances, measured over four seasons in a trial along the sandy, dry, Cape West Coast of South Africa

Abstract

Foliage nutrient content of 3 to 6-year old Eucalyptus species/provenances (E. camaldulensis, E. globulus and E. grandis x E. tereticornis) were analysed for eleven elements over a four-year period. The trial was planted on three sites, adjacent to each other, all deep acidic sands with an annual rainfall of about 400 mm along the Cape West Coast. With the exception of the elements Ca, Na and Cu, highly significant differences between species means occurred. The elements K, Na, Mn and Cu showed highly significant differences between sites, with Na values constantly higher in each year on the site closest to the ocean and lowest on the site furthest away. The very high Na values in foliage was ascribed to uptake of Na deposited by water or wind from the sea and the high levels might be toxic for sensitive species. Differences between year means were highly significant for all elements analysed but there was no indication that a decline occurred over the years. Except for Fe, Ca, Mn and B, which appeared to be adequately supplied in the soil, all other elements were low to deficient and trees should benefit from fertilisation. Of the three species E. globulus tends to be the most sensitive towards a low N, P, K and Mg status and is expected to benefit most by fertilisation.