| Summary: | <i>Eucalyptus pellita</i> has rapidly emerged as the species that has replaced <i>Acacia mangium</i> in broad-scale commercial plantations in Indonesia following widespread losses due to disease and in soils that have suffered a steady decline in phosphorus (P) under plantation forestry. Conversion from a nitrogen (N)-fixing to a non-N fixing species is expected to change the nutrient dynamics and the management required to maximise productivity. In this study in South Sumatra, responses of <i>E. pellita</i> to the application of N, P, potassium (K) and calcium (Ca) fertilisers were assessed at a number of trials on sites with varying site history; <i>A. mangium</i> was planted at one site to compare the species’ responses to N and P. The growth of <i>E</i>. <i>pellita</i> responded significantly (<i>p</i> < 0.01) to P’s application but not to N, K or Ca, with the addition of P increasing the stem volume by 32.6 m<sup>3</sup> ha<sup>−1</sup> at 3 years of age compared with no addition of P fertiliser; the demand for P in the first two years of growth was, respectively, 4.8 and 6.8 kg ha<sup>−1</sup>. This positive and large response appears to be because <i>E. pellita</i> has a lower efficiency in its use of P than <i>A. mangium</i> and is, therefore, more responsive than <i>A. mangium</i> to the addition of P. The reason for the lack of response to N remains unclear, although demand for N as well as K and Ca was high. These results suggest that sites recently converted to <i>E. pellita</i> from <i>A. mangium</i> and also new ex-native forest sites will be likely to only respond to P addition and that the response of <i>E. pellita</i> is likely to be greater than for <i>A. mangium</i> to maximise yield. At present, additional N, Ca or K fertilisers are not required, but this may change in the future.
|
|---|
