Growth at age 30 months of Acacia and Eucalyptus species planted in Imperata grasslands in Kalimantan Selatan, Indonesia

Abstract

The trials tested a range of establishment techniques for Acacia and Eucalyptus species for pulpwood plantations grown in leached and degraded soils under Imperata grassland (alang alang) in South Kalimantan (Kalimantan Selatan). The results reported here are from measurements at age 30 months. Acacia mangium from Wipim (PNG) had the best growth (57 m 3 ha −1); this was 70–80% greater than A. mangium from Subanjeriji (Indonesia). Apart from Acacia crassicarpa, other acacias grew less well and produced multiple stems. Hybrids of Eucalyptus grandis × Eucalyptus urophylla grew exceptionally well and produced an average of 37–46 m 3 ha −1. E. urophylla from Wetar also produced 29 m 3 ha −1. Amongst other Eucalyptus species, fungal infections and insect damage to foliage increased mortality and reduced total volume production. Chemical weed control of Imperata grass was very important for the successful establishment of all species resulting in a doubling of total volume production of A. mangium (from 26 m 3 ha −1 without weed control to 51 m 3 ha −1 with weed control), and an 11-fold increase in total volume production of E. urophylla (from 1.8 m 3 ha −1 without weed control to 21.3 m 3 ha −1 with weed control). Cultivation with a large disc plough increased height growth of A. mangium but had no statistically significant effect on total volume production on this clay loam soil. Fertiliser substantially improved growth of A. mangium producing a total volume of 61 m 3 ha −1 in response to the highest rate of NPK (180, 78, and 150 kg ha −1 of N, P and K, respectively), compared with 41 m 3 ha −1 without fertiliser. There was no response to additional applications of trace element fertiliser to this soil. Slow release fertiliser gave growth responses in A. mangium similar to other fertiliser applied at rates of up to 20 times greater. The enduring and most important treatments with respect to growth of A. mangium in this environment were the selection of Wipim provenance, chemical weed control and NPK fertiliser, each of which contributed between 29 and 38% of total volume production.