The effect of applied phosphorus and seed source on the growth of an Acacia mangium Willd. plantation on a low productivity site in South Sumatra

Ultisols are commonly found in the tropics and are potentially suitable for plantation forestry. However, as well as being acidic (pH 5.0), they are commonly infertile and require fertiliser addition if commercial yields are to be achieved. A field experiment on a low productivity Ultisol at Lematang, South Sumatra, investigated the effect of seed source on the height, diameter and volume of Acacia mangium until age 36 months. Four seed sources were used: Ap = Papua, Indonesia; Aw = Wipim, Papua New Guinea; As = local source of Subanjeriji, Indonesia; Ad = Deri-deri, Cairns Region Queensland, Australia. A randomised complete block design with four replications accommodated two levels of P, 0 and 100 kg P ha−1 in a factorial combination with material from each of the four seed sources. Early responses were found to P, but by 36 months the responses were no longer significant. Significant effects of seed sources were found on diameter and volume at age 36 months. There was no significant interaction between treatments for all measured variables. © 2025 CSIRO. Published by Informa UK Limited, trading as Taylor & Francis Group.