Nutrient management of contrasting Acacia mangium genotypes and weed management strategies in South Sumatra, Indonesia

Abstract

Tropical plantations are an important source of forest products both to meet the growing demand for wood, and to facilitate the transition from native forests to more sustainably produced forest resources. Management of these plantations for optimal productivity and resource-use efficiency is vitally important, and nutrient management is a critical component of sustainable plantation production. In this study, we explored the response of Acacia mangium plantations in South Sumatra, Indonesia, to fertiliser and their requirement for fertiliser, focusing on phosphorus (P) at establishment. Almost all plantations across a series of 11 sites were highly responsive to P fertiliser, with nine of the 11 sites having more than double the productivity in P-fertilised treatments at age 1 year compared with control treatments. However, the quantity of P required for 90% of maximum growth was generally low by age 2 or 3 years, and 10 kg P ha -1 at establishment was sufficient to ensure that at least 90% of maximum growth was captured across all the experimental sites. At a 12 th site, we explored the interactions between genotype and weed control, and found that both effects were additive in the response of the plantations to P, and thus there was no substitutability between management types: weed control, genotype and P needed to be managed in combination to achieve maximum productivity. ARTICLE HISTORY

Growth Responses of Eucalyptus pellita F. Muell Plantations in South Sumatra to Macronutrient Fertilisers Following Several Rotations of Acacia mangium Willd.

“…This limited the viability of its comparison with E. pellita to age 1.5 y when A. mangium had a similar stocking rate and 16% more standing volume. This higher mortality may have contributed in part to the lower P response (around 33%) than in E. pellita (around 136%) that was also lower than found previously in South Sumatra [8], Central Sumatra [23] and in Kalimantan [40]. The proportional response of A. mangium to P gradually declines with age [8]; in these trials, E. pellita maintained a consistently higher response with age.…”

“…Hence, E. pellita grown on a site that had previously supported three rotations of A. mangium had a higher response to P than on a site recently converted from secondary forest; this was presumably related to a lower nutrient stock in the soil (Table 1) and/or perhaps changes in soil properties during the three previous rotations at the Core site. In South Sumatra, the application of 36 kg P ha −1 early in the rotation at seven sites planted to E. pellita resulted in a 38%-198% increase in stand volume at age 3 y [26]; the application of a range of P rates at planting at ten sites planted to A. mangium resulted in a 40%-180% increase in stand volume at age 1 y [8]. In A. mangium, site responsiveness is linked to a range of soil characteristics and particularly the physical characteristics of subsoil [27].…”

“…Ferreira and Stape [28] have also linked responses to fertiliser application by tropical E. urophylla in south-eastern Brazil to soil type. Although this understanding of site characteristics can be very important for determining fertiliser responses, for P in South Sumatra a single rate of 10 kg ha −1 was considered sufficient to maximise the yield at harvest for A. mangium [8], a finding linked to the lack of any significant volume response to P fertiliser application by age 6 y [9]. However, as the potential response increases with the number of rotations and as the yield of E. pellita at age 3 y was 70% greater following P application in this study, more than 10 kg ha −1 may be required to maximise growth responses.…”

“…The application of P fertiliser is required to maximise the productivity of A. mangium across a wide range of site conditions in South Sumatra [7,8]. This observation was supported by the finding that soil-extractable P had declined over the course of a second rotation of A. mangium, also in South Sumatra; exchangeable K and Ca also declined [9].…”

A review of nutrient, water and organic matter dynamics of tropical acacias on mineral soils for improved management in Southeast Asia

“…Although this volume gain tended to increase over time, the proportional response was diminished because the overall standing volume increased at a greater rate. Interestingly, the P fertiliser requirement (calculated as the amount of P required to reach 90% of the maximum productivity) was less than 10 kg ha −1 P at every site (Mendham et al 2017), so a universal dose of 10 kg ha −1 P was recommended to be sufficient across all planting sites within the study region of South Sumatra. It was further recommended that further refinement of diagnostics of P fertiliser requirement would not be cost effective within that region.…”