Date released
20 April 2018

Applying just the right amount of fertiliser allows smallholder tree growers to get the most for their money. This study worked out how much phosphorus is needed by acacia trees during the first 3 years of growth. It also found that weeding does not substitute for phosphorus – both are needed for the best results.

In Indonesia many smallholders make a living from supplying timber to the pulp mills. The focus is on short-rotation trees, so that the farmers get returns on their investment in 4–6 years. Using just the right amount of fertiliser is important, both for cost-effectiveness – fertiliser represents a major cost for smallholders – and for environmental sustainability, to reduce the amount of excess fertiliser applied to soils.

This study looked the application of phosphorus, one of the key nutrients needed by growing plants, to acacia, a common plantation tree, over the first 3 years of tree growth. The findings were that phosphorus was very beneficial during the first year, more than doubling the rate of growth of the trees. After 1 year, however, applying phosphorus had much less effect – just small amounts were needed for optimum growth.

The researchers, who were from CSIRO, Gadjah Mada University in Yogyakarta, and PT Musi Hutan Persada in Palembang, also studied whether the presence of weeds changed the need for phosphorus. If weeding reduced the need for phosphorus, this might be a preferred strategy for smallholder famers. However, this was found not to be the case – the best growth results were achieved with both weeding and phosphorus application.

Reference: D.S. Mendham, E.B. Hardiyanto, A. Wicaksono and M. Nurudin (2017) Nutrient management of contrasting Acacia mangium genotypes and weed management strategies in South Sumatra, Indonesia. Australian Forestry, Vol. 80, No. 3, pp. 127–134. DOI: 10.1080/00049158.2017.1331701

The open-source publication of the above paper is part of wider initiative by ACIAR to disseminate the results of its projects as widely as possible. The move towards supporting open access is in line with ACIAR’s thinking on free and fair knowledge sharing in pursuit of more productive and sustainable agricultural systems.