Applying the right amount of fertiliser to Acacia trees in South Sumatra

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.