The amount of money Australia reaps from resources and energy commodity exports is expected to fall this financial year, despite a pickup in volumes shipped overseas.
The prediction on Wednesday came as the federal government's commodity forecaster released its latest quarterly report, which also flagged further falls in the price of iron ore.
The Bureau of Resources and Energy Economics (BREE) expects the price of iron ore, Australia's biggest export, to average $US94 a tonne in 2014, 26 per cent below last year, and remain there next year.
Iron ore prices have tumbled by nearly 40 per cent since January and now sit below $US80 a tonne amid a slowdown in demand from Chinese steelmakers and higher production levels in Australia.
The fall in iron ore prices is expected to push down the overall value of Australian commodity exports for 2014/15.
BREE expects earnings from those exports to fall one per cent to $192 billion this financial year, with earnings from iron ore forecast to drop four per cent.
It blames the fall on higher export volumes for most commodities being offset by lower prices and the high Australian dollar.
But while overall earnings are set to fall, export volumes are tipped to rise, particularly for LNG and iron ore.
BREE expects commodity export earnings will rise at an average rate of seven per cent a year from 2013/14 to $274 billion in 2018/19.
"For several commodities, including iron ore and coal, prices are projected to rebound after 2016 as consumption growth starts to catch up with the recent jumps in production capacity and the recent investment in the sector will contribute to a rapid increase in Australia's export volumes," BREE said.
BREE also forecast Australian economic growth moderate to 2.5 per cent in 2014/15, from 3.1 per cent last financial year, as capital investment falls and the dollar remains high.
It said mining was again the key contributor to Australia's economic growth in 2013/14, followed by financial services, construction and consumption expenditure.
"However, the high value of the Australian dollar, further declines in capital investment as the construction of large-scale resources projects are completed and the high cost of doing business will be key challenges to maintaining this growth rate over the short term," BREE said.
It predicts the challenges will persist into this financial year and contribute to a forecast moderation in economic growth.
Australia's GDP would then recover to trend growth of around three per cent in the remaining years to 2018-19.