China overtook Japan in March to take the title, but the figures for April and those for May released yesterday suggest it has won it for keeps.

The change has been little recognised partly because it is widely believed it happened some time ago. Politicians have been referring to China as "Australia's biggest trading partner" for years.

This description, though, was a bit of sleight of hand. China was the biggest source of our imports, not the biggest destination for our exports. When exports and imports were added together, China only narrowly beat Japan.

No longer. Our exports to Japan collapsed in the first five months of this year. From more than $6 billion a month in November and December they fell to $3 billion in April and $2.5 billion in May.

Exports to China, previously earning us $2 billion to $3 billion a month, jumped to a record $4.3 billion in March, and then $3.6 billion and $3 billion.

Unless Japan's economy recovers quickly — and there are scant signs that it will — China will continue to outshine Japan for years. In May it accounted for one in every four ships leaving Australia.

Austrade's chief economist, Tim Harcourt, calls the phenomenon "bamboo shoots", to distinguish it from the "green shoots" of economic recovery pundits are looking out for worldwide.

He says China's huge fiscal stimulus measures are paying the same sort of dividends there as ours are in Australia, especially in China's second and third-tier cities.

Virtually being forced to spend on infrastructure, those cities are buying Australian iron ore and increasingly Australian coal amid the realisation that Chinese coal is dirty.

Japan's economy is shrinking rather than growing — as China's is — and it cannot compete. As well, says Mr Harcourt, Australian small and medium-size businesses now find it easier to peddle their wares in China than in Japan. "There's still resistance in the field of financial services but, when it comes to most Australian small businesses, there's no Great Wall of Trade."