EXCLUSIVE: Japanese conglomerate Sumitomo Corporation of Japan has taken a half share in Australian grain business Emerald Group Australia Pty Ltd.

Emerald runs grain pools in its own right but also manages a number of grain buying operations through joint ventures and alliances.

These include joint ventures with Southern Quality Produce Co-operative in Victoria's Western District, Southern Agventure in southern NSW and another with WAFarmers in Western Australia.

Emerald chairman Alan Winney said the sale of a half share in the business to Sumitomo allowed his company to grow much faster and opened up new grain selling opportunities in Asia.

"We have had a good relationship with Sumitomo over the years,'' Mr Winney said.

"They're the No.1 wheat importer of Australian wheat.

"And for the past 18 months, we have been the sole supplier to them.''

Sumitomo has a half share in Australian Bulk Alliance, the operator of a number of grain storages in southeastern Australia and 50 per cent ownership of the Melbourne Port Terminal.

An associated company, Sumitomo Chemical Company, recently took a 20 per cent stake in local chemical manufacturer Nufarm.

Sumitomo has been operating in Australia for about 50 years and has extensive interests in the mining, automotive, agricultural and food industries.

The Japanese company has bought into flour mills in Asia.

Mr Winney said there would be very little change in Emerald's operation with Sumitomo taking a half share.

Three Sumitomo directors would join the six-member board, with Mr Winney remaining as chairman and Mich Cattanach as executive director.

Mr Winney said the deal opened up big growth opportunities for Emerald.

"This is an opportunity to be involved with a company that, net asset wise, is 80 times bigger than AWB or GrainCorp and 40 times bigger than Viterra,'' he said.

"We have got some real serious growth prospects.''

Mr Winney said the new arrangement would not alter the way Emerald did business with Sumitomo.

"There is no compulsion to supply (grain to) Sumitomo,'' he said.

"If we're not competitive or their price is not going to maximise returns to our pools, then we don't have to sell.

"We can't become their accumulator.

"But what it does mean is that Emerald now has access into Sumitomo's Asian flour mills.''