A Chinese conglomerate has negotiated the sale of part of Australia's largest cotton farm, Cubbie Station, almost four years after the company was ordered to sell down its stake.

Key points: Macquarie has acquired a 49 per cent stake in Cubbie Station

Macquarie has acquired a 49 per cent stake in Cubbie Station Cubbie owners say they will voluntarily handover up to 10 gigalitres of water

Cubbie owners say they will voluntarily handover up to 10 gigalitres of water A statement says the water handover plan has been developed with governments

Chinese textile giant Shandong Ruyi bought 80 per cent of the Southern Hemisphere's largest irrigation farm in 2012, but the sale was only approved on the provision the company reduce its ownership stake to 51 per cent.

Cubbie Station is located 500 kilometres west of Brisbane on the Queensland and New South Wales border.

Macquarie has acquired a 49 per cent stake in Cubbie Station under a deal the companies say has been approved by the Foreign Investment Review Board.

Significantly, the companies say they will voluntarily handover up to 10 gigalitres of water, back to environmental flows and downstream users, after dry periods.

Cubbie Station can store up to 469 gigalitres.

"The particulars of the commitment have been developed with engagement from the relevant Commonwealth and Queensland authorities so that it will help meet their respective environmental water objectives," Macquarie and Shandong Ruyi said in a statement.

'Meaningful commitment'

Macquarie Infrastructure and Real Assets (MIRA) said the voluntary water contribution aligned with "our investment thesis for long-term sustainable farming operations".

"We understand the responsibilities that we have to local communities and investors," MIRA head of agriculture Liz O'Leary said.

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"The voluntary water contribution … is a meaningful commitment that will increase the volume of water in the Culgoa River and Lower Balonne intersecting streams, at the most critical times.

"It is also an example of the private and public sectors engaging with one another to develop new ways of helping to meet environmental objectives, while enabling productive use of the land at times of high flows."

Less needs to be recovered from other farmers

Upgraded pumps were installed in 2017 on Cubbie Station. ( ABC Rural: Sarina Locke )

Water Minister David Littleproud said the voluntary water contribution "will be highest during periods of low to medium flow in the river system".

"The deal on environmental water will contribute to Basin Plan targets and mean less water needs to be recovered from other farmers," Mr Littleproud said in a statement.

He said the announcement "will give certainty to communities doing it tough in the Northern Basin as they push through the drought".

Cubbie's properties, located in south west Queensland near the towns of St George and Dirranbandi, have a total holding of 93,000 hectares.

Two years of negotiations

Cubbie Station CEO Paul Brimblecombe touring the station. ( ABC Rural: Sarina Locke )

Cubbie Agriculture chief executive officer Paul Brimblecombe told the ABC a "complex deal" had been made with the Macquarie-run agricultural fund, which he conceded had taken longer than expected.

"Our discussions have gone on with Macquarie now for just on two years and both parties have taken the appropriate time to, extensive due diligence to reach this outcome," Mr Brimblecombe said.

The value of the sale has not been disclosed.

Mr Brimblecombe said Cubbie's 42 employees would continue in their roles under the deal.