A "MISGUIDED push" to protect the reef from agricultural run-off could cost Queensland sugar growers $1.3 billion over 10 years, Canegrowers has claimed.

The organisation said the controversial reef regulations would slice into farmers' nitrogen applications, resulting in huge on-farm losses in Mackay, Proserpine and Plane Creek.

The farming group commissioned a report that estimates the changes would reduce Mackay region grower's annual farming incomes by $4.6 million if nitrogen applications were to be reduced by 10 per cent.

If farmers were required to cut nitrogen use by 30 per cent, farm losses in Mackay could tally $19.3 million, the report said.

Reduced productivity would decrease cane crushing in Mackay by 187,000 to 672,000 tonnes.

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Across Queensland the total productivity losses would be equivalent to two sugar mills becoming redundant, it said.

Mackay grower and Canegrowers chairman Paul Schembri said it was a "zealous campaign" against growers as they struggled to reduce their impact to the Great Barrier Reef.

"This anti-industry dogma is posing a real risk to the livelihoods of the thousands of people who work in the sugarcane industry and to the Queensland state economy," he said.

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Environment and the Great Barrier Reef minister Leeanne Enoch said the Canegrowers report exaggerated what the reef regulations would mean for farmers.

Ms Enoch said they did not require growers to reduce nitrogen levels by 30 per cent, and the proposed limits were in line with Canegrowers' own industry standards.

"All the requirements under regulations are based on the cane industry's own Six Easy Steps approach," Ms Enoch said.

"The requirements allow growers to tailor fertiliser use across their farms, considering different soil types and constraints so they can optimise fertiliser use and maximise profitability."

But Mr Schembri said the new legislation meant controls could be ramped up beyond the industry recommended levels.

"The ramped-up reef regulations implemented last year are based on an intent to push growers to this level (a 30 per cent cut)," he said.

A Senate inquiry into the reef regulations would be held in Brisbane on Monday July 27 and Tuesday July 28.