CANE farms in the Clarence Valley converting to macadamias are having a "negative impact" on the cane industry, according to NSW Cane Growers' Association executive officer Pat Battersby.

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While Mr Battersby denied the increase in macadamia farms in the area were a threat to the cane industry, and claimed that over the past six months more land has gone back into cane, he said the association would argue that "cane land is cane land".

"We believe that macadamia trees going into floodplains is not ideal, and we would like to see that land used as cane land," he said.

"In our opinion it's best used for cane, that the floodplain is more suited to cane than macadamias. It's not a threat, we've got a lot of land under cane in NSW, but it is a negative impact.

"No-one can tell people what to do with their land, but we would argue that the best type of return on the floodplains is from sugar cane."

However, Department of Primary Industries development officer Jeremy Bright said while there were significant issues that needed to be considered when growing macadamias on floodplains, there was a strong potential for the plant.

"Floodplain areas that are currently producing macadamias are achieving some of the highest yields per hectare in Australia," he said.

"Expansion in macadamia farming on the coastal fringe of the NSW North Coast has been limited to date. However, with good site selection, appropriate land preparation and management, the potential for this industry to increase is huge."

Palmers Channel macadamia farmer Bruce Green said the soil in floodplains suited macadamias.

"The ideal soil is sandy loam, and macadamias like that free soil so they can grow their roots out and get established pretty quick," he said.

"You've only got to go two or three kilometres towards the lake (Wooloweyah) and you haven't got that, it's hard sort of country, you wouldn't worry about planting macadamias out there. It doesn't suit all the Clarence, so I don't think the macadamias will be a threat to the sugar industry," he said.

"Water is not a problem either. About 90% of my farm goes under in a flood, but as long as you've got a handful of leaves sticking out at the top of the water, you won't lose your tree, it's not a problem.

"The biggest problem we had was that we didn't stake our trees when we first planted them, and the wind would just blow them over."