The Baird government's plan to loosen land-clearing laws in the state may struggle to get through Parliament, with the Shooters, Fishers and Farmers Party indicating they will heed opposition to the new bill from farmers.

NSW Farmers, the industry's peak body, has demanded "drastic changes" to the draft biodiversity bill before it would give its support to cut "red tape" further.

Farmers are angry the draft mapping provided to them to assess whether they could clear native vegetation is proving to be "totally inappropriate and inaccurate", NSW Farmers president Derek Schoen said.

The cost of proofing the maps could run into tens of thousands of dollars on big properties and "would make the exercise unviable", Mr Schoen said.