Peat is sold for fuel and as garden compost
They will tell a public inquiry that it is vital they are given permission to cut more peat from the Somerset Levels.
The five-week inquiry, which begins on Tuesday, will consider how much land to open up for peat extraction and quarrying in the county during the next decade.
One peat producer, Andrew Rowland, said: "We will lose customers to foreign imports because we will not have enough acreage to harvest.
More restraint
"It means the industry in Somerset will shrink, as well as transport and local engineering."
In areas where Somerset sinks below sea level, peat provides local landowners with much-needed income.
It is sold for use as a fuel and also as garden compost.
Peat producers say the land available from which to dig peat is running out and they need more.
But while quarry firms and peat producers are calling for new sites, environmentalists are urging more restraint.
Groups like Friends of the Earth and the RSPB have been campaigning for years for measures to stop the peat industry harvesting from wetlands.
The Somerset Levels and Moors were classed as an environmentally-sensitive area (ESA) in 1987.
They are home to threatened bird species and meadow flowers which need to grow in wet, unploughed ground.
Once dug, a field can not be reused for peat production and hence the industry is seen by some environmentalists to be ruining the landscape.
The public inquiry in Glastonbury will discuss how much stone can be quarried in Somerset in the next ten years.
The county's limestone is highly sought after for road and house building.
It is thought the inquiry will allow further quarrying in the county but peat producers are likely to be told to find alternatives to digging up the Levels.