New rules are needed to put the brakes on the proliferation of giant country mansions that are eating into the region's scarce farmland, Metro Vancouver directors say.

Metro's board voted Nov. 13 to ask the province to empower the Agricultural Land Commission to limit the size of the residential footprint – where people live – on agricultural lands.

They're also urging that the income threshold to be counted as a farm be raised "to a level consistent with a viable and sustainable agricultural operation."

That would make it harder for rural home owners with expansive estate grounds to qualify for the much lower agricultural property tax rate.

"It's really unfair for people to buy a farm property, place a house in the centre and basically make it unviable for farming," said Surrey Coun. Linda Hepner, vice-chair of Metro's agriculture committee.

Such homes should be closer to the road than is often the case, she said, and of a "size that's reasonable within today's standards of farming."

Metro isn't trying to define how big a farm house and its yard and parking lot can be, but hopes Victoria will charge the ALC with resolving the thorny issue.

"Some governing body should determine it," said Richmond Coun. Harold Steves, the agriculture committee chair. "Right now every city and municipality is trying to figure it out for themselves."

Some local municipalities have moved to draw up farm home plate bylaws, which restrict how much of an agricultural property can be used for residential purposes, but a consistent set of rules across the region has proven elusive.

Steves said some homes exceed 10,000 square feet, with vast parking lots, that have clearly been built by people wanting an expensive country lifestyle who have little interest in farming or ensuring the land continues to produce food for the region.

Value-added food processing and agri-tourism revenue should be counted as food income, the board also recommends, but efforts should be made to filter out other non-farm or food-related income.

Steves said that includes money made by digging gravel pits on farm land.

"Gravel extraction actually destroys the land, instead of preserving it."

Wood cutting and horse boarding revenue should also be excluded, Metro says, while income from making wine or preserves should count.

The Metro position is in response to the recommendations last summer of the B.C. Farm Assessment Review Panel.

The panel has advised Victoria to eliminate the current split property assessments on farmland, which tax houses at a higher residential rate and the farmland at the lower agriculture rate.

Metro contends the change to tax the entire property as farm would encourage residential uses to sprawl and could trigger a run on agricultural land by those wanting cheaply taxed land on which to build a dream home.

The review panel proposals would set a new minimum of $3,500 per year in farm income to qualify for the agricultural assessment classification, a number Metro says is too low.