SALEM — Legalized marijuana in Oregon may spur more home-building on farmland unless regulators revise existing land use rules, according to legal experts.

To build a dwelling on high-value farmland, the property must generate at least $80,000 in gross revenues for several years under current rules.

Because marijuana sells at prices far beyond conventional crops, it would be relatively easy for landowners to meet that income test and build more homes in farm zones, legal experts say.

“People who want to protect farmland are afraid of speculation — not for growing marijuana, but for development,” said Rob Bovett, legal counsel for the Association of Oregon Counties, during a recent forum on marijuana policy. “I suspect some of those rules will be tweaked.”

Voters approved legalized recreational marijuana in Oregon last year, and the Oregon Liquor Control Commission is aiming to write regulations for commercial production of the psychoactive crop by 2016.

Oregon’s land use system is intended to permit farm dwellings for commercial growers and discourage “martini farms,” but marijuana has thrown the current income-based approach into question, said Bill Kabeiseman, a land use attorney.

“The economic implications of marijuana growing have changed the underpinning of the rule,” Kabeiseman said.

The possibility that lawmakers and regulators will change the income test, possibly with a marijuana-specific provision, is more likely than a marijuana-fueled surge in home-building, he said.

For example, Oregon lawmakers are considering a proposal that would disallow dwellings in conjunction with marijuana production on land zoned for exclusive farm use.

Leland Berger, an attorney for marijuana businesses, said he’s concerned about that concept because marijuana growers face security risks and may want to live near their crop.

“I think there’s got to be a better way to structure that,” he said.

Marijuana legalization has also raised questions about whether the crop will make growers eligible for property tax deferrals.

Bovett of the Association of Oregon Counties, said that marijuana will probably end up qualifying for such deferrals but some counties will probably seek to restrict its cultivation in farm zones.

Whether counties have the legal authority to prohibit or limit marijuana production is still being debated.

Oregon counties may enact local regulations unless clearly pre-empted by state law, Sean O’Day, legal counsel for the League of Oregon Cities, said.

O’Day said that local ordinances for marijuana are not pre-empted by Measure 91 — which legalized the crop — but marijuana attorney Leland Berger said that was the initative’s intention.

Revisions being considered by lawmakers may strengthen language that pre-empts local ordinances on marijuana production and processing, Berger said.

Even so, counties could argue that they are allowed to regulate marijuana because the Oregon statute is pre-empted by federal law, under which the crop remains illegal, Kabeiseman said.

“Can a county prevent a particular type of farming is an interesting question,” he said.

The Capital Bureau is a collaboration between EO Media Group and Pamplin Media Group.