Assessor is the decider: What exactly is a farm?

How many chickens does it take to make a farm? How many cows must a landowner have to qualify as a farmer? And do grazing horses a real farm make?

Thanks to changes to Minnesota's Green Acres Law -- which dictates how agricultural land is defined and taxed -- those are among questions that county assessors are wrestling with as they prepare to send out their 2009 tax statements.

The law was changed in May to address what the Legislature considered abuses by developers who were paying low agricultural rates on large tracts of land, costing government an estimated $40 million a year in tax revenue, according to the Legislative Auditor.

But a quick-fix approach by the Legislature has led to unintended problems, upsetting farmers, conservationists, rural lawmakers and assessors, who have had to deal with the consequences this year.

"It's a big headache," said Wright County Assessor Greg Kramber, who estimates the county will eventually spend more than $250,000 to reassess more than 12,000 agricultural parcels to comply with the new law. "It's an administrative nightmare."

Since May, he and other county assessors have visited tens of thousands of parcels to reassess their value and determine not just if a property qualifies as a farm, but also to see how much of that land is productive and how much is not.

Kramber said assessors are literally being asked to determine if someone is a legitimate farmer or simply has a hobby farm operation that is being used to dodge high property taxes.

Adding to the confusion is the fact that agricultural can be anything from raising hogs and keeping bees for honey to growing soybeans and selling maple syrup derived from trees. And the law is not specific on how many cows or pigs or chickens it takes to qualify, leaving it all up to local assessors to decide.

"A lot of it is subjective," said Kramber. "We have to dissect each farm into portions. We literally have to figure out how many chickens does it take to be productive. That's what it comes down to."

The changes in the law, which has been around more than 40 years, were passed after being tacked onto the omnibus tax bill at the end of the last legislative session. Therefore, opponents argue, it did not get as much scrutiny as it should have before being approved.

Kramber said he has been getting about 200 calls a day from farmers upset about the changes. Like many assessors, Kramber has held meetings to talk about the law. At a recent meeting, he had almost 500 angry farmers questioning him.

"We have a lot of conflicts with a lot of taxpayers," he said.

The administrative headaches assessors are facing are only part of the problem.

Assessors must now divide each parcel into productive and non-productive categories, and tax the non-productive acreage -- such as woods or swamps -- at market value rates regardless of whether the land is farmable or not.

That has conservationists and county planners concerned that farmers might damage the environment by plowing under their woods or wild areas to start producing crops as a way to avoid paying the higher property taxes.

Wright County, for example, has a large number of lakes and rivers, and Kramber said many farmers use non-productive agricultural land as a buffer zone between their farms and the water.

"Our members are really upset," said Brian DeVore, a researcher at the nonprofit Land Stewardship Project. "We have gotten more calls about this than anything else recently. It's really hot right now."

That has raised the concern that farmers might be unable to afford such a lump payment, or that the payment might be more than the profit made on the sale of the land.

"Nobody is against paying taxes, because they are all invested in the community," said Hilary Dorsey, who owns land in Sherburne County. "But there are lot of questions."

Dorsey said the taxes on her daughter's horse farm have increased almost 150 percent as a result of the changes, in part because simply having horses is not considered productive agricultural use of land.

The state Department of Revenue, which administers the Green Acres program, is aware of the problems and complaints resulting from the law changes.

"We're working with assessors and legislators on ways that the law can be amended to mitigate obvious problems that assessors and landowners are having right now," said Kit Borgman, a spokeswoman for the Revenue Department.

But that is of little comfort to thousands of farmers statewide who are facing property tax increases in 2009.

"We don't know what is going to happen," said Dennis Beise, a farmer in Rockford Township who is among hundreds in Wright County upset with the new guidelines. "The way the law is set up now is going to hurt a lot of people."