Don’t be surprised if sometime next year you see acres and acres of what appears to be marijuana growing, unfenced, in the desert.

But don’t bother stopping to pick some to smoke.

Gov. Doug Ducey on Monday signed legislation that finally authorizes Arizona farmers to grow hemp. Proponents contend that the plant, which can produce things like fibers for clothing and oils for soaps, would give Arizona farmers some new options to make money off something that likely would grow well in the desert environment.

“This bill opens Arizona to the possibility of a new agricultural product,” the governor said in a prepared statement, saying the measure “could have a positive economic impact for the state.”

And it’s only taken nearly two decades to get here.

The issue isn’t so much industrial hemp. Instead it’s the fact that it really is a form of marijuana.

Prior legislation was sidelined amid questions of how law enforcement could differentiate between crops.

The law that takes effect next summer seeks to resolve that two ways.

First, it contains a clear chemical definition of what is not being made legal. That includes anything with a concentration of tetrahydrocannibinol, the psychoactive element of marijuana, of more than 0.3 percent.

“Expecting to get high on hemp is like expecting to get drunk on a case of O’Doul’s,” quipped Sen. Sonny Borrelli, R-Lake Havasu City, during debate on his legislation, referring to the non-alcoholic beer. “It’s a waste of time.”

Second, the only people who will be able to grow the crop are those who have permission of the state Department of Agriculture. The agency will not only be able to inspect the facilities but also prohibit the use of hemp seeds it has not specifically authorized.

And the agency is going to get $500,000 a year to hire inspectors and police the industry.

This change is a long time in coming.

The House and Senate actually voted in 2001 to allow the state’s universities to research industrial hemp as a cash crop, only to have the measure vetoed by then-Gov. Jane Hull, who said she didn’t want to spend public money on a project that “may detract from the goals I support.” Anyway, Hull pointed out that federal law prohibited the possession and growing of all forms of cannabis plants.

Legislation in 2002 to have research funded by commercial interests faltered even with sponsors having a press conference in front of an American flag made with hemp fibers.

Part of what changed is the 2014 federal Farm Bill which specifically allows universities and state to cultivate industrial hemp for research if allowed by state law and the grow sites are certified and registered by the state. And a 2015 federal law removed hemp from the list of controlled substances as long as its THC content did not exceed 0.3 percent.

The National Conference of State Legislatures reports at least 35 states have now passed law related to industrial hemp.

Borrelli said hemp farming makes sense in a place like Arizona, where farmers could probably get four cuttings of the plant a year.

“It’s very economical,” he said, saying hemp uses 90 percent less water than cotton.

Even with all that, this year’s measure still raised questions. Sen. Gail Griffin, R-Hereford, wanted to know how law enforcement will know whether a crop is legit or not. Borrelli said the key is a grower or processor having proper credentials.

If not? “Then they’re going to go to jail,” he said.

Borrelli also said that context is important.

He said most of the marijuana being cultivated for medical use is grown in climate-controlled greenhouses. But hemp, Borrelli said, is likely to be found in an open field.

And Sen. John Kavanagh, R-Fountain Hills, a former police officer, said law enforcement has access to field test kits that can quickly determine whether a plant is legal or otherwise.