Anne Arundel County police, while searching an elegant horse farm yesterday for a missing person, unearthed what they described as the biggest illegal drug-manufacturing plant ever found in the area.

The cache was so huge, police said, that they had to call in a private waste disposal company today to haul away hundreds of pounds of chemicals found at the 26-acre Summerhill Farm off Rte. 214 (Central Avenue).

Police charged Robert M. Krohn, 28, of Annapolis, who said he was the owner of the farm, with attempted manufacture of a controlled dangerous substance. Krohn, who told police he is a biochemist and printer, was released without bond after appearing before a District Court commissioner today.

According to police, the equipment and materials recovered were capable of producing hundreds of pounds of methamphetamine, a central-nervous-system stimulant valued at $30,000 an ounce. The drug is sold under the street name "crank" at $10 a dose. Police estimated that the material found had a potential for producing $143 million worth of illegal drugs.

Police called in federal Drug Enforcement Administration personnel to help sort through the find. Steve Demchuk of the DEA made an inventory of the chemicals and said, "It's a big one."

DEA agent Dave Noll estimated there were enough chemicals, including drums of methylamine, triethylamine and phenyl acetic acid, to manufacture 400 pounds of "crank."

The chemicals were stored in a drafty shed bordering the half-mile driveway to an imposing colonial mansion, which sits on a hill surrounded by oak trees. There were about a dozen 55-gallon drums in the shed, along with tools and equipment, a gas mask, rifle shells, dry chemicals, plastic tubing and home-made condensing columns, all in a jumble.

The laboratory where the "meth" allegedly was made was in the upstairs of the house, police said. Police Lt. C.E. Smith said there was no furniture in the house other than the laboratory equipment and a loaded and cocked .45-caliber pistol.

Police happened on the laboratory during the course of a search for Stephen J. Finch, whom Sgt. Ed Lyons described as a "loner" who rented an adjoining farm and who has been missing since Jan. 4. Finch was still missing today.

On Thursday, 40 searchers and the State Police helicopter covered about 1,600 acres of rolling farm land looking for Finch. After one of the searchers noticed a door open at the main house at Summerhill Farm, Lyons and other police went in, thinking Finch might be there. Instead, they found the lab.

Some of the officers immediately went for a search warrant while others secured the area. They said Krohn was arrested when he showed up at 5:30 p.m. The search warrant did not arrive until after midnight, so police were on the scene all night, sorting through evidence.

As Sgt. John Mosley, a police drug specialist, sifted through complicated equipment, he called the lab the work of "a highly creative and intelligent person. Unfortunately, he guided his talents in the wrong area."

From the outside, the house appears to be occupied, with a tractor and pickup truck in the driveway, lights lit and a horse barn 50 yards away with two horses, named Unique Ink and Aspen, in the stalls.

Mary Ann Greene, who lives within sight of the 160-year-old farmhouse, said, "Occasionally you'd see someone up there exercising the horses but otherwise it was very quiet. We didn't know if anyone was living there or not."

Capt. Curtis Nunn said police were upset about Krohn's release without bail, but he added, "there's nothing we can do about it." Smith said Krohn was "cooperative to the point of being polite."