Ah, spring on the farm: Cows grazing in new-green fields. Streams sparkling in the sun. Tractors tilling the rich soil. Large tank trucks spewing smelly, black sewage.

On agricultural land across much of Pennsylvania and New Jersey, treated waste -- human, household and industrial -- has become a common fertilizer. At least half of all the sewage generated in both states -- about two million tons a year -- is spread on fields where grains, feed corn and grasses are grown.

Barred from ocean dumping, driven by the need to find someplace for all that waste, federal regulators and state environmental officials have promoted its use on farmland for more than two decades.

For just as long, a debate has percolated about its safety. Some scientists contend that the small quantities of contaminants in the waste -- metals such as lead and mercury, as well as bacteria and viruses -- could pollute the soil or groundwater and threaten public health.

On one point, both sides agree: If sludge is put on farmland, it should be done with care.

By the end of this month, however, sludge-spreading in Pennsylvania and New Jersey will be on the honor system.

No longer will the states keep track of how much sludge is applied, or where. Or by whom. Or what's in it.

Under the new rules, waste will be tested by state water-quality inspectors on random visits to sewage-treatment plants -- perhaps once a year. But finding acceptable places to spread the sludge; keeping it away from streams, wells, vegetable and fruit crops; controlling the amount applied; checking that no environmental problems develop -- those responsibilities will shift to the plant operators. And they, not the states, will keep the records.

Why the changes?

Because Washington wants all states to cut the red tape that has slowed sludge disposal, and Pennsylvania and New Jersey are among the growing crowd that has eagerly obliged. The Ridge administration has even calculated the money to be saved by eliminating paperwork and monitoring: $83 million.

This new official view of sludge -- as a beneficial soil supplement that needs virtually no government regulation -- will be ``a shock to a lot of people,'' conceded Dennis Hart, of the New Jersey Department of Environmental Protection. ``It's going to take a long time for people to say, `We're trusting of the system. We don't need all the monitoring.' ''

For critics of the new rules -- from scientists to food processors -- it may take a very long time.

``Sewage sludge has nice nutrients,'' said Ellen Z. Harrison, director of Cornell University's Waste Management Institute, which has studied sludge use for a decade. ``The thing we sometimes forget is that it also is industrial waste.''

Harrison and her Cornell colleagues say the standards set in the new rules -- which mirror four-year-old federal guidelines -- are not adequate to protect public health. The amount of metals allowable in sludge is 10 times too high, they contend.

Of equal concern to them is what the regulations do not say. There is no requirement that sludge be tested for organic chemicals (such as PCBs) or for bacteria, viruses (hepatitis A, for example), and parasites (including Giardia or others that can sicken humans).

That also worries the National Food Processors Association, which represents 28 of the nation's largest processing companies. Rick Jarman, the group's director of technical and regulatory affairs, said the new regulations were based on a dubious assumption: that sewage-treatment plants operate every day under quality-control programs that are above reproach.

Never fear, say sewage-plant operators: They have been policing themselves all along.

Jay Snyder runs the sewage-treatment plant in Ephrata, Lancaster County, which spreads sludge on 800 acres in the county. Some plant managers, including Snyder, give their sludge to farmers, even plowing it into the soil for them at no charge. Others have to pay farmers up to $40 a ton to take the sludge, or hire private haulers to dispose of it.

Pennsylvania ``has never had the manpower'' to closely monitor the entire process, Snyder said.

``The operators,'' he said confidently, ``can do the job.''

Deregulation of sludge in Pennsylvania and New Jersey is part of a movement that began in 1993, when the federal Environmental Protection Agency relaxed its own sludge guidelines, setting specific ceilings for only a handful of pollutants in the waste. If those limits are observed, sludge can go almost anywhere, the EPA said.

Last year, responding to the controversy over sludge use, a federal scientific panel concluded that the waste presented a ``negligible risk to the consumer, to crop production, and to the environment.'' But the panel urged more study, conceding its testing had been limited.

Throughout the sludge debate, the marketing machine has gone full tilt. Proponents of deregulation envision the day when sludge is such a hot commodity that farmers and backyard gardeners alike are standing in line for it.

A few years back, the waste-treatment industry even sponsored a contest to give sludge a spiffy new name. More than 250 entries poured in, including ``sca-doo,'' ``hu-manure,'' ``hu-doo'' and ``bioslurp.'' The winner: ``biosolids.''

This p.r. makeover troubles many scientists.

Sludge hasn't changed, said one Cornell researcher -- it has just been ``linguistically detoxified.''

Spend time these spring days watching traffic on the Route 30 bridge that spans the Susquehanna between Lancaster and York Counties, and eventually, tank trucks full of sludge lumber into view. The two counties receive more of it than any others in Pennsylvania.

Some residents fear that sludge may become the area's most lucrative cash crop, with farmland valued more for waste disposal than for its capacity to grow food.

They also worry that the lure of a quick buck -- coupled with minimal government oversight -- may lead unscrupulous sludge haulers to overload the land with waste until the soil and water are so contaminated that they are worthless.

Even now, when a farm goes on the market, mortgage bankers are quick to ask: Has sludge been applied here?

Sludge is spread on 5,000 acres in Lancaster and 3,000 in York. A lot of it comes from somewhere else. The majority of the 20,138 tons that Philadelphia ships westward each year ends up there. Until recently, Lancaster County sent half its sludge across the river to York County.

Among the most active sludge haulers in the two counties is Star Rock Farms of Manor Township, Lancaster County, a family partnership created in the 1970s by John E. Barley and his brother, Abram. John Barley, a Lancaster County Republican elected to the Pennsylvania House in 1984, is chairman of the Appropriations Committee.

The Barley family's sludge business has sparked controversy -- and volumes of local newspaper stories -- in Lancaster and York Counties in recent years.

In 1986, the Barleys signed a long-term, no-bid contract with the Lancaster Area Sewer Authority (LASA) to haul and spread its sludge on fields. Over the next decade, the sewer authority paid Star Rock more than $5 million. Ultimately, the partnership owned 3,000 acres in Lancaster and York Counties -- land used to both spread sludge and grow grain.

This year, LASA's contract with Star Rock had called for disposal fees to rise to almost $1 million annually. But LASA decided to find a cheaper way to get rid of its sludge, said authority chairman Carl Neff.

LASA cut its payments to Star Rock by about 25 percent, halted sludge shipments to York County, and has begun disposing of 10,000 tons in a nearby landfill. It also plans to invest $10 million in improvements that will allow the authority to produce ``exceptional quality'' sludge that can be marketed to consumers.

The Star Rock operation was turned over to the Barley brothers' sons ``five or six years ago,'' John Barley said in a recent interview.

However, he remains interested in sludge.

In 1995, when state environmental officials were considering changes in the sludge-application rules, Barley wrote a letter on his official House stationery urging less-restrictive regulations. He said later that his comments had not been an effort to influence government oversight of a family business, but an offer of his expertise on the subject.

He wrote the letter, he said, to urge state officials to enact regulations ``in sync'' with federal guidelines. And they have, he said.

In York County, sludge-spreading has provoked lawsuits, protests and midnight acts of vandalism.

Tensions erupted a year ago at a Chanceford Township farm leased to Star Rock. Vandals damaged four tractors used to spread sludge.

Township residents have compiled long lists of complaints against Star Rock. They say sludge pours off hillsides into backyards, down driveways and into the pristine streams that crease the steep valleys. Sludge is not promptly plowed into the soil, they say, and after it is applied, insect swarms drive them inside.

The state found no violations.

One of the most outspoken opponents of sludge-spreading in York County is Sandy Smith, who has lived in Chanceford Township, high above the Susquehanna. ``This area is called River Hills,'' she said, ``and river hills are one place where sludge has no business.''

The great volume of sludge carried west across the Susquehanna angers Smith and her neighbors. ``Lancaster County has become a septic tank, and that's what they're creating here in York County,'' she said.

In nearby Hellam Township, at the west end of the Route 30 bridge, sludge also is on residents' minds.

Until a year ago, thousands of tons were spread on five farms there, including sludge from the Lancaster Area Sewer Authority and Columbia Borough, to the east. The risk of groundwater pollution is a particular worry in Hellam, said Township Manager Nancy Halliwell.

Seventy percent of Hellam residents use well water. A 1990 study found nitrate levels on the rise in 38 of 50 wells tested. Nitrate in groundwater is a problem that plagues many areas of Lancaster and York Counties, often caused by excessive use of fertilizers and animal manure. Some of Hellam's tainted wells were near old sludge application sites; all are on or near farms, Halliwell said.

In the spring of 1996, the township adopted an ordinance regulating sludge. It required haulers to get township permits and list the source of the sludge. It also required them to get liability insurance.

Almost immediately, Hellam Township was sued by the Columbia Municipal Authority and Springettsbury Township, which spreads sludge in Hellam. Township officials found they couldn't enact sludge rules stricter than the state's.

The lawsuit is pending, with sludge-spreading temporarily halted in the township.

Who is responsible if a load of sludge poisons the soil?

The new regulations are not clear on that question.

Here is how Pennsylvania's Department of Environmental Protection answered in one document: ``. . . [E]veryone has responsibility and potential liability.''