Jack Manuel, who lives adjacent to the farmland, told the group of about 20 residents that Harp had told him he would "pull the plug'' on the sludge if there were objections.
"I will stand by that statement,'' Harp said Thursday morning.
The objections were raised despite studies that several Maryland Department of the Environment officials said showed sludge application is safe and effective.
Harp said he believes there is no danger but said his neighbors are more important than the benefit he derives from the sludge applications.
"I was approached three or four years ago by county and state officials who wanted to use part of my farm for sludge application,'' Harp said.
He read and studied information and agreed after he became convinced it was safe and effective. The 80 to 90 acres in question are part of the farm that is in an agricultural land preservation district, Harp said.
"There have been three applications on that land - last spring, last fall and the past two weeks this spring,'' Harp said.
The farmer gets the sludge for free, saving him the cost of applying other types of fertilizers. The state saves money by not having to dispose of the sludge elsewhere at a high cost.
State officials Wednesday defended the program as the safest and cheapest way to get rid of tons of the treated sewage byproduct.
There are 880 farms in Maryland - 76,000 acres - receiving sludge.