[permaculture] Poplar trees may be new draw for pig farms

Saor Stetler saor at ycbtal.net
Tue Dec 16 13:44:20 EST 2003

Poplar trees may be new draw for pig farms

Tuesday, December 16, 2003
By Estes Thompson, Associated Press

WHITAKERS, N.C. — After years of struggling with the dirty disposal 
problem of sludge from hog waste lagoons, researchers have come up with 
a possible green solution: poplar trees that suck up the waste like soda 

If the procedure works well enough to be approved by state water quality 
officials, it could more than cut in half the cost of closing a waste 
lagoon, currently done with bulldozers and dump trunks.

"It is a simple method," said Frank Humenik, coordinator of the animal 
waste management program at North Carolina State University.

Humenik has been working with Oregon researchers who have been 
experimenting the past few years with technology that relies on groves 
of fast-growing hybrid poplars to suck up waste.

Studies have found the trees can absorb nearly 3,000 gallons of effluent 
per acre per day, ridding the ground ammonia and nitrogen by safely 
metabolizing the compounds in their woody tissue.

Oregon State University water quality researcher Ron Minor said it could 
take 10 years before the trees clean the land well enough that it can be 
used again.

"Over time, the trees take up the nutrients and it is natural 
purification," Humenik said. "With the trees, you have a harvestable 

The current method approved by the state of North Carolina to clean up 
hog lagoons is complex. First, the liquid is drained from the top of the 
lagoon onto existing sprayfields of grass at the farm. Then the farmer 
pays to have the sludge scooped out and trucked away to be spread thinly 
on acres of fields.

"We don't like to haul that stuff around," Humenik said.

Humenik said the sludge usually isn't welcomed by neighbors of the 
fields. The cost and politics of cleanup may be the reason only 20 
lagoons were closed last year in the state, he said.

There are 1,700 inactive lagoons in North Carolina waiting cleanup and 
4,500 more lagoons in use. North Carolina ranks second in hog production 
at 9.6 million animals, behind Iowa at 15 million head.

National Pork Board figures show one animal produces between 8,000 
pounds and 64,000 pounds of waste a year, depending on its development.

Cleaning out a typical lagoon could cost as much as $40,000 an acre, not 
counting the cost of land on which to spread the sludge. The sludge 
can't fertilize crops for human consumption. Humenik said the typical 
lagoon cleanup using the poplars would cost between $15,000 and $20,000 
for a lagoon that is two to three acres.

Source: Associated Press

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