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Studies Evaluate Pollution-Fighting Polyacrylamides

An environmentally friendly compound already employed to stop soil from eroding can also keep nutrients and bacteria from leaving fields or farmyards. New studies by Agricultural Research Service (ARS) scientists at the agency’s Northwest Irrigation and Soils Research Laboratory, Kimberly, Idaho, pinpoint the pollution-fighting potential of these compounds, called polyacrylamides or PAMs. The goal: keep pollutants from making their way to ponds, lakes, streams and rivers.

Earlier work by the Kimberly researchers showed that mixing small amounts of PAM, a powder, into irrigation water can reduce soil erosion by up to 99 percent. PAM does that by holding soil particles in place. Otherwise, they might wash away as irrigation water travels down furrows or falls from overhead sprinklers. The team’s work helped open the door to use of PAM on more than one million acres of American farmland.

More recently, the scientists analyzed PAM’s prowess in grabbing nutrients such as nitrogen and phosphorus. Excess amounts of these and other nutrients from fertilizers can become pollutants, according to ARS soil microbiologist James A. Entry at Kimberly.

The team also scrutinized PAM’s interaction with disease-causing bacteria found in cow, pig and fish manure. Entry and colleagues showed that PAM alone reduced nutrients and manure-borne pathogens in water samples by 90 percent. When PAM was combined with aluminum sulfate or calcium oxide, the pollutants were reduced by as much as 99 percent.

PAMs and their use to trap pollutants are routine in the wastewater treatment industry. But the ARS farm-oriented studies are a first.

An article in the July 2002 issue of the ARS monthly magazine, Agricultural Research, tells more.

ARS is the U.S. Department of Agriculture’s chief scientific research agency.