Wood chips can help filter nutrient-laden runoff

10/25/2013 09:01:00 AM
Vicky Boyd

wood chip drainage systemCourtesy Cornell UniversityWorkers build a trench at the Homer C. Thompson Vegetable Research in Freeville, N.Y.A trench filled with wood chips can provide a simple solution to the complex problem caused by agricultural runoff.

In a trial conducted at the Homer C. Thompson Vegetable Research Farm in Freeville, N.Y., Cornell University researchers found the technique provided promising results, according to a news release.

"It’s a big problem in New York. It’s a big problem everywhere. We are a little desperate to find some way to get rid of nitrates,” Todd Walter, a Cornell University hydrologist, said in the release.

The work involved digging large square trenches that were then filled with wood chips and covered with dirt.

The field drains flow into these bioreactors.

The decomposing wood chips release carbon that feeds bacteria, which in turn use nitrate from the runoff water as part of their respiration process.

The end produce is nitrate gas, a less dangerous form.

Some of the trends also contained biochar, a charcoal-like material from the carbonization of biomass.

The work will be expanded to four or five farms in Upper Susquehanna in the Chesapeake Bay watershed, where an estimated 300 million pounds of nitrogen has led to poor water quality.

Similar techniques have been tested in the Midwest.

In Iowa, the trenches cost $7,000 to $10,000 to treat drainage from 30 to 100 acres.

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