THIRD WORLD NETWORK INFORMATION SERVICE ON SUSTAINABLE AGRICULTURE
Dear friends and colleagues,
Re: Research shows synthetic nitrogen undermines long-term soil health
A team of American researchers has demonstrated that synthetic nitrogen fertilizer is bad for the soil in the long-run, as it depletes soil carbon and nitrogen. Their findings also refute claims of synthetic nitrogen being a climate stabilizer through the build-up of soil carbon.
The scientists studied data from the Morrow plots on the University of Illinois’ Urbana-Champaign campus, ‘the world’s oldest experimental site under continuous corn cultivation’. The Morrow plots were first planted in 1876.
They discovered that synthetic nitrogen fertilizer stimulates soil microbes, which feast on organic matter, thus depleting the latter and reducing the soil’s ability to store organic nitrogen. A large amount of nitrogen then leaches away, fouling groundwater, as well as is released as nitrous oxide, a potent greenhouse gas.
A treadmill effect results, as with the ability to store organic nitrogen compromised, only one thing can help heavily fertilized farmland maintain yields: more additions of synthetic nitrogen.
In their latest paper, “Synthetic Nitrogen Fertilizers Deplete Soil Nitrogen: A Global Dilemma for Sustainable Cereal Production,” the researchers found that instead of a build-up of nitrogen in the Morrow plots that received annual lashings of synthetic nitrogen, the opposite happened. Soil nitrogen declined significantly in every subplot sampled.
Earlier analyses of soil organic carbon in the surface layer in the Morrow plots from 1904 to 2005 showed that soil organic carbon rises steadily over the first several decades when the fields were fertilized with livestock manure. After 1967, when synthetic nitrogen was introduced, it steadily drops. In other words, synthetic nitrogen causes a break down in organic matter faster than plant residues can create it.
Please find below an article reporting on the research.
With best wishes,
Lim Li Ching
Third World Network
131 Jalan Macalister,
New research: synthetic nitrogen destroys soil carbon, undermines soil health
23 FEB 2010 9:47 AM
BY TOM PHILPOTT