Study asserts that nitrogen can leach into groundwater for decades

21 November 2013 22:22  [Source: ICIS news]

HOUSTON (ICIS)--Scientists in Canada and France have determined through a joint study that nitrogen fertilizer remains within the fields much longer than previously estimated and for decades can leach into groundwater suppliers, the researchers announced on Thursday.

The study entitled "Long-term Fate of Nitrate Fertilizer in Agricultural Soils" was led by researcher Mathieu Sebilo at the Université Pierre et Marie Currie in Paris, France, and by Bernhard Mayer with University of Calgary’s Department of Geoscience.

Their research determined that the loss of synthetic nitrogen fertilizer in groundwater occurs at low rates over many decades, and it could take many years to reduce nitrate contamination in groundwater. These sources of groundwater include the aquifers that many regions count on to supply their population with drinking water.

The scientists found that three decades after application of nitrogen fertilizer to agricultural soils that as much as 12–15% was still present in the soil’s organic matter, with an additional  8–12% of the nitrogen having already leached in the water supplies.

Based on these calculations, it estimate that the amount of leaching from those applications could continue to be released in low amounts for at least another 50 years.

“There’s a lot of fertilizer nitrogen that has accumulated in agricultural soils over the last few decades, which will continue to leak as nitrate towards groundwater,” said Bernhard Mayer.

The researchers said the most common contaminant of drinking water is nitrates and is particularly present in agricultural areas. In addition, the study asserts that high rates of fertilizer applications may also raise the natural nitrate levels found in certain vegetables, such as lettuce and root crops.

This fact concerns health officials because it is believed that long-term exposure to nitrates through food and water may increase health problems, especially the rate of thyroid diseases.

In order to combat this issue, the study advocates that farmers apply the necessary fertilizer at the appropriate rate and at the time that crops are most likely to absorb the maximum amount in order to reduce nitrate contamination.


By: Mark Milam



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