Long-term fate of nitrate fertilizer in agricultural soils

Increasing diffuse nitrate loading of surface waters and groundwater has emerged as a major problem in many agricultural areas of the world, resulting in contamination of drinking water resources in aquifers as well as eutrophication of freshwaters and coastal marine ecosystems. Although empirical c...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2013-11, Vol.110 (45), p.18185-18189
Main Authors: Sebilo, Mathieu, Mayer, Bernhard, Nicolardot, Bernard, Pinay, Gilles, Mariotti, André
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Animal, plant and microbial ecology
Applied ecology
Applied sciences
Aquifers
Biological and medical sciences
Biological Sciences
Colorimetry
Contamination
Drinking water
Environmental Monitoring - statistics & numerical data
Environmental Pollution - analysis
Environmental Sciences
Eutrophication
Exact sciences and technology
Fertilizers
Fertilizers - analysis
France
Fundamental and applied biological sciences. Psychology
General agronomy. Plant production
Grassland soils
Groundwater
Groundwater - chemistry
Mass Spectrometry
Nitrates
Nitrates - analysis
Nitrates - pharmacokinetics
Nitrogen
Nitrogen Isotopes - analysis
Nitrogen, phosphorus, potassium fertilizations
Organic fertilizers
Organic soils
Oxygen Isotopes - analysis
Physical Sciences
Plants - metabolism
Pollution
Soil - chemistry
Soil and water pollution
Soil biochemistry
Soil organic matter
Soil pollution
Soil science
Soil water
Soil-plant relationships. Soil fertility. Fertilization. Amendments
Time Factors
Water treatment and pollution
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Summary:Increasing diffuse nitrate loading of surface waters and groundwater has emerged as a major problem in many agricultural areas of the world, resulting in contamination of drinking water resources in aquifers as well as eutrophication of freshwaters and coastal marine ecosystems. Although empirical correlations between application rates of N fertilizers to agricultural soils and nitrate contamination of adjacent hydrological systems have been demonstrated, the transit times of fertilizer N in the pedosphere–hydrosphere system are poorly understood. We investigated the fate of isotopically labeled nitrogen fertilizers in a three–decade-long in situ tracer experiment that quantified not only fertilizer N uptake by plants and retention in soils, but also determined to which extent and over which time periods fertilizer N stored in soil organic matter is rereleased for either uptake in crops or export into the hydrosphere. We found that 61–65% of the applied fertilizers N were taken up by plants, whereas 12–15% of the labeled fertilizer N were still residing in the soil organic matter more than a quarter century after tracer application. Between 8–12% of the applied fertilizer had leaked toward the hydrosphere during the 30-y observation period. We predict that additional exports of ¹⁵N-labeled nitrate from the tracer application in 1982 toward the hydrosphere will continue for at least another five decades. Therefore, attempts to reduce agricultural nitrate contamination of aquatic systems must consider the long-term legacy of past applications of synthetic fertilizers in agricultural systems and the nitrogen retention capacity of agricultural soils.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1305372110