Soil mineral nitrogen availability was unaffected by elevated atmospheric pCO2 in a four year old field experiment (Swiss FACE) |
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Authors: | Gloser Vit Je íková Marta Lüscher Andreas Frehner Marco Blum Herbert Nösberger Josef Hartwig Ueli A |
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Institution: | (1) Faculty of Science, Department of Plant Physiology, Masaryk University, Kotlarska 2, Brno, Czech Republic;(2) Institute of Plant Sciences, ETH-Zürich, 8092 Zürich, Switzerland;(3) Institute of Plant Sciences, ETH-Zürich, 8092 Zürich, Switzerland |
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Abstract: | The effect of elevated (60 Pa) atmospheric carbon dioxide partial pressure (pCO2) and N fertilisation on the availability of mineral N and on N transformation in the soil of a Lolium perenne L. monoculture was investigated in the Swiss FACE (Free Air Carbon dioxide Enrichment) experiment. The apparent availability of nitrate and ammonium for plants was estimated during a representative,
vegetative re-growth period at weekly intervals from the sorption of the minerals to mixed-bed ion-exchange resin bags at
a soil depth of 5 cm. N mineralisation was measured using sequential coring and in situ exposure of soil cores in the top 10 cm of the soil before and after the first cut in spring 1997. High amounts of mineral
N were bound to the ion exchange resin during the first week of re-growth. This was probably the combined result of the fertiliser
application, the weak demand for N by the newly cut sward and presumably high rates of root decay and exudation after cutting
the sward. During the first 2 weeks after the application of fertiliser N at the first cut, there was a dramatic reduction
in available N; N remained low during the subsequent weeks of re-growth in all treatments. Overall, nitrate was the predominant
form of mineral N that bound to the resin for the duration of the experiment. Apparently, there was always more nitrate than
ammonium available to the plants in the high N fertilisation treatment for the whole re-growth period. Apparent N availability
was affected significantly by elevated pCO2 only in the first week after the cut; under high N fertilisation, elevated pCO2 increased the amount of mineral N that was apparently available to the plants. Elevated pCO2 did not affect apparent net transformation of N, loss of N or uptake of N by plants. The present data are consistent with
earlier results and suggest that the amount of N available to plants from soil resources does not generally increase under
elevated atmospheric pCO2. Thus, a possible limiting effect of N on primary production could become more stringent under elevated atmospheric pCO2 as the demand of the plant for N increases.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | elevated atmospheric carbon dioxide nitrogen cycling N mineralisation Swiss FACE |
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