Phytotron studies to compare nitrogen losses from corn-planted soil by the 15-N balance or direct dinitrogen and nitrous oxide measurements |
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Authors: | O Heinemeyer K Haider A Mosier |
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Institution: | (1) Bundesforschungsanstalt für Landwirtschaft, Institut für Bodenbiologie, D-3300 Braunschweig, Germany;(2) FAL, Institut für Pflanzenernährung und Bodenkunde, D-3300 Braunschweig, Germany;(3) USDA, 80522 Fort Collins, CO, USA |
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Abstract: | Summary Containers filled with soil mixed with potassium nitrate highly enriched in 15N were planted with corn (Zea mays L.) and kept in a phytotron under controlled conditions for 79 days. Soil water content was normally maintained at exactly 60% water-holding capacity (–33 kPa), but it was increased several times to 85% (–5 kPa) for short periods to favour denitrification. The soil headspace was sealed from the phytotron atmosphere and aerated by a continuous stream of air. Nitrous oxide emission was measured by estimating the N2O concentration differences in the air entering and leaving the containers. Emission of N2 was estimated by mass spectroscopy from changes in the N2 composition in the temporarily enclosed soil headspace. Both methods were carefully checked for accuracy by different tests. At specific times during the experiment the distribution of 15N between plants and soil was determined and a 15N balance established. Emission of N gases peaked at times of increased water content and reached maxima of 149 and 142 g N pot–1 day–1 for N2O and N2, respectively. While N losses of 5% ± 2% were indicated by the 15N balance, only 1.1% ± 0.3% loss from 2.7 g applied N was estimated from the N2O and N2 measurements after 79 days. Possible reasons for these differences are discussed. |
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Keywords: | Phytotron study Corn plants Denitrification 15N balance N2 flux by 15N method N2O flux by gas chromatography |
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