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Lack of increased availability of root-derived C may explain the low N2O emission from low N-urine patches

Carter, Mette S.; Klumpp, Katja and Xavier, Le Roux (2006) Lack of increased availability of root-derived C may explain the low N2O emission from low N-urine patches. Nutrient Cycling in Agroecosystems, 75, pp. 91-100.

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Online at: http://dx.doi.org/10.1007/s10705-006-9014-1

Summary

Urine deposition on grassland causes significant N2O losses, which in some cases may result from increased denitrification stimulated by labile compounds released from scorched plant roots. Two 12-day experiments were conducted in 13C-labelled grassland monoliths to investigate the link between N2O production and carbon mineralization following application of low rates of urine-N. Measurements of N2O and CO2 emissions from the monoliths as well as δ13C signal of evolved CO2 were done on day -4, -1, 0, 1, 2, 4, 5, 6 and 7 after application of urine corresponding to 3.1 and 5.5 g N m-2 in the first and second experiment, respectively. The δ13C signal was also determined for soil organic matter, dissolved organic C and CO2 evolved by microbial respiration. In addition, denitrifying enzyme activity (DEA) and nitrifying enzyme activity (NEA) were measured on day -1, 2 and 7 after the first urine application event. Urine did not affect DEA, whereas NEA was enhanced 2 days after urine application. In the first experiment, urine had no significant effect on the N2O flux, which was generally low (-8 to 14 μg N2O-N m-2 h-1). After the second application event, the N2O emission increased significantly to 87 μg N2O-N m-2 h-1 and the N2O emission factor for the added urine-N was 0.18 %. However, the associated 13C signal of soil respiration was unaffected by urine. Consequently, the increased N2O emission from the simulated low N-urine patches was not caused by enhanced denitrification stimulated by labile compounds released from scorched plant roots.


EPrint Type:Journal paper
Keywords:13C, denitrification, grassland, nitrification, nitrous oxide, root scorching, soil respiration, urine
Subjects: Soil > Nutrient turnover
Environmental aspects > Air and water emissions
Research affiliation: Denmark > DARCOF II (2000-2005) > I.13 (DINOG) Dinitrogen fixation and nitrous oxide losses in grass-clover pastures
Deposited By: Ambus, Professor Per
ID Code:10145
Deposited On:14 Dec 2006
Last Modified:12 Apr 2010 07:34
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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