|
|
|
|
|
| Petersen, Søren O.; Bol, Roland; Dittert, Klaus; Christofides, Calliopi; Roslev, Peter; Hansen, Martin N.. |
| Managed grasslands can accumulate soil organic carbon and thereby remove CO2 from the atmosphere. When grazed, however, the interaction between N inputs (fertilization, feeding, N fixation) and excretal returns can lead to sward deterioration and elevated emissions of N2O in urine patches. Both effects may reduce the positive effect of carbon storage on the greenhouse gas balance. A field plot study was carried out between 19 September and 4 October 2001, in which cattle urine amended with 13C- and 15N-labelled urea was added to a sandy loam pasture. Two levels of urea, corresponding to 23.3 and 39.8 g urea-N m-2, were compared with an unamended control. Ammonia losses corresponded to 14 and 12% of the urea-N applied in the low (UL) and high (UH) urea... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/2906/1/Ghent_presentation_020604.ppt |
| |
|
|
| Bol, Roland; Petersen, Søren O.; Christofides, Calliopi; Dittert, Klaus; Hansen, Martin Nørregaard. |
| Urine patches are significant hot-spots of C and N transformations. To investigate the effects of urine composition on C and N turnover and gaseous emissions from a Danish pasture soil, a field plot study was carried out in September 2001. Cattle urine was amended with two levels of 13C- and 15N-labeled urea, corresponding to 5.58 and 9.54 g urea-N l-1, to reflect two levels of protein intake. Urine was then added to a sandy-loam pasture soil equivalent to a rate of 23.3 or 39.8 g urea-N m-2. Pools and isotopic labeling of nitrous oxide (N2O) and CO2 emissions, extractable urea, ammonium (NH4+), and nitrate (NO3-), and plant uptake were monitored during a 14 d period, while ammonia (NH3) losses were estimated in separate plots amended with unlabeled urine.... |
| Tipo: Journal paper |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4060/1/4060.pdf |
| |
|
|
| Petersen, Søren O.; Stamatiadis, Stamatis; Christofides, Calliopi. |
| Nitrogen excreted by cattle during grazing is a significant source of atmospheric nitrous oxide (N2O). The regulation of N2O emissions is not well understood, but may vary with urine composition and soil conditions. This laboratory study was undertaken to describe short-term effects on N2O emissions and soil conditions, including microbial dynamics, of urea amendment at two different rates (22 and 43 g N m-2). The lower urea concentration was also combined with an elevated soil NO3- concentration. Urea solutions labelled with 25 atom% 15N were added to the surface of repacked pasture soil cores and incubated for 1, 3, 6 or 9 days under constant conditions (60% WFPS, 14°C). Soil inorganic N (NH4+, NO2- and NO3-), pH, electrical conductivity and dissolved... |
| Tipo: Journal paper |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4062/1/4062.pdf |
| |
|
|
|
