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N20 emissions from soil amended with cattle slurry under mediterranean conditions
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Advisor(s)
Abstract(s)
N2O emissions are affected by several factors, including type of fertilizer, edafo-climatic
conditions and mitigation measures applied. However, one single N2O emission factor of
1.25% of total N applied is usually used. For two years a field experiment was carried out in
central Portugal, to evaluate the effect over soil N2O emissions originated from the
application of cattle slurry (CS) to a double-cropping system producing maize and oats. The
use of a nitrification inhibitor (DCD) was evaluated as emission mitigation measure. A
mineral fertilizer treatment (MIN) and a Control were included and the DCD effects were
tested together with MIN (MIN+DCD) and CS (CS+DCD). Total N input was equal for all
fertilizing treatments (oat 80 kg N ha-1; maize 170 kg N ha-1). N2O fluxes were measure on
165 sampling dates, using a photo-acoustic spectroscopic infrared gas analyzer. The poly
propylene chambers used (2 per plot) were kept at fixed locations throughout all each cultural
period. Gas samples were taken when chambers were closed (t0) and 1h later (t1), and fluxes
were calculated based on changes in headspace concentrations between t1 and t0. The
calculated hourly emissions were integrated over time to estimate the total daily emission and
the emission over the measurement period during each season. The emission factor based on
N application (EF) was calculated using EF(%) = 100 × ((N2Ofert – N2OControl) / Napp), where
N2Ofert represent the cumulative N2O flux (kg N ha-1) in the fertilized plot, N2OControl the
cumulative flux in the zero-N treatment, and Napp the amount of applied N (kg N ha-1).
Independently of the cultural period considered, the most important fluxes were observed 8-
10 days after fertilizers incorporation and during the following 20-40 days. The highest value
(297 g N-N2O ha-1 day-1) was measured in MIN, during first autumn-winter crop. Annual NN2O
losses were higher in the first year, with a wettest autumn and a warmer summer than
usual. The higher values were measured with the use of mineral fertilizers (4.65 and 4.21 kg
N ha-1 in MIN+DCD and MIN, respectively), which were 60-70% higher than those measured
with slurry application or without fertilization (1.85, 1.55 and 1.33 kg N ha-1 in CS+DCD, CS
and Control, respectively). Mean annual EF values measured were 0.76, 0.63, 0.12 and
0.07%, in MIN+DCD, MIN, CS and CS+DCD, respectively. The DCD use, namely with
mineral fertilizer, didn’t produce an evident effect on total N2O losses.
Description
Comunicação da qual só está disponível o resumo.
Keywords
Greenhouse gas emissions Soil fertilization Nitrogen Nitrification inhibitor
Citation
CARNEIRO, J.P. ; COUTINHO, J. ; TRINDADE, H. (2012) - N20 emissions from soil amended with cattle slurry under mediterranean conditions. In International Symposium on Emissions of Gas and Dust from Livestock, Saint-Malo, 10-13 junho - Proceedings. [S.l. : s.n.]. p. 29. Comunicação.