IRRIGATION FREQUENCY EFFECT ON GHE FROM A PADDY SOIL AT THE EBRO
DELTA (SPAIN)
Maris, Stefania Codrutaa, Teira-Esmatges, M. Rosaa
a
Dpto. de Medio Ambiente y Ciencias del Suelo. Universitat de Lleida, Avda. Rovira Roure 191, 25198
Lleida
1. Introduction and objective
With the objective of assessing the effect of continuous and intermittent irrigation on
GHG emission, nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4)
emissions from flooded rice paddy fields were semi-continuously sampled by the
closed chamber method (with C2H2) (Yoshinari et al., 1977; Aulakh et al., 1983, 1984;
Bergsman et al., 2002) at an experimental plot in the Ebro Delta in Spain for a whole
cultivation season (April 2011 to September 2011) and till November 2011 (after
harvest).
2. Results and discussion
The overall average nitrogenous emission under continuous irrigation for a sampling
time of 173 days was -0,29 kg N-N2O ha-1 and 2,33 kg N-(N2O+N2) ha-1. The overall
(173 days) average nitrogenous emissions under intermittent flooding was -0,54 kg NN2O ha-1 and 3,41 kg N-(N2O+N2) ha-1. Therefore complete denitrification was the
dominating process in nitrogenous emission and intermittent irrigation increased N(N2O+N2) emission relative to continuous flooding (Figure 1).
5,0
4,5
kg (N2+N2O)-N/ha
4,0
3,5
3,0
2,5
2,0
1,5
1,0
0,5
0,0
CI
TRATAMIENTOS
II
Figure 1. Cumulative (N2+N2O)-N emission during the sampled period. CI: continuous irrigation,
II: intermittent irrigation
The soil CO2 production measured in this study represents the total of microbial and
plant root respiration, except measurements made after harvesting when plants were
not present. The CO2 production rates measured from the intermittent irrigation plots
(839,15 kg CO2 ha-1 in 173 days) were higher than those from continuous irrigation
plots (600,53 kg CO2 ha-1 in 173 days) (Figure 2). Carbon dioxide emissions were
higher in the intermittent plots due to the occurrence of aerobic conditions in the soil
that coincided with high air temperature.
It has generally been accepted that mineral nitrogen has the potential to
enhance emission of methane from paddy soils. Recently, ammonium-based
fertilization was demonstrated to stimulate methane consumption in rice paddies.
Water drainage is another important factor reducing methane emission, while flooded
paddy is one of the major anthropogenic sources of atmospheric methane. The results
showed that on average methane emission decreased with intermittent irrigation and
ammonium sulphate application (-1011,18 kg CH4 ha-1 in 173 days) in comparison to
continuous irrigation and the same ammonium sulphate application (-797,27 kg CH4
ha-1 in 173 days) (Figure 3).
Figure 2. Cumulative CO2 emission during the sampled period. CI: continuous irrigation, II:
intermittent irrigation
-100
CI
II
-300
kg CH4/ha
-500
-700
-900
-1100
-1300
TRATAMIENTOS
Figure 3. Cumulative CH4 emission during the sampled period. CI: continuous irrigation, II:
intermittent irrigation
3. Conclusion
The management of water and mineral fertilizer application are the main factors
affecting nitrogenous, carbon dioxide and methane emissions. The results suggest that
it is important to design water management and fertilizer application strategies to
mitigate greenhouse gas emissions by paddy soils.
References
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