Methane emission during a cultivation period from an Italian rice paddy

Abstract

CH4 release rates from rice paddies were measured in Vercelli, Italy, in 1983 during a complete vegetation period, using a static box system. The rice paddies were found to be a source of atmospheric methane during the time of flooding. The CH4 release rates range between a few milligrams of CH4 per square meter per hour and 51 mg CH4 m−2 h−1 and show a seasonal variation with maximum emission rates between tillering and flowering. Averaged over the complete vegetation period, the CH4 release rate accounts for 16 mg m−2 h−1. Significant differences in the CH4 release rates of unfertilized field plots and plots fertilized with mineral fertilizer (CaCN2) were not observed. The CH4 release rates show strong diurnal variations, with highest values in the late afternoon and lowest values in the early morning, which coincides with the temperature variation in the upper soil layer (1–10 cm). These variations must be taken into account in estimating reliable global CH4 emission rates from rice paddies. CH4 is almost exclusively emitted into the atmosphere by gas bubbles during the first 6 weeks after flooding the rice paddies, that is, on fields without vegetation. Afterwards, 80% of the observed CH4 transport from the paddy soil into the atmosphere was due to diffusion through the stems of the rice plants. Transport by diffusion through the paddy water appeared to be of minor importance. The global annual CH4 emission from rice paddies is estimated to be of the order of 39–94 Tg yr−1 (Tg = 1012 g) for 1940 conditions and 70–170 Tg yr−1 for 1979 conditions, indicating a secular trend of the CH4 emission by rice paddies of about 1.6% per year during the last 35 years.

Sensitivity of wetland methane emissions to model assumptions: application and model testing against site observations

“…Our estimate is in the middle of current estimates of 26-120 Tg CH 4 yr −1 (Fig. 13c) (Olivier et al, 2005;Cao et al, 1995;Yan et al, 2009;Chen and Prinn, 2006;Wuebbles and Hayhoe, 2002;Cao et al, 1998;Holzapfelpschorn and Seiler, 1986;Seiler et al, 1984;Scheehle et al, 2002;Sass, 1994). For instance, Cao et al (1998) estimated global emissions from rice paddies to be ∼53 Tg CH 4 yr −1 using MF rice paddy areas.…”

Diel Variation of Methane Fluxes in Summer in a Eutrophic Subtropical Lake in China

“…Temperature sometimes has an important effect on C b flux in various ecosystems (Holzapfel-Pschorn and Seiler 1986, Wang 2001, Edwards et al 2001). Heyera and Berger (2000) found that in the coastal area of the southern Baltic Sea, there was a significant correlation between C& diurnal emission and water temperature.…”

Identification of iron-reducing microorganisms in anoxic rice paddy soil by 13C-acetate probing

“…Soil slurry incubation and geochemical analyses Two soils were used, both sampled near the Italian Rice Research Institute near Vercelli, Italy (for general soil characteristics see Holzapfel-Pschorn and Seiler, 1986). For the main experiment, 'recycled soil' was used, a soil that had been used earlier for growing rice in large microcosms at our greenhouse in Marburg and, thus, had been depleted in organics and nutrients (for details see Conrad and Klose, 1999).…”