A 3‐year continuous record on the influence of daytime, season, and fertilizer treatment on methane emission rates from an Italian rice paddy

Abstract

CH4 emission rates have been measured in an Italian rice paddy between 1984 and 1986, covering three vegetation periods. For these measurements a fully automated, computerized sampling and analyzing system was developed which allowed the simultaneous determination of CH4 emission rates at 16 different field plots. CH4 emission rates showed strong diurnal and seasonal variations. Diurnal changes correlated with changes in soil temperature. During the season, CH4 emission rates showed a first maximum in May–June before tillering and a second maximum in July during the reproductive stage of the rice plants. In 1985 and 1986 two maxima were observed during summer in addition to the first maximum in the rate of CH4 emission during spring. Application of mineral and/or organic fertilizer strongly influenced the CH4 emission rates, depending on the type, rate, and mode of fertilizer application. Thus the rates decreased by at most 40% and 60% after fertilization by deep incorporation with 200 kg N/ha urea and 200 kg N/ha ammonium sulfate, respectively. Application of 200 kg N/ha calcium cyanamide led to a reduction of the first maximum of CH4 emission but caused the second maximum to increase, the overall result being that the seasonally averaged CH4 emission rate was comparable to that observed in unfertilized fields. Application of rice straw at a rate of 12 t/ha enhanced the rate of CH4 emission by a factor of 2 compared with the control. Higher application rates of rice straw did not cause a further increase in CH4 emission. The complete records of CH4 emissions over three vegetation periods indicate an average seasonal CH4 emission rate from unfertilized fields of 0.28 g CH4/m2 d, with a range of 0.16–0.38 g CH4/m2 d. Based on this value and applying the observed temperature dependence of the CH4 emission rates, the global annual CH4 emission from rice paddies is estimated to be in the range of 50–150 Tg, with a likely average of 100 Tg. This figure represents between 19% and 25% of the global CH4 emission, indicating that rice paddies are one of the most important individual sources of atmospheric CH4.

Effect of Water and Straw Management Practices on Methane Emissions from Rice Fields: A Review Through a Meta-Analysis

“…2. Schütz et al (1989) reported that application of rice straw at 5 t/ha and 12 t/ha increased CH4 rates by factors of 2.0 and 2.4, respectively, compared with no addition of straw.…”

“…Average values for each straw incorporation rate were used. The selection of this model was based on the literature, where CH4 emissions have been reported to increase with straw addition until certain value where no further increase in emissions occurs with further addition of straw (Schütz et al, 1989;Kludze and DeLaune, 1995). As a result, the regression equation indicated in Eq 1 was obtained:…”

“…Although the relationship between CH4 emissions and straw application has been reported in several studies carried out in Italy (Schütz et al, 1989), Japan (Yagi and Minami, 1990;Naser et al, 2007;Xu and Hosen2010), United States (Cicerone et al, 1992;Bossio et al, 1999;Kongchum et al, 2006), China (Hou et al, 2000;Lu et al, 2000;Zou et al, 2005;Wang et al, 2010;Zhang et al, 2011), Thailand (Chareonsilp et al, 2000Vibol and Towprayoon, 2010), India (Jain et al, 2000;Khosa et al, 2010), and Philippines (Neue et al, 1994;Denier Van der Gon and Neue, 1995); knowledge gaps related with the combined effect of the type, dose, and quality of rice straw with varying water regimes still remain.…”

Community structure of bacteria and fungi responsible for rice straw decomposition in a paddy field estimated by PCR-RFLP analysis

“…Although the decomposition rate of rice straw (Shiga et al 1985;Watanabe et al 1993) and the effects of its application on methane flux (Schutz et al 1989;Yagi and Minami 1990;Watanabe et al 1998) and nitrogen cycling (e.g. nitrogen fixation, immobilization, and mineralization of nitrogen; Yoneyama et al 1977;Yoneyama and Yoshida 1977a, b, c;Roger and Watanabe 1986) in paddy fields have been studied in detail, the microorganisms responsible for rice straw decomposition in paddy fields have not been well documented.…”

Relationships between methane emissions and soil microorganisms in a double-rice field in southern subtropical China

“…The metabolism of these different microbial communities completes the degradation of organic carbon from large molecules to the most reduced status like methane (Chidthaisong and Watanabe 1997;Hou et al 2000;Le Mer and Roger 2001). The other two procedures that are also included in the emissions of methane from soil to atmosphere (Schu¨tz et al 1989) are: reoxidation and transportation. Both production and oxidation of methane are closely related to the populations and activities of soil microbial communities.…”