Methane Emission From Paddy Fields as Influenced by Different Water Regimes in Central Java

Abstract

The concentration of methane (CH4) in the atmosphere is increasing at 1% per annum and rice fields are one of the sources that contribute to about 10-15% of the atmospheric CH4. One of the options to reduce greenhouse gas emission from rice fields is probably through water management. A field study was conducted to investigate the effects of water management practices on CH4 emission from rice field plots on a silty sand Aeric Tropaquept soil at Research Station for Agricultural Environment Preservation, Jakenan, Central Java, Indonesia, during the dry season of March to June 2002. Four water regimes tested were: (1) 5 cm continuous flooding (CF), (2) 0-1 cm continuous flooding (ST), (3) intermittent irrigation (IR) where plots received continuously 5 cm of flooding with two times of draining at 15-20 and 25-30 days after transplanting (DAT), and (4) pulse irrigation (PI) where plots were watered until 5 cm level and left to dry by itself until the water table reached 30 cm beneath soil surface then watered again. The total CH4 emissions of the four water treatments were 254, 185, 136 and 96 kg CH4 ha-1 for CF, ST, IR and PI, respectively. Methane emission increased during the early growing season, which coincided with the low redox potential of -100 to -150 mV in all treatments. Dry matter weight of straw and filled grain among the water treatments did not show significant differences. Likewise, total grain yield at 14% moisture content was not significantly different among treatments. However, this result should be carefully interpreted because the rice plants in all water treatments were infested by stem borer, which reduced the total grain yield of IR64 between 11% and 16%. This study suggests that intermittent and pulse irrigation practices will be important not only for water use efficiency, but also for CH4 emission reduction.

Methane efflux in rice paddy field under different irrigation managements

“…In the absence of water, soil is oxygenated and CH 4 efflux is mitigated (Setyanto & Bakar, 2005;Johnson-Beebout et al, 2009). However, climatic conditions may affect soil moisture and suspending irrigation alone may not be enough to promote soil oxidation.…”

“…However, different results with this irrigation system have been obtained by different authors. Lima et al (2003) found 12 % more CH 4 emission with intermittent irrigation than with continuous flooding, while Setyanto & Bakar (2005) found 62 % less CH 4 emission using the same irrigation systems. On the other hand, Nugroho et al (1997) did not find any effect of irrigation systems on CH 4 emission.…”

“…Consequently, soil water content may vary regardless of the irrigation system used. Due to these factors, it is very difficult to evaluate the real potential of alternative irrigation systems on CH 4 emission mitigation (Nugroho et al, 1997;Lima et al, 2003;Setyanto & Bakar, 2005, Johnson-Beebout et al, 2009). This study aims to evaluate different irrigation systems on CH 4 emission from a paddy soil (Albaqualf) cultivated with rice.…”

Potensi Pemanasan Global dari Padi Sawah System of Rice Intensification (SRI) dengan Berbagai Ketinggian Muka Air Tanah

“…Besarnya emisi yang dilepaskan, baik gas CH4 dan N2O, sangat dipengaruhi oleh beberapa faktor, di antaranya adalah sistem irigasi, jenis varietas padi, dan penggunaan pupuk (Cai, Xing, Yan, Xu, Tsuruta, Yagi, & Minami, 1997;Setyanto, Makarim, Fagi, Wassman, & Buendia, 2000;Setyanto, Rosenani, Boer, Fauziah, & Khanif, 2004;Setyanto & Bakar, 2005). Sistem irigasi yang digunakan akan mempengaruhi parameter lingkungan biofisik dalam tanah yang berakibat terhadap perubahan aktivitas mikroorganisme dalam tanah.…”

“…Cara ini ini dapat mengurangi potensi pemasanan global dan bahkan dapat meningkatkan produktivitas. *GWP dihitung untuk periode waktu 100 tahun dengan persamaan GWP = 25CH4 + 298N2O (IPCC, 2007) ** Emisi GRK merupakan total fluks masing-masing gas dan dihitung dengan metode numerik model Simpson (Arif et al, 2015) Potensi pemanasan global tidak hanya dipengaruhi oleh ketersediaan air di lahan yang direpresentasikan oleh tinggi muka air, tetapi juga faktor lain seperti varietas padi, penggunaan pupuk dan kondisi iklim setempat (Cai, et al, 1997;Setyanto & Bakar, 2005). Oleh sebab itu, perlu percobaan dengan budidaya SRI dengan multiparameter dan multi-lokasi untuk keragaman potensi pemasanan global yang akan dihasilkan.…”