International Journal of Engineering and Technology, Vol. 10, No. 2, 2013, pp. 73-81 ISSN 1823-1039 2013 FEIIC 73 EFFECT OF CULTIVATION SYSTEM ON THE METHANE EMISSION FROM RICE SOIL P.Fazli 1* , Hasfalina C. M. 1 , M. Azwan 1 , Azni I. 2 , Umi Kalsom M. Shah 3 and Aimrun W. 1 1 Department of Agricultural and Biological Engineering, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. 2 Department of Chemical and Environmental Engineering, Universiti Putra Malaysia, Selangor, Malaysia. 3 Department of Bioprocess Technology, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. *Email: par.fazli@gmail.com ABSTRACT Methane (CH4) is a potent green house gas and second in importance after carbon dioxide (CO2) with a global warming potential of 25 times more than CO2. Paddy fields are important sources of methane and contribute in approximately 15–20% of the annual global methane efflux. Cultivation systems can affect the methane emission by their different water management and practices. One of the cultivation methods is the system of rice intensification (SRI). Considering the water management system and the plant density, in this method less methane is expected compared to conventional cultivation method. Consequently, current study has been done to evaluate the influence of two SRI methods on methane emission. For this purpose, closed chamber applied to measure methane emission. As a result, conventional method showed the highest total methane flux with emitting of 26.4 g CH4 m -2 compared to original SRI treatments and triangular pattern (7.7 g CH4 m -2 and 8.9 g CH4 m -2 ). The pattern of water management was the most influencing factor lead to lower methane emission in SRI treatments. In addition, SRI treatments produced higher yield than the conventional method. This could be a promising result toward a sustainable rice production. Keywords: cultivation system, methane emission, plant density, rice, water management. INTRODUCTION Methane is a powerful greenhouse gas with global warming potential (GWP) of 72 over a 20 years period [1]. Paddy fields are important sources of methane, so that from 50% of global methane emissions by agriculture 11% come from cultivation of rice [2]. Since, rice (Oryza sativa L.) (2n=24) belonging to the family Graminae and subfamily Orazoidea., is the staple food for one third world’s population, its production is ant icipated to increase from 458 million tonnes to over 750 million tonnes by the year 2020. Besides, methane emissions from flooded rice will increase to about 150 million tonnes in 2025 [1]. Conventional rice cultivation uses flooding continuously method as water management. Likewise, natural wetlands, flooding rice field cuts off entering the oxygen from the atmosphere to the soil. Therefore, it could induce an anaerobic condition within the soil. Anaerobic condition is necessary for biodegradation of organic matter. Meanwhile, methanogens as methane producers motivate to be active [3] and produce methane as a metabolic by-product. Activation of these microorganisms can be influenced widely by water regime type. On the other hand, there are some microbial communities such as methanotrophic bacteria in the surface soil layer and the rhizosphere, which are responsible for methane oxidation before release into the atmosphere [4]. Aerating the soil can provide a favorable condition for methanotrophs to oxidize the methane effectively before it can escape to the atmosphere. On the other hand, system of rice intensification (SRI) is a cultivation method, which was developed during the early 1980’s in Madagascar [5]. SRI oblong-triangular is a modified SRI, which is similar to SRI original except for cultivation pattern. In this cultivation method, 3 seedlings per hill separated by 7 cm with 40×45cm regular distances would be transplanted (24 plants per m 2 ) [6]. SRI utilizes a specific water management called alternate wetting and drying water management (AWD) [7]. Avoiding flooding the soil continuously using AWD in 3-6 day cycles might make SRI capable to suppress methane emission. This way, we expect less methane emission compared to the conventional method. Besides, in aerated soils the aeranchyma texture in rice plant would not develop and thus, the methane transportation ability of rice will be low. Other principle of SRI method leading to less methane emission is planting single seedlings at two-leaf stage (8-15 days in tropical climates) 1-2 cm deep in original SRI (18 plants per m 2 ) [8].