Horizontal and Vertical Emissions of Methane from a Drained Tropical Peat Soil Cultivated with Pineapple

Int. J. Biosci. 2016 International Journal of Biosciences | IJB | ISSN: 2220-6655 (Print), 2222-5234 (Online) http://www.innspub.net Vol. 9, No. 5, p. 10-18, 2016 RESEARCH PAPER OPEN ACCESS Horizontal and vertical emissions of methane from a drained tropical peat soil cultivated with Pineapple (Ananas comosus (L.) Merr.) A. V. Jeffary1, O. H. Ahmed*1,2, R. K. J. Heng3, L. N. L. K. Choo1,4 1Department of Crop Science, Faculty of Agriculture and Food Science, Universiti Putra Malaysia (UPM), Bintulu Campus, Bintulu, Sarawak, Malaysia 2Institut Pertanian Tropika, Universiti Putra Malaysia, Serdang, Selangor Darul Ehsan, Malaysia 3Department of Forestry Science, Faculty of Agriculture and Food Science, Universiti Putra Malaysia (UPM), Bintulu Campus, Bintulu, Sarawak, Malaysia 4Soil and Water Management Programme, Strategic Resource Centre, Malaysian Agricultural Research and Development Institute (MARDI), Roban, Saratok, Sarawak, Malaysia Key words: Emissions, Horizontally, Methane fluxes, Tropical peatlands, Vertically http://dx.doi.org/10.12692/ijb/9.5.10-18 Article published on November 21, 2016 Abstract Drained tropical peat soils especially for agricultural purposes could lead to methane (CH4) emission into the atmosphere. Methane emission from peat soils to the atmosphere depends on rates of methane production, consumption and ability of the soil and plants to transport the gas to soil’s surface and also within soil particles. The objective of this study was to determine CH4 fluxes horizontally and vertically from the floor and wall of the pit of a tropical peat soils cultivated with Ananas comosus (L.) Merr. and to determine the relationship between CH4 transportation and CH4 emission from a drained tropical peat soils. Gas samplings were conducted in the dry and wet seasons. The horizontal emission of CH4 in the dry and wet seasons were 2.96 t CH4 ha-1yr-1 and 4.27 t CH4 ha-1yr-1, respectively. The vertical emission of CH4 in the dry and wet seasons were 0.38 t CH4 ha-1yr-1 and 0.50 t CH4 ha-1yr-1, respectively. The total amount of the horizontal and vertical CH4 emissions in the dry and wet seasons were 3.34 t CH4 ha-1yr-1 and 4.47 t CH4 ha-1yr-1, respectively. Horizontal emission of CH4 was higher in the wet season due to increase in water table which resulted in increase of CH4 emission. Therefore, it can be concluded that horizontal emission of CH4 is higher than vertical emission suggesting that there is a need for direct CH4 measurement from cultivated peat soils to ensure that CH4 emission is neither underestimated nor overestimated. * Corresponding Author: O. H. Ahmed [email protected] 10 Jeffary et al. Int. J. Biosci. 2016 Introduction Methane fluxes are dependent on the rates of CH4 Peatlands cover approximately 400 million hectares production and consumption, so is the ability of soils of the Earth’s land surface (Maria, 2008). Peatlands and plants to transport CH4 to the atmosphere. occur mainly in the northern hemisphere (North Methane is produced under highly reduced conditions America, Russia, and Europe) whereas tropical by methanogenic bacteria (Maria, 2008). Thus, it is peatlands occur in the mainland of East Asia, produced in the saturated zone of peat soil and once Southeast Asia, Caribbean, Central America, South produced it can be transported to the atmosphere America, and Southern Africa (Maria, 2008). The through diffusion, ebullition (bubbling) or as current estimation of undisturbed peatland is diffusion or mass flow through vascular plants approximately 30-40 million hectares (Maria, 2008). (Maria, 2008). In Southeast Asia, peatland covers approximately 27.1 Methane emissions from peatlands are related to million hectares (Hooijer et al., 2010) where 2.6 water table position (Roulet et al., 1992) and peat million hectares of the peatland occur in Malaysia temperature (Bubier et al., 1995). The three major (Ismail and Jamaludin, 2007). Sarawak has the environmental factors that control CH4 emission rates largest area of peatland in Malaysia, covering from peatlands are water table position, temperature, approximately 1.4 million hectares, which is and substrate properties such as pH and mineral equivalent to 50% of the total land area (Andriesse, nitrogen content (Barlett and Harriss, 1993; Moore 1988). Globally, agriculture is considered to be and Dalva, 1993; Crill et al., 1988). It has also been responsible for approximately two-thirds of the suggested that the CH4 consumption rate depends on anthropogenic sources (Melling et al., 2006). management factors such as drainage, compaction, and nitrogen (N) fertilization (Weitz et al., 1998; Ball Agriculture, forestry, and peat extraction for fuel and et al., 1997; Hansen et al., 1993). In the drained part horticultural purposes are the major causes of of peatlands, CH4 is easily transported through lateral peatland disturbance because, as the peats get inter-connected pore spaces. disturbed, the alteration in its hydrology results in the oxidation of peat soils. These activities alter the The emissions of CH4 have recently attracted greenhouse gases balanced (Maria, 2008). Concern of considerable attention because of their contribution the role of peatlands as the main carbon to the global climate change. Methane loss is also sequestration has been expressed because greenhouse important because soil C must be stored for gases (GHGs) emission contributes to global warming sustainable crop production. In spite of intensive (Daud, 2009). Cultivation of different crops has international research efforts, the newest global CH4 balances still have considerable uncertainties in different impact on the environment (Azqueta and evaluating the specific sources for enhanced CH4 Sotelsek, 2007). Currently, there is lack of (IPCC, 1996; Mosier, 1996). Uncertainties mainly are information on soil CH4 emissions horizontally and because of the variability in soils and environmental vertically from pineapple cultivation on drained conditions, time, and method used for measurement tropical peatlands. (Mosier, 1996; Firestone and Davidson, 1989). Current practices in the measurement of CH4 Research findings on GHG emissions in tropical emissions from peatland surface often give peatlands planted with pineapples are usually controversial and unsolved results in which various controversial due to lack of standard information factors contribute to the problem. For example, CH4 (Ahmed and Liza, 2015). Besides, the contribution of can be consumed by aerobic microbes during its pineapples cultivation to GHG emissions is important transportation to the soil surface and dissolve in because 90% of pineapples are widely grown on peat water, thus, transported away from peatlands. soils of Malaysia (Raziah and Alam, 2010). 11 Jeffary et al. Int. J. Biosci. 2016 Failure to account for these GHGs losses from The von Post Scale of Humification shows that the drained tropical peatlands could underestimate future peat soils are sapric peat (well decomposed peat) with rates of increase in atmospheric GHGs and their humification (Ahmed and Liza, 2015). The mean effects on global environmental change processes temperature of the peat area ranges from 22.1 to 31.7 (Page et al., 2007). Currently, there is limited °C with relative humidity ranging from 61 to 98% (Ahmed and Liza, 2015). The annual mean rainfall of information on soil CH4 emissions emission from the area is 3749 mm during the wet season. The pineapple cultivation on drained peat soils. Current monthly rainfall is more than 400 mm whereas practices in the measurement of CH4 emissions are during the dry season, the mean rainfall is 189 mm only from the surface of peat soils. Research findings (Ahmed and Liza, 2015). on CH4 emissions in tropical peats planted with pineapples are usually controversial due to few or lack Greenhouse Gases Emission Measurements of standard information (Ahmed and Liza, 2015). Horizontal and vertical emissions of CH4 were Methane emissions are commonly measured using measured from the surface and the wall of the peat closed chamber method in a very limited area and soil using different chamber methods. The horizontal time (Zulkefli et al., 2010). This leads to inconsistent emission of CH4 from the surface of the peat soils was and sometimes controversial issues which are related measured using I-shaped closed chamber method to lack of rigid information. Although pineapples are whereas the vertical emissions of CH4 was measured cultivated on tropical peat soils, there is little using the L-closed chamber method (Ahmed and information on CH4 emissions from peats cultivated Liza, 2015). The CH4 emission measurements were with pineapples based on different transportation carried out at 0-5 cm and 5-10 cm peat soil depth, approach (horizontal and vertical emissions). respectively. Measurements of the CH4 emission were carried out in 10 m x 10 m drained peat soil plots Based on the above justification, the objectives of this cultivated with pineapple. Methane flux sampling was study were to: (i) quantify horizontal and vertical CH4 carried out for 24 hours at every 6 hours interval emissions from a drained tropical peatlands (between 0600 hr to 0600 hr) in July 2015 (dry cultivated with pineapple using two chamber methods season) and December 2015 (wet seasons). The five and (ii) determine the relationship between CH4 sampling periods used in this study to obtain a 24 transportation and CH4 emission from a drained tropical peatlands. In this study, we hypothesized that hours CH4 emission are listed in Table 1. horizontal emission of CH4 into the atmosphere from peat soil cultivated with pineapple will be higher than Soil CH4 Horizontal Emission Measurements that of vertical emission. This hypothesis is based on The horizontal movement of CH4 emissions from the the assumption that the mechanism of transportation peat soil surface was measured using the closed of CH4 is influenced by horizontal and vertical chamber method (Norman et al., 1997; Crill, 1991). movements. The fabricated I-shaped chamber was gently pressed vertically on the surface of the soil pit at of 3-5 cm Materials and methods depth.

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