Short-term effect of urea on CH₄ flux under the oil palm (Elaeis guineensis) on tropical peatland in Sarawak, Malaysia
2006
MELLING, Lulie | GOH, Kah Joo | HATANO, Ryusuke
Methane flux was measured monthly from August 2002 to July 2003 at an oil palm plantation on tropical peatland in Sarawak, Malaysia, using a closed chamber technique. Urea was applied twice, once in November 2002 and once in May 2003. The monthly CH₄ flux ranged from -32.78 to 4.17 μg C m⁻² h⁻¹. Urea applications increased CH₄ emissions in the month of application and emissions remained slightly higher a month later before the effect disappeared in the third month after application (i.e. back to CH₄ uptake). This effect was the result of increased soil [graphic removed] content that was not immediately absorbed by the oil palm following urea application, which reduced the oxidation of CH₄, resulting in its enhanced emission. By using the Cate-Nelson linear-plateau model, the critical soil [graphic removed] content causing CH₄ emissions in the oil palm ecosystem was 42.75 mg kg⁻¹ soil. However, the inhibitory effect of [graphic removed] on the oxidation of CH₄ was mitigated by low rainfall and the pyrophosphate solubility index (PSI), where the former might increase oxidation of CH₄ and the latter was a reflection of the low soluble substrate for methane production. Thus, the splitting and timing of urea applications are important not only to optimize oil palm yield, but also to reduce soil [graphic removed] content to minimize CH₄ emissions and, therefore, its potential negative impact on the environment.
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