CO2-CH4, and N2O Emissions From Oil Palm Plantation On Deep Peat as Affected by N Fertilization

Through drainage and nitrogen (N) fertilization, oil palm plantation on peatlands affect emission of the main greenhouse gases (GHG) - carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Oil palm plantations on peat can also remove CO2 from the atmosphere via photosynthesis, but the carbon not stored in the biomass or in the peat is returned back to the atmosphere as CO2. Anaerobic conditions typical for peat soils are highly favorable for the production of CH4 and N2O. This study investigated the short-term effect of N fertilization on CO2- CH4 and N2O emissions from a deep peat soil (~ 8 m) planted with young oil palms (1 year) at a density of 148 palm ha-1 in Bakrie Sumatera Plantation, Jambi. The measurements were conducted in September - October 2010 in an N fertilizer trial with 3 doses of N fertilizer: 0 g urea palm-1 (N0), 200 g urea palm-1 i.e. 14 kg N ha-1 (N1), and 400 g urea palm-1 i.e. 28 kg N ha-1 (N2). The fluxes of gas from the soil surface were measured by using the closed-chamber method. CO2 was analyzed using an Infra Red Gas Analyzer (IRGA) while N2O and CH4 were analyzed by gas chromatography. Results show a short-term increase in emissions of CO2 and CH4 following urea application. After 10 days the emissions were back to normal. The cumulative difference between N1 and N0 and between N2 and N0 was 0.9 Mg C-CO2 ha-1 and 1.4 Mg C-CO2 ha-1 respectively for CO2 emissions, 0.17 kg C-CH4 ha-1 and 0.25 kg C-CH4 ha-1 respectively for CH4 emissions. The same cumulative differences for N2O emissions were 2 and 8 kg N-N2O ha-1, respectively. N2O, CO2 and CH4 were 73, 27 and less than 1%, respectively of net greenhouse forcing due to a single N fertilization event. (Résumé d'auteur)