Effect of soil types and nitrogen fertilizer on nitrous oxide and carbon dioxide emissions in oil palm plantations

Oil palm (Elaeis guineensis Jacq.) production in Indonesia and Malaysia is currently the focus of concern due to its potential impact on the environment via greenhouse gas emissions. Oil palm plantations have been reported to release large quantities of nitrous oxide (N2O) into the atmosphere, which is most likely linked to nitrogen (N) fertilizer use. However, there are still limited studies comparing effects of the type of soil and N fertilizer on N2O and carbon dioxide (CO2) emissions. This study aimed to evaluate the effects of soil types and N fertilizer on N2O and CO2 emissions in oil palm plantations. N2O and CO2 emissions were measured for 15-16 months from 2010-2012 in Tunggal sandy loam soil, Indonesia, and in Simunjan sandy soil and Tatau peat soil, Malaysia. Within each site, treatments with coated fertilizer and conventional fertilizer, and unfertilized with and without tillage, were established. N2O and CO2 fluxes showed high variabilities with seasons, types of soil and fertilizer treatments. The mean of the N2O fluxes from each treatment in the Simunjan sandy soil was the lowest among the three soils, ranging from 0.80 to 3.81 and 1.63 to 5.34 mu g Nm(-2) h(-1) in the wet and dry seasons, respectively. The mean of the N2O fluxes from each treatment in the Tunggal sandy loam soil ranged from 27.4 to 89.7 and 6.27 to 19.1 mu g Nm(-2) h(-1) in the wet and dry seasons, respectively. The mean of the N2O fluxes was found to be the highest among the three soils in each treatment of the Tatau peat soil, ranging from 131 to 523 and 66.1 to 606 mu g Nm(-2) h(-1) in the wet and dry seasons, respectively. The N application rate of coated fertilizer was about half that of conventional fertilizer and was applied as deep placement. In the Tungal soil, coated fertilizer reduced N2O emissions by 31 and 48% in wet and dry seasons, respectively, compared to the conventional fertilizer, and was similar to unfertilized treatment. However, N2O emissions increased in Simunjan and Tatau soils during dry seasons. There was no significant difference between treatments. These results show that N2O and CO2 fluxes in the tropical oil palm plantations were significantly affected by the type of soil, but not always by fertilizer treatments.