EFFECTS OF ENVIRONMENTAL FACTORS ON SOIL N2O FLUXES FROM OIL PALM PLANTATION ON TROPICAL PEATLAND

摘要

The objectives of this study were to quantify soil nitrous oxide (N2O) fluxes and identify the environmental factors influencing soil N2O fluxes from three different ages of oil palm plantation on tropical peatland in Sarawak, Malaysia. Monthly soil N2O fluxes were measured from July 2006 until June 2008 in three different ages of oil palm plantation (1,5 and 7-year old palm) on tropical peatland using a closed chamber method. Soil N2O flux from 1-year old palm was significantly higher (383.4±93.6 μgm~2 hr~(-1)) than from 5-year old palm (140.7±29.4 μg m~(-2) hr~(-1) ') or 7-year old palm (235.0±55.8 (μgm~2 hr~(-1)). This may be due to the canopy of the younger palms being still open, thus that exposing the soil surface to direct sunlight, resulting in higher soil temperatures which increased the soil N2O flux. Multiple regression analysis revealed that air temperature, soil temperature at 10 cm, relative humidity and water table depth were significantly correlated with soil N2O fluxes in 1-year old palm only. However, water table depth was an important factor in controlling the soil N2O fluxes in oil palm plantation on tropical peatland regardless of palm age. Understanding the processes of N2O formation and the factors influencing these emissions is fundamental in managing soil N2O fluxes in cultivated tropical peatland.