Effect of land-use changes on nitrous oxide (N2O) emission from tropical peatlands

Abstract

Tropical peatlands could be a potential source of nitrous oxide (N₂O) which has a significant impact on global warming. To reduce N₂O emission and develop best management practices for peatlands, the formation and emission rates of N₂O as affected by land-use management (i.e., changing peatland into agricultural land) and the factors affecting the process must be understood. Therefore, one field and three laboratory incubation experiments were carried out during 1998–99 using peatland soils from 12 sites in South Kalimantan (Indonesia) and one site in Sarawak (Malaysia) to quantify the N₂O emission and the factors affecting it. The results from the field experiment showed that land-use managements, changing water table and locations had a significant impact on N₂O emission. Changing peatland into cultivated lands (cultivated upland and paddy field) enhanced the N₂O emission. For example, cultivated upland Cassava crop resulted in the highest amounts of N₂O emission (1.04 mg N m⁻² h⁻¹) compared to other treatments. The N₂O emission during 1998 was higher than those during 1999 because of the changing water table and dry season in 1998. The laboratory experiments showed that the N₂O emission was also strongly influenced by land-use management, soil moisture contents, addition of ammonium fertilizer or rice straw and soil depths. For example, the flooded conditions stimulated the N₂O emission compared to that at 60% moisture contents. Similarly, the addition of ammonium fertilizer suppressed the N₂O emission compared to control treatments because of the high ammonium contents that inhibit nitrification. Nevertheless, incorporation of rice straw to soil samples from 20 to 40 cm soil depth stimulated N₂O emission.