Nitrous oxide emission derived from soil organic matter decomposition from tropical agricultural peat soil in central Kalimantan, Indonesia(Environment)

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Our previous research showed large amounts of nitrous oxide (N_2O) emission (>200 kg N ha^<-1> year^<-1>) from agricultural peat soil. In this study, we investigated the factors influencing relatively large N_2O fluxes and the source of nitrogen (N) substrate for N_2O in a tropical peatland in central Kalimantan, Indonesia. Using a static chamber method, N_2O and carbon dioxide (CO_2) fluxes were measured in three conventionally cultivated croplands (conventional), an unplanted and unfertilized bare treatment (bare) in each cropland, and unfertilized grassland over a three-year period. Based on the difference in N_2O emission from two treatments, contribution of the N source for N_2O was calculated. Nitrous oxide concentrations at five depths (5-80 cm) were also measured for calculating net N_2O production in soil. Annual N fertilizer application rates in the croplands ranged from 472 to 1607 kg N ha^<-1> year^<-1>. There were no significant differences in between N_2O fluxes in the two treatments at each site. Annual N_2O emission in conventional and bare treatments varied from 10.9 to 698 and 6.55 to 858 kg N ha^<-1> year^<-1>, respectively. However, there was also no significant difference between annual N_2O emissions in the two treatments at each site. This suggests most of the emitted N_2O was derived from the decomposition of peat. There were significant positive correlations between N_2O and CO_2 fluxes in bare treatment in two croplands where N_2O flux was higher than at another cropland. Nitrous oxide concentration distribution in soil measured in the conventional treatment showed that N_2O was mainly produced in the surface soil down to 15 cm in the soil. The logarithmic value of the ratio of N_2O flux and nitrate concentration was positively correlated with water filled pore space (WEPS). These results suggest that large N_2O emission in agricultural tropical peatland was caused by denitrification with high decomposition of peat. In addition, N_2O was mainly produced by denitrification at high range of WFPS in surface soil.
一般社団法人日本土壌肥料学会の論文

Nitrous oxide emission derived from soil organic matter decomposition from tropical agricultural peat soil in central Kalimantan, Indonesia(Environment)

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