N2O-N Emissions from Organic and Conventional Paddy Fields from Central Java, Indonesia

To evaluate the effect of farming system on gaseous emission of N from soil, the measurements of nitrous oxide (N2O) were taken in organic and conventional paddy fields in tropics. Eleven soil samples from organic and neighboring conventional sites in Central Java, Indonesia were incubated at two different moisture contents expressed as water filled pores (WFPS), namely 75% WFPS and 100% WFPS. Emission of N2O-N at 75% WFPS was significantly higher in conventional management than in organic management. At 100% WFPS, the N2O-N emission was also higher in conventional than in organic farming system. Although it was not significantly different, it has significantly and positively correlations with SOC, total N and initial mineral N content. Due to the swelling ability of the high clay which is contained in soil samples, less N2O-N emission in 75% WFPS than in 100% WFPS was observed in the present study. The range of N2O-N emission at 75% WFPS was 0.01 – 0.03 kg N2O-N/ha in organic farming and 0.005 – 0.16 kg N2O-N/ha in conventional farming; for organic farming at 100% WFPS, the N2O-N emission was 0.04 – 61 kg N2O-N/ha and in conventional farming was 0.08 – 74 kg N2O-N/ha. This study concludes that organic farming in paddy fields might have more promising potential to mitigate N2O-N emission than conventional farming in paddy fields.