PHOSPHORUS EFFECTS ON N2O AND NO EMISSIONS FROM ACACIA MANGIUM SOIL

Özet

Öz An incubation experiment was conducted to examine the effects of phosphorus (P) application on N2O and NO emissions from soils of an Acacia mangium plantation in Indonesia. The soils were incubated for 30 d with and without adding P (Ca(H2PO4)2; 2 mg P g･soil-1) after adjusting water-filled pore space (WFPS) to 75% or 100%. N2O/NO ratio in both 75% and 100% WFPS in control soils were higher than 1, suggesting that N2O and NO were emitted mainly from denitrifying bacteria. P addition increased N2O emission under both WFPS conditions and NO emission under 75% WFPS, which was attributed to two reasons. Firstly, the stimulation of O2 consumption by general heterotrophic activity, which was suggested by significant increase in CO2 production in P treated soils, promoted developing stronger anaerobic conditions required for denitrification. Secondly, P addition could also have relieved the P shortage for denitrifying bacteria, producing N2O and NO. Our results suggest the application of P fertilizer has a potential to stimulate N2O and NO emissions from Acacia mangium plantation at least when soils are under relatively wet conditions. The results also suggest that P limitation in tropical soils might be suppressing the emissions of N2O and NO, because it limits the activity of nitrification and/or denitrification.