NITROUS-OXIDE EMISSIONS FROM FERTILIZED SOILS - SUMMARY OF AVAILABLE DATA

Direct measurements of fertilizer-derived N2O emission data from 104 field experiment reported in agriculture and soil science literature that were obtained between 1979 and 1987 were summarized and used to estimate woldwide fertilizer-derived N2O emissions. Although without statistical determination, there appears to be a trend between emissions and type and quantity of fertilizer applied; the available data does not indicate a trend between emissions and a particular soil type or agriculture system. Using the fraction of the N fertilizer evolved as N2O and fertilizer consumption estimates for five fertilizer types, 0.1 to 1.0 Tg N2O-N (avg. 0.3;median 0.2) were estimated to be released during the 'sampling period.' If these estimates are doubled to account for emissions after the sampling period and emissions from fertilizer lost in drainage water and groundwater, the expected rage would be 0.2 to 2.1 Tg N2O-N (avg. 0.7; median 0.5) emitted into the atmosphere in 1984. The magnitude of this estimate is in agreement with recent global estimates. If 100 Tg N fertilizer are consumed worldwide in the year 2000, the global release of fertilizer-derived emissions into the atmosphere will probably not exceed 3 Tg N2O-N in the year 2000. It is estimated that 23 to 315 Gg N2O-N were emitted into the atmosphere from fields of culivated leguminous crops in 1986. Future research needs were suggested.