DIRECT MEASUREMENT OF NITROUS OXIDE FLUX FROM SOIL

A simple technique for direct measurement of nitrous oxide flux from soils is described. These fluxes were measured at several locations in Essex County in southwestern Ontario and were found to be low from bluegrass and clover sod (3.17 – 4.01 × 10 9 molecules cm −2 s −1 ), intermediate from continuous corn and non-agricultural marsh land (16.8 – 32.2 × 10 9 molecules cm −2 s −1 ), and high from corn in rotation following alfalfa sod (133 × 10 9 molecules cm −2 s −1 ). Considerable variability in rate was observed from day to day and from site to site irrespective of soil type or crop management system. Comparisons are made with measurements obtained in various geographical areas by others.