This study investigated CO2 and N2O emissions from soil receiving long-term cattle feedlot manure applications under rainfed and irrigated conditions in semi-arid southern Alberta, Canada. Soil available N and CO2 and N2O fluxes were measured after fall crop harvesting and prior to next spring's seeding from plots that had received 0 and 60 t ha(-1)yr(-1) cattle feedlot manure application with (Mi0 and Mi60) or without irrigation (Mr0 and Mr60) for 27years. Both CO2 and N2O fluxes varied considerably over the 7-month nongrowing season. Cumulative CO2 emissions from manured treatments (Mr60 at 2.20 t ha(-1) and Mi60 at 2.36 t ha(-1)) were 2.6times values from nonmanured treatments (Mr0 at 0.83 t ha(-1) and Mi0 at 0.92 t ha(-1)). Similarly, cumulative N2O emission from manured treatments (Mr60 at 4.54kg ha(-1) and Mi60 at 5.34kg ha(-1)) were 8-12times values from nonmanured treatments (Mr0 at 0.40kg ha(-1) and Mi0 at 0.70kg ha(-1)). Growing season irrigation had no effect on CO2 and N2O emission over the nongrowing season.
