Very interesting and encouraging findings.
Paddock scale - much less N2O emitted from mixed sward than ryegrass/clover mix. 
Emission factor for ryegrass clover about 0.75% while emission factor for mixed sward 0.45%. Of course, there are caveats and nuances but an exciting finding. More carbon lost from mixed sward due to differences in grazing regime.   
Very clearly shows the importance of simultaneous measurement of N2O and C balance. 