I can't easily find what are the main (and in what order of magnitude ) causes of agri emmisions . It goes abit like this.
1 . Belching and farting of bovines and I presume ovines and pigs.
2. Something about fertiliser.
3. Something about machinery emmisions.
4. Emmisions from animal waste storage.
AND ways to reduce agri emmisions.
1. Food additives (Something about seaweed)
2. Feed alternatives..?
3. Rotational grazing..?
4. Covering slurry/dung heaps..?
5. Might tie in with 4....biodigesters.
6. Decrease in fertiliser usage.
7. Decrease in animal numbers.
Please feel free to add some more.
I reckon it will be a incentified major decrease in numbers and fertiliser. And a big push towards extensive/organic farming.