Smell of cow shit brings a promise with it

This will sound daft, but I know spring is one its way, not because January is slowly drawing to a close, but because I can smell the cow shit in the air.
I arrived back her at Higher Lank about ten minutes to midnight, and getting out of the car, the first thing I noticed was the smell of cow shit. I am not trying to be funny - for once - when I say I like the smell a great deal. (The waste from vegetarian animals simply doesn't smell offensive.)
The thing is that you can never smell the cow shit in the winter. Why, I don't know. Perhaps it is too cold, but then that can't really be the answer because last week when we had a mild smell, I still couldn't smell it. But now I can, and now I know spring is on its way.
BTW Another smell I like a lot is that of silage.