You'd need to cite some sources for that. And explain where the millions of tons of animal manure go.
Here in Northern Europe 100% of manure from housed animals is used, either spread as manure or, increasingly, used for biomethane
That's the wrong statistics to look it - 100% of waste coffee is used. They already have it, good management will figure out a way to use it.
But you cannot make an argument that we have to keep drinking coffee because fertiliser industry will collapse without waste coffee.
There are thousands of studies about impacts of intensive animal faming on landscape, economy, health and society in general, they are all negative. This was settled like 40 years ago.
You said
> Only a small percentage of manure is reused as fertiliser because transporting it is expensive, and messy
That's straight up false, for Northern Europe anyway.