Mod: Bjornelux
You can fill it with excess slurry from your cows , pigs ... it is a slurry storage. You need the trailer in my last comment I placed here on top off the comments.
The compost mod,; naja,,,, you can dump gras, straw, silage, virtualy anything in it, and it creates compost soil, wich you can sell at the compoststorage at the BGA. you need the included bucket for the LiebherrFrontloader.
Compost gives you money in return.