Unloading slurry at biogas ??
I guess you will have to feed the biogas plant silage or manure first and then can get/buy the slurry it produces. ( in FS15 you didnt have to buy it, but could use it as a second slurry silo ) Interesting thing is you can sell slurry at a certain farm at a higher price then is stated as price at the biogas plant.