Present invention relates to a locking and emptying system of a refill cartridge containing nutrients or chemicals, said system comprising at least one replaceable refill cartridge, at least one receiving socket for the refill cartridge, in every receiving socket a locking mechanism of the refill cartridge, discharge means of the refill cartridge and control means of the locking system and for each refill cartridge a emptying container. The control means of the locking system are set to release the empty refill cartridge from the receiving socket only when the emptying container has enough free volume to receive the content of the next refill cartridge.