How on earth can you get 450 000 litres in this, does it come with an underground bunker ?

Two requests:
- please describe the purpose of the trailer better (English: This is a mobile slurry holding tank to park at the edge of the field. This tank should be transported empty and filled with slurry once parked by the field.)
- please create something similar to serve as a mobile grain silo for rapid selling when prices are high. :-)

Google Translate:
Zwei Anfragen:
  - Bitte beschreiben den Zweck des Anhängers besser (Englisch: This is a mobile slurry holding tank to park at the edge of the field. This tank should be transported empty and filled with slurry once parked by the field.)
  - Erstellen Sie bitte etwas Ähnliches als mobiler Getreidespeicher für schnellen Verkauf, wenn die Preise hoch zu dienen. :-)