The invention discloses a water feeding pump or a fertilizer applying pump for a pump station of a fertilization and irrigation system. The water feeding pump (2) or the fertilizer applying pump (3) is a centrifugal pump. The centrifugal pump includes a volute and an impeller. The impeller includes a front disc (12), a rear disc (13), and main blades (14), and a plurality of back blades (18) distributed along a circumferential direction are disposed on a back surface of the rear disc, where an auxiliary rotating disc (11) is disposed between the impeller and a rear side wall of the volute, the auxiliary rotating disc is a rotating member and is driven by the back blades of the impeller to rotate.

The drying-up method includes introducing a purge gas into a suction container of a pump apparatus, passing the purge gas through a flow-path switching device in the suction container while the purge gas bypasses a submersible pump in the suction container, introducing the purge gas that has passed through the flow-path switching device into a suction container of a pump apparatus, and passing the purge gas through the flow-path switching device in the suction container while the purge gas bypasses a submersible pump in the suction container.