The invention relates to a precision anti-blocking liquid fertilizing gun. The fertilization gun comprises a switch combination, a liquid measuring
barrel, a gun bar and a gun head, wherein the liquid measuring
barrel, the gun bar and the gun head are communicated in sequence. A distribution chamber, which is divided into an upper chamber and a lower chamber by a water discharging
plunger piston, is disposed in the upper part of the liquid measuring
barrel. The upper chamber is provided with a fertilizing amount adjusting device. The side wall of the distribution chamber is provided with a general water inlet
pipe, and a lower-chamber water inlet
pipe communicated with the lower chamber. The general water inlet
pipe is communicated with the upper chamber through an upper-chamber water inlet pipe. A controlling
plunger piston, the top of which is connected to the switch combination through a connecting rod, is disposed in the distribution chamber. The side of the gun head is provided with a water outlet. An anti-blocking
plunger piston, which is connected with the controlling plunger piston through an anti-blocking connecting rod, is disposed inside the gun head. When the switch combination is normally opened and is not working, the controlling plunger piston is at the bottom of the distribution chamber, the lower-chamber water inlet pipe is communicated, the upper chamber and the lower chamber are in a
pressure balance, the water discharging plunger piston is at the highest position and the anti-blocking plunger piston closes the water outlet. When the switch combination is closed and fertilization is performed, the lower-chamber water inlet pipe is closed by the controlling plunger piston, the pressure in the upper chamber is larger than the pressure in the lower chamber, the water discharging plunger piston is moving downward, the anti-blocking plunger piston is moving upward and the water outlet is opened.