The invention relates to a rotary
drill bit. The rotary
drill bit comprises a fixed tip, main
cutting edges and
chip discharging grooves; the main
cutting edge and the
chip discharging grooves are distributed on a
conical surface, a protruding fixed tip is arranged at the conical tip, integral forming is conducted by adopting high-speed
tool steel, by means of the rotating fixed tip and the main
cutting edges, a
tree stump is drilled downwards and to the periphery from the center of the
tree stump until the
tree stump is completely crushed. The strength and rigidity of the integral rotary
drill bit are high, and the drilling efficiency is high. The invention further provides a portable rotary drilling rig. The portable rotary drilling rig comprises a hand frame, a power device, a transmission rod and the rotary
drill bit; detachable connection is adopted, the portable rotary drilling rig can be disassembled into parts convenient to carry, so that the portable rotary drilling rig can betransported to the complex
terrain in a forest conveniently, re-assembled and crushes tree sumps of diseased trees on the spot. The invention further provides a tree stump crushing method. On the condition that the tree stump does not need to be dug out, the portable drilling rig is adopted for directly crushing the tree stump in soil on the spot, and the
nematode epidemic situation can be effectively controlled in time.