Cardiff Crown Court heard that Powell had kicked Mr Barnett so hard, that spectators on the touchline heard the bone in his leg crack.
Attack victim Ashley Barnett criticised the comments by a Gwernyfed club official and Mr Barnett called for Ian Powell to be banned for life from playing.
Cardiff Crown Court heard that Powell had kicked Mr Barnett so hard, that spectators on the touchline heard the bone in his leg crack.
Jailing Powell for six months, Judge Peter Jacobs said: "Assaults committed on rugby and football pitches are not exempt from criminal law."
The court had been told that Powell, of Carlsgate, Hay-on-Wye in Powys, kicked Mr Barnett during a Welsh National League game in January.
Mr Barnett - playing at number eight for Cardiff side Canton RFC - suffered a double fracture of the leg and was so badly injured that he will never be able to play again.
Powell - a second row forward with Gwernyfed in Powys - admitted a charge of inflicting grievous bodily harm.
Ray Lewis, prosecuting, said that Powell, a forestry worker, had not intended to cause such injury.
"But he accepts he was reckless as to whether such an injury would be caused," Mr Lewis said.
"Witnesses saw him kick Mr Barnett and his broken leg was a direct result of the kicking."
Judge Jacobs told Powell: "You were playing in a rugby match which had become niggly.
"You became disgruntled with an opponent and kicked him with considerable force which directly or indirectly caused the double fracture."
Both Gwernyfed RFC and the Welsh Rugby Union conducted their own inquiries into the incident, but decided to take no further action.
After the hearing, Gwernyfed RFC chairman Chris Phillips said Powell would be welcome to play for the club again.