He said it was a breach of trust of the families who sent the boys to Kawana expecting they would be treated with the respect they deserved.
Kawana's lawyer, Ian Hard, said his client had been a victim of abuse when younger, although he was not using that as an excuse for his behaviour.
It was the first time Kawana had committed offences "in this manner" Mr Hard said, and he had already engaged in counselling.
With that in mind, Mr Hard called on the judge to sentence Kawana to community work or intensive supervision.
That was rejected by Judge Grace.
Mr Hard said Kawana was no longer a farm manager as he had sustained a severe back injury.
Kawana had been granted interim name suppression until his sentencing. Police prosecutor Garry Wilson said the families of the boys involved had wanted his name made public.