SA mum admits daughter's killing

A mother has admitted the manslaughter of her four-year-old daughter who was repeatedly placed on a motorbike which crashed into a backyard tree.

Ashlee Jean Polkinghorne, 22, entered the guilty plea in the South Australian Supreme Court on Thursday, after days of legal argument before her scheduled trial.

She admitted unlawfully killing Chloe Valentine between January 16 and 21, 2012 at the Adelaide suburb of Ingle Farm.

Benjamin Robert McPartland, 27, pleaded guilty to the same charge last December.

Prosecutors have alleged Chloe was repeatedly put on the 50kg bike before it crashed into a tree.

The pair, who are on bail, are due to face a sentencing hearing next week.