Adverse poverty, especially in rural and farming areas pushes children into child labour.
This was one finding of a study done by the Human Sciences Research Council (HSRC), which released a statement during World Day against Child Labour on Tuesday.
The study was conducted in Mpumalanga, the Western Cape and KwaZulu-Natal.
The International Labour Organisation (ILO) estimates that 132million children aged five to 14 work on farms all over the world.
This year's theme - Harvest for the Future - was used to highlight the plight of children working on farms.
According to the study, adverse poverty, especially in rural and farming areas, pushes children into child labour.
Leading the pack is KwaZulu-Natal, where nine out of 10 children aged between 12 and 16 are engaged in agricultural work.
"Poverty makes them vulnerable, but child labour cannot be fully eliminated without tackling poverty, enforcing labour laws and bringing offenders to book," said Judica Amri-Makhetha, an ILO representative in South Africa.
Professor Andy Dawes of the HSRC, who led the study, said a distinction should be made between child work and child labour.
"Child work includes paid and unpaid work in agriculture and also includes all activities that do not break the law.
"Child labour, on the other hand, is in breach of the law and includes all activities that are detrimental to the child's wellbeing," said Dawes.
It was found that 91percent of children in KwaZulu-Natal work on sugar cane, banana and citrus farms.
Mpumalanga was second at 59percent and the Western Cape was third at 17percent.
The causes of child agricultural work included a need to help the family, parental alcohol abuse and parental interest in keeping children busy, said Dawes.
"This resulted in children missing school, injuries and damage to health as a result of using heavy machinery and dangerous tools meant for trained adults.
"Most of them even experience depression and anxiety," said Dawes.
Francisca Velaphi of the Department of Labour said they, together with other stakeholders, have submitted a proposal on Child Labour Programme of Action (CLPA) to cabinet. The aim of the proposal is to put an end to work that harms children.
"Cabinet has noted the CLPA and is looking into the cost implications," said Velaphi.