* South Africa in midst of political land debate
* Whites still control most of commercial arable land
* Zimbabwe farm union leader urges sensible talks
* Zimbabwe's economy crashed after Mugabe's land grabs
HARARE, July 21 (Reuters) - A Zimbabwean farmers' union leader warned white South African farmers they should agree a deal to share land with the black majority before they suffer the same fate as neighbours in Zimbabwe who were violently removed from their properties.
Land redistribution is a burning political issue in South Africa and has divided the ruling African National Congress (ANC) ahead of a December conference where President Jacob Zuma's successor as party leader will be chosen.
Many Zuma supporters are demanding land expropriation from whites without compensation, while the radical Economic Freedom Fighters (EFF), an increasingly popular four-year-old party, has told South Africans to occupy unused land illegally.
Although Zuma has said any land reform will be done sensibly and within the law, there are concerns that the populism in South African politics could lead to the scenes witnessed in Zimbabwe in the early-2000s.
Zimbabwean President Robert Mugabe permitted violent land seizures from white farmers, beginning in 2000, that prompted the international community to cut off ties and sent a once-promising economy into a tailspin.
"We were arrogant. We thought they would never take the land because we were too important for the economy," Peter Steyl, president of Zimbabwe's Commercial Farmers Union, the nation's biggest commercial farming union, told Reuters.
"You never think it will happen until people turn up at your door armed with machetes, off their heads. It gets pretty real."
"They are facing the same situation in South Africa. I would tell them: 'it's better to give a little bit now than lose everything when things go too far'."
South Africa's government says only eight million hectares of arable land have been transferred to black people since the end of apartheid in 1994, less than 10 percent of the 82 million hectares available and a third of the ANC's 30 percent target.
The ANC is under pressure to win back many poor, black voters who have switched allegiance to the EFF, founded by Julius Malema after he was expelled from the ANC for misconduct.
Malema, a former protege of Zuma who has become a thorn in his side, is due to appear in court on charges of inciting violence due to his comments on land grabs.
Steyl said taking land without compensation would be disastrous and would prompt investors and foreign institutions such as the International Monetary Fund and World Bank to turn their back on Africa's most developed economy.
"That would be blind stupidity. It's possible you will never recover," Steyl said. "I know there are huge problems with unemployment in South Africa. Everyone needs to come to the table to negotiate."
Agriculture employs 850,000 people in South Africa, or 6 percent of the workforce, and the country of 56 million is a major food exporter.
Jannie de Villiers, CEO of South African commercial farming group Grain SA, said he was confident there would be no repeat of the chaos in Zimbabwe because South Africa's constitution does not allow land expropriation without compensation.
He also said South African white farmers were committed to working with the government on land reform.
"We realise there is a lot more we can do to allow land reform to happen. We think the percentage chance of going down the Zimbabwe route is very small," de Villiers told Reuters.
ANC LEADERSHIP VOTE
How to address the inequality that still exists 23 years after the end of white-minority rule will be the central debate at the ANC leadership vote in December.
Veteran politician Nkosazana Dlamini-Zuma, Zuma's ex-wife, is expected to run on a campaign to radically transfer wealth from the white minority to the black majority, including land reform.
Her main opponent is expected to be Deputy President Cyril Ramaphosa, who has also called for wealth redistribution but has made tackling government corruption and winning back investor confidence priorities.
Steyl warned against politics driving land reform, as happened in Zimbabwe when Mugabe allowed land grabs to secure the loyalty of the military.
The knock-on effects were disastrous. Zimbabwe tumbled into recession, inflation peaked at 500 billion percent. Unemployment is now above 90 percent.
"Don't allow it to happen to you," Steyl said. "You have to engage. You have to be sensible. You mustn't allow desperation to win they day." (Additional reporting by Ed Stoddard; Writing by Joe Brock, editing by Peter Millership)