Agri SA said the aim of the Black Monday campaign was to create awareness about farm murders in particular and crime in general.
Executive Director, Omri van Zyl, told Algoa FM News that being a farmer in South Africa "is the most dangerous occupation in the world".
He said this situation was unacceptable given the country's Constitutional democracy, rule of law and the principles that have to be applied.
"It's not just a farming campaign, it's a South African campaign that's saying enough is enough, we've had enough of crime and violence in this country, let's start doing something about it.
A group under the banner "Genoeg is Genoeg" reportedly organised the demonstration on social media following the murder of Klapmuts farmer Joubert Conradie.
Thousands of South Africans took to the streets across the country in support of the Black Monday campaign, with marches in George, Mossel Bay as well as Oudtshoorn.
In Nelson Mandela Bay, neighbourhood safety group Farmcomm, supported by other neighbourhood watch groups, held a motorcade procession on the N2 in support of the campaign.
Farmcomm's Willie Bosch stressed that this initiative was apolitical.
Bosch said "this is not a political thing" as there are farmers of all races who also suffer under the scourge of violence.
"We are talking about supporting the farmers in general all over South Africa," Bosch said.
Meanwhile, several posts on twitter showed people displaying the old South African flag and in at least one instance the AWB flag was seen flying at the back of a vehicle.
Agri SA's Van Zyl said "that's historical stuff that does not form part of our progressive future and for us the focus in on the future and the next generation and keeping our farmers safe."
"I'm not sure how that is going to help us protect rural communities of all cultures and create a sustainable South Africa," Van Zyl said.
