The near-identical accidents within 48 hours of each other have highlighted the plight of farm workers around the the city of Foggia in the Puglia region, where thousands of foreign nationals spend the summer season harvesting tomatoes, often at the mercy of day labourer recruiters sometimes linked to organised crime.
Striking demonstrators shouted “we are not slaves, no to exploitation” as they made their way from the countryside towards Foggia.
Italy's government has scrambled to respond to the outcry over the deaths, with hardline Interior Minister Matteo Salvini declaring war on the “mafia” in and around Foggia and promising to eradicate it “street by street, town by town”, during a visit to the region on Tuesday.
Both the road crashes in the region happened when lorries transporting tomatoes slammed into vans carrying foreign farm workers returning from their day's work.
An accident on Saturday left four African farm workers dead and four others seriously injured, while Monday's smash killed 12 people, all non-EU citizens.
The Foggia province hosts thousands of Africans who spend the summer harvesting season picking tomatoes in blazing temperatures alongside workers from eastern Europe, typically Romanians, Bulgarians and Poles.
Although most of those working in the fields in Italy have regular papers, they rarely receive the benefits and salaries required by law, and many live in squalid conditions.
They are often beholden to the recruiters, who operate as intermediaries and collect a portion of the workers' pay.
For years, unions and associations that help migrant workers have called for a public transport system to be created around Foggia for the peak harvest season.
The Puglia region has now budgeted for such a system, governor Michele Emiliano said on Monday, but he added that cooperation and transparency from the farms was crucial.