Could be they are burning the cane fields to get ready for harvest?
I'm not on the island so I can't confirm or deny what happened, but it is the zafra(sugar harvest) until about May and I have seen them burning the fields this time of year before.
It might be a good idea to put a premium on sugar harvested in the next few months to create a demand for Haitian cane cutters. They sometimes let cane fields sit unharvested for years until the price makes it worth their while to cut it.