Farmers are advised not to bury dead stock, plastics, household rubbish and vegetation in the same offal pit, as the breakdown of the combined material could create a toxic leachate, which could be hazardous to humans.
The leachate could move through the soil into waterways and groundwater without being broken down and provide an additional source of contamination.
Environment Southland’s land sustainability officer David Moate said disposing of dead stock, especially at this time of year, was not a new problem.
He was not aware of any dead stock collection services being offered in Southland.
"Every year we have challenges around dead stock. It is a constant problem for the farmers.
"If animal carcasses are buried with plastics, old timber, vegetation and household rubbish, the breakdown process produces a really toxic, really awful leachate with chemicals including ammonia, nitrogen, phosphorous and bacteria, which will dissolve plastic and copper and discharge heavy metals.
"There is an active risk to human health from the leachate," Mr Moate said.
"We would encourage farmers to bury their domestic rubbish, dead stock and vegetable matter separately."
Some farmers are burning dead stock, and while that is legal, there are factors around odour, and smoke to be considered.
"Burning is not a practice that is common."
