Pesticide residue may rule out certain types of organic production on some Tasman properties, the head of an organic certification agency says.
Bio-Gro New Zealand chief executive Seager Mason, of Nelson, said poultry, meat and dairy plus some vegetable production was susceptible to chemical transfer, but pesticide residue concerns were not
new to organic growers.
His comments followed a Waikato University report suggesting pesticide contamination on many properties in the Nelson region. Detailed locations were not given.
"If an area is to remain as an orchard it's not usually a problem, but you couldn't run poultry on areas with residue, and there are a few vegetables unable to be grown, such as garlic, which contains oil and can absorb the residue," Mr Mason said.
Tasman Mayor John Hurley said last week that identifying properties could result in new standards being applied if land use was to be changed.
He said yesterday that this was more likely to apply to people buying lifestyle blocks and unaware of the criteria needed to certify land for organic production.
Property owners would be notified individually if their land was found to be in an area likely to contain pesticide residue, such as DDT.
Most at risk were areas used for orchards before 1975, when use of some chemicals was at its highest.
Mr Mason said organic growers and the meat and dairy industries had been aware of the problem for several years.
"All organic farms operating have had soil tests," he said.
"They have been tested over the past five years."
He said pesticide residue limited the amount that could be produced organically in any area, rather than whether a property could be certified as organic, but anyone considering changing to organic production needed to check for DDT first.
It was not usually a problem with pipfruit or grapes, as the chemicals could not be transferred through the trees or vines to the fruit.
The dairy, meat and poultry industries were more susceptible to chemical transfer through meat, milk and eggs, which could accumulate to higher levels than what was in the soil.
Mr Mason said chemical residue was "everywhere" in Nelson and Tasman, although some soils had tested with zero levels.
Auckland organic researcher and consultant Dr John Clearwater said that because pesticide residue was mostly bound in the soil, it was unlikely to travel from the plant into the fruit.
Landowners wanting to test for pesticide residue should check levels of mercury, lead, arsenic and copper.
- NZPA
Herald Feature: Conservation and Environment
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