Developer stands by product

“It’s a wonderful technology to reduce the environmental footprint of farming but due to a potential trade issue it has had to be suspended,” Lincoln University’s Professor Keith Cameron told Dairy News.

He says he’s “fairly confident” those trade issues will be overcome, though stresses that’s not his area of expertise. “It’s been proven it’s not a health risk at the levels detected.”

Ironically, that very safe nature of the compound – “it’s ten times safer than the table salt we put on our food every day” – is part of the problem: it’s so safe it was never added to the lists of pesticides for which maximum residue levels (MRLs) are set, he says. “So we’ve ended up with the default level which is zero.”

Now that some organisations, such as the US Food and Drug Administration, have started testing for it, an internationally accepted MRL is needed. How long that will take he’s not sure, but some trading blocks, such as the EU where DCD has been used for decades, already have a TDI (tolerable daily intake) for it, he notes.

As for Otago University researcher Marc Schallenberg’s paper suggesting DCD could upset water ecosystems (see story below/opposite/pXX), Cameron suggests DCD in water is likely to be the lesser of two evils. “Nitrates in water are probably a bigger problem than a trace amount of DCD.”

In soil, the chemical is typically broken down after two-three months but in water it is much less: “more like ten days.” 

Those breakdown rates seem unlikely to change even in the face of repeated, year-after-year use as studies in Germany show no change in soil enzyme activity after 25 years DCD treatment, he points out.  Work in New Zealand spanning 4-5 years’ use also shows no change in its breakdown.

Cameron says while he “looks forward to the day this effective tool is brought back into the toolbox,” in the meantime there are things farmers can do to manage nitrate losses, regardless of DCD’s suspension:

• Whole farm soil test.

• Budget nitrogen inputs, outputs and losses.

• Precision apply fertiliser.

• Use winter active forage species.