'Spray and pray' farming practice condemned

Hillsides are being sprayed and sown from the air in Rangitikei. PHOTO/ SUPPLIED

The new practice of spraying out steep hillsides to grow winter crops for cattle causes erosion and must be regulated, environmentalists say.

Known as "spray and pray", it involves helicopters spraying hill country with herbicide and then adding seeds and fertiliser to grow high energy winter crops for cattle. It's becoming more common, especially for large farming operations.

It's a feature of the inland Rangitikei District, which is drained by the Rangitikei River, one of 15 in New Zealand with a Water Conservation Order. But it is done elsewhere as well.

National Fish and Game Council CEO Bryce Johnson was alerted to the effect on the river by Taihape fishing guide Stephen Mattock, who told him the water was sometimes cloudy at times when there had been no substantial rain.

It's happening because vegetation cover has been stripped off, Mr Johnson said.

"It's a sitter for erosion, and it could be an absolute disaster."

The practice has increased in the last decade, Rangitikei environmental consultant Greg Carlyon said. It's a drive to get more out of the hill country, and, like feedlots, a way to keep cattle gaining weight over winter.

When the soil is bare rain washes it into waterways, along with its organic matter, nitrogen fertiliser, phosphorous and animal faeces. Topsoil, "the farmers' gold", is both lost and compacted by the heavy animals.

Mr Carlyon believes some of the helicopter work may be subsidised by fertiliser companies.

Farmers should have to get resource consent for the practice, he said. They were likely to carry on with it until told to stop, and he wanted Horizons Regional Council to step in.

"Horizons has a statutory obligation to monitor the effects of land use."

The council's land manager, Grant Cooper, said officers didn't know how widespread the practice was. But Mr Carlyon said they would, if the council had done the aerial surveys promised before 2010.

"I think they're taking a "We haven't looked, so we can't see it" approach."

Though the One Plan had no rules specific to aerial spray cultivation, it did require resource consent for cultivation of land with a more than 20degree slope, he said. But its definitions of cultivation, vegetation clearance and land disturbance could all be called into question.

"I think they're trying to find a way to not have to do their job," Mr Carlyon said.

Mr Cooper said the council was looking at the matter, and needed to know more about the environmental impacts of the practice.

For people using best practice management techniques, the impact should be reasonably minimal, he said. The One Plan requires a minimum buffer zone between crops and waterways on slopes steeper than 20degrees.

"But of course it depends on the accuracy of the spraying application. Sometimes trees go. Sometimes they will spray over the fence. Sometimes a riparian margin gets sprayed out."