Excessive agri-chemical use by the farmer in Queen Elizabeth Park is not appropriate on public land and their licence should not be renewed in 2020, Friends of Queen Elizabeth Park trustees believe.

The trustees learned of a large spray event on park farmland visible from State Highway 1 several weeks ago.

The farm licence-holder, Wairarapa-based Beetham Pastural Ltd, is not required to notify the public of imminent spraying and it is the third such event since Beetham took over the licence in 2015.

Friends chairman Russell Bell said the trustees have decided to ask park managers Greater Wellington Regional Council not to renew Beetham's five-year licence for another five years because the farming method conflicts with the Reserves Act.

''Independent and GWRC surveys of water quality indicate that it is declining year on year and that is because of what is happening in the farm paddocks."

"Flora and fauna is an important aspect of a recreation reserve such as QEP and farming must not lead to the degradation of flora and fauna, nor the degradation of water quality.

"Independent and GWRC surveys of water quality indicate that it is declining year on year and that is because of what is happening in the farm paddocks."

Friends trustee Peter Brooking said an Official Information Act request revealed Beetham Pastural in their first year of operation used more than 46,000 litres of toxic sprays over 59 hectares of park farmland.

"It was a recipe of herbicides and insecticide that annihilated all green foliage and insect life.

"There is no reason to believe that this year's spraying differed from the regime begun in 2015.

The insecticide is designed to kill springtails, whose role in a healthy ecosystem is to transport nutrients for the enrichment of the soil.

"Springtails interfere in the agrichem method of monocrop establishment and every other insect that happens to be within the many hectares sprayed are collateral damage."

Mr Brooking said trustees had canvassed public opinion in the communities that neighbour the park, Raumati South and Paekakariki, and say there is widespread dismay and angst at the volumes of chemicals being used for the purpose of intensive farming that threatens the fragile ecology of the park.

"Also, nobody knows how far the sprays drift over land, in the soils, through the waterways and out to sea. Chemical drift is a real health concern to residents and park users.

"The park was not closed, nor residents and park visitors warned during the recent two days of prolonged spray application on the farm.

"People are asking us how the farmer is allowed to do this on public land."

A Wellington Regional Council spokesperson responds:

"We are confident that these pasture renewal practices were consistent with all applicable regulations and guidelines, and spraying of herbicides is only undertaken by suitably qualified contractors strictly in accordance with manufacturer's guidelines and the terms of the farm licence.

"Herbicide selection and rates of application have been determined by H&T Agronomy, and is based on the weeds present.

"The pasture renewal plan was reviewed by our Land Management advisor and some minor changes made (to fertiliser application) as a result.

"Sparta insecticide (20ml/ha) will be applied to control springtails, which can eat out the seed.

"The areas sprayed have been farmed for decades and there is almost no native vegetation in these paddocks.

"Plants emerging naturally are typically exotic weeds.

"There will be no run-off to streams as part of this; the spray was applied at a rate that it dries on the plant, and it was applied in conditions that eliminate drift.

"These areas are well away from park tracks and recreation areas so there is no risk to the public.

"As a result we have no concerns about Beetham Pastural Ltd's pasture renewal programme."