Thursday, 14 February 2019 09:30

Cutting nutrient loss poses big challenge for farmers

Written by 
Hawke’s Bay farmer Andy Hunt and MyFarm consultant Rachel Baker. Hawke’s Bay farmer Andy Hunt and MyFarm consultant Rachel Baker.

A Hawkes Bay project aimed at cutting nitrogen losses has provided challenges and lessons for its farmers involved.

Two dairy and two drystock farmers in the Tukituki catchment took part in ‘Greening Tukituki’ — a project now closing — to help them meet nutrient loss obligations under the Hawkes Bay Regional Council (HBRC) plan change 6. 

The project closes amid growing disquiet about shortcomings in the nutrient software system Overseer as a regulatory tool. 

A recent report by Parliamentary Commissioner for the Environment Simon Upton found gaps and shortcomings in Overseer that undermine confidence in its suitability as a regulatory tool to be used on farms.

The Hawke’s Bay plan change requires farmers to match their nitrogen losses to their land use capability (LUC) classification, spanning eight different classes based on a property’s physical characteristics.

The results from two farms shows what many farmers face in the catchment and in New Zealand as every region starts to grapple with plan changes managing nutrient losses.

Takapau feedlot farmer Rob Foley found the project invaluable in presenting him with options when the data gathered showed that his 1100 dairy cows grazed over winter were a key source of nitrogen losses.

His options were to either do expensive bore testing to determine how much nitrogen was being leached from cow urine, or consider a lower nitrogen-loss type of farming.

He opted for the latter, dropping the cows for half the number of bulls, reducing his LUC loss from 41kg/ha/year to 36kg.

“While the cashflow is definitely reduced by not having the dairy grazers, financially it is still profitable running the bulls instead,” he says.

Other things examined during the project have included losses from winter wheat and examining different grass species including plantain to absorb nitrogen.

“For us the project was definitely worthwhile... in showing us how to become more compliant, and to demonstrate to council how hard it is to do these things and still make a profit.”

Ashley Clinton dairy farmer Andy Hunt has not had all his nitrogen issues solved by the project, but it has lifted the hood on some of his options, and highlighted to the regional council how challenging meeting nitrogen loss targets can be. Hawkes Bay Regional Council was a supporter of the Tukituki project.

Much time and energy has gone into working out options for the 360-cow operation to get it within 30% of its LUC nitrogen leaching rate limit of 21kg N/ha/year; at present it is about 40% over its LUC allocation.

The Hunts accept there is no ‘silver bullet’ solution to getting the farm within that limit, but planting more plantain in the farm pasture mix may help; this has been shown to help reduce nitrogen losses.

“But the project has also highlighted that plantain is not included in the Overseer model, and until it is this possible tool is out of our hands to some extent,” says Hunt.

But he was encouraged by the regional council’s positive attitude to using plantain.

Another option for Hunt could be to build a composting barn, but the $500,000 cost would require that he got more assurance from the regional council that the operation would be compliant if he went ahead with it. 

An alternative is to further reduce the stocking rate of the already low-stocked farm but this impacts on profitability and long-term viability.

“You could say the project has not solved our problems, but it has certainly raised the profile of them and has highlighted these challenges to the council that we face to meet these standards.”

Picture-perfect farms still unsure

Project manager and MyFarm agribusiness consultant Rachel Baker said there is much uncertainty about how farms in the catchment will meet the plan change standards.

“And this is from farms that at face value are picture-perfect – well run, with healthy stock and owners who care about the environment.

“Plantain looks like it could be a game changer in helping reduce nitrogen losses, and that is supported by peer reviewed science. It’s something many farmers including Andy Hunt have also been sowing in their swards for a few years now.

“And in the case of Rob, he moved quickly by stopping dairy cow grazing and replacing them with bulls, and immediately reducing the magnitude of nutrient loss.  However this in turn presents a challenge for where dairy cows will be wintered in future.”

She said the project had also put the practical realities of the council plan change in front of those who implement it, and had helped council staff and farmers better understand the plan’s impact.

The Greening Tukituki project was sponsored by Agmardt, Hawkes Bay Regional Council, Beef + Lamb NZ, Ballance Agri Nutrients, DairyNZ and ANZ. The full report can be viewed at


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