Trial builds climate resilience

Northland farms are likely to be first to face the effects of a warming climate that the rest of New Zealand will experience over time.

That is why farmers are paying close attention to the scientific work of the Northland Dairy Development Trust.

A five-year trial looking at how farmers can mitigate and adapt to climate change is under way on the trust's Northland Agricultural Research Farm, near Dargaville.

AgFirst Northland consultants Kim Robinson and Chris Boom are contracted by the NDDT to manage the science on the research farm, which is owned by all Northland farmers.

The farm was gifted to be used for the study of farm systems so the trial, which has been running for a year so far, fits perfectly into that remit, Robinson said.

"The research is strongly farmer-driven and the latest concerns about the effects of climate change and the changing regulations have led to the current trial," she said.

"Farmers want to know how different types of pasture will perform in a warmer climate and at the same time how they can meet the Government's targets to lower greenhouse gas emissions on their farms.

"While there is plenty of modelling information, farmers are uncertain what strategies will work and whether their farms will still be profitable," Robinson said.

The research farm is split into three farmlets, each with its own herd, which is milked into three separate vats.

Colour codes are used to keep track of each herd and pastures they graze.

The Current farmlet and its herd has a red colour code, and has an existing ryegrass and kikuyu pasture with imported feed used to fill feed deficits. It has a stocking rate of three cows per hectare and up to 190kg of nitrogen fertiliser applied per hectare.

The Alternative Pastures farm, which has a blue colour code, has the same stocking rate and fertiliser applications, but has at least 75 per cent of pastures in other species such as fescue, cocksfoot, legumes and herbs with imported feed to fill feed deficits.

The Low Emissions farm, which has a green colour code, uses existing ryegrass and kikuyu but targets a 25 per cent reduction in methane emissions and a 50 per cent reduction in nitrous oxide emissions compared with the Current farm. The stocking rate is lower, at 2.1 cows per hectare, with no nitrogen application and little or no imported feed supplements.

Robinson said the paddocks were all randomised at the start so the herds experienced similar terrain and farm management rules are kept the same to keep those factors from affecting the scientific experiment.

"The farmlets are run by our very experienced farm manager Kelvin Horton and the trial is overseen by a committee of local farmers and scientists, which meets every two weeks," she said.

"They are all good farmers and so we have some pretty good debates."

Robinson said the farm was high performing and the farm business had to perform as a commercial enterprise. "It's a real farm. The only difference is we take normal farm systems and overlay the science."

Robinson said the upper North Island was already seeing more dominance in kikuyu and paspalum and a decrease in the performance of ryegrass due to milder winters and hot, dry summers.

"The prediction is that there will be significantly more hot days over 25C by the end of the century.

"Farmers are beginning to introduce alternative species to ryegrass in an attempt to increase pasture productivity and persistence. There is little known about how this will impact milk production or composition, and the grazing management strategies required when these species cover a large proportion of the farm."

She said the trial aimed to develop new pasture management guidelines for farmers who were used to ryegrass management principles.

The farmlet trial commenced in June and will run for four years to test these systems under a range of climatic conditions.

Trial measures would capture a large range of data including pasture and milk production, milk composition, profit and labour data on the three systems. The separate vats would allow the analysis of any changes in milk composition from herds on alternative pastures.

Initial results of pasture quality monitoring had indicated the two pasture types had similar pasture quality through late winter and spring, but the alternative pastures showed higher quality through most of summer and autumn.

Robinson said the trust had decided to try to meet 2050 industry targets of a 25 per cent drop in methane relative to the Current farmlet, which reflects most Northland farming systems.

The 2050 target of net zero nitrous oxide would be difficult to achieve through farm management change alone, but the trust had decided to aim for a reduction of 50 per cent.

"We expect other technologies and offsetting will be used in future farm systems to achieve the net zero emissions target," she said.

The NDDT had been consulting DairyNZ scientists and working with NZAGRC, AgResearch and Fonterra to maximise the data and learnings from the project.

The two main funders of the project are the Ministry of Primary Industries (MPI - Sustainable Food and Fibre Fund) and New Zealand dairy farmers through DairyNZ. Additional support is provided by Fonterra, Hine Rangi Trust and NDDT. NDDT is also supported by Farm Source, Ballance Agrinutrients and FIL.

Fortnightly updates are posted on Facebook and the NDDT website www.nddt.nz. There is also the opportunity to visit the farm or receive fortnightly email updates.