Pasture: NARF responding to climate change

RESEARCH WRAP NORTHLAND AG RESEARCH FARM

NARF farm manager Kelvin Horton, NDDT coordinator Kim Robertson, and NDDT science manager Chris Boom ponder the damaged ryegrass pasture in April. Picture by Kim Robinson.

Words and photos: Delwyn Dickey

The rolling Northland countryside is a rich green patchwork of ryegrass and kikuyu in early summer. But come autumn, much of the ryegrass is struggling as the hot dry weather sucks moisture out of the soil, often leaving the shallow rooted grass in trouble.

Northland is warming up and is at the forefront of the effects of climate change in New Zealand farming. By 2040 there are likely to be between 20 – 30 more days annually with temperatures above 25 degrees Celsius, with increasing droughts.

The warming climate is already putting pressure on farming systems using traditional ryegrass-based pasture, and is seeing more farmers looking to alternatives. On top of this the Government is also giving farmers a clear message to reduce greenhouse gas emissions.

With this in mind the Northland Dairy Development Trust (NDDT) is running a four-year trial at NARF at Dargaville. The farm is split into three 28 ha farmlets.

Three different farming systems will look at performance using alternative pastures, reducing emissions on a traditional ryegrass-based farm, and the farming system recently highlighted in their previous trial as being the most profitable, being used as the control. (See the July issue of Dairy Exporter).

The current/control farm uses ryegrass and kikuyu pasture, and only palm kernel expeller (PKE) to fill feed deficits before milk fat evaluation index (FEI) limits are reached, with a stocking rate of three cows per hectare, with up to 190kg of applied nitrogen per hectare.

The alternative pastures farm will have at least 75 percent of fescue, cocksfoot, legumes and herbs pasture, and also use PKE to make up feed deficits.

Stocking rates will also be three cows per hectare and up to 190kg of applied nitrogen per hectare. Fonterra has provided funding to monitor if there is a difference in milk quality and composition from the alternative pastures, NDDT coordinator Kim Robinson says.

The low emissions farm will use existing ryegrass and kikuyu farm pasture and targets a 25% reduction in methane emissions and a 50% reduction in nitrous oxide emissions (compared to the current farm). The stocking rate will drop to 2.1 cows per hectare, with no nitrogen application. There will be imported supplement but little or no imported feed. While the farming industry will have until 2050 to reduce their emissions by about this level, there is no reason to wait, Robinson says. “Let’s try this now and see what happens.” To get the alternative pastures farm up and running by the trial start in June, 9ha was sown in May 2020 with combinations of fescue - or fescue and cocksfoot, with white, red and Persian clover. Another 11 ha has been sown in March, with fescue - or fescue and cocksfoot, with white clover, red clover and a small amount of chicory. Pasture quality monitoring so far, has already shown the fescue/cocksfoot pastures out performing kikuyu and ryegrass during summer and autumn, while on par during winter and spring. Animal health effects including things like heat stress, will also be measured, Robinson says, with a rumen bolus on each cow to record temperature and ‘The warming climate is activity, to help already putting pressure indicate if the on farming systems using traditional ryegrass-based animal is sick or unwell after eating on the different pasture, and is seeing pastures. Farmax more farmers looking to and Overseer alternatives.’ computer modelling suggests milk production will be higher under all climatic conditions on the alternative pasture farm, while the low emissions farm is predicted to have significantly lower production. The full trial parameters, modelling, and early results can be found on nddt.nz website. The project is funded by DairyNZ, MPI (Sustainable Farming Fund) and Hine Rangi Trust.