Building a better pasture

Funded through the Federal Government’s Future Drought Fund, the aim of the latest trial is to identify how to fill pasture grazing needs year-round on the farm.

Research has indicated a linear increase in operating profit of $250/hectare from each additional tonne/ha of dry matter consumed by milking cows.

Twenty plots have been allocated, sown in autumn 2023 with 12 species mixes, growing on the side of a hill as a dryland crop on the 180ha research farm.

The plots were sprayed out twice pre-sowing.

Varieties sown include cocksfoot, fescue, clovers, chicory, plantain and yarrow, among others.

Depending on the weight of each seed type, they were sown using power harrows and air seeding at a rate of 20-40kg/ha, targeting an outcome of 750 plants/square metre.

Nitrogen was applied eight times across most of the plots, mostly in spring and autumn — initially 200 units of N on the rye=grass, 100 units N on the mixed species, and no N treatment on the legume-heavy plots. There was a 20 per cent stepdown in application of N going forward.

Dr Anna Thomson, research scientist at the Ellinbank research farm, hosted a tour of the trial on July 5.

The current trial plot builds on a previous trial that analysed the growth, volume, dry matter and regrowth after grazing of rye-grass pasture varieties.

Anna said she was also researching how the root systems of multispecies varieties affected soil type and health; what is the optimal percentage of legumes in pasture; and the effect of varieties on perennial rye-grass growth and volume.

“We didn’t want to be too limited in diversity of pasture species,” she said.

“Over the year, some mixtures outperformed the perennial rye-grass.

“In summer, herb heavy pasture continued to grow compared with rye-grass.

“The role of herbs is to fill feed gaps in summer.”

A report on the first year’s growth is due by the end of this year.

In spring this year, an economic analysis of milk production will be added to this pasture research study.

“We’ll be measuring milk production and milk solids and hoping to see a slight increase in milk yield and improvements in milk quality,” Anna said.

“We hope to compare pasture growth with seasonal changes in milk production, metabolisable energy changes, and changes in plant growth compared with the weather.”

Some of the key indicators they are already measuring includes fibre, carbohydrates, protein and energy levels in the pasture.

“We’re finding there’s lower fibre in the multispecies compared to rye-grass,” Anna said.

The SmartFarm also uses technology in the dairy to collect methane emissions from cows, during milking, twice a day.

“We should be able to measure any change in methane output and compare it to what the cows are grazing,” Anna said.

Anna said the trial plots will be managed to reduce seeding by the pasture and a weed management strategy is in place.

“During the establishment phase, the plots were mowed a couple of times,” she said.

She is currently seeking expressions of interest from dairy farmers interested in allowing on farm trials on their properties, to be established in autumn 2025.