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Press Releases Giant grass to replace Canterbury’s lost shelter belts?

A side effect of the growth of irrigated dairy farms in the dry Canterbury Plains is that in order to facilitate large-scale central pivot irrigation, many of the region’s traditional pine and macrocarpa shelterbelts have been removed.

The dairy industry is aware that this is not desirable, particularly because it raises issues of animal access to shelter and the impact of irrigated intensive farming on an alluvial plains ecosystem. But now there is a potential solution in sight and one that will meet the needs of animal welfare, the environment and irrigators.

PhD student at Lincoln University Chris Littlejohn, with sponsorship from Westland Milk Products and DairyNZ, has been conducting a study, Miscanthus Grass on Dairy farms: multiple benefits, which looks at the use of giant (up to 4m tall) bamboo-like perennial grass as a shelter plant on Canterbury dairy farms.Westland supplier Mark Williams has hosted the trial on his Kirwee property near Burnham Military Camp. It is the first known study specifically looking at the value of miscanthus as a shelterbelt plant.

While the trial is still underway, initial results are very promising. They indicate that miscanthus is not only an effective shelter plant for animals, it also shelters pasture – promoting grass growth and reducing moisture loss and therefore reducing the amount of irrigation needed. An extra benefit is that miscanthus can be harvested annually to provide a cheap and easily extracted renewable diesel fuel.

Steve Wratten, Professor of Ecology at Lincoln University, who is supervising Chris’s PhD, says there is potential for miscanthus to revolutionise dairy farming on the Canterbury Plains.

“No other product seems capable of providing these three key benefits,” Wratten says. “Effective animal shelter, effective pasture shelter and a cash return in the form of renewable diesel. Plus it can be used as fodder, as a superior bedding material in calf sheds, and, dried, as fuel for boilers to reduce dependence on diesel, coal and electricity.”
Westland Milk Products Environmental Manager Chris Pullen says it was this multi-purpose potential that attracted Westland to the research project as principal sponsor.

“Our customers frequently ask how we ensure that the products they are buying are ethically produced from an animal welfare, sustainability and environmental point of view. We can’t just say we are concerned about these issues, we have to be able to demonstrate it.”

It’s not just Canterbury’s cold southerlies that cows appreciate shelter from, Pullen says. “Miscanthus can equally shelter stock from the summer’s hot and dry nor’westers, which can be as stressful for cows as they are to humans, with a resulting impact on production.

“Farmers naturally want to do their best by their animals, and are always looking for ways to increase production. Therefore a shelter plant that can improve pasture growth and reduce stock stress is of real interest.”

Pullen says that effective water management is also a critical issue, especially for Westland’s Canterbury suppliers, so anything that contributes to irrigation efficiency is worth investigating.

One of the key benefits of miscanthus is that irrigation pivots can roll right over it, Chris Littlejohn says. “The traditional tree shelter belts met a need at the time but they are inflexible and not multi-use. Gorse was also introduced as a shelter plant but became a major plant pest. The great thing about the miscanthus we use is that it is a sterile hybrid (technically it is Miscanthus x giganteus or Mxg) so it cannot reproduce itself by seed. It is spread by creeping rhizomes, but this is a very slow process as the plant is not vigorous, so any spread outside of the desired area is easily controlled by grazing or spray.

As a perennial that regrows from its underground rhizomes, miscanthus can last for many years, and grows back very quickly after an annual harvest to use the foliage for renewable diesel, fodder, or its many other uses.

“Under centre pivot irrigation, yields of 30 t of dry matter per hectare are achievable,” Littlejohn says. “That produces about 9000 litres of renewable diesel per hectare at a cost of around $1.10 per litre (compared with around $1.50 at a fuel station). In Rome, a whole fleet of city buses is powered by the renewable diesel produced from miscanthus.

“Overseas, the machinery used to extract renewable diesel from miscanthus is quite large, even though the process itself is quite simple compared to the production of biodiesel from used plant oils such as fish-and-chip cooking oil, which is an intensive and complex process. Our hope is that someone in the agricultural industry in New Zealand can be encouraged to import the technology, but in the form of a smaller mobile plant that can go from farm to farm to extract the diesel. The farmer could then choose whether to keep that product on-farm for his own vehicles or sell it.”

Wratten says that miscanthus needs to be watered but that is what makes it ideal as a shelter plant on Canterbury’s irrigated farms.

“Better still,” he says,” Chris’ studies show that the shelter from a line of miscanthus produces an eight to 10 percent increase in grass growth. That’s real return for the farmer right there!”

Littlejohn says he has teamed up with Samuel Dennis and his team from AgResearch who are doing work on pasture yield analysis. This involves closely monitoring pasture growth in selected paddocks.

“I use their machinery for monitoring pasture growth effect from miscanthus shelter and they use collected data for their research on pasture yield analysis, which produces detailed pasture yield maps at the time of grazing.”

Westland Milk Products and Lincoln University will host a by-invitation field day on the test site property on 14 May this year to demonstrate the potential of miscanthus to the likes of dairy companies and agricultural service providers. Next year, when the trial plots will be at their best, a full field day for farmers will be held.

The miscanthus used in Chris Littlejohn’s trials originates from Japan and is a sterile hybrid of M. sacchariflorus x M. sinensis. Mxg is the genotype most commonly recommended for renewableproduction. The plants for the shelter belt trial were sourced from Miscanthus New Zealand Limited.


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