Using science to identify forage value

Using science to identify forage value

Monday 14th March 2022

A scientific method already used widely across medicine and forensic science could provide a fast and cost effective way for New Zealand farmers to identify the nutritional value of native forage and exotic forage.

Massey University Masters student Gregory Coleman is researching the effectiveness of Attenuated Total Reflectance Fourier Transform Infrared (ATR-FT-IR) spectroscopy to enable farmers to accurately analyse nutrients in shrubs and trees.

His research is one of the many trials and studies underway through the Hill Country Futures Partnership programme (HCF).

The $8.1m five-year partnership programme is co-funded by Beef + Lamb New Zealand, the Ministry of Business, Innovation and Employment, PGG Wrightson Seeds and Seed Force New Zealand. It is focused on future proofing the profitability, sustainability and wellbeing of New Zealand’s hill country farmers, their farm systems, the environment and rural communities.

It incorporates traditional science research, farmer knowledge, social research and citizen science and has a strong emphasis on forages and providing decision-making tools to help farmers select the best forage option for different land management units.

One aspect of the research is to gather robust scientific evidence on the potential of native shrubs and trees in steep erosion-prone hill country. This will help inform farmers’ decisions around planting.

Potentially, native shrubs could be used to help retain erosion-prone land, enable farmers to claim carbon credits while still also using the land for grazing, and provide a complementary forage for sheep and cattle. Feral deer are known to graze on certain native shrubs and the research will assess the suitability of these for livestock.

Gregory’s role in the programme is to help identify a faster and more cost-effective process for farmers to test nutritive qualities of the native shrubs.

“There are two other methods which are commonly used to analyse the nutritive content of plants but these can cost up to $200 per sample,” he said. “ATR-FT-IR chemometrics method is much cheaper and faster. It has already been used to analyse pasture species in New Zealand, but this is the first time it has been applied to native New Zealand plants, so it’s a chemistry first.”

Griselinia, Coprosma, Pittosporum, Horeria, Mahoe and Pseudopanax are being used in the trial. Samples are freeze dried and then ground up, with only a tiny amount needed for analysis.

The samples are first analysed for their nutrient content in the lab by wet chemistry, then they are scanned with the ATR-FT-IR equipment. Both the wet chemistry data and the scanned are then used to develop calibration equation for the different nutrients.

“This has the potential to be a faster, cheaper and better predictive method for farmers than the alternatives previously used,” says Gregory.

“Farmers could send a sample of their crop to the lab to be freeze-dried, ground up and then run through the ATR-FT-IR equipment. Based on the calibration equations developed in this project a table with the nutrient content of the sample will be provided to the farmer.

“We have a good system in place and we now need to explore more analysis methods to ensure we have the most accurate calibration to use for the predictions.

“If it proves as reliable as the other two methods, the benefit for farmers will be a cheaper, faster method of analysing forage crops on their land. At a later stage of the project we will be trialling using fresh samples, rather than freeze-dried, which will mean farmers could get results even faster.”

Gregory was born in the UK – where he developed an interest in agriculture through visits to a family farm – before moving to New Zealand in 2014. He graduated from Massey in 2021 with a BSc, major in chemistry and minor in earth science. He is due to complete his Masters research in June this year.

“I’m finding it really interesting applying chemistry to potentially help hill country farmers,” he says. “It’s very satisfying. There’s the biodiversity side, getting natives back on slopes and using New Zealand shrubs and trees as an alternative to imported plants like pines; There’s the potential to help address erosion and also provide an alternative forage. All that could be very good for hill country farms.”

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