The pasture advantage

New Zealand has a reasonably reliable rainfall and grass to thank, at least in part, for its verdant lush greenness that makes the country’s rural landscape so easy on the eye. But underlying those rolling vistas of pasture and crop is a vast surplus of plant protein that creates a paradox for our farming sector.

“Grass fed” red meat and milk products are in high demand internationally, increasingly recognised for their high-quality, nutrient-dense food value. However, having more crude protein available in pasture than livestock are capable of digesting leads to the protein being converted and excreted as nitrogen. This in turn contributes to excess nitrate-nitrogen in water systems and aquifers.

New Zealand scientists are working on ways to extract protein from our abundant forage crops, including ryegrass and alfalfa, in a way that can deliver an alternative protein for human food. This could offer a means to better balance livestock diets, without diluting the “grass fed” value proposition. Alternatively, after recovering the protein, the residual fractions could go towards making biofuels to drive a low-emissions future.

Dr Lee Huffman Food Solutions Leader at Plant & Food Research, and her team are focused on maximising the total amount of protein extractable from pasture crops. The team have developed proprietary systems and processes to do so that include technology adopted from other sectors, including vegetable juicing and milk protein isolation.

“The technology we have developed could apply to any soft, leafy green plant, including common pastoral feed crops ryegrass, alfalfa, kale and forage brassicas.

“Our modelling shows that alfalfa and ryegrass are the best crops for establishing a plant protein industry in New Zealand. Traditional technologies have focused on extracting RuBisCO, a protein that is only 50% of the total protein available. We’ve developed a technology with a much higher yield, extracting as much protein as possible. Combining a high potential yield with existing land use and reduced environmental impacts creates an attractive economic proposition for establishing a new food sector.”

Previous extraction work has also tended to focus mainly on the lower value animal feed market. Huffman and her team see an opportunity for formulating both high-value human and companion animal and fish food products using protein extracted with their closely guarded technology. Extracting food-grade proteins from leafy plants is not an easy task. The competition from well-established seed crops like soy and peas is significant, amplified by the economies of scale that vast broad-acre farms in the United States, Canada and Brazil offer.

Subsidisation of traditional seed crops in many of those countries can tilt the economics against emerging technologies, which may struggle to achieve the capital investment required to scale up to commercial production.

One advantage in favour of leaf protein is the high nutritional value, with leaf proteins being “complete proteins” containing all nine essential amino acids for human nutrition – a rare attribute for a plant protein.

A further economic challenge facing recovering protein from pasture crops is that New Zealand dairy farmers have great economic success in converting pasture to milk, and the significant capital tied up in their milking platforms encourages maximising milk production. That need discourages growing pasture crops to extract protein directly, rather than through milk solids.

But in a world where dairy farmers encounter increasing pressure to lessen their environmental impact, redirecting a portion of the farm from milk production to grass protein extraction may provide an avenue for that gentler footprint.

Modelling on-farm performance reveals that nitrogen-nitrate losses can be significantly reduced, and greenhouse gas lessened somewhat, when a portion of the farm is closed off to grazing and the pasture recovered for protein extraction, with the residual “cake” fed to cows as a supplementary feed.

Plant & Food Research has engaged farm consultants to analyse how much of a reduction in nitrogen-nitrate losses such a dietary tweak may provide, and how this could be incorporated into farm nutrient management plans for improved environmental performance. As the primary sector develops mechanisms for allocating and pricing on-farm environmental impacts, the incentive to consider such technology is likely to grow.

For non-dairy farmers the opportunity to grow a pasture crop for protein harvest offers another valuable cash crop or additional diversified income for dry-stock farmers. “But it is a long runway to commercialisation and involves working hard to bring on board enthusiastic industry players,” says Allan Main, Business Manager at Plant & Food Research.

Meanwhile, there is a clear trend towards diversifying protein consumption amongst consumers, which provides a growing opportunity for new plant proteins. Around a third of the population in Aotearoa New Zealand are already limiting their meat consumption, with 15% eating a largely vegetarian or flexitarian diet. That drift is expected to continue as consumers increasingly factor in environmental considerations to their dietary choices.

“The proteins we are extracting also have an amino acid profile that is comparable to the ‘ideal’ protein, it is functional with properties that can be managed during processing, for example solubility, gelling and emulsifying qualities,” says Huffman.

Other pasture protein extraction work is also being undertaken in New Zealand by Leaft Foods based in Lincoln. The company has recently received $8 million funding, through the Ministry for Primary Industries, to develop protein technology. Just as protein from grass may be used to fuel humans, the cellulose by-product of protein extraction could also play a role as a substrate for low-emissions fuel for vehicles, particularly as New Zealand moves towards a decarbonised 2050. While electric vehicles will play a role, aided by rebates, internal combustion engines could provide an opportunity to replace petrol with lower-emitting ethanol blends, or “flex-fuel” which includes blends of up to 85% ethanol.

A study by the Argonne National Laboratory in Illinois has found using plant-sourced ethanol will reduce emissions compared with conventional petrol by as much as 88% to 100%, depending upon the feedstock used. In addition, it also reduces the release of other harmful compounds, including benzene, a suspected carcinogen.

Scientists in Wales are developing “grassohol”, grass-sourced cellulosic ethanol suitable as a fuel feedstock. Ironically, in a region once renowned for its coal production, the Wales-based work is focusing on high-sugar ryegrass varieties that produce greater volumes of ethanol and which have also proven ideal for high-producing dairy cows.

Researchers in Nebraska have also found switch grass, an adaptable grass that can grow on millions of hectares of land that cannot support grain crops, is a suitable ethanol carbohydrate feedstock. Trials reveal it can produce six times the energy output to energy consumed to create the ethanol, with 94% lower emissions than regular petrol.

Flex-fuel vehicles are not new to New Zealand, and back in 2006 Ford was hailing the arrival of this country’s first flex-fuel vehicles, two Ford Focus hatchbacks. Those vehicles had the ability to run on up to 85% ethanol to gasoline and were touted as a means to assist New Zealand to meet its (then) Kyoto Protocol obligations, with biofuel emissions not counted as greenhouse gases.

Brian Cox, CEO of the Bioenergy Association of New Zealand, says considering grasses for fuels is a “no brainer” that provides the country with a low-emissions option without wholesale electric vehicle (EV) adoption, and farmers another income stream.

“I was first approached by a scientist 20 years ago about this, but little came of it. However, we do now have a government that is wanting to understand more about its options here, and that is encouraging.

Just as farmers turn surplus grass into silage bales to feed out during tight times, the same bales can be held and sold to ethanol processors as needed, providing a useful additional income option.

“For an area using a food bio-digestor to create ethanol, they could add in the silage as needed, depending upon the flow of raw materials.” Sheena Thomas, strategy lead for Z Energy’s biofuels, says the company is evaluating whether to re-commission its biodiesel plant in South Auckland as the Government’s Sustainable Biofuels Mandate takes effect from 1 April 2023.

The Government mandate initially requires fuel to contain 1.2% sustainably sourced biofuel, rising to 3.5% by 2025.

“The critical thing with any biofuels investment is to have policy certainty, because that is key to having the confidence to make capital investment. The mandate goes a long way towards providing some certainty, which is why we are currently completing a detailed front-end engineering assessment for our plant.”

Whilst the main feedstock for Z’s biodiesel is inedible tallow – a by-product of meat production — plants and crops are also considered for the company’s other focus on aviation biofuel. For this, Z Energy has worked with Scion researchers on options using forestry waste and woody biomass in consortiums that have also included Air New Zealand, LanzTech and Refining NZ. There is a range of feedstock that can be used for biofuel production, including rotation crop such as sugarbeet, or miscanthus, a plant similar to switchgrass, which has shown promise as a biofuel feedstock in the United States.

Thomas says that the country’s medium- to long-term strategy for biofuels should fit within the broader decarbonisation pathway recommended by the Climate Change Commission. Specifically, the focus should be on electrification of the light vehicle fleet (which currently relies on petrol), and biofuels for the harder to decarbonise areas such as heavy freight, aviation and marine. Counter-intuitively, the playing field for biofuels is currently heavily weighted towards ethanol, and this needs to change in order to encourage more local biodiesel processors to engage.

“Ethanol is currently exempt from excise tax as well as carbon tax under the Emissions Trading Scheme (ETS), but this is not the case for biodiesel, which is only exempt from ETS. This effectively gives a significant tax break to ethanol-blended petrol, which is ironic given the diesel fleet will prove harder to decarbonise without a low-carbon liquid fuel alternative and therefore that is where the incentive should be placed.”

Dr Stewart Collie, Team Leader for AgResearch’s Bioproduct and Fibre Technology Unit, said he and his colleagues are researching how biofuels and bio-refining could fit into the bigger picture of pastoral farming in New Zealand.

“For us it is about understanding what the best combination of processes are for fitting into pastoral farming.”

He acknowledges the conflicts that have arisen between “food versus fuel” in the past overseas – for example in the United States there’s been a conflict between corn grown for ethanol and for food.

“It is a little more indirect for ryegrass, but ultimately food is where ryegrass has been channelled. But bio-refining may provide the potential to achieve both from the same source, providing both a reduced protein feed source, and a cellulose feedstock stream for ethanol production from the ‘squeezed’ ryegrass.”

AgResearch scientists are analysing the models that may be best suited to farmers participating in bio-refining, including looking at whether some level of on-farm refining could be done, or delivery made to a central point.

“It really comes down to thinking about how the pieces all fit together in a way that is economically as well as environmentally valid.”