Grass and clover can provide more than animal feed

Growing leys – grass and clover – is nothing new in Swedish agriculture. But in the arable farming regions dominated by cereal production, leys are less common. One reason is that there needs to be a market for what is harvested.

This was one of the starting points when researchers at Chalmers began exploring the potential of green biorefineries, where grass and clover can be processed into several different products.

“From a cultivation and soil perspective, introducing grass and clover leys into a crop rotation dominated by cereals has a range of positive effects on both the soil and the environment. Farmers are well aware that growing grass and clover improves soil quality, but the challenge is finding a market for this biomass resource,” says Christel Cederberg, Professor of Sustainable Agricultural Systems at Chalmers.

One opportunity became apparent when Danish researchers began extracting protein from fresh grass in pilot facilities.
“When we heard that Danish researchers had begun extracting protein from fresh grass in pilot plants and producing a protein feed that could replace imported feed, we saw another major advantage: by biorefining the protein from leys, we could reduce dependence on soy protein, which is associated with a number of environmental problems,” says Göran Berndes, Professor of Biomass and Land Use at Chalmers.

“It was quite natural for us to pursue this opportunity, as it is in line with our previous research into ways of developing the production and processing of biomass to provide a wider range of bio-based products while at the same time mitigating the negative environmental impacts of agriculture,” he continues.

Both Christel Cederberg and Göran Berndes work at the Division of Physical Resource Theory, Department of Environmental and Energy Sciences at Chalmers University of Technology.

Protein is only one part of the grass

In a green biorefinery, freshly harvested grass and clover are pressed and the protein is separated. The protein can be used as animal feed, thereby replacing some of the soy imported into Europe.

Christel Cederberg points to several potential environmental benefits of such a shift:
“If we can replace soy with grass protein, there are a number of environmental benefits. Particularly important are substantially reduced negative impacts from pesticides, more circular nutrient systems, maintained soil fertility and better conditions for biodiversity in agricultural landscapes.”

But protein is only one component of the biomass. The refining process also produces large quantities of fibre-rich residual streams that can be used in several ways.

 “So far, the by-products have mainly been used to produce biogas, but we see many additional possibilities, including biochar, textiles and even carbon capture, where the captured CO₂ can either be stored permanently underground or used as an industrial feedstock instead of fossil carbon dioxide,” says Göran Berndes.

 The potential to use the fibre-rich biomass as a raw material for various bio-based materials is also being investigated. Christel Cederberg stresses, however, that this is still an area that requires further development.

“It is too early to say which applications are the most promising today. More development work is needed.”

An extreme summer puts farmland in focus

The ability of agricultural soils to cope with a changing climate has become particularly relevant following the summer of 2026. Repeated heatwaves and prolonged lack of rainfall depleted soil moisture in parts of Europe. In August, the European Commission’s Joint Research Centre (JRC) reported worsening prospects for several summer crops and severe losses in the areas most affected. The same prolonged drought and extreme heat also contributed to extensive forest and wildfires.

Could increasing the amount of land under grass and clover make agriculture more resilient? Christel Cederberg explains what research tells us about the agricultural soil itself.

“Yes, but this is a long-term strategy. We know from long-term field experiments – trials conducted at the same site for several decades – that more diverse crop rotations, and particularly the inclusion of leys, increase the amount of carbon in the soil. Or, to put it more simply: the soil’s organic matter content increases.”

This, in turn, affects the soil’s ability to withstand periods without rainfall.
“The soil’s water-holding capacity increases, making it better able to withstand dry periods. A higher organic matter content also improves soil structure, particularly in clay soils, allowing roots to penetrate deeper and access water,” says Christel Cederberg.

This is therefore not a quick solution to a single dry summer, but rather a question of how agricultural soils develop over the longer term.

What happens if more farmland is used for grass and clover?

Growing more grass and clover also means using land that could otherwise be used for other crops. Could expanding ley cultivation therefore reduce food production?

In Sweden’s cereal-growing regions, increased ley cultivation would primarily replace cereals.

“When farmers replace cereals with what is known as a break crop – in this case a ley crop – they do so with the least productive cereal crop in the rotation, meaning the one with the lowest margin and yield. Introducing leys into the crop rotation also has positive effects on the yields of other crops, although these effects are difficult to quantify and can vary from year to year depending on weather conditions,” says Christel Cederberg.

She also points out that in a normal year, Sweden produces enough cereals to be a net exporter.
“Ley cultivation obviously uses agricultural land in Sweden and could lead to reduced cereal exports. But when we use grass to extract protein feed and reduce soy imports, land is freed up in South America, which reduces competition for land and pressure from deforestation in that part of the world.”

“On a global level, agriculture’s land requirements could either increase or decrease if Europe expands ley-based production of protein feed,” says Göran Berndes. “The net effect depends on which soy production is displaced, as well as on how ley cultivation affects crop yields within European agriculture.”

The researchers have also investigated land-use effects in a study in which they modelled the large-scale introduction of perennial grass into crop rotations across more than 81,000 areas in the EU and the UK. When the researchers accounted for the effects on the yields of other crops and the potential to replace soy protein with protein from grass, the additional global demand for agricultural land was relatively small. In some of the scenarios studied, land requirements instead decreased. The study also showed potential for increased carbon sequestration, reduced erosion and lower nitrogen losses to water.

How the rest of the grass biomass is used also matters.
“If we also take into account the use of side streams to produce biogas and other bio-based products – and assume that these products would otherwise be produced from other cultivated biomass – land requirements decrease further.”

From grass in the field to a green biorefinery

Part of the research has been carried out within Green Valleys, a Swedish-Danish research and collaboration project focusing on green biorefineries. Chalmers is one of several partners, together with organisations including Agroväst, the Swedish University of Agricultural Sciences (SLU), Hushållningssällskapet Sjuhärad and Aarhus University. The project includes two demonstration facilities: one at the Sötåsen agricultural college in Region Västra Götaland, Sweden, and one at Aarhus University in Denmark.

Christel Cederberg has served as Chalmers’ contact person within Green Valleys, and both she and Göran Berndes have participated as researchers in the project. The work is now continuing in a new project constellation called Land2Value, which also includes Norwegian partners.

“By taking a broad approach – from land use to industrial processes and the use of bio-based products – and examining a wide range of sustainability aspects, our research can contribute to the further development of today’s bio-based systems and help ensure that the transition from fossil-based to bio-based systems delivers multiple benefits,” says Göran Berndes.

Work at the demonstration facilities has provided both practical experience and broader insights.
“In terms of both knowledge and practical know-how, we have learned a great deal from building and operating the biorefineries at the demonstration facilities: the challenges of handling different types of grass and clover biomass under different weather conditions, how these conditions affect product quality, and how the press cake performs as a feedstock for biogas production,” says Christel Cederberg.

But an important lesson is that the technology itself is only one part of what needs to work.
“One particular lesson is that the whole concept really requires a systems perspective, in which logistics, infrastructure and scale are important components. The entire system, including the people who operate within it, needs to be considered – and what kind of business model is best suited to making it work? There are challenges here.”

Why are there not more green biorefineries?

If grass and clover can provide protein, energy and materials while also contributing to healthier soils, the obvious question is why green biorefineries have not yet become more widespread.

There are both practical and economic barriers.
“These are complex systems to establish. Investment costs have risen in recent years. What kind of business model should the system have? It is also very difficult to compete in markets – feed, agriculture and food – where low prices currently seem to outweigh almost everything else,” says Christel Cederberg.

Long-term policy conditions also influence the willingness to invest.
“As with other activities, willingness to invest is affected by the long-term conditions. Stakeholders need confidence that policies and policy instruments will maintain favourable conditions over the long term,” says Göran Berndes.

Related:

• Study: Large-scale deployment of grass in crop rotations as a multifunctional climate mitigation strategy

• Västra Götalandsregionen – Green Valleys

• Agroväst – Green valleys