By growing perennial crops such as grass and clover grass instead of cereals, it is at the same time possible to increase the yield in the field, reduce the leaching of nitrate and the use of pesticides. Thus, perennial crops contribute to reducing the impact on the aquatic environment in Denmark. In a new project, supported by GUDP, researchers from Aarhus University, among others, will investigate how the production of grass for green protein will be able to reduce nitrate leaching sufficiently to be able to protect groundwater and waterworks' extraction areas, and meet the Danish “vandområdeplanerne”.

“Parts of the catchment area of ​​the Limfjord have difficulty meeting the “vandområdeplaner” (water area plans). There is simply a need for a significant reduction in nitrate leaching. And measures such as wetlands or mini-wetlands have only a low potential here, because there is such a low degree of drainage,” explains senior researcher Christen Duus Børgesen from the Department of Agroecology.

According to Christen Duus Børgesen, traditional measures such as catch crops and reduced nitrogen fertilization will not always be enough to achieve the reduction targets, just as they are very costly.

Perennial crops combined with biogas production

When collective and traditional measures are not enough, the cultivation of perennial crops for green biorefining and biogas production can be an opportunity to both achieve the reduction targets for nitrate leaching, just as it can ensure climate-friendly energy production and maintain economically sustainable agricultural and food production. At least that is the hypothesis for the new project, which is called GGP4H2O.

“The project is based on a drinking water catchment area in Salling. Here they have experienced increasing nitrate content in the groundwater. So, we will optimize the effect of grass cultivation as an N-tool and document the economics of grass production as a resource for green protein production, biogas and cattle feed here. In addition, we will also map the environmental effect of converting the production of maize, cereals and rapeseed to an environmentally optimized grass production as a basis for a future production of green protein,” explains Professor Uffe Jørgensen from the Department of Agroecology.

The GGP4H2O project will thus test grass production for the production of green protein as a tool for the protection of ground- and surface water within a specific area near the Limfjord. After this, the findings can be used elsewhere in the country. At the same time, the project will look at the quality of the grass for both green protein production and biogas production from sidestreams in the process. This will be tested and analyzed in collaboration with BiomassProtein and GreenLab Biogas, just as other stakeholders and farmers will be involved in the project.

Climate and environmentally friendly production systems

The goal is that with the GGP4H2O project it will be possible to optimize the production chain's yield, protein quality, energy value, environmental and climate impact in the collaboration between the project partners. It is precisely also a goal of the project to develop new production systems that can be accepted by and benefit all parties in a local area.

The project has the following sub-goals:

• Development of grass production as an effective large-scale N instrument for the protection of groundwater and surface water in Denmark
• Analysis of the economy and environmental and climate effects of local grass production as a basis for green protein production at BiomassProtein and biogas production at GreenLab Skive Biogas
• Test and develop the organization of local drinking water stakeholders together with farmers and agricultural advisers in cultivation guilds with the aim of being responsible for joint operation around grass production and protection of groundwater and surface water
• Optimize, in field trials, conversion of grasslands while ensuring protection against nitrate leaching
• Determine the amount and quality of extracted grass protein in order to optimize grass mixture, fertilization level and time of harvest