Transforming agricultural practices—or entire farming systems—may seem ambitious or even utopian. However, the trans4num approach promotes a stepwise, reflective and iterative process to integrate nature-based solutions(NBS). This method benefits individual farm sites and cumulatively contributes to a broader shift from linear to circular nutrient management. 

Intensive farming systems are increasingly challenged by persistent environmental issues such as nutrient runoff, soil degradation, and declining biodiversity. Traditional nutrient management practices often fail to address these challenges adequately, resulting insignificant negative ecological impacts that extend beyond the farm. By integrating NBS such as cover crops, riparian buffer strips, and agroforestry, farmers have the opportunity to recycle nutrients effectively, improve soil fertility, and mitigate environmental damage. A key challenge is that no single solution can be universally applied; each farm has unique characteristics such as soil type, climate, and existing management practices. A range of locally adapted strategies is necessary to generate meaningful, cumulative changes that pave the way for a transformation from linear to circular nutrient management. Moreover, there is a critical need for a stepwise and reflective approach. Each intervention must be evaluated to ensure it contributes not only to local improvements but also to the transformation toward circular nutrient management. This methodical progression helps prevent missteps and ensures that the innovations adopted are both effective and sustainable over the long term. 

Adopting a stepwise approach in nutrient management offers several significant benefits for both individual farm operations and the broader agricultural community. It creates a dynamic network among farmers, advisors, and other stakeholders who share a common interest in sustainable practices.

• Small actions in light of transformation

The trans4num INSPIRE Hackathon 2024 fostered innovation and collaboration in sustainable nutrient management, integrating Nature-Based Solutions (NBS) with digital tools to strengthen research-practice connections and international cooperation. The trans4num INSPIRE Hackathon 2024 accelerated innovation in sustainable nutrient management by fostering collaboration between farmers, researchers, and technology experts. It provided a platform for developing and testing practical solutions, ensuring that NBS and digital tools could be effectively applied in real agricultural settings. The event helped bridge the gap between scientific research and practice, enabling participants to co-create scalable and impactful innovations.

Despite the proven benefits of NBS, their adoption in agriculture remains slow due to limited awareness, complexity, and a lack of decision-support tools. Farmers, researchers, and policymakers need practical, data-driven solutions to integrate NBS into real-world farming systems. Key outcomes included AI-driven geo spatial analysis, agent-based modeling, and interactive NBS toolkits, all aimed at improving nutrient efficiency, biodiversity, and ecosystem resilience. The hackathon also played a crucial role in strengthening international cooperation, particularly between Europe and China, by facilitating knowledge exchange and setting the stage for future joint initiatives in sustainable agriculture. Beyond generating innovative solutions, the hackathon empowered participants by expanding their skills and professional networks. It provided hands-on experience with cutting-edge technologies, encouraged interdisciplinary problem-solving, and raised awareness about the importance of NBS in modern farming. By combining technology, research, and stakeholder engagement, the event contributed to shaping policy, research, and practice, ensuring that sustainable nutrient management becomes a core element of future agricultural systems.

• Cultivating innovation - trans4num INSPIRE Hackathon highlights

Soil organic matter (SOM) is ~50% carbon; the rest includes nutrients like N, P, S, O, and H that support microbial life. Microbial activity enhances soil structure, water retention, aeration, and root growth, making SOM a vital nutrient reservoir. Most carbon is stored in soils, so soil organic carbon (SOC) plays a key role in climate regulation. Yet, SOC is easily lost through conventional farming, which disrupts soil structure and hinders carbon replacement. Effective land management is essential to make soils reliable carbon sinks. However, knowledge gaps remain about which practices, or combinations, best enhance SOC. Promising options include reduced tillage, perennial crops, cover cropping, managed grazing, manure or compost application, and residue retention. The impact of any NBS depends on how it's combined with others. Rothamsted's LSRE tests systems integrating compost, cover crops, reduced tillage, and perennials. 

Even small increases in SOM and SOC benefit soil health, boosting water and nutrient use efficiency, soil structure, and biodiversity (e.g. earthworms). In the global north, carbon-rich soils must be responsibly managed. Globally, soils (mainly agricultural) could sequester over a billion additional tons of carbon per year. Nature-Based Solutions (NBS), like those tested in Rothamsted's LSRE, support SOC and SOM through practices such as reduced tillage, residue retention, compost and manure application, and leys in crop rotations. These practices enhance microbial activity and nutrient cycling, contributing to long-term soil and planetary health. NBS create favorable conditions for sustaining soil function and resilience. SOM is typically measured via Loss on Ignition (burning off organic matter), while SOC is more precisely assessed using the Dumas method (dry combustion), which quantifies CO₂ released by heating soil in oxygen-rich air.

• Soil carbon stewardship and Nature-based solutions: Managing Soil organic carbon

Traditional use of synthetic insecticides poses risks to both agriculture and food systems. They can harm human health through exposure or contaminated food, and pests are developing resistance, reducing their effectiveness. In oilseed rape, the cabbage stem flea beetle (CSFB) has become a major threat, especially in the UK and northern Europe. Since neonicotinoids were withdrawn, farmers rely on pyrethroids, yet resistance is now widespread. Reducing synthetic insecticide use must be balanced with effective pest control and crop protection, aligning with the One Health approach. EU policy, including Directive 2009/128/EC, promotes sustainable pesticide use and encourages farmers to adopt integrated pest management (IPM) strategies that are more resilient and environmentally sound. 

Implementing regenerative practices can enhance crop resilience to pests, but it’s essential to anticipate trade-offs. Practices like reduced tillage, habitat creation, crop diversification, and organic amendments foster a farm ecosystem that works with nature. These measures can strengthen crops, promote beneficial insects, and improve pest tolerance. However, leaving residues on the soil surface may increase slug pressure.

Healthier soils build stronger plants.
Regenerative agriculture improves soil structure and fertility through compost, cover crops, and minimal disturbance. Healthy soils support robust plant growth, making crops less attractive to pests.

Rotations break pest cycles.
Many pests target specific crops. Rotating crops interrupts pest life cycles and naturally reduces their populations.

Beneficial insects reduce pest pressure.
Parasitoids and other allies thrive in no-till systems, where they overwinter in the soil and help control pests.

Lower reliance on costly inputs.
Reducing pesticide use cuts costs and protects beneficial insects.

Regenerative pest management leads to fewer outbreaks, stronger crops, and a more resilient farm system.

• Nature-Based Solutions for insect pest management

Cut-and-carry green manure systems are increasingly promoted as plant-based alternatives to chemical fertilizers in nutrient management strategies. This study evaluates the impacts of such systems on seed potato yield, soil health, and nutrient cycling in Northern Netherlands. Despite short-term improvements in soil structure and microbial diversity, long-term results reveal challenges in maintaining nutrient availability for crops. 

There is growing pressure to reduce chemical fertilizer use due to environmental risks and resource scarcity. Nature-based solutions (NBS), such as plant-based manures, can support more circular nutrient flows, especially where animal manure is unavailable. However, it remains unclear how complete substitution with green manure affects soil function and crop yield, especially under nutrient-deficient conditions. This long-term field trial tested a system relying entirely on cut- and carry-green manure and crop rotation. Results were compared to conventional systems using chemical or animal manure-based fertilization. We assessed soil nutrient profiles, microbial dynamics, and calculated soil health scores.

Cut-and-carry green manure systems can contribute to more circular and plant-based nutrient management, especially in areas where animal manure isn’t available. In our field trials, applying clover silage improved soil structure early in the growing season and boosted microbial diversity. The system also showed potential for carbon and nitrogen fixation, which are important for building long-term soil fertility.

However, the full replacement of chemical fertilizer with plant-based inputs brought some challenges. Nutrients were not always available when the potato crop needed them most, and competition between soil microbes and plants likely reduced nutrient uptake. As a result, yields were lower and soil health declined by the end of the season. 

• Cut-and-carry green manure: opportunities for plant-based nutrient management i…

Viruses are a serious threat to seed potato cultivation, often causing deformities and yield loss in affected plants. Symptoms include leafroll and mosaic patterns on the leaves. To identify and remove infected plants, seed potato growers carry out field inspections throughout the growing season. If too many infected plants are found, the crop may be rejected by the certification authority (Dutch: NAK).

These viruses are primarily spread by aphids, which transmit the virus by piercing the plant. To prevent this, farmers spray insecticides and mineral oil onto the crops. However, an increasing number of these products have been banned in recent years, making it more difficult to protect the plants effectively. As a result, alternative methods are being explored, such as covering the potato crop with straw to reduce aphid pressure. In this study, not only straw but also fresh grass and grass-clover were used. This choice was made because straw requires nitrogen to decompose. The aim of the study is to find out whether grass and grass-clover have the same effect on aphid populations as straw.

Reducing the use of synthetic fertilizers is a key priority for seed potato growers. One specific area for improvement is the additional application of mineral nitrogen used to help break down straw. When straw is applied to reduce aphid pressure in the field, it competes with the potato plant for nitrogen, as straw decomposition consumes nitrogen from the soil. This study explores whether grass-clover and/or fresh grass could serve as effective alternatives to straw. These options are evaluated alongside the traditional method of using mineral oil. The research also investigates whether intercropping different types of green manures between the potato ridges can offer a natural solution to virus problems. The green manure begins growing earlier than the potato plant, so aphids may settle on the green manure instead, potentially reducing the risk of virus transmission to the crops. 

• Plant-based fertilizer and natural crop protection in seed potatoes

Planty Organic is a long-term farming experiment that began in 2012 at the SPNA experimental farm in Kollumerwaard. It focuses on organic crop production using only plant-based inputs. Instead of animal manure or synthetic fertilizers, the system uses legumes, cover crops, green manures, and "cut-and-carry" plant material to feed the soil. The main crops include potatoes, pumpkins, grains, and grass-clover.

Planty Organic began with a question from a group of organic arable farmers in the Northern clay region of the Netherlands: How can we make better use of nitrogen in organic farming—and improve efficiency without relying on animal manure or synthetic fertilizers? That question sparked the start of the Planty Organic experiment in 2012. The research uses a crop plan typical for the region—potatoes, pumpkins, carrots, grains, and grass-clover—supported by green manures. What makes it unique is its commitment to plant-based inputs only. For the first 10 years, no minerals or manure were added. Instead, grass-clover was harvested and returned to the field as fertilizer—a method known as “cut and carry.” After this initial period, compost and bokashi were introduced into the system. However, even today, no animal manure or synthetic fertilizers are used—staying true to the plant-based approach that inspired the project.

One of the main challenges with plant-based fertilization is the mismatch between nitrogen supply and crop demand over time. This imbalance can lead to significantly lower yields for certain crops. We currently lack detailed knowledge about the optimal timing and methods for applying plant-based fertilizers. Understanding how to synchronize nutrient release with crop needs is crucial for improving performance and reliability in fully plant-based systems.

• Planty Organic: Long-term crop rotation with plant-based nutrition

There is a growing need for research into alternative fertilization methods in grain cultivation. Conventional farming typically uses a combination of synthetic fertilizer and a second application of slurry. In organic farming, fully animal-based fertilizers are more commonly used. The challenges differ between the two systems. Organic farming already relies largely on circular fertilizers, but the availability of animal manure is limited, creating a demand for alternative sources. In conventional farming, linear (non-renewable) fertilizers are still widely used, accounting for about 50% of total fertilizer input. The key challenge here is reducing dependence on these inputs. Fertilizer price shave risen sharply in recent years, and concerns about nutrient leaching into surface water are becoming increasingly urgent. A potential solution for both systems could be increased use of plant-based fertilizers, such as alfalfa or grass pellets.

The use of plant-based fertilizers offers a major opportunity to reduce chemical fertilizer use in conventional farming. Additionally, it can help lower the use of animal manure in both conventional and organic grain cultivation. By introducing this third fertilization option, farmers become less dependent on synthetic and/or animal-based fertilizers. The use of more natural products is also expected to improve soil biodiversity, which in turn supports better soil health. 

Grain farming often operates on tight margins, so rising fertilizer costs can have a significant impact on profitability. At the same time, the Netherlands faces a pressing challenge to improve water quality, an issue in which the agricultural sector plays a key role. Regulations on fertilizer use are becoming increasingly strict. The need to maintain yields while also improving water quality is urgent. Using plant-based fertilizers to help prevent nutrient leaching is a practical and forward-looking solution that fits well within the operations of many farms. 

• Green fertilizers: Lucerne and clover pellets for winter wheat

The AgriFuture project at Kollumerwaard focuses on seed potato cultivation as a key element within a future-proof crop rotation system. Seed potatoes come with specific demands regarding soil quality, crop rotation, and disease management, making them a relevant case in the transition toward more sustainable arable farming. The aim is to explore how seed potato cultivation aligns with the core principles of AgriFuture, such as:

• AGRIFUTURE: Innovative crop strategies for seed potato cultivation

The goal of AgriFuture is to develop a future-proof crop rotation system that meets the needs of tomorrow’s farming practices. In this ‘farm of the future’, solutions are explored at the systems level for some of agriculture’s most pressing challenges, including: 

• AGRIFUTURE: Innovating crop rotations & soil health on clay soils

Nature-based solutions (NBS) aim to address societal and environmental challenges through the sustainable use of nature. However, their design and implementation require robust, continuous environmental data to guide planning and assess effectiveness. Traditional field-based monitoring is often too costly, time-consuming, or spatially limited to provide the required information at scale. Remote sensing bridges this gap by offering consistent, spatially explicit, and regularly updated environmental data. It supports the early identification of priority intervention areas, baseline assessments, and long-term impact monitoring. In a changing climate, where adaptive management is crucial, these capabilities are essential to the resilience and success of NBS.

Remote sensing supports NBS implementation in multiple strategic ways:

• Monitoring nature: remote sensing as a key enabler of nature-based solutions

Soil profile demonstrations are vital because soil remains a "black box" for many farmers. While the benefits of Nature-Based Solutions (NBS) are real, they often lie hidden below the surface. By analyzing soil profiles, we make these benefits visible—providing farmers with clear, tangible proof that sustainable practices improve soil health and fertility. This hands-on approach shows how different management techniques affect root growth, microbial activity, and soil structure. Farmers often judge soil by surface signs, which can be misleading. Digging deeper reveals the true impact of practices, helping them see the changes beneath their feet. Soil profile demonstrations turn abstract science into visible, practical knowledge. By making the invisible visible, we empower farmers to make better decisions that support long-term sustainability.

Empirical understanding is key to changing farming practices. Soil profile demonstrations offer visual proof of improvements like better structure, more organic matter, and higher water retention. Farmers see how cover crops, reduced tillage, and manure improve soil health—benefits often hidden from the surface. By revealing real results, demonstrations bridge the gap between science and practice, building trust in NBS. Farmers observe changes in porosity, root growth, and biological activity, strengthening the link between practices and soil quality. This boosts confidence in adopting and maintaining sustainable methods. Soil profiles also support peer learning, encouraging collaboration and shared knowledge. When farmers can see the long-term value of NBS, they’re more likely to make informed choices that support soil, yield, and resilience—advancing the shift to regenerative agriculture.

• Look into the soil to understand the benefits of NBS for soil

A decline in the population of many bird species has been observed (Eurostat 2020). A good opposite example is the common kestrel in the southern part of Hungary (Baranya-county), where the farmers, nature conservation experts and the ornithologists protects the kestrel population with combined forces, for a decade now. 

One of the major challenges for crop farmers(mostly for no-till, min till farmers) is the increasingly widespread common vole (microtus arvalis). In the latest years their presence was a deterring factor in many farmers yields. Due to the climatic changes, no tillage agriculture and the regulatory environment, their numbers skyrocketed, often leading to the formation of a gradation. (D. Roos, 2019). By cause of intensive agriculture, the number of field protecting tree strips is decreasing. That’s affecting the kestrel population negatively since they don’t build their own nests, mostly occupying nests built by different crow species. 

The best solution that is also proved by many researches is to install nesting crates for the common kestrel. As mentioned before they aren’t building their own nests and they are very exposed to the environmental changes (E. Baltag, 2014). Our solution is to provide artificial nests for them to nest successfully. According to the report of the Foundation on Nature Values of Baranya, after installing the kestrel boxes, there has been a rapid growth in the population indicating that the local problem was mainly caused by a lack of nesting sites. Another nature based solution regarding this topic is a biological rodent management. The kestrel is a natural predator to the common vole. The larger the kestrel population, the better they can control the vole population, which means farmers can use less rodenticide, which is essential for sustainable farming.

• Fostering population growth of kestrel (Falco Tinnunculus) in agricultural areas

Satellite monitoring enables a cost effective solution to understanding the spatial variation throughout a large NBS site. It provides an effective way of monitoring effects after applying a NBS, and enables better and more precise understanding of the potential of applying a NBS on a regional scale. 

In the trans4num Decision Support Tool, we focus on the effects of introducing NBS across an entire region. In the Danish site this region contains more than 40.000 fields. Here a primary focus is on the spatial effect of the NBS, where the effect of decisions is highly affected by aspatial component. This requires deep understanding of the spatial variation of the arable land in the region. Satellite monitoring provides a crucial input to this understanding, and can help in measuring the actual effect of implementing a NBS across the region. In order to understand the context of a large region, it is key to know the crops on individual fields on every growth season, an application where satellite monitoring is a very efficient tool to provide insights on the most important crops.

Manual data collection, like soil sampling, at individual fields is at best sparse, and with varying degree of details across farms. Data collected withdrones, enables very precise high resolution data, however the cost of collecting data, makes it very hard to obtain for large regions, especially in atemporal context, where data has to be fetched throughout the growth seasons. Remote sensing makes the trade-off whereprecision and spatial resolution is sacrificed for high temporal resolution, and complete spatial coverage. This makes a perfect match for the regional scale at which the trans4num Decision Support Tool operates. Here the focus is not on optimization within a specific field or farm, but at a regional scale. Hence the high resolution from more precise sources like UAV monitoring is of no to little benefit.

• Regional scale satellite monitoring

In today’s agricultural and industrial systems, a significant portion of biological resources is either wasted or underutilized. While green biomass like grass and clover is rich in valuable components—such as fibers, sugars, and nutrients—most of its potential remains untapped after initial processing for protein. Traditional value chains often stop at the primary product. However, sustainability and economic resilience require that we go further—transforming secondary outputs (like pulp and brown juice) into inputs for new value chains. This is known as cascade utilization. 

At the same time, industrial decarbonization pathways, such as Power-to-X (PtX) technologies, are creating new resource flows like excess heat and biogenic CO₂. These flows, if coordinated wisely, can serve as inputs for agriculture and green refining. Unlocking this interconnected potential will require: 

• Circular systems in action: cascade utilization and industrial symbiosis

Grass refining turns green crops into high-value protein, feed, and bio-based materials. trans4num supports this climate-friendly approach to boost soil health, reduce emissions, and strengthen circular farming in Denmark and beyond. 

Denmark's agricultural sector faces pressing environmental challenges—including nutrient surpluses, biodiversity loss, and oxygen depletion in inland waters. These issues are exacerbated by high levels of greenhouse gas emissions from conventional farming practices. To address these impacts while maintaining high food production, there's a growing need for regenerative agricultural systems that are both economically viable and ecologically sustainable. 

This calls for a fundamental restructuring of how we grow food, use land, and manage nutrients. Green leafy crops such as grass, clover, Lucerne, and nettle represent a promising solution. These crops not only thrive in Danish conditions, but also: 

• From grass to value: refining green biomass for protein and nutrients

Replacing traditional feed crops with perennial grasses in intensively farmed regions can benefit both terrestrial and aquatic environments, increase biodiversity, and help mitigate GHG emissions. Advancing biorefinery production and supply chains could create incentives for farmers to shift their cropping rotations towards more grass-based systems. Poor ecological status of aquatic environments, low biodiversity, and loss of soil carbon are significant challenges associated with high-intensity agriculture. With agriculture covering about 62% of the landscape, the agricultural sector in Denmark is no exception. Cereals and maize account for 52% and 7% of the Danish cropping area, respectively, making the agricultural landscape dominated by monoculture feed crops with a relatively high environmental impact. As an alternative, perennial grasses, when managed properly, can improve nutrient use efficiency, enhance soil carbon storage, and reduce the negative impact of farming on biodiversity.

The substitution of grass on cereal and maize field scan yield a new source of protein through protein extraction from grass through the biorefinery. In the biorefinery grass is pressed producing a green juice and a fiber fraction. From the green juice, protein is extracted through heating or steaming and can be fed directly to monogastric animals - thereby replacing the less sustainable soya feed. The fiber fraction can be fed to ruminants (e.g. cattle) or distributed to the biogas plant. In addition, the biogas plant also receives manure etc. from the field, and the energy produced here can be transferred to run the biorefinery. The biogas remnants including potentially produced biochar finally is recycled back to the local fields as fertilizer and/or to promote carbon storage in the soil, thereby contributing to circularity of the system.

• Grass-based cropping systems: transforming the Danish agricultural landscape