Understanding Silvoarable Systems: Integrating Trees with Crops in the UK
A cobnut and apple alley cropping agroforestry system combined with herbal lays and legumes
In our ongoing series on agroforestry, we’ve discussed the benefits of integrating trees with farming, focusing so far on silvopastoral systems, which combine trees with livestock. In this post, we turn our attention to silvoarable systems, where trees are combined with arable crops. Silvoarable agroforestry offers exciting opportunities for farmers to diversify their production, improve the resilience of their land, and contribute to environmental sustainability.
Let’s explore what silvoarable systems are, how they’re designed, and the benefits they can offer to UK farmers.
What Is a Silvoarable System?
A silvoarable system integrates trees with arable crops on the same piece of land. This approach allows farmers to produce valuable tree products such as timber, fruits, or nuts while continuing to grow their usual crops. The combination of these two components creates synergies that can enhance crop productivity, improve soil health, and increase biodiversity.
In practice, silvoarable systems are often set up as alley cropping, where rows of trees are planted at intervals, with arable crops grown in the alleys between the rows. Trees may also be scattered across the field or planted along field boundaries in shelterbelts that protect crops from wind and erosion.
Designing a Silvoarable System
Designing an effective silvoarable system requires careful planning to ensure that both the trees and crops thrive. Here are the key considerations when setting up a silvoarable system:
Tree Species Selection: The choice of tree species depends on the specific goals of the farm. Poplar, walnut, hazel, and cherry are commonly used in silvoarable systems in the UK. Poplar is fast-growing and ideal for timber and woodfuel, while walnut and hazel can produce high-value nuts in addition to timber. You may also choose fruit trees like apple or pear, which can provide both fruit and shade for crops.
Tree Spacing and Layout: The spacing of trees in a silvoarable system is critical to ensure that the crops receive enough light and resources. Trees are usually planted in wide rows to reduce competition for sunlight. For example, trees may be spaced 10-20 metres apart, depending on the species, with arable crops grown in the alleys. This layout allows farm machinery to move easily between rows for planting, harvesting, and other operations.
Crops Suitable for Silvoarable Systems: Silvoarable systems are highly flexible and can support a wide range of crops, including cereals, vegetables, and root crops. The choice of crops will depend on the local climate, soil conditions, and the spacing of the trees. Some crops, such as wheat and barley, may benefit from the protection provided by trees, especially in windy or exposed areas.
Rotation and Timing: Farmers may need to adjust their crop rotation schedules to accommodate the growing needs of the trees. While the trees mature, crops can continue to grow in the alleys, making full use of the land. As the trees grow taller, they may begin to cast more shade, so selecting crops that are tolerant of lower light levels can be beneficial in the later years of the system.
Soil and Water Management: Trees in a silvoarable system help to improve soil structure and reduce water runoff. Their deep roots prevent soil erosion and leaching, while also improving water retention in the soil. However, it's important to manage competition for water between the trees and crops, particularly in drier regions.
Benefits of Silvoarable Systems
Silvoarable systems offer a range of benefits that go beyond the traditional separation of farming and forestry. Here are some of the key advantages:
Improved Soil Health: Trees help to improve soil fertility by cycling nutrients from deeper soil layers. Leaf fall from the trees adds organic matter, which enhances soil structure, promotes microbial activity, and reduces the need for artificial fertilisers. In addition, tree roots help prevent soil erosion, making the land more resilient over time.
Windbreaks and Microclimate Benefits: In the UK, where strong winds can damage crops and reduce yields, trees in a silvoarable system act as natural windbreaks. This not only protects crops from wind damage but also creates a more stable microclimate, which can boost crop growth. For example, reduced wind speed can decrease evaporation, helping to retain moisture in the soil.
Diversified Income Streams: One of the major benefits of silvoarable systems is the ability to generate additional income from tree products. Whether through the sale of timber, wood fuel, nuts, or fruits, farmers can diversify their revenue streams and reduce their reliance on a single crop. This can help mitigate risks associated with price fluctuations in agricultural markets.
Increased Biodiversity: The introduction of trees into arable systems increases the complexity of the farm ecosystem, which can enhance biodiversity. Trees provide habitats for birds, pollinators, and other beneficial insects, which contribute to natural pest control and pollination services. This biodiversity boost helps create a healthier and more resilient farm environment.
Carbon Sequestration and Climate Resilience: Trees in silvoarable systems sequester carbon both above and below ground, making these systems an effective tool in mitigating climate change. As the UK works to meet its carbon reduction targets, silvoarable systems offer farmers a way to contribute to national goals while enhancing the sustainability of their land.
Long-Term Productivity: By integrating trees into arable land, farmers can maintain or even increase the overall productivity of their land over time. The presence of trees can reduce the need for external inputs such as fertilisers and pesticides, lowering costs while enhancing the long-term health and resilience of the land.
Silvoarable Systems in the UK
While silvoarable systems are more common in Southern Europe, they are gaining interest in the UK as a way to create more sustainable and productive farming systems. Examples of silvoarable systems in the UK include the use of poplar trees in combination with cereal crops, as seen in trials at Leeds University Farm, and the integration of hazel coppice with vegetable production at Wakelyns Agroforestry in Suffolk.
These systems demonstrate how silvoarable designs can be adapted to different crops and farm types, providing both environmental and economic benefits. As government policies increasingly support agroforestry, more UK farmers are exploring how trees can be incorporated into their existing farming systems.
Getting Started with Silvoarable Systems
If you’re considering integrating trees into your arable farming operations, starting with a small pilot project is a good way to experiment with the design and management of a silvoarable system. Be sure to choose tree species that suit your climate and soil conditions, and consider how the trees will interact with your chosen crops.
Government grants and incentives are available to support the establishment of agroforestry systems, making it easier for farmers to invest in these practices. Consult with agroforestry specialists to ensure that your system is designed for long-term success, both ecologically and economically.
Conclusion
Silvoarable systems offer UK farmers a valuable opportunity to diversify their production, improve the resilience of their land, and enhance environmental sustainability. By combining trees with arable crops, farmers can create a more productive, biodiverse, and climate-resilient farming system. In the next article, we’ll discuss how trees are a perfect fit for chicken farms.
Stay tuned for more insights on how to incorporate trees into your farming practices!