Soils are an inherent part of the landscape and an important natural resource providing a range of services including food production, biological habitats and a platform for man-made structures.
Healthy soils are a key component of a sustainable farming sector in the UK. Over 70 per cent or 17.2 million hectares of the UK land area is farmed, of which a third can be cultivated. Today, the UK is 60% self-sufficient in food and a significant exporter of agricultural products too.
However, recent years have brought unprecedented challenges for farming and the soils it relies on; from periods of drought to extreme floods. This coupled with intensive farming practices has led to an increase in soil degradation; through erosion, compaction and loss of organic matter.
There is a growing realisation that the condition of many British soils is reaching a crisis point. Many experts believe some soils in the east of the UK could have as few as 100 harvests left unless action is taken to restore them. On average, soil degradation costs the economy of England and Wales £1.2 billion every year.
Washed or blown away
Soil type, slope and farming practice can all increase the risk of soil erosion, but climate change and an increase in frequency of severe weather events is magnifying the impact of erosion.
Wetter winters and more frequent extreme rainfall events have seen an increase in soil erosion, as a result of water run-off. On exposed, bare slopes farmers have had to watch as their soil is washed off their farm into ditches, onto roads and into neighbouring properties, removing valuable nutrient-rich top soil and organic matter.
On more vulnerable soils, especially peat and sandy soils, strong winds result in topsoil, seeds, fertiliser and agrochemicals being blown off the farm, causing damage to ditches and water courses. Drier parts of the country in Yorkshire, East Midlands and East Anglia are particularly susceptible. The increased frequency of dry summers is likely to make the problem worse.
The loss of soil and seeds sown by the farmer is not only a cost to the farm business but also to society. Soil erosion reduces long-term fertility of the soil and its ability to support sustainable food production. It also affects the rate water can infiltrate into the soil, increasing the pollution of water courses through runoff of soil sediment, seeds and fertilisers. This leads to sedimentation and contamination of streams and rivers, which damages fisheries and wildlife, and increases water treatment costs. It can take up to 500 years to form 1cm of topsoil.
How can trees help?
Tree belts can act as natural barriers to protect soils and crops from the full impact of intense rainfall or strong winds. A mix of broadleaved trees and shrubs planted in the right place, along contours, perpendicular to prevailing winds or in areas known to be vulnerable, can help to prevent soil erosion.
Trees also help reduce soil and water movement by increasing water infiltration rates of the soil and slowing the flow of transported sediments. By trapping pollutants bound to soil particles, trees help reduce water pollution, acting as nutrient sinks. Organic matter added from leaf litter and root debris can also promote soil structure which in turn will help reduce surface water run-off.
Integrating trees in the right place within a farming system can play an important role in preventing soil erosion. These trees also provide a home to a wide range of wildlife, absorb carbon and add to the connectivity (beauty) and diversity of the landscape.
We have many years’ experience working with landowners across the UK, planting trees to help provide solutions to soil erosion and you can take advantage of our publications.