Robert Munro, Ely Land and Water Team Leader for the Environment Agency said: “Our officers are regularly told that these challenges have arisen due to ‘exceptional rainfall events’. However, with this happening year after year, these events can no longer be interpreted as exceptional or unprecedented.”
Ed Bramham Jones, Head of Land and Water at the Norfolk Rivers Trust said: “We’ve experienced acute problems with soil compaction, made worse by the late harvesting of crops, leading to large amounts of surface runoff reaching ditches and road surfaces, and ultimately ending up in our precious and fragile chalk streams.”
Below: Runoff from a saturated pig field, which also has a manure heap located close to a watercourse
It is essential that channels are not dug through a buffer strip to release a build-up of runoff to a watercourse. This would be seen as a direct and deliberate act of pollution, and could lead to enforcement action taken by the Environment Agency; being reported to the Rural Payments Agency (RPA); and be in breach of cross-compliance and contrary to any stewardship agreement.
Below: Runoff from a harvested potato field
Best practice advice from Norfolk Rivers Trust (NRT)
For high-risk arable crops such as potatoes, maize and sugar beet:
- Choose fields that have low runoff risk by looking at the topography, proximity to watercourses and soil health – sands, silts and those with low soil organic matter are particularly vulnerable to runoff.
- Refer to the ‘source, pathway and receptor’ model (see diagram) when considering water flow across a site and how best to mitigate. For example, relocating gateways to higher ground, leaving in cover crops for as long as possible or breaking up tramlines and wheelings with a ridging device (available to trial for free through NRT’s Water Sensitive Farming Initiative).
- Wait for correct weather conditions to harvest and minimise trafficking. Prevent all driving on margins and buffers.
- Cultivate immediately after harvest and if possible, sow a cover crop. Ensure road surfaces are swept and left clear after loading.
- Look at reduced tillage systems to build soil health and organic matter.
- Undersow maize to provide a green cover at harvest.
- Know where designated and restricted areas are located including Groundwater Source Protection Zones (SPZs). Pig units should not be located within a SPZ1 or SPZ2, and caution should be taken when considering a site near to a watercourse, field drain or protected area such as a SSSI.
- Carry out a risk assessment of the site to look at field topography, previous cropping and soil nutrient content and structure.
- Mitigate compaction and prevent runoff. This can involve moving gateways and creating ‘no-go’ areas such as wide buffer strips and margins. Use cover crops and grass leys both between and within pig pens.
- Track humps, cross drains and silt traps can be installed to intercept surface flow.
- Be prepared to rest and rotate pens around the site.
Below: Wide green margins for intercepting runoff
Defra’s Site Suitability for Outdoor Pig Farming
BPEX’s Good Soil Management Practice: A Guide For Outdoor Pig Keeping
Sugar beet growing best practice guide: Working together to achieve sustainable management of soil and water in sugar beet production
Potato Growing: A best practice guide for improving soil health, and water quantity and quality
NRT Case study: Working with an outdoor pig unit to reduce soil and water pollution