Enhancing ditches for wildlife can yield valuable points in environmental schemes, as well as helping meet the aims of the Campaign for the Farmed Environment. Rebecca Inman of FWAG reports

Ditches are vital wetland habitats across large parts of the countryside, particularly in areas of arable farmland, which can become even more valuable with the right management.

With their mix of permanent water and relative undisturbed rough vegetation, they can provide important refuges for small mammals, including harvest mice and water voles and nesting birds, such as reed bunting. A well-managed wet ditch can also develop a rich flora of wetland plants.

Ideally, all ditches on a farm should be managed on a rotational basis, clearing short sections of the ditch bank, typically a quarter to a third of the bank length each year. This minimises cost and provides a variety of habitats. Undertaking the work over a three-to-four year cycle is recommended as this will allow remnant vegetation from the unmanaged areas in any one year to recolonise the cleared lengths.

This rotational approach is particularly beneficial to invertebrates as different groups of species are associated with soil depths and varied maturity of vegetation. Suitably managed ditches can provide habitat for marginal herb species such as ragged robin, sneezewort, marsh bedstraw, purple loosestrife and greater bird’s-foot trefoil.

After clearing a length of ditch, spread the excavated material evenly on adjacent land at least 1m from the top of the ditch bank to comply with cross-compliance rules. Farmers in Environmental Stewardship need to take extra care to check the prescriptions relating to their options to ensure they are complying with the rules.

Careful management of ditches will ensure there are varied water levels across the farm, which will benefit different species of wildlife. However, what may benefit one species may not be good for others so an understanding of the requirements of target species is vital.

Similarly, variation in the aspect of ditch slope also favours different groups and species. To provide habitat for marginal plants, creation of a shelf or berm can stimulate growth and, if placed at the bottom of the bank, will provide habitat for water voles.

Where reprofiling is undertaken, this should be in 100m stretches, and undertaken on one side of the bank at a time.

Rebecca Inman is a farm conservation adviser with Essex FWAG

• For more on the Campaign for the Farmed Environment, visit our dedicated webpage.

Good ditch management

The potential movement of large amounts of water from fields into the ditch network means the risk of diffuse pollution is a serious concern to the farming industry, as is the risk of pesticides and fertilisers entering these watercourses.

However, good ditch management can eliminate – or at least significantly reduce – these risks. On top of this, careful observation of ditches can allow growers to act on potential problems before they result in pollution of watercourses or soil erosion and resultant sedimentation.

Signs to look out for include noticeably discoloured water running into ditches, sewage fungus developing from run-off entering the ditches and the absence of ditch-side vegetation.

Where these signs are observed, growers should consider allowing grasses and other marginal vegetation to develop in dry ditches to slow sediment movement during periodic rainfall. Where drainage will not be impeded, allow reeds and rushes to establish as these will be effective in absorbing nutrients, slowing sediment movement and aiding its settlement.

Case study: Kelvin and James German, Rookery Farm, Cambridgeshire

Set in the Fens near Warboys, Kelvin and James German have moved away from cutting all ditch vegetation annually to a rotational approach after seeing the benefits of minimising sediment run-off.

Kelvin is also responsible for managing Internal Drainage Board (IDB) ditches that form the arteries of the fen landscape. The main IDB ditch on the farm is slobbed out every two years and the smaller farm ditches are cleaned on a three-to-four-year rotation.

Re-profiling one side of his ditches to 45 degrees on a five-to-10-year basis provides more support to the bank and helps to increase the volume of water that can be stored by increasing the ditch diameter. This increased water capacity plays an important role during high flood risk.

With the wrong tide on the coast, the 40ft drain can be closed and fen farmers ordered to stop pumping into the main drain. The extra capacity created by widening the ditches acts as insurance because it reduces the risk of on-farm flooding and topsoil loss, he says.

Kelvin has created berms in some of the ditches and planted reed beds in others under Environmental Stewardship. The adoption of these management practices has resulted in a noticeable increase in biodiversity on the farm, which grows wheat, potatoes, oilseed rape and peas.

“Recent records show great-crested newts, toads and frogs as well as a large population of water voles.”

Dead wood left in the ditches serves as perches for kingfishers, which are observed frequently.

Managing ditches for wildlife

• Manage on rotational basis

• Clear banks in a three-to-four-year cycle

• Variation in ditch slope

• Create shelf or berm to provide habitat for water voles and marginal plants

• Leave dead wood as perches for kingfishers.