The research that puts field drainage to the test

Henny Lowth introduces a drainage trial that aims to get water from the wrong place to the right place.

Mass grant funding for field drainage dried up in the 1980s. Even well-maintained drains installed then will now be creaking and groaning, especially when extreme wet weather hits.

The GWCT Allerton Project site at Loddington, on the Leicestershire/Rutland border, hosts a 320-ha mixed arable and livestock demonstration farm.

One of its fields was well poised to investigate the pros and cons of installing a new drainage system in August 2025.

The historic drainage system had been in place for over 40 years, with clear evidence of poor drainage in the deep, clay-loam soil, with crops failing in wetter seasons.

As part of the DRAIN-WISE project, a trial was set up in the poorly drained field, which will run for three cropping seasons.

• The old drainage system was ripped up
• The field was split into two 4-ha halves
• The eastern half was left undrained
• The western half got a new drainage installation
• Direct-drilled and ploughed treatments were also overlaid across the whole field

The new drainage system has been designed to cope with the extreme rainfall predicted to occur more often because of climate change.

It features 80 mm laterals at 17 m spacings, which lead to 100 to 160 mm mains backfilled with 10 to 20 mm gravel, up to 300 mm from the surface.

The drains discharge into a field ditch.

We are contributing funds for the comprehensive measurements needed to assess the differences between old and new.

For example, the researchers will assess key soil-health indicators, nutrient and pesticide levels in drainage waters, and field productivity.

In its first season, the system got a solid test, with autumn and winter both relatively wet.

Some areas, including Leicestershire, recorded their wettest winter on record, since the Met Office series began in 1836.

In January alone, 100 mm of rain fell at the site, giving the drained section an estimated 4 million litres of water to cope with.

Prior to setting up the trial, the team had already tested and implemented many softer drainage solutions at the site.

For instance, they saw benefits from:

• Reducing tillage intensity – especially less plough usage
• Using ultra-low ground pressure tyres
• Managing organic residue levels
• Increasing non-cash-crop areas, such as beetle banks, grass buffer strips and autumn-sown cover crops

The harder drainage options will complement the softer approaches to manage complex water flows.

It is about putting the right drain in the right place.

Ultimately, the approaches will build resilience and put the field in a stronger position to deal with the next deluge and reduce rapid surface run-off.

Reductions in waterlogged soils should also reduce nitrous oxide and methane emissions, which are both greenhouse gases with higher potency than carbon dioxide, lower earthworm mortality and increase soil health and crop performance.

Ultimately, the work will quantify the impact of new drainage schemes and provide a forum for constructive discussions on the role of drainage in UK farming systems.

The DRAIN-WISE project partners include AHDB, The Allerton Project, Anglian Water, Farm Services Ltd, GW Axup & Co Ltd, Mastenbroek Ltd, National Association of Agricultural Contractors and Syngenta. Additional funding has been provided by the Cambridge Trust.