Zero metaldehyde zones give mixed results

Mixed results have been reported by the water companies involved in the four zero metaldehyde pilot projects, resulting in some changes to the pilot schemes in the coming season.

The projects, which were set up ahead of last year, involved a voluntary ban on the use of metaldehyde slug pellets on high-risk fields in certain catchments, and represented the first stage of a new approach to tackling pesticide spikes in water.

For the farmers involved, high risk fields were identified and agreed according to a score based on risk factors, including soil run-off/leaching potential, field slope and proximity to a watercourse. On these areas, they were encouraged to use the only alternative active ingredient available (ferric phosphate), where slug control was necessary.

See also: Academy: handling slug pellets and machine preparation

All four of the pilot catchments were chosen for their different characteristics and challenges, explains Alister Leggatt of Affinity Water, as well as to see whether this type of targeted approach could have a role in helping the water industry comply with the Water Framework Directive.

“They were a mix of small and larger catchments, so that we could identify any issues with rolling it out across larger river basins, as well as being both rural and semi-urban catchments. They also had varying levels of farmer engagement and dialogue.”

Grower uptake

This final point – farmer engagement – seems to have been the sticking point, he says. “The best results were achieved where the growers were actively involved and motivated to take part. Where they weren’t engaged, for whatever reason, treatment decisions weren’t taking field risk into account.”

As a result, first-year findings have ranged from significant and marginal reductions in metaldehyde detections in raw water compared with the previous year, through to evidence of no clear water improvements. And one pilot producing a disappointing result of levels on a par with previous bad years (see Pilot scheme results).

“Autumn 2014 did spring some surprises,” admits Mr Leggatt. “We began to find metaldehyde in water after the first heavy rainfall in October, with more catchments being affected than in previous years. There were also some record, short-lived spikes in several catchments, but fewer regulatory sample failures overall.”

This shows that the industry-wide collaboration still has a steep learning curve to climb, he suggests. “What’s important is that we understand the challenges that each of us faces, so that we can work together to achieve the reductions that are needed.”

So is a targeted approach the right way forward? Both the water industry and the Metaldehyde Stewardship Group believe that is, providing that there’s a good level of farmer participation and engagement.

“There’s no doubt that the most positive results came from the areas where farmers understood the difficulties faced by water companies, were encouraged to take part in the trial and had access to the guidance that they needed,” acknowledges Mr Leggatt.

“The fact that they were able to explain their agronomic requirements was also important.”

Three of the four pilots are continuing with this approach into a second year. Anglian Water, however, is introducing a new way of working with farmers, and is carrying out a trial project around six key reservoirs.

The company plans to incentivise farmers, so they will receive payments to cover any additional costs and for taking part.


Pilot scheme results

Mimmshall Brook (Affinity Water)

  • 2014 was an improvement on 2013 – metaldehyde levels peaked at 0.108µg/l, down from 0.322µg/l.
  • 91% voluntary participation in the pilot (11 farms)
  • The pilot will run for a second year in 2015

Leam (Severn Trent)

  • 2014 was slightly worse than 2013 – metaldehyde levels peaked at 0.425µg/l
  • 31% voluntary participation (85 farms)
  • The pilot will run again in 2015, with farmer visits planned

Pincey Brook (Thames Water)

  • 2014 better than previous years, but concentrations still exceeded drinking water standard at 0.215µg/l (down from 1.427µg/l in 2013)
  • 73% voluntary participation (26 farms)
  • Repeating the exercise in 2015

Pitsford (Anglian Water)

  • Disappointing take-up and results in 2014, highest metaldehyde level was 9.28µg/l in December 2014
  • New strategy for 2015
  • Incentivised metaldehyde substitution trial proposed

Successful participation in Hertfordshire

Alistair White, Mimmshall Brook farmer

© Tim Scrivener

For Hertfordshire grower Alistair White (pictured), being involved in one of the pilot catchments has been a positive experience.

Farming 444ha of combinable crops as BW Field & Partners from his base at Potters Bar, Mr White points out that 60% of his fields are deemed to be “high risk”, so he has avoided applying metaldehyde-based pellets to them for the last year.

“Across the two sites that we farm, only two of our fields aren’t in the Mimmshall Brook catchment,” he reports. “So we have agreed to do things differently for the last 12 months, for everyone’s benefit, but it really hasn’t been difficult or too onerous.”

He acknowledges that he was experienced in using two types of slug pellets on the farm, due to the high number of watercourses on his land. “Once you know the settings and are familiar with your application equipment, it’s not difficult to switch pellet type.”

However, Mr White recalls that autumn 2014 wasn’t the most challenging of seasons, either for slugs or workload management. “Slug numbers weren’t overwhelming and the weather was good to us. We managed to get all the crops drilled into good seed-beds and were able to consolidate them, which reduces slug movement.”

The use of Deter-treated seed and a stubble cultivator after the oilseed rape crop also helped, either by repelling slugs or removing the volunteers that they like to feed on.

“As a result, we didn’t have to use many slug pellets in the wheat after rape. Everything seemed to be working in our favour and we had time to get the cultural controls done.”

His oilseed rape crops did receive one full treatment with slug pellets, with some areas warranting a second application.

“We lost a round 20% of our rape crop due to flea beetle,” he continues. “So we now have liquid fertiliser applicators on our rape drill. That helps to get the crop up and away quickly, which is useful for avoiding slugs.”

There has been good co-operation and communication with Affinity Water throughout the first trial year, notes Mr White. “They have been keen to get it right and have consulted with us at every stage. The trial isn’t compulsory, but it is in everyone’s interest to make it work.”

He was given his treatment maps by the local catchment officer, with minor changes then having to be made to them. His agronomist, Tom Scotson of ProCam, was also involved in the two-way exchange of information, so that the right treatment decisions could be made.

“Slug control costs are higher where ferric phosphate has to be used,” points out Mr Scotson. “But with the right mindset and good agronomic management, it is possible to minimise any financial penalty.”

Looking forward, both Mr White and Mr Scotson hope that similar results can be achieved in the Mimmshall Brook catchment in a year with high slug pressure. “That will be a sterner test.”