Alternative methods for terminating cover crops

This field lab is investigating alternatives to ploughing or glyphosate for terminating cover crops. The group are trialling a range of techniques including roller crimpers.

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Field Lab Timeline

    3/29/2016 11:00:00 PM
  • Idea formed

    Idea formed
  • 11/2/2016 12:00:00 AM
  • First Meeting

    First Meeting
  • 1/8/2017 12:00:00 AM
  • Trial Farms confirmed

    Trial Farms confirmed
  • 1/15/2017 12:00:00 AM
  • Researchers join the team

    Researchers join the team
  • 7/19/2017 11:00:00 PM
  • Final methods decided

    Final methods decided
  • 8/21/2017 11:00:00 PM
  • Funding proposal finalised

    Funding proposal finalised
  • 9/3/2017 11:00:00 PM
  • Start of trial

    Start of trial
  • 11/9/2017 12:00:00 AM
  • Progress review

    Progress review
  • 11/10/2017 12:00:00 AM
  • Methodology and protocols for termination

    Methodology and protocols for termination
  • 12/1/2017 12:00:00 AM
  • Data analysed

    Data analysed
  • 1/31/2018 12:00:00 AM
  • Results Meeting

    Results Meeting
  • 3/23/2018 12:00:00 AM
  • Crops drilled

    Crops drilled
  • 5/14/2018 11:00:00 PM
  • Second progress meeting

    Second progress meeting
  • 6/15/2018 11:00:00 PM
  • Establishment measurements

    Establishment measurements
  • 7/16/2018 11:00:00 PM
  • Triallist reflections

    Triallist reflections
  • 8/29/2018 11:00:00 PM
  • Yield measurements

    Yield measurements
  • 9/4/2018 11:00:00 PM
  • Further results meeting

    Further results meeting
  • 1/1/2019 12:00:00 AM
  • Final report

    Final report
For further information hover over the above milestone marks
  • Discussion

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  • Achievements

    May 2019

    Final report for field lab published

    After some delays due to staffing changes, the results have been analysed and the final report for the 'Alternative methods for terminating cover crops' field lab has been published. For the full report, use your free log in and click 'view more documents' on the top right of this page to view and download the file.

    In summary, outcomes of the trials included:

    • examples of different cover crop species or mixes grown on different soil types

    • a measure of the how effective different cultivation methods were on cover crop termination at these sites (where possible the researchers were able to test for statistical significance of results).

    This field lab has been encouraging in that no negative impacts on following crop establishment were found from the range of cover crop termination methods used on the three sites. However, more field trials are required to better understand the efficacy of different termination methods in different situations.

    If you would like to be part of a further field lab to look at the efficacy of cover crop termination methods in different scenarios, please get in touch - email . If you're attending Groundswell 2019, come to the IF stand at the Agricology tent and speak to a member of the team to discuss how you can get involved.

    Milestone: Final report

    July 2018

    Harvest protocols & next steps

    Harvest Protocols:

    • Triallists have confirmed that they are happy with the protocol.
    • Farmer E suggested using garden canes to differentiate the plots – it was agreed this will be added to the protocol.
    • The researcher will create the yield harvest maps.

    Next steps:

    • Seed quantities for next set of cover crops to be determined and second year triallists confirmed.
    • The next meeting will be planned for after harvest once seed quantities have been finalised.
    • The farmers will collect a list of observations to accompany the yield data.

    Milestone: Yield measurements

    July 2018

    Triallist reflections continued


    FARMER F - Site 1:

    • Cover crop mix: Oil radish, spring oats
    • Next crop is Maize (Fodder) so yield data may not be collected
    • Treatments: Round up and disked
    • Maize drilled on 25th May
    • Establishment of the Maize consistent across the field, no oilseed rape streaks.
    • (Photos from the 13th March- week after the heavy snow fall so Cover crop had taken a beating)

    Site 2:

    • Cover crop mix: Phacelia, mustard, berseem clover, buckwheat
    • Weather killed quite a lot of the cover crop (March photos in group discussion)
    • Treatments: Round up and disked
    • Following maize crop has even establishment across treatments


    • The group's coordinator noted that it might be good to collect rainfall information (when it is wet vs dry)
    • It would be useful to get a few observations such as weeds through growing crop

    Milestone: Triallist reflections

    July 2018

    Triallist reflections continued

    FARMER E - Site 1:
    • Cover crop mix of beans and phacelia
    • Treatments were flail and roll
    • Flail was done a week earlier than the roll treatment because the roller had to be brought in
    • Barley drilled on 18th March
    • Harvest has been early so the lateness of treatments due to poor winter has not been an issue
    • There were a few thistles in both treatment areas in the following cash crop- no big difference between the two treatments.

    Site 2:

    • 4 cover crop mixes used:
    - Radish
    - Mustard, Phacelia
    - Early radish
    - Stubble
    • 4 treatments: rolled once, rolled twice, flailed and crimper rolled
    • Flail used on the 25th November, roller on the 9th December.
    • Glyphosate was used around the edges of the plot and in the commercial area of the cash crop.
    • Barley drilled as next crop
    • There were no stalks present in the barley in the mustard & phacelia plot but some crimped radish present.
    • The triallist noted that the radish in the following crop hasn’t caused any issues despite not all being killed by either the treatments or the cold weather.
    • Some snail damage across all treatments but not bad.
    • Green area index small but it was noted that this is likely due to weather conditions as opposed to the treatments.


    • The triallist feels the observations he has made are more useful than the data collection (especially due to the weather this year) and these should be used to guide what they want to do next year
    • He did not find the treatments too much trouble to do but noted that busier farmers may struggle with these treatments.


    Milestone: Triallist reflections

    July 2018

    Triallist first year reflections


    • Cover crop mixes: strips of phacelia, mustard, berseem clover, buckwheat and stubble
    • Destruction method: 25 lambs grazing (late last year)
    • Overall across the treatments and mixes there were docks and creeping thistle.
    • Significant differences in the tiller counts across the treatments / mixes.


    • Cover crop mixes split evenly between:
    - Oil radish, spring oats
    - Phacelia, mustard, berseem clover, buckwheat
    • Treatments: Glyphosate and liquid N fertiliser. Destruction on 5th April
    • Liquid N fertiliser treatment had no effect on the cover crop.
    • Looks to also have a positive effect on following crop- N available to it
    • Pip noted that the liquid N fertiliser actually seemed to help the cover crop grow.
    • Glyphosate was then used on the liquid N fertiliser strips
    • Drilled on 8th May
    • Normally this triallist wouldn’t want to kill off a cover crop as late as he did with the N fertiliser strips but this year it seems to actually be an advantage as it has helped retain soil moisture for the following crop.
    • Normally cover crops would be killed off before Christmas but this year keeping them in longer was better.
    • Current crop is doing well although the triallist isn’t too sure where its finding its moisture but attributed it to not cultivating so not disturbing the soil structure
    • The phacelia, mustard, berseem clover & buckwheat mix was killed off better than the oil radish & spring oats mix.


    • Found that radish is very hard to kill off with some radish also coming back in the cash crop,
    • Farmer E noted that the areas where he failed has some radish sprouting again but not in the crimper strips,
    • He also attributed this to the crimper roller crushing the top of the root leading to it to rot, helping it to be killed off.


    Milestone: Triallist reflections

    May 2018

    Trial progress comments

    Two of the triallists noticed the plough “went easier” on bits of land that had had cover crops. “There are benefits even if you're not following the system fully through.”

    Liz Bowles commented that historically drilling dates were based on ploughing to make sure the land held enough moisture, but perhaps with cover crops and their aftermath holding more moisture than traditional methods, it may enable later drilling to be successful.

    Another group member commented that it depends what you’re trying to achieve with the cover crops e.g. with an organic system weed suppression would be best with a thick crop to achieve a matted layer on the ground. You must get the main bit right.

    Although the aim of the trial is to test different cover crop destruction methods and measure yield impact there are many other benefits to cover crops for soil improvement and weed suppression etc.

    The triallists will try to retain the same trial strips for next year so that they can observe the cumulative effects on the soil and crops.

    Milestone: Second progress meeting

    May 2018

    Researcher update

    The researcher observed that cover crops were preventing smaller weed seeds from germinating. The maize was planted with a companion crop across the trials with control plots that had wheat volunteers in.

    2 different cover crop mixtures - mustard and radish vs just radish:

    “You could quite clearly see that where the radish cover crops were and where the mustard is in the cover crop, there is a detrimental effect on the companion crop seed germination – but there was no effect on maize seed germination.” This effect could be due to an allelopathic effect.
    “It was quite interesting to observe that, so we're looking at altering cover crop mixtures now if we're going to go down the companion crop route with maize.”


    Mustard could be effective at inhibiting smaller weed seed germination.
    Paul Brown comments: Definitely something in that. Could be the chemical reaction with the radish or a number of things.
    “What we’ve learned is there’s no substitute for getting cover crops in early” e.g. in August, question whether drilling cover crops is worth doing in September as this won't work (he believes this is true UK-wide). Killing off the cover crops tends to be in November – January, with more people looking to kill before Christmas.

    Milestone: Second progress meeting

    May 2018

    Triallist progress update

    Farmer E

    The cover crop followed wheat prior to drilling spring malting barley. It was harvested early last year so there was still lots of moisture in the ground.
    The cover crop mix went in early and came out very well. Mustard was waist height and flowering.

    Destruction took place on the 25th November. The triallist thought that by this time the cover crop has done most of its growing so may not have much more to offer after this, but questioned himself as to whether he destroyed it too early as possibly it could have taken up more nitrogen.

    Field 1. Blocks 1, 2, 3 and 4 – radish/mustard and phacelia/early radish/stubble:
    ● Roll once
    ● Rolled twice
    ● Crimper – 9th December
    ● Crimped twice
    ● Flailed

    Field 2. Field beans and phacelia:
    ● Rolled vs. Flailed

    Observed Findings:
    The cover crop was destroyed more quickly when crimped twice.

    When flailed – green shoots were coming up from below – not as dead as the crimped ones (also not as good for weed suppression as crimping or rolling).

    Subsequently the areas only treated once did die – just slower.

    Destruction was quite good. The rest of the field (commercial area) had a high level of glyphosate early before drilling. Initially glyphosate was not used on the trial area, but he did give it a light application before drilling (couldn’t afford black grass to establish).

    Hindsight – doesn’t think this level of glyphosate was quite high enough as there are some grass weeds but he concluded that the mechanical destruction “going forwards will enable us to use less glyphosate”.

    Milestone: Second progress meeting

    May 2018

    Triallist progress update

    Farmer C

    Both mixes (A&B) were drilled on the 1st September. They all looked very good in March however the berseem didn’t make it.
    ● Sprayed liquid fertiliser from a fan jet to try and scorch and kill off the cover crop
    ● Control: Glyphosate before drilling
    April 5th was the trial, this was a couple of months later than is typical as the triallist needed the right conditions to do it.

    Outcomes: Despite perfect conditions the liquid fertiliser treatment had no effect on either mix. This triallist was left with a patchwork quilt – bright green vs. slightly less green. He noted that the “Radish really enjoyed the fertiliser” so he had to use glyphosate to kill it off.

    Learning: The cover crops weren’t sensitive enough to be killed by the fertiliser (as he has seen previously). The triallist thinks he could kill other cover crops using this method if he caught them at the right time. Another triallist suggested if it had also been rolled and bruised beforehand this may have made a difference.

    The cover crop trial areas then went into Spring linseed – sown 3rd May.

    Questions from the triallist:
    When is the optimum time to drill? Wait for a flush of black grass to pass?
    Is it better to concentrate on soil temperature rather than set specific dates?

    Milestone: Second progress meeting

    May 2018

    Triallist progress update

    Farmer B

    Organic: The organic trial was written off as the crop was established in late September which led to poor establishment with crops only growing to 8 inches and was not competing well with weeds and hence it was ploughed down rather than testing different destruction options.

    Conventional: Conventional cover crops grew very well. The cold weather took out the peas and the mustard with temperatures down to -9 degrees which on reflection was useful. Peas acted as a mulch for the rest of the winter.

    Snow flattened most of it (9” snow in December) and left patchy cover crops with volunteer wheat. “Looking back I should’ve put a graminicide on it.”

    Learnings: Might not put cereals in the cover crops this year as then can use a graminicide to take out the volunteer wheat, which just leaves broad leaves which are easily managed in the following crop without using glyphosate. “It won’t fit every farm and every rotation but suits us”. He did “glyphosate it all off before drilling this year just to get on top of everything.”

    Reflections: “Learned more this year from failing... This is actually management of cover crops, as the management to start with is just as important as the destruction”.

    Milestone: Second progress meeting

    May 2018

    Next Meeting Tuesday 15 May

    Group meeting to discuss progress of the crops drilled this spring and next steps.


    9:30am Refreshments
    10:00am Introductions
    10:30am Catch up on progress from farmers involved in the trial
    11.30am Update on trial next steps
    12:15am Farm walk to look at crops following cover crops

    1.15pm Lunch

    2pm Next steps including next meeting date
    2.30pm Meeting close

    If you would like to join the meeting, please contact the group coordinator for further details.

    Milestone: Second progress meeting

    March 2018

    Crops drilled

    After destroying the cover crops via flail mow, rolls, glyphosate and Opico Heva crimper roller, Farmer D has drilled a crop of Propino barley at 200 kg/ha.

    Milestone: Crops drilled

    March 2018

    Triallist progress update

    The researcher has been on trial site visits and her updates from the triallists are as follows:

    Farmer A: Covers destroyed by sheep grazing, now discussing further cult treatments and spring drilling

    Farmer B: Establishment problems and bad luck with weather unfortunately cause this site to be called off

    Farmer C: Destruction treatment plan to discuss, waiting for good conditions

    Farmer D: Termination by flail mow, rolls, glyphosate and Opico Heva crimper roller complete and treatment areas recorded on GPS. Waiting on for conditions to be good for drilling

    Farmer E: Destruction treatment plan to discuss, waiting for good conditions

    Milestone: Progress review

    November 2017

    Methodology and protocols for termination

    Pre- termination observations (to be conducted the day of termination) to include:
    - Cover crop height
    - Crop density
    - Growth stage of the cover crop (Buds, flowering ect)
    - Identification of each species (guide to be provided)

    • Termination of cover crops
    - Once treatments have been applied, weekly photographs will to be taken at the same position in the cover crop
    - Photographs to be taken above the cover crop and down the plot (sideways)

    • Cash crop establishment
    -cash crop assessment to be undertaken 2 weeks after drilling

    Milestone: Methodology and protocols for termination

    November 2017

    Progress report since cover crops sown

    Update on cover crop establishment from each trial site:

    Farmer A:
    • Cover crops sown the 2nd September
    • Mixes are not well established so will limit the destruction methods
    • Only the mustard and radish are growing
    • Phacelia, oats and beans not establishing
    • Buckwheat has been removed by frost

    Farmer B site 1:
    • Cover crops sown 24th August
    • Established well and currently flowering
    • Destruction will start within the upcoming week or two
    • Buckwheat removed by frost
    • The optional mix used is a mix of peas, oats and Buckwheat

    Farmer B site 2:
    • Sown his own spring beans and Phacelia mix on the 28th July
    • The Kings seed mixes sown 2nd August
    • Mustard has grown quite tall which has shaded out the Phacelia a little
    • The radish is leafy with nice roots
    • All mixes have established well

    Farmer C:
    • Spring oats have yielded but the buckwheat has been lost by losing the flowers when combining.
    • Establishment of the mixes varied
    • There are Docs and Creeping Thistles present in the cover crops but the farmer noted that this is not uncommon on his farm.

    Milestone: Progress review

    July 2017

    Methods review and finalising

    The group met to review methods previously discussed and finalise what each triallist would do on their farm.

    In the 8 different farm locations, some triallists will use 1 field and others 2.

    There was some discussion over what cover crop mixes to use, with these being finalised as below:

    • Spring cropping will cover more of the industry so everyone except Farmer A will sow in Autumn. Farmer A has already sown his cover crop.

    • The group decided on 2 standard mixes which shall be used on all sites so they can quantify costs etc. There will then be other mixes the farmers can try. (Farmer A will only be using 1 of these cover crop mixes).

    • The group wanted something hard to kill in order to test the termination approach so the cover crop cannot die in frost.

    • Drilling date will not realistically be completely uniform across the sites. The recording of the drilling date is most important - so that these can be compared at the end of the trial. The target is to drill the last 2 weeks of August or 1st week of September.

    Final mixes:
    - A group mix for all sites: Oil Radish, spring oats
    - B group mix for all sites: Phacelia, buckwheat, mustard and berseem clover.
    - C optional choice

    The cover crop termination strategy was also discussed and finalised:

    • Farmer A to terminate in October, all others in Feb/March.

    • There was discussion on whether to try and get another crimper roller but the group have decided to use 1 for continuity for year 1 with the possibility to try and get another one next year.

    • If they need to use glyphosate after any of the approaches the farmer will need to record this, but it is fine as they need to do what’s best as a commercial farm. Triallists also need to record man hours if they hand pull any blackgrass.

    Milestone: Final methods decided

    July 2017

    Triallists plan and research support

    The farmers will trial as follows:

    Farmer A (organic):
    Control- Plough
    A- Crimper roller
    B- Rolls (type TBC)
    C- Grazing sheep

    Farmer B (conventional):
    Control- Glyphosate
    A- Crimper roller
    B- Rolls (type TBC)
    C- Mulching

    Farmer B (organic):
    Control- Plough
    A- Crimper roller
    B- Rolls (type TBC)
    C- Mulching

    Farmer C (conventional):
    Control- Glyphosate
    A- Crimper roller
    B- Ring rolls
    C- Liquid fertiliser

    Farmer D (conventional):
    Control- Glyphosate
    A- Crimper roller
    B- Rolls (type TBC)
    C- Flailing

    Research/ On farm assessment:
    • ADAS will look at cover crop establishment with quadrats
    • ADAS will look into cover crop pre-termination
    • Farmer will record weekly photos
    • ADAS & Farmers to look at the following cash crop establishment
    • Yield data of cash crop to be recorded against termination strategy (Not by Cover crop mix).
    • Researcher noted that the £10K innovative farmer funding will cover the 1st years research but will need to look for other funding in year 2.

    A WhatsApp group will be created so farmers can add any observations to the group, as well as a tool to remind people of key stages throughout the trial.

    The next meeting will be on Friday 10th November at Shimpling Park.

    Milestone: Final methods decided

    January 2017

    ADAS join the team

    Helen Holmes and Sarah Cook from ADAS Ltd have been invited by the AF Group to be researchers on the field lab.

    Milestone: Researchers join the team

    November 2016

    First meeting to discuss ideas

    Over 20 farmers met to discuss ideas for alternatives to glyphosate for terminating cover crops, enabling successful establishment of a subsequent cash crop.

    The proceedings started with a discussion of the current practices used by attendees. A great deal of variation in the cover crops, time and method of termination currently used by group members was revealed.

    This was followed by a presentation focussing on Green Cover Crops.

    A brief overview of the outcomes of the meeting:
    The various termination methods will be compared to a control of Glyphosate or bare stubble and current cultivation techniques:-
    • Roller Crimper
    • Mowing (Flailing)
    • Rolling (with frost)
    • Shallow cultivations (carrier)

    Measuring and analysing:-
    • Efficiency of termination
    • Cover crop establishment
    • Cash crop establishment
    • Overall profit margin impact

    6 attendees have said that they would like trials to take place on their farm, these are located in Warwickshire, Oxfordshire, Norfolk, Suffolk and Essex on a mixture of conventional and organic farms. The coordinator plans for the field lab to last three years.

    As well as discussion about cover crop termination, attendees went on a farm walk at Shimpling Park Farm where they saw the sheep John Pawsey is using as part of his arable rotations.

    Milestone: First Meeting

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