Buckwheat for couch control

This field lab is investigating the potential for buckwheat (and other crops) to reduce couch grass infestations.

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Field Lab Timeline

    4/30/2016 11:00:00 PM
  • Field lab development

    Field lab development
  • 8/7/2016 11:00:00 PM
  • First meeting

    First meeting
  • 2/24/2017 12:00:00 AM
  • Discussion meeting

    Discussion meeting
  • 3/24/2017 12:00:00 AM
  • Methods confirmed

    Methods confirmed
  • 4/14/2017 11:00:00 PM
  • Trial starts

    Trial starts
  • 5/29/2017 11:00:00 PM
  • Trial monitoring

    Trial monitoring
  • 10/9/2017 11:00:00 PM
  • Progress meeting

    Progress meeting
  • 11/13/2017 12:00:00 AM
  • Second year methods discussion

    Second year methods discussion
  • 11/16/2017 12:00:00 AM
  • Second year methods decided

    Second year methods decided
  • 3/13/2018 12:00:00 AM
  • Second year progress meeting

    Second year progress meeting
  • 3/13/2018 12:00:00 AM
  • Second year trial begins

    Second year trial begins
  • 5/14/2018 11:00:00 PM
  • Continued trial monitoring

    Continued trial monitoring
  • 7/8/2018 11:00:00 PM
  • Second year seed sown

    Second year seed sown
  • 8/13/2018 11:00:00 PM
  • Results dissemination

    Results dissemination
  • 1/30/2019 12:00:00 AM
  • Third year methods confirmed

    Third year methods confirmed
  • 3/31/2019 12:00:00 AM
  • Monitoring of ground cover at emergence

    Monitoring of ground cover at emergence
  • 9/19/2019 11:00:00 PM
  • Termination of buckwheat

    Termination of buckwheat
  • 11/8/2019 12:00:00 AM
  • Analysis of year 3 results

    Analysis of year 3 results
  • 11/29/2019 12:00:00 AM
  • Final meeting

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

    To see the latest activity please log-in (group members only).

  • Achievements

    June 2020

    Final report published

    The final report of this trial can be viewed in the 'Documents' section at the top right hand corner of this page (login necessary - free to sign up).

    Key conclusions include:

    - A ‘cautious thumbs up to buckwheat’ as a method of couch control
    - Combining approaches may be the most effective in controlling buckwheat, with targeted cultivations in early spring before sowing the buckwheat
    - After the wet winter of 2019-2020, there were clear benefits to soil structure, SOM and crop growth of buckwheat over bastard fallow
    - One trial indicated that other fast-growing green manures which quickly put on large amounts of biomass such as phacelia may also be effective couch grass control
    - Some evidence of a potential allelopathic effect of buckwheat incorporation, which would inhibit couch growth. More research is required in this area
    - One trial host felt that due to reduced labour requirement, reduced fuel consumption and increased soil benefit, the buckwheat method of couch control was preferable and more reliable than hoping for a good summer and sufficient time for multiple cultivations

    - Couch distribution spreads unevenly, therefore distribution may not have been accurately recorded. A larger sample size in future research would produce reduce the margin of error in the results
    - Broadcasting green manures onto the soil surface may increase predation by birds and limit available moisture for the seed. This may have caused the reduced buckwheat germination rates seen in some of the trials

    More research is necessary to understand whether there is a longer term impact of using buckwheat on improved soil organic matter, reduced nutrient leaching and cultivations.

    Milestone: Final meeting

    October 2018

    Buckwheat terminated

    Two of the triallists have terminated and incorporated their buckwheat cover crop, sown late due to delays with difficult weather conditions including a cold wet spring and a very dry summer this year.

    An update from one of the triallists: I flailed the buckwheat and rotavated it to about 15/20 cm depth, the buckwheat mulch incorporated beautifully, I then rolled it immediately. I’ll now wait two weeks for alleopathy to dissipate, then sow phacelia to protect the soil for winter.

    Milestone: Second year trial begins

    September 2018

    Methods reflection and decisions for third year

    The group found that digging holes to monitor the couch infestation was very time consuming and agreed that visual assessment is the easiest method of assessing couch cover, they found the potential for bias on choosing where the holes were dug was also a problem. They also agreed that this could be standardised across the trials by producing a visual assessment sheet using one of the grower's scoring system: 0 = no couch, 10 = 100% couch cover. Photographs illustrating each point on the scoring system would be good and descriptions of each stage. This will be produced over winter 18/19 ready for spring assessments in 2019.

    It was also agreed that the timing of assessments should be carried out at at the same point in the rotation each year. One grower suggested in spring after ploughing and cultivating but prior to spring crop (onion) establishment.

    The seed size was highlighted as an issue for drilling – the triallists have not been able to get seed deep enough for moisture/ avoiding predation which needs to be addressed.

    The group also agreed that green manures and leys as pure stands provide a way in for couch grass to get established. It is better to move away from pure clover leys and multi-species mixes are better for couch control. They have also found that cultivation is effective as a control.

    The group would like to undertake a cost comparison of buckwheat against other seed/ fallow as well as factoring in labour and work flows.

    Please log in for free and see the attached presentation under 'Field Lab Documents' for an overview of the field lab to date.

    Milestone: Second year methods decided

    September 2018

    September meeting discussion

    Ian Wilkinson led a discussion more generally around green manures and weed control:

    Ian drills buckwheat at 1.5 inches, he also noted that there is a big daylight effect on the growth rate of buckwheat – generally it is good to get it in early.

    The date that the buckwheat is cut/ mulched will effect the outcome – this is something that having a control in trials helps to account for.
    The multiple benefits of green manure/ ley mixes should be considered when planning as it is often difficult to directly attribute benefits to one species/ management method - the couch control effect of buckwheat (if seen) is likely to be due to a combination of factors (i.e. competition, allelopathy, cultivations etc.)

    It would be good to compare buckwheat grown on it’s own with buckwheat grown as part of a mixture. One option is to sow buckwheat as a ‘nurse crop’ with a longer term ley (at sowing rate of 8-10 kg buckwheat/ ha) then flail/ remove the buckwheat and allow the ley to grow on. Ian has done this with sheep grazing off the buckwheat. There was discussion about the allelopathic effects of buckwheat and whether this technique would impact the ley growth (not seen at Ian’s farm) – or whether the effects were more pronounced post incorporation.

    Historically buckwheat was grown to increase phosphate. In a dry year buckwheat can also help keep moisture – by providing canopy cover for the green manure.

    Milestone: Progress meeting

    September 2018

    Weed control and green manures / buckwheat meeting

    This meeting on Wednesday 12th September will open a second year of trials and is looking for further growers to be involved. Please visit the Eventbrite page to register for free: https://www.eventbrite.co.uk/e/weed-control-and-green-manures-buckwheat-for-couch-control-tickets-48829035961


    10.30: Arrival and coffee in the farm shop
    10.45: Welcome and introductions (Sally/Dominic and all)
    11.00: Introduction to the group and trial updates and planning (Sally/Dominic and triallists)
    11.30: Weeds and green manures – management options (Ian Wilkinson)
    12.00: Discussion
    12.30: Tour of Purton Trial and green manures (Ed Sweetman)
    13.30: Lunch and close

    Location: Purton House Organics, Church Street, Purton, SN5 4EB


    Please contact us at info@innovativefarmers.org or Field Lab the coordinator at sally.w@organicresearchcentre.com on and we'll be happy to help.

    Milestone: Second year methods discussion

    September 2018

    New triallist

    From the September meeting which kicked off a further year of trials, another grower has decided to join the trials.

    Milestone: Second year methods decided

    August 2018

    Second year triallists

    FARMER A: The ground was prepared in June and is ready for sowing once conditions allow.

    FARMER B: The 2017 assessments have been completed, but the results remain inconclusive and the triallist wants to gain a further year of experience and data on the effects of buckwheat.

    A small area (0.1 Ha) has been sown for the second year of trials. One half of this is buckwheat and the other summer quick fix seed mix.

    "I have shallow ploughed and rotovated the whole area and then gone through with the tines once to reduce the couch burden as I would pretty much always aim to do anyway, I intend not to do any other cultivations before sowing (although I may rotovate once more to bring up moisture if no suitable weather window before end of June).

    I think that last year I ended up doing a similar amount of cultivations for both buckwheat and bastard fallow areas (3 for buckwheat and 5 for non-buckwheat) and so thought it would be a more useful comparison to see what buckwheat did compared to another green manure with minimal cultivations.

    I'm also considering putting buckwheat into my rotation at the very beginning before establishing a two year fertility building ley in late August / early September - the idea being to attempt to clean up any couch so that it doesn't take hold in the ensuing 2 years. Clearly this is only going to be effective if the buckwheat really does have a specific impact on couch."

    For the latter trial, no baseline has been undertaken and so the triallist will take anecdotal observational data to record.

    Milestone: Second year trial begins

    July 2018

    Triallist update

    FARMER C: This farm won't be formally participating in the buckwheat trial this year. In last year's trial a mix of couch, redshank and buckwheat grew without the buckwheat being able to outcompete the former two species. Considering the extremely dry conditions this year (which the triallist thinks may be at least partially responsible for last year's poor emergence), it will be difficult for them to get the buckwheat seed established.

    The triallist needed to destroy and cultivate in last year's buckwheat/redshank/couch crop in mid-July, in between very wet weather. A dense stand of Westerwolds were then drilled in September to keep the ground covered over winter in place of the buckwheat, which was ploughed in in the early spring this year.

    "Interestingly, that plot (3000 m2), which we have prepared for squash and leeks, is now almost entirely couch-free - unimaginable if you could have seen it back in July. I have spent the past few days crawling through it hand-planting thousands and thousands of leeks and I haven't spyed a single couch rhizome."

    Whether the above result is due to the allelopathic affects of the previous spring / summer buckwheat, the 6 weeks of regular cultivations last summer or the competition from a very dense stand of Westerwolds is uncertain due to the range of methods carried out since it was in the ground.

    The triallist still has a sack of buckwheat seed left, and if the opportunity arises will drill it in a suitable place and share observations.

    FARMER E: Due to a lack of a gap in this triallist's rotation, he won’t be sowing any buckwheat this year. The couch assessment of post-treatment couch growth will be assessed this August however.

    Milestone: Second year trial begins

    July 2018

    Sowing seed for 2018

    This year has been very dry so far, and the triallists are still waiting for some rain to sow their buckwheat seed. Two triallists have bought in new seed (Farmer A and B) whilst another two are considering the possibility of trialling a second year. Farmer C may sow some of last year's seed.

    Milestone: Second year seed sown

    October 2017

    Field lab next steps

    At this progress meeting the next steps for each farm involved where discussed. The triallists reflected on what they had experienced with the trial this year, and made decisions based upon how the buckwheat has performed and what is practical in their farming systems.

    • FARMER A: Considering it as a practice run and would like to give it another go, perhaps with higher seed rates, drilling it rather than broadcasting and next time would use irrigation if a similarly dry season. They felt that there is not a lot of reason for assessing yield in the following crop or couch as the buckwheat didn’t grow this year. They are also interested in the mechanism of control and the allelopathic effects, but it is not certain where this is most effective: while growing, after cutting, or after incorporation? A review article suggests all three - see Fig. 1 in the review paper on 'Buckwheat for Weed Suppression' [Field Lab Documents].

    • FARMER B: Suggested that they might have a control of another crop (e.g. establishing a ley directly) rather than a bastard fallow – or use different seed rates of buckwheat. However, for practicality reasons they would prefer not to do a control in the next year.

    • FARMER C: Deciding if they would do it again. Sowing a single stand of a crop goes against the grain, but might consider using buckwheat as part of a mixture. Will assess crop yields and couch under double-sown strip to see if that had more effect than in the larger plot. One positive was the flowers with lots of bees and hoverflies – which they considered was still a good reason to grow buckwheat again.

    • The group's researcher Dominic Amos is to speak to Doves Farm manager about their buckwheat management and find out about drilling dates, drilling rates, seed depth etc. Doves Farm has used buckwheat to smother weeds to good effect in the past and continues to save buckwheat seed each year by swathing and harvesting to remove seed cost.

    Milestone: Progress meeting

    October 2017

    Farmer A review

    Carried out 3 treatments:
    1. Pure buckwheat stand – was topped due to fat hen
    2. Buckwheat with white clover/trefoil – mowed and treated as clover
    3. Bastard fallow control

    Farmer thoughts and observations:
    • Would have liked to have had the trial drilled by a contractor but this was not possible, so broadcast (70 kg/ha) was used as this was the usual method for their green manures. However, germination/establishment was really poor and very little buckwheat emerged, so plots were managed as if no buckwheat.
    • Not really possible to compare plots for efficacy of treatment due to lack of buckwheat.
    • AD has heard couch accumulates phosphate. Buckwheat is a P-lifter. This raised a question of whether the mechanism of control comes from P competition?

    Milestone: Progress meeting

    October 2017

    Farmer B review

    Farmers thoughts and observations:

    • Mid-May sowed 2 areas with buckwheat, broadcast and Cambridge-rolled – mowed off by late August/early September. Was too wet to plough in, so left as a dead mulch. One plot had very bad potato volunteer weed issue. Now has sown a rye/vetch mix over all plots.
    • Didn’t have the equipment to do a bastard fallow. Not much machinery available, so stopped bastard fallowing.
    • Couch grew very well!
    • ES felt that as it was his first year growing he hadn’t really got to know the ground well enough and might do the trial differently with a bit more knowledge of his fields.

    Milestone: Progress meeting

    October 2017

    Farmer C review

    Farmers thoughts and observations:

    • Didn’t manage a control (pressure of space).
    • Ploughed 16th May but the plot didn’t plough well due to the dry weather. Seeds were sown on the 17th May just before some good rain. Problems with drill so the seed was broadcasted instead. Still patchy germination, however. Had a 3-way battle with the couch, redshank and buckwheat for supremacy. Mown down and sowed with Westerwolds at the end of September. Still seems to be a lot of couch in the plot.
    • One strip was double-seeded (140 kg/ha!) This did a lot better with very little weed underneath.
    • Could there be a problem with lack of N? The plot chosen was at the end of the rotation after 4 years of cropping.

    Milestone: Progress meeting

    October 2017

    Farmer E review

    Farmers thoughts and observations:

    • My plot was 12 m by 25 m which was divided in two. I sampled on 17th June. I walked the whole plot and roughly measured the areas showing couch. Plot A (control) showed 7.7% coverage and Plot B 12.8%
    • The plots were then spring tine harrowed on 17th June and sown on 26th June: Plot A with Cotswold Seeds standard Summer Quick Fix and Plot B with SQF but with mustard replaced by buckwheat. I irrigated with about 12 mm of water.
    • My subsequent observations are that buckwheat coverage was inadequate allowing some weeds to get away (mainly Fat Hen and Annual Nettle). When the crop was flailed on 7th September and the residue had died off there was much less weed on plot B (despite my previous comment).
    • Also tried the SQF with mustard compared to with buckwheat on a larger field plot. However I had a similar experience with the buckwheat being very thin.

    Milestone: Progress meeting

    October 2017

    Autumn first year trial review meeting

    The group met to discuss each triallists progress throughout this first year. Each farm's review can be seen in the subsequent posts. During the meeting the following issues were also raised and discussed:


    • The simpler the procedure the better as far as the growers were concerned. Most concurred they wished they’d done it earlier before it got too busy. It was also too dry to dig holes once they’d left it to May or June.

    • Separating out and weighing the rhizomes - was it really necessary? Some found that just giving a visual score or taking a photo of the rhizomes dug from each sample hole was enough. North Aston Organic just did a visual score. Abbey Home Farm did both and found that they seemed to match.

    • FARMER A: Found that in some plots where strips of couch from previous pathways – if the random sampling hit these (or didn’t) this could skew results.

    Other thoughts

    • Green manures and leys as pure stands provide a way in for couch grass to get established. Better to move away from pure clover leys. Multi-species mixes are better.

    • The size of seed is an issue as most growers don’t have arable drills and tend to broadcast green manures. Not been able to get buckwheat deep enough to get enough moisture and avoid predation by birds.

    • Importance of combining approach – hammer the ground first with cultivations before sowing the buckwheat. Late sowing of buckwheat allows more time for cultivations and it could be the factor influencing the survival of couch (or not) in the subsequent crop.

    • Ploughing followed by rotavating can be an effective control - Farmer A has moved away from rotavating due to damage to soil structure and smearing/panning when soil is wet – uses power-harrow.

    • Phacelia is a very effective summer/autumn green manure which is cultivated in very easily in the spring.

    Milestone: Progress meeting

    March 2017

    Triallist update

    Unfortunately due to unforeseen circumstances, Farmer D will not be able to take forward this trial. The remaining 4 triallists will be continuing this year however.

    Milestone: Methods confirmed

    February 2017

    Second meeting - methods discussion

    The group coordinator, research and participants met to discuss the details of the trial methods. The outcomes of this are below:

    • Due to the price of buckwheat, a cost comparison of using it with a bastard fallowing alternative is needed. We will look at labour and work flows.
    • As people have different situations, space available, kit and rotations, it will be difficult to standardise everything across the farms. Therefore,
    this year will act as a proof of concept, in order to have a look at buckwheat on the host farms with controls and come back and compare notes.
    • All farmers will do a baseline sampling of couch before starting the trial. This will involve digging and weighing roots from 30 x 30cm x 20cm holes, a visual soil assessment (using the GREATsoils protocol) and physical description of texture (e.g. sandy clay loam). The protocol is to be finalised and distributed.
    • In order to help in standardising, all participants could use the same source of buckwheat and a similar sowing date of early May. The sowing rate of 70kg/ha will be used (Cotswold recommended rate).

    The trials are to be as follows:
    • Farmer A: Buckwheat with crimson clover and white clover vs. bastard fallowing. (Originally we considered buckwheat as a pure stand but comms with Lynn Tatnell suggest it works better in combination with other cover crops such as clovers).
    • Farmer B: Buckwheat incorporate July =>fertility building. Bastard fallow control until fertility building.
    • Farmer C: Cultivating first =>early June sowing =>mid August incorporation => 3 weeks =>cereal rye cover. Bastard fallow control until rye sown
    • Farmer D: Buckwheat => fertility building => crop (maybe cost dependent).
    • Farmer E: Trial as part of summer quick fix (Cotswold mix, but with buckwheat instead of mustard) over/winter => brassicas. Rolling half vs. not rolling. Compare with summer quick fix with mustard.

    Milestone: Methods confirmed

    February 2017

    Second meeting discussion continued

    To assess differences post-trial, the following will be undertaken:
    • As photos are important in recording and evaluating progress and differences, these will be taken regularly.
    • Couch assessments will be undertaken at the same time next year.
    • Yield assessments in the following crop.
    • Soil biology post trial.
    • Physical plot markers can be used, but it will be important to match plots to operations e.g. boom width of irrigation/number of beds etc.

    The next meeting was scheduled to be at Abbey Home Farm, in the first week of August.

    Photos from the meeting can be found here: https://flic.kr/s/aHskSqMKXk

    Other useful resources from the group can be found here:
    • https://www1.maine.gov/dacf/php/gotpests/weeds/factsheets/Quackgrass-organic.pdf
    • http://www.bcpc.org/wp-content/uploads/2016/11/Angela-Huckle-v2.pdf
    • https://horticulture.ahdb.org.uk/sites/default/files/research_papers/CP%20086_Report_Final_2016.pdf
    • https://www.cabdirect.org/cabdirect/abstract/20143111151

    Milestone: Methods confirmed

    June 2016

    Field lab trial proposal

    Aims: The field lab would attempt to evaluate the potential for buckwheat (and other crops) to reduce couch grass infestations. Anecdotal evidence has shown it to work well within the rotation at Abbey Home Farm (AHF). Can it be built into rotations to reduce the couch grass burden on farms?

    Proposed methods: The methods proposed would be to trial growing buckwheat on AHF and on other participating farms, alongside a summer fallow control, with monitoring of couch grass before, during the growing season and in subsequent crop(s). Another crop e.g. oats or simply next crop in rotation could be included in the trial. AHF apprentices could be used for data collection (weed counts using quadrats).Costs of each method would be recorded.

    Possible outcomes: Buckwheat is shown to be an effective tool for reducing couch burden in rotations and the experience of AHF is replicated on other farms. Information on the costs and benefits of growing buckwheat will be shown to give farmers more information on the technique and enable adoption.

    Benefits to farmers: it would contribute to sustainability of farms, reducing use of cultivations which can damage soil structure and fauna and/or herbicide use. It could also It could increase the use of buckwheat as an alternative grain crop, as well as a green manure/cover crop. Growing buckwheat may have additional benefits in terms of mobilising soil P, providing nectar for pollinators/beneficials, that might not be measured as part of this field lab.

    Milestone: Field lab development

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