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Alternative methods for terminating cover crops

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This field lab investigated alternatives to ploughing or glyphosate for terminating cover crops. The group trialled a range of techniques including roller crimpers.


The idea for this field lab originated when one member sought an opportunity to trial and test the feasibility of destroying cover crops with a double-roller crimper machine, and the other desired to find a way to destroy no-till cover crops without the use of glyphosate. 


In total six farmers opted to be involved on seven field sites, of which two sites were organic. Field sites were in Cambridgeshire, Suffolk, Norfolk and Oxfordshire.

How it works


Cover crops and living mulches are often used to build organic matter and suppress weeds between main crops in rotations. 


However, reduced and minimum tillage cultivation systems which reduce damage to soil structure, have been difficult to achieve in organic systems where ploughing is the primary method of control for many weed species.  Reduced tillage systems have been more readily achievable in non-organic systems which permit the use of herbicides such as glyphosate to control weeds and kill off cover crops. There is some risk of an EU ban on the use of glyphosate.

Outcomes of the trials included: 

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

·       Measuring 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).


It was hoped that the farm-scale trials would allow non-organic farms to reduce herbicide input, and allow both organic and non-organic farms to control weeds more sustainably and improve soil health. 

Trial design

Farm-scale trials compared different termination methods to a control of bare stubble and current cultivation techniques or the use of glyphosate.  The termination methods included:


  • Roller Crimper (The crimper-roller method involves killing off a cover crop using equipment that has been developed in Italy and at the Rodale Institute.  An overwintering cover crop of e.g. rye and vetch is killed off and laid flat by rolling when it is flowering.  The following crop is then direct drilled into the dead mulch).
  • Mowing (Flailing)
  • Rolling (with frost)
  • Shallow cultivations (carrier)

The Field lab measured:

•         Efficiency of termination

•         Cover crop establishment

•         Cash crop establishment

•         Overall profit margin impact


The field lab helped evaluate the success of these methods in a farm scale replicated trial, analysed by the researchers, RSK ADAS. It was hoped that this would provide valuable examples of cover crop agronomy that would be beneficial to soil structure and the environment and may well be relied on in a future where glyphosate may be banned.


Cover crop seeds were donated by Kings Crops.


Latest updates

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.


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Start of trial

The trial started in September 2017

The crops were drilled in March 2018

Group Coordinator

A portrait of Liz Bowles.
Liz Bowles

Soil Association


Liz was the Associate Director of Farming and Land Use at the Soil Association. She left in 2022 to join Farm Carbon Toolkit.