Sheep grazing on cover crops

The group will explore the impact of grazing sheep on over-winter cover crops on soil properties, crop performance and the management of livestock within an arable rotation.

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Field Lab Timeline

    6/14/2020 11:00:00 PM
  • Initial meeting with farmers

    Initial meeting with farmers
  • 7/14/2020 11:00:00 PM
  • Reviewing trial design and identifying fields

    Reviewing trial design and identifying fields
  • 8/9/2020 11:00:00 PM
  • Hub site soil nitrogen assessments

    Hub site soil nitrogen assessments
  • 8/14/2020 11:00:00 PM
  • Establish cover crops on all sites

    Establish cover crops on all sites
  • 9/29/2020 11:00:00 PM
  • Cover crop establishment assessments

    Cover crop establishment assessments
  • 2/15/2021 12:00:00 AM
  • Cover crop biomass and quality assessments; soil assessments

    Cover crop biomass and quality assessments; soil assessments
  • 8/14/2021 11:00:00 PM
  • Yield assessments

    Yield assessments
  • 9/29/2021 11:00:00 PM
  • Cost-benefit analysis

    Cost-benefit analysis
  • 10/29/2021 11:00:00 PM
  • Field lab meeting to discuss results and conculsions

    Field lab meeting to discuss results and conculsions
For further information hover over the above milestone marks
  • Discussion

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  • Achievements

    April 2022

    Interim results

    Both the hub site (Norfolk) and satellite site 2 remained involved throughout the trials. The trials compared areas of ungrazed cover crop with areas of grazed cover crop or stubble.

    Interim results show a positive story for the grazed cover crop - that there was no obvious detrimental effect from grazing:
    - There were no significant differences between soil health other soil structure in the different treatments, despite being on quite wet soils.
    - The difference in VESS (visual assessment of soil structure) scores was negligible.
    - There were generally very good earthworm levels across all treatments; possibly slightly more in the grazed areas. A 'good' earthworm population is considered to be where there are 8+ earthworms per soil pit.
    - There was very good N uptake in the cover crop; grazing made the nitrogen more readily available. Although the hub site drilled the cover crop quite late - at the very end of August 2020 in sandy soil and therefore accumulated less biomass, it achieved reasonable levels of nitrogen update at 50kg N/ha. VESS scores were around 1.5 for the grazed plots (a good score). There was higher N uptake for the following spring barley in the first year of the trials (year 2 results are TBC).

    - The sheep trod lots of cover crop biomass into the ground and ate the stalks, which are considered less palatable. Results on livestock weight gain are TBC.

    The ADAS researcher is working through final harvest data at both sites. Ideally, the yield maps would correlate with the results on better N uptake in the following cash crop. At satellite site 2, there was a slightly higher yield in the following arable crop in the area cover crop treatments (with grazed cover crop areas showing the highest yields) vs those without cover crops.

    The group believe that the lack of a detrimental effect on soil structure from grazing the cover crops was down to good grazing management (i.e. stocking densities, avoiding stocking in particularly wet conditions).

    Milestone: Field lab meeting to discuss results and conculsions

    December 2020

    Want to run your own trial?

    Are you interested in running a trial on your farm to determine the impact of grazing cover crops with sheep?

    ADAS & AHDB staff have produced a useful guide that can be found in the Documents section of this page (log-in required, sign-up is free). The guide includes tips on how to set out your tramlines and, which fields to avoid including in your trial, what to measure/record and how to interpret the results.

    If you have further questions, send them to field lab coordinator Emily Pope - emily.pope@ahdb.org.uk

    Milestone: Reviewing trial design and identifying fields

    November 2020

    Cover crops sown

    Cover crops (mix of mustard, vetch, phacelia, winter oats and stubble turnips) have established at all the farms.

    Hub Site: In December, the researcher will take biomass samples of the crop, GPS those sample points and revisit once grazing has finished. Grazing to begin in January 2021.

    Satellite site 1: The farmer was late to set up the site but has a field of stubble and cover crop (manure applied) and will start grazing in January 2021.

    Satellite site 2: Grazing to start in late November - early December. The farmer will take on some extra assessments, including recording animal live weight and visual assessment of soil structure (VESS).

    Milestone: Establish cover crops on all sites

    July 2020

    Trial design

    Three farms are hosting trials. The hub site location has been selected by the farmers because it represents the soil type that is most applicable to other farmers in the group. To complement the hub site, the satellite sites will follow a consistent trial design, but assessments can be tailored to address the most important areas of interest to each of the farmers.

    Objective 1: Select trial plots. The farmers and researchers will evaluate satellite data and field history to select one field at each farm that will be appropriate to generate precise and robust data. Fields that have previously been in grass, grazed or received organic manure amendments will be avoided as all of these factors will influence the trial results.

    Objective 2: Monitor the impact of grazing sheep on over-winter cover crops and monitor soil, crop and livestock indicators in the cover crop and the subsequent arable cash crop. Three treatments at each site: 1) cover crop grazed, 2) cover crop not grazed, 3) stubble. Treatment boundaries.

    Data collection at the satellite sites will be done by the farmers: species composition and biomass of cover crops (the same mix will be planted); cover crop utilisation (how much is trampled into the ground or not palatable); yield.

    At the hub site, additional measurements will be taken by the researchers: VESS; earthworm counts; pentrometer resistance; bulk density; soil mineral nitrogen; photos

    Objective 3: Calculate the environmental, agronomic and animal husbandry cost benefit of grazing over-winter cover crops to the livestock and arable farm enterprise. Management records and diaries will be kept by the farmers to allow a cost-benefit analysis.

    The following assessments/records will be completed:
    • All inputs (e.g. cost of cover crop seed)
    • Cost of any additional feed
    • Use of glyphosate to destroy cover crop
    • Livestock performance: Liveweight gain; stocking rate; body condition; any other health issues
    • Details of infrastructure required

    Milestone: Reviewing trial design and identifying fields

    June 2020

    Background to the trial

    The group met in a virtual meeting in June to discuss introduce themselves, discuss the farmers' motivations for participating in this field lab (e.g. cost/benefit,; grazing value of cover crops; nitrogen supply & impact on following crops; soil structural condition, etc.) and hear feedback on the trial design proposed by ADAS researchers. A wide range of arable farmers attended the event, as well others which have livestock for grazing.

    This farmer-managed replicated trial design will be located at three sites - one hub site plus two remaining 'satellite' sites. The design of the network in this way will enable the group of farmers to allocate the project budget most effectively to generate robust data. All sites currently grow cover crops.

    Hub site: North Norfolk, light sandy loam soil over chalk. Sheep are off-wintered at the site in collaboration with local a sheep farmer.

    Satellite site 1: Staffordshire, medium, sandy loam and stony soils. 5 year rotation consisting of a 2-year clover ley, 1-year of vegetables and 2-years of cereal crops.

    Satellite site 2: Cambridgeshire, peaty soils with high SOM. Operates a wheat, maize, salad and vegetable rotation.

    The trialists are interested in the grazing value of cover crops and what species to grow, as well as the impact on following crops and soil conditions.

    In addition, other farmers will be supported to follow the methodology of the Field Lab, including providing them with the trial layout and procedures to complete their own assessments and analysis.

    Milestone: Initial meeting with farmers

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