Good green manures

This field lab is looking at different green manures that are required under Scottish farmers EFA (Ecological Focus Area) in the greening requirements. The farmers involved want to find out if the green manures have benefits to soil and crops, and will trial a range of different green manures mixes.

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Field Lab Timeline

    6/30/2016 11:00:00 PM
  • Idea formed

    Idea formed
  • 7/29/2016 11:00:00 PM
  • Seed mixes decided

    Seed mixes decided
  • 3/2/2017 12:00:00 AM
  • Preliminary results meeting

    Preliminary results meeting
  • 5/31/2017 11:00:00 PM
  • Summer trialling

    Summer trialling
  • 6/14/2017 11:00:00 PM
  • Summer trial meeting

    Summer trial meeting
  • 8/13/2017 11:00:00 PM
  • Green manures terminated

    Green manures terminated
  • 9/3/2017 11:00:00 PM
  • Winter crop sown

    Winter crop sown
  • 11/1/2017 12:00:00 AM
  • Winter trialling

    Winter trialling
  • 12/4/2017 12:00:00 AM
  • Winter trial meeting

    Winter trial meeting
  • 12/21/2017 12:00:00 AM
  • Results meeting

    Results meeting
  • 4/15/2018 11:00:00 PM
  • Following cash crop drilling

    Following cash crop drilling
  • 7/29/2018 11:00:00 PM
  • Effect on crop analysis

    Effect on crop analysis
For further information hover over the above milestone marks
  • Discussion

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  • Achievements

    March 2018

    Full results of cover crop effects on soil

    None of the mixes emerged as a clear winner for all the things that we measured, so when you are choosing your mix you should think about what you want it to achieve.

    The following conclusions have been drawn for the different mixes grown:

    For soil structure we found that the most diverse mix (oats, vetch, and phacelia) was best. This mix contained a legume, and was best for total nitrogen in the soil.

    For earthworms, the mix that was established without ploughing (radish and mustard) was best.

    For increasing organic matter, highest yield (so potentially could increase organic matter most when incorporated), and capturing most nitrogen the best mix was oats and rye.

    For cost, the oats and rye mix was cheapest, and could be further reduced by cutting the seed rate.

    The seed costs are relatively high, as a relatively high seed rate was used because of the later sowing date. So by reducing seed rate, and by using home saved cereals, seed costs could be reduced, particularly for the oats and rye mix which was very thick. This will obviously depend on time of year and weather conditions.

    We will be going out and assessing the following crop. We will look at how green the crop is, to get an idea of the amount of nitrogen that was captured, and will also assess the yield of the following crop. We have added two new farms to the trial to look at summer green manures, and will be reporting on their progress.

    Please log in for free to download the attached presentation under 'Field Lab Documents' to read the full findings so far.

    If you want to be part of it or if you want more details about the field lab, get in touch with dmichie@soilassociation.org.

    Milestone: Results meeting

    March 2018

    Thankerton results

    The results so far from the soil assessments at Thankerton show that:

    •Oats, vetch, and phacelia are good for soil structure
    •Mustard and radish (least cultivations in establishment) is best for earthworms
    •Oats and rye are best for bulk (organic matter) and nitrogen

    Please log in for free to download the attached presentation under 'Field Lab Documents' to read the full findings so far.

    The following crop of spring barley now needs to be assessed later this year to get full results and better understanding of the cover crop mix performances.

    Milestone: Preliminary results meeting

    October 2017

    South Lanarkshire initial results

    Initial results assessing the yield and protein content in fresh weight and dry matter of the green manures, as well as the worm weight and number, were discussed. Oats and rye had the highest quantity and energy, although radish and mustard had the highest protein and worm numbers. The report for these results can be found when logged-in under the 'Field Lab Documents' section on this page.

    The forage analysis and subsequent crop yield measurements are to follow.

    Milestone: Preliminary results meeting

    September 2017

    Stirlingshire green manure termination

    The cover crops at the Stirlingshire site will be terminated using chemical methods but that aim to avoid soil compaction. Winter wheat will then be sown, and assessments of its yield will be undertaken next year.

    Although the above was originally planned, the green manures were killed off too early and the wet weather meant that the winter wheat was not able to be sown. This means that the wheat crop yield will not be able to be assessed, and decisions are underway for the possibility of another year of trialling.

    Milestone: Winter crop sown

    August 2017

    Cost vs weed and soil health performance of green manure mixes

    At one of the new triallist's sites in Stirlingshire, different green manure mixes were sown in spring, and the progress of their establishment followed into summer. In July, assessments of the root penetration, soil structure, number of earthworms per spade of soil and a visual assessment of weed cover were undertaken on the different mixes. The effectiveness of these combined parameters for soil health and seed-bed preparation were compared to the cost for each of the four different mixes, as well as factoring in the potential cost of needing to use machinery to plough and harrow.

    The higher cost of the improved 5-seed mix without inoculation was thought to be cost-effective for the benefits it provided for the soil and biodiversity. The report for this can be found in the 'Field Lab Documents' section on this page when logged in.

    Milestone: Green manures terminated

    July 2017

    BBC Radio Scotland interview

    On Saturday 22nd July BBC Radio Scotland’s Out of Doors programme aired an interview with triallist Gavin from the green manures field lab and David Michie from the Soil Association. They explained how the trial aimed to benefit to soil and wildlife in the area, and Gavin highlighted how he had seen an 8 inch growth in the deep rooted crops over just a couple of months. The interviewer Euan remarked at the number of swallows he could see (around 40) and David related how the diversity of green manures hoped to increase soil biology, insects (bees and hoverflies could be seen) and therefore birds. Gavin mentioned that other farmers in the area have been showing interest in the field lab trial too. Euan remarked how the trial fields sit creating colour and diversity amongst a landscape of barley fields.

    Cost was also discussed, and despite seed expenditures, David explained that triallists are already seeing a saving on fertiliser costs. The long term benefit of soil health improvement was further highlighted.

    Gavin described the green manures in 3 of his trial plots:
    • Mustard, red clover and triticale
    • Oil seed radish, red clover and italian rye grass
    • Red clover and chicory

    The programme also explores the advantages of schemes like green manure in light of Brexit and Gove’s recent speech.

    For a limited time, the link can be found here (listen at 00:35:00): http://www.bbc.co.uk/programmes/b08yn8b4

    Milestone: Summer trialling

    July 2017

    Summer meeting

    The group is exploring which green manure mixes are best suited to Scottish soils and climate. Recent meeting on 18th July looked at establishment of 5 summer green manure mixes & measured soil health. There are 2 farms with summer mixes in just now, and one more farm with winter mix now into spring barley. The next meeting will take place in September/October 2017 to look at establishment and quality of a wheat crop following a summer mix.

    Milestone: Summer trial meeting

    April 2017

    Stirlingshire seed mixes

    The Stirlingshire triallist has decided upon the following seed mixes to compare their effect on soil health, weed prevention and crop yield:

    Mix 1 - Ordinary mix: mustard and phacelia:
    5kg/ha £3.50/kg
    £17.50/ha
    90% Mustard white
    10% Phacelia

    Mix 2 - Basic 5 mix: legume, cereal, grass, brassica, chenopod (quinoa):
    65kg/ha £0.85/kg; £55.25/ha
    93.5% Mascani oats
    3% Westerwolds rye grass
    0.5% Quinoa
    2% Mustard white
    1% Crimson Clover

    Mix 3 - Improved 5 mix (ie 2x legumes vetch & crimson clover) without inoculation:
    75kg/ha £0.95/kg
    £71.25/ha
    20% Humbolt Rye
    64.5% Mascani Oats
    7% Magnus peas
    5% Vetch
    2% Crimson Clover
    1% Oilseed Radish
    0.5% Reed Canary Grass

    Mix 4 - Improved 5 mix (ie 2x legumes vetch & crimson clover) with inoculation:
    75kg/ha £1.20/kg
    £90/ha
    20% Humbolt Rye
    64.5% Mascani Oats
    7% Magnus peas
    5% Vetch
    2% Crimson Clover
    1% Oilseed Radish
    0.5% Reed Canary Grass

    Milestone: Seed mixes decided

    April 2017

    New triallists

    Two more farmers, based in Stirlingshire and Aberdeenshire, will be trialling summer green manures this year.  The same assessments will be undertaken at these sites, and meetings held to discuss the results.  It is hoped that another triallist will undertake winter green manure site for later in the year.

    Milestone: Summer trial meeting

    March 2017

    Initial results

    At this early stage it is difficult to say which green manure has worked best, however the analysis shows that:

    Forage - Radish and mustard (and winter barley volunteers) had the highest protein, and the oats and rye had the highest energy (both measured by kg of dry matter).

    Soil structure - All of the plots had very good soil structure. The oats, vetch and phacelia plot had the best soil structure, and the oats and radish had the poorest (although it was still very good).

    Earthworms - The earthworm numbers were by far the highest in the radish and mustard plot. This is the plot that had the least cultivations as it was broadcast sown after a light harrowing. The high earthworm numbers were probably more to do with the cultivations than the seed mix.

    The next important step is to see how the following crop of spring barley performs.

    Questions will be:
    Will one part do better than others?
    Will the soil structure benefits and earthworm numbers make any difference?
    Will some green manures increase soil organic matter?

    Please see the attached field lab document 'initial results' for more information.

    Milestone: Preliminary results meeting

    March 2017

    Preliminary results meeting

    The main aim of the meeting was to look at how the different green manure mixes are performing and to discuss preliminary data – soil structure; earthworm numbers and weight; and green manure yield.

    Differences in plots and ploughing ease was noted; one plot was noticeably better than the others – suggesting that the green manures had benefited the soil quality.  Nitrogen data from soil analyses was also discussed. See the following achievement post for more info on initial results.

    Following on from this, the next step is to assess the growing crop – this will be done visually by stating how green the crop is in each plot to give an indication of residual N. This will likely be a score from 1-5 (1 = yellow-green, 5 = blue-green). The grain yield in the following crop will also be analysed. Soil structure will be further assessed using VESS, and more earthworm counts taken.

    Milestone: Preliminary results meeting

    September 2016

    Decision on seed mixes - South Lanarkshire

    We decided to choose several different seed mixes. We went for: radish and mustard; oats and radish; oats and vetch and phacelia; and oats and rye. We expect there to be differences in ease of establishment, frost-tolerance, and benefits. We will go out and visit the growing green manure to see what the differences actually are.

    Milestone: Seed mixes decided

    June 2016

    Field lab idea developed

    The coordinator David Michie (Agricultural Development Manager at Soil Association Scotland) had discussions with a host farmer, Leslie Sloan, about different green manures that are required under his EFA in the greening requirements. We wanted to find out if the green manures had any benefits and discussed the different green manures mixes that can be used. We wanted to measure any benefits that different green manures can provide to the soil and following crop.

    When considering what the EFA allowed under the requirements, the groups identified a selection 5 seed mixes that could be used for the trial.

    Milestone: Idea formed

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