Producing efficient high-quality humified compost

Investigating the Controlled-Aerobic-Composting method of producing a compost that is fully nutrient and crumb stabilized, in the form of clay-humus-complexes and long-chain humic acids, as well as other high quality humus substances, within 6 - 8 weeks

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Field Lab Timeline

    12/1/2015 12:00:00 PM
  • Initial idea formed

    Initial idea formed
  • 3/1/2016 12:00:00 PM
  • Field lab development

    Field lab development
  • 6/19/2016 11:00:00 AM
  • Start first trial windrow

    Start first trial windrow
  • 7/31/2016 11:00:00 PM
  • Apply for funding (equipment and materials)

    Apply for funding (equipment and materials)
  • 8/20/2016 11:00:00 AM
  • Complete first windrow (8 weeks)

    Complete first windrow (8 weeks)
  • 9/25/2016 11:00:00 AM
  • Workshop on humus management and C-A-C method

    Held at Wardington Manor

    Workshop on humus management and C-A-C method
  • 10/29/2016 11:00:00 PM
  • Analyses of first windrow

    Analyses of first windrow
  • 3/7/2017 12:00:00 AM
  • Second year trial methodology decided

    Second year trial methodology decided
  • 4/30/2017 11:00:00 PM
  • Second workshop on windrow making

    Second workshop on windrow making
  • 5/10/2017 11:00:00 PM
  • Second year trials begin

    Second year trials begin
  • 6/24/2017 11:00:00 PM
  • Data collected from windrows

    Data collected from windrows
  • 7/30/2017 11:00:00 PM
  • Coordinator and researcher meeting

    Coordinator and researcher meeting
  • 9/11/2017 11:00:00 PM
  • Progress check on international triallists

    Progress check on international triallists
  • 9/12/2017 11:00:00 PM
  • Start of second windrow

    Start of second windrow
  • 9/29/2017 11:00:00 PM
  • Group members complete windrows

    Group members complete windrows
  • 10/9/2017 11:00:00 PM
  • Developing testing methods for wider group

    Developing testing methods for wider group
  • 10/31/2017 12:00:00 AM
  • Second round of funding

    Second round of funding
  • 11/24/2017 12:00:00 AM
  • Apply for funding (testing)

    Apply for funding (testing)
  • 1/15/2018 12:00:00 AM
  • Trial continues into second year

    Trial continues into second year
  • 1/22/2018 12:00:00 AM
  • Continuing windrow measurements

    Continuing windrow measurements
  • 3/12/2018 12:00:00 AM
  • New windrow making

    New windrow making
  • 5/6/2018 11:00:00 PM
  • Further windrow measurements

    Further windrow measurements
  • 5/20/2018 11:00:00 PM
  • Compost analysis

    Compost analysis
  • 8/19/2018 11:00:00 PM
  • Initial growth tests

    Initial growth tests
  • 9/2/2018 11:00:00 PM
  • Solvita testing of coordinators windrows

    Solvita testing of coordinators windrows
  • 9/9/2018 11:00:00 PM
  • Results analysis

    Results analysis
For further information hover over the above milestone marks
  • Discussion

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

  • Achievements

    August 2018

    Growth results

    The initial growth results for sweet pea height and flower stem length have been positive for the controlled-aerobic-compost (CAC) applications.

    On the 18th May, plants growing in the Klausman plot were on average 2% shorter than the plants growing in the control plot. The plants growing in the CAC plot were 36% taller.

    This result suggests that CAC may be better at helping plants to establish and grow quicker than the Klausman compost, possibly due to more readily available crop nutrients, (see compost analysis document).

    On the 11th June, plants growing in the Klausman plot were on average 15% taller than the plants growing in the control plot. The plants growing in the CAC plot were 22% taller. CAC heights are less variable (19%) than the Klausman (29%) or the Control (40%) on this assessment date.

    By the 20th of July, plants growing in the Klausman plot were on average 12% taller than the plants growing in the control plot. The plants growing in the CAC plot were 33% taller. CAC heights are less variable (19%) than the Klausman (29%) or the Control (36%) on this assessment date.

    The results suggest that the CAC may be effective in increasing final crop height compared to no treatment as well as in comparison to the Klausman compost.

    Please log-in for free and see the attached 'Initial growth results - CAC field lab' under the Field Lab Documents section.

    Milestone: Initial growth tests

    July 2018

    Compost comparison results

    The two main compost types being analysed in this trial were sampled and analysed by NRM for a suite of properties and nutrients. A second batch of compost currently being made will also be sampled and analysed to add to the results below.

    The analysis showed the following:

    - The Controlled-Aerobic-Compost (CAC) has a greater concentration of available nutrients than the Klausman for all except Magnesium, Calcium, Manganese and Zinc (all measured in mg/l). Notably, available N, P and K are all in greater concentration in the CAC compost. The ratio of nitrate to total mineral N should be above 80% for mature compost – in CAC it is 98% and Klausman 97%.

    - pH and density are also slightly higher – CAC pH = 7.8 and Klausman = 5.5. The pH of the Klausman compost is too acidic. Normally compost is slightly alkaline and should be around pH 7-8, as with the CAC compost.

    - Dry matter and density is also higher than the Klausman compost. Dry matter = 67.7% vs 27.9% and density = 383.2 kg/m3 vs 135.6 kg/m3. This means that the moisture content of the CAC is lower, however it is not clear whether this is a negative point at this stage.

    - Conductivity further scores higher for the CAC compost at 1884 uS/cm vs 569 uS/cm.
    The higher concentration of available nutrients and conductivity can act as a good proxy for expected crop yields this summer.

    Please log-in for free and see the attached Field Lab Documents ('Compost comparison results') for further details.

    Milestone: Compost analysis

    June 2018

    Microbial analysis samples

    The coordinators are taking samples of their compost-incorporated soils to give to the researcher who is sending this off for microbial analysis. The analysis will include phospholipid fatty acid to determine the microbial community present in each sample. This follows on from the previous years analysis of active and total fungal and bacterial populations, to give a clearer picture of what activity (microbial function and structure) is happening in the soil of the trial plots once the compost has been applied.

    Milestone: Compost analysis

    April 2018

    Second year trialling begins

    The coordinators and researcher met to look at the start of the trial - sweet peas have been planted in the coordinators' polytunnel with alternate planting of control and compost beds. This alternate planting accounts for the climatic gradient within the polytunnel. Only the most aggressive weeds are being removed from around the sweet pea stems.

    Later in May, the coordinators will be trialling with the compost outside. This will include growing spinach, kale and nasturtiums. Two further outside trial plots will grow flowers including cosmos and dalias. Cosmos will be planted mid-late May and dalias in September. These two plots will also be grown to accommodate for a nutrient gradients across them.

    The measurements to be taken and recorded from all of the above plots throughout the growing season will be:
    - Height
    - First flowering date
    - Flower size (diameter)
    - Colour vibrancy (scale of 1-5)
    - Vigour (scale 1-5)
    - Resistance to drought
    - Brix (3 leaves per plant, kale)
    - Insects (3 leaves per plant, kale)

    Photos will also be taken throughout the season so that records can be cross-compared in the analysis.

    During this meeting, the researcher also took samples of the CAC compost and the Klausman compost to send off for a nutrient analysis. Results will be posted soon.

    Milestone: Second year trials begin

    January 2018

    New Zealand and Mozambique update

    Updates from New Zealand since the start of compost making in October are that the windrow is going well and weather has been somewhat variable - there have been both mild and hot temperatures which have at times meant the compost pile has needed watering. However, recently rain has prevented the team from turning the windrow, and it has not always been able to get up to an ideal temperature. There have also been some issues with the CO2 monitor which they are working to fix. For the time being, the team are recording the smelliness of the windrow. Please see photos of the ongoing trial in the Field Lab Documents tab to the right of the page.

    We have had updates from Vamizi Island, Mozambique, that the compost windrow is working well to provide good crops of spinach, tomatoes and herbs. The triallist has delayed her trip and will be going out to the island to discuss the initiation of a further 5 compost windrows. She will also be discussing training at the local school for children to build their own with the view to creating a school garden from the compost.

    Milestone: Continuing windrow measurements

    December 2017

    Grant awarded for testing

    The field lab has been awarded a top-up grant to cover useful compost tests for 6 trial sites, including:

    1) NRM compost suite - Dry Matter, Bulk Density, Dry Density, pH, Conductivity, Nitrate-N and Ammonium-N with calculated soluble N, Chloride, Sulphate, Potassium, Phosphorus, Magnesium, Calcium, Sodium, Iron, Manganese, Zinc, Copper and Boron. This objective and robust data will indicate compost quality and help with comparisons between piles.

    2) Solvita compost test kits. These are a simple method for growers to test the maturity of compost by measuring CO2 and NH3 output from the piles. It offers growers a reasonably accurate method for determining compost maturity and can be compared to the output from lab tests to see if the kits could be used by the rest of the group as a simple in-situ test.

    These tests will provide information on the physical, chemical, and biological parameters, enabling comparison of different composting techniques. The growers will also be performing several low cost tests such as a cress test (to assess phytotoxicity) and a growing test of a target crop to validate compost end use. The growers will also assess the compost in a practical sensory manner (touch, smell, pliability, colour, etc.) using their own knowledge of growing media for their farms.

    Milestone: Apply for funding (testing)

    September 2017

    Triallist viewpoint

    In addition to the update on the Welsh windrow composition, this triallist also gave her thoughts on why they decided to do the trial:

    "We were aware that we were not doing best for soil, but trying to build up to it. We have been doing rotations and farming poultry but with the wet summers, it has been more difficult to cultivate. There are more nettles, thistles and docks growing in the fields. We have always tried composting by turning and stacking up materials, but it started to feel like this method was not good enough – so we thought we would invest in this method of aerating compost. There is always a lot of woodchip available, so we thought it would be good to mix with the green waste that we already have. We want to get as good a product as we can do.

    We’ve always known that making good compost was the right thing to do for soil microorganisms, and aware that the poultry are living symbiotically with the soil. We wanted to use something that is giving life back to the soil. Creating this compost is the biggest resource we’ve ever invested in, and we felt it necessary to do so. It’s also great to be a part of the group, creating friends and being actively connected.

    This year the weather held up until around July / August, however since it has been very wet. We wanted to make another windrow at the beginning of august but has only just put one out in September because of the bad weather.

    So far in the trial (including last year and the windrow made in May this year) we have been very pleased with the end results of the compost on the farm."

    This triallist said that using sheeting is hard work in the wet weather, but otherwise the windrows have not been hard work. She noted that one day of dry weather can change everything very quickly; however unfortunately there has been a lack of good weather recently. This makes farming in the area generally very difficult, but the results of the compost are encouraging.

    Milestone: Progress check on international triallists

    September 2017

    Update from Welsh windrow

    Another triallist recently let us know what ingredients she uses in her compost windrows in west Wales.
    Her compost ingredients are:

    - Woodchip from hedgelaying = hawthorn, blackthorn, willow, hazel, ash, alder. These were chipped using greenmech machine before adding to the compost.

    - Green from polytunnels – courgette tops, bean tops, green leaves etc. from horticulture.

    - Poultry muck from mobile sheds – poultry 50% grass diet + wheat/pea/oat diet.

    - Horse muck mixed with imported bark peelings stripped from pine trees grown in the Ystwyth valley and processed at local sawmill – horses live in coral 6” bark peeling on the ground, only fed grass/hay from their fields.

    - Oat straw- home grown from chick/pullet rearing shed mixed with poultry muck.

    - Waste/recycled cardboard from egg packing.

    - Docks, thistles, nettles and grass cut and collected from poultry fields with mini direct cut forage harvester.

    - Biodynamic preps - 500 + 502,503,504,505,506,507.

    - Inoculant of microorganisms.

    Milestone: Progress check on international triallists

    September 2017

    Land Gardeners update

    An update from the Land Gardeners on the start of their second lot of windrow making:

    We used basically the same material for each pile - but there was some variance as the greens we were using was a mix of weeds, grass clippings, vegetable and flowers.

    Of the 3 piles one is on a concrete base as we wondered if that affected the heating of the piles at all, and it did in fact get hotter more quickly than those on soil.

    The 3 static piles have not heated up in the same way as those that were turned after making. They have stayed in the 20’s whilst the CAC piles are in 40’s and 50’s - so there is more action in the piles that were all mixed up.

    For group members - please see the Activities tab for photos of these windrows.

    Milestone: Start of second windrow

    September 2017

    Update from the Mozambique windrow

    One group member is trialling windrows on Vamizi Island, Mozambique. We have had chance to catch up with her recently and hear about the background to the trial on the island.

    The small coral-based island has very little growing medium for farming, which has been non-existent on the island. Those living on Vamizi live from fish and imported cassava and rice, with no vegetables in their diet. This group member and a local Women's Group are working together to learn the process of windrow and compost making to grow vegetables for the first time on Vamizi. They are using only locally available materials, including leaf mulch and woody stems from the scrubby, hardy island vegetation and goats dung.

    This group member is taking part in the trial as she finds the composting a "fascinating process", and the Women's Group have commented that they "can’t believe how sweet the smell is" and are "amazed by the heat" from the compost pile. With no soil being present on the island, there has also been a sense of revelation at the connection between compost and vegetables.

    We will be receiving a further update after a visit to the island in November, accompanied by a blog and photos. Thanks to the triallist for the update and sending on photos - you can see these on the activities section.

    Milestone: Progress check on international triallists

    July 2017

    Coordinator and researcher meeting

    It was agreed that the coordinators would trial a range of different compost piles, including:

    1. CAC standard (ingredients + inoculant + method)
    2. CAC static, “scientific” control (ingredients + inoculant)
    3. Parfey pile (ingredients + inoculant + alternate method – turning at set intervals)
    4. Wild card Pile, Possibly Biodynamic (ingredients + different inoculum + method)

    The other triallists will only test the first two to keep the trial more manageable. The coordinators also have an interest in biodynamic practices, and therefore will include a pile with practices from this. Only one factor is changed between each pile. . The Parfey pile also only changes the method, which is similar to a half way house between the CAC method and a static method. The final biodynamic pile only changes the inoculant.

    The researcher noted that it is important that "all piles are composed of exactly the same ingredients in the same proportions, and are managed in the same way, so for instance if you add water to one pile, you should add the same quantity of water to all the other piles."

    Compost piles will be tested in Summer / Autumn which will then inform the best testing methods. The research and coordinators will meet again to then discuss the best testing methods for the wider international group.

    Milestone: Coordinator and researcher meeting

    July 2017

    Group meeting

    The group coordinators met with the researcher to verify methods and the funding needed for this next year of trials. Methods will include:

    1. Visual test – What does it look like, feel, smell, how do things look like they are growing? Are there changes you have noticed on the farm/garden?

    2. Basic analysis - NRM lab: basic compost test

    3. Growing tests - Cress test and a growing test (e.g. sweet pea test, or something growing in a pot). This will help to see, for example, if there is any phytotoxic effect in the compost. Any growing tests must have same growing conditions e.g. same watering regime, same place.

    4. Microbiology – We will be able to identify output for functional difference between two piles of compost ie difference in community.

    It was agreed that the researcher start the funding application and also take samples to be tested. The coordinators agreed to check that all international group members have the equipment they need, and are considering holding an international compost event next year.

    Milestone: Coordinator and researcher meeting

    May 2017

    Second year trials start

    The second year of trials for those in more temperate climates will begin around the 11th May. Those in Mozambique have been ongoing due to the warm climate. Trials in New Zealand will begin in October.

    Milestone: Second year trials begin

    May 2017


    The Land Gardeners will run a second workshop for those further interested in learning the windrow methodology.

    Milestone: Second workshop on windrow making

    March 2017

    New trial year methodology

    The group confirmed that they have decided to use the same methods as the previous year, as they felt they worked well. This will also add results and evidence to the data for this trial.

    Milestone: Second year trial methodology decided

    October 2016

    Members learn how to perform the C-A-C method

    Members of the group attended a workshop at Wardington explaining how to properly perform the C-A-C method, preparing them to create their own windrows in the following spring. All equipment for creating the windrows has been purchased and delivered to participants. The first finalised windrow, created by the Landgardeners, was used as an example - see photographs in field lab comments.

    Milestone: Workshop on humus management and C-A-C method

    August 2016

    Our grant application was successful

    We applied to Innovative Farmers for a small grant to help towards the equipment costs for all 12 participants. We are delighted that we have been successful and can now get all the equipment together to start the field lab trial.

    We aim to apply for further funds soon towards the testing needed to assess the methodology confidently. We are working with Dominic, our researcher from ORC, to identify the most effective and cost efficient way to get the data we need.

    Milestone: Apply for funding (equipment and materials)

    April 2016

    Summary of trial method - construction

    The method for the trial has been determined and is outlined in summary below. Full details are available in the field lab documents.

    The triallists will be provided with the equipment to enable the construction of a 5m windrow for measuring the temperature and CO2 levels accurately.

    For each windrow:

    a) the material-combination (for each trial participant) will be chosen according to the C:N ratios of the (locally available) materials, creating a final C:N ratio of 30:1
    b) the combination of materials used will also depend on their structure and properties
    c) 10 % clay/loam-soil will be added, by volume
    d) (if available) 10% finished compost will be added, by volume
    e) the daily monitoring will consist of: temperature, CO2 and moisture assessment
    f) turning: will take place according to CO2 content (min 5% O2 during the whole process) and temperature (max. 65°C)
    g) watering: will ensure 55-60% moisture throughout the whole process

    Recordings are made daily and photos taken to feed back to the group.

    As each participant is making their windrow using their own locally sourced materials, in varying climates and using different methods of turning the windrows (ie at least one participant will be using a compost turner) there will be variations between participants. However all participants will be following the same key principles as outlined above.

    Milestone: Field lab development

    April 2016

    Summary of trial method - testing

    The finished material assessment and testing is summarised below. Full details area available in the field lab documents.

    After 8 weeks the participants’ compost will be assessed by the standards for mature compost, of the Controlled-Aerobic-Composting Method by Luebke-Hildebrandt.The initial tests will allow us to answer our key question: Will a Controlled-Aerobic-Composting process fully digest and humify organic matter in 6 - 8 weeks, under different circumstances?

    A sample of each triallist's compost is compared to a defined sample using:

    a) physical observation of undigested OM
    b) water test - visible floating OM
    c) water filter test - assessing colouration of filtrate
    d) open and closed cress seed test - observation of cress seed germination, growth and biomass production in a sample
    e) chemistry tests - nitrates, nitrites, ammonium, sulphides, pH, proportions of C, N and OM, C:N ratio, and conductivity

    Milestone: Field lab development

    April 2016

    Summary of trial method - possible outcomes and benefits to farmers

    We are expecting to use the Controlled-Aerobic-Composting method in different contexts (ie varying materials available for composting, different climates, large scale and microscale farming) to produce a defined compost quality, with the ability to form highest quality humus and transfer this humifying ability to agricultural soils, to re-establish the ability of soils to detoxify, hold nutrients & carbon and supply all substances needed by plants.

    The end product of a Controlled-Aerobic-Composting process should be a universally usable compost - whether by direct application or as a base for compost teas - for application on croplands, fruit & vegetable production, lawn care, potting soils, greenhouses, and so forth. It would be an effective amendment for conventional as well as organically farmed soils.

    Milestone: Field lab development

    April 2016

    Background to the field lab

    We founded The Land Gardeners because we are passionate about soil health. We would like to find ways of improving soil health both for our own growing and for others - in horticulture and farming - as we passionately believe that having a healthy soil is the key to successful growing, healthy crops, healthy animals and ultimately healthy people.

    The idea of this field lab to test controlled aerobic composting as a soil improver arose after meeting the creator of the new composting method. Growers and farmers from all around the world immediately showed interest in participating with the trail - from farms in New Zealand and Paris to an island near Mozambique.

    Milestone: Initial idea formed

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