Growing with peat-free woodchip compost

The field lab explored the use of woodchip compost as a component in peat-free propagation material in horticulture and evaluated its performance relative to other growing materials.

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Field Lab Timeline

    12/2/2013 12:00:00 PM
  • Idea Formed

    Idea Formed
  • 2/3/2014 12:00:00 PM
  • First sowing

    Cabbage and leek and seeds sown

    First sowing
  • 2/24/2014 12:00:00 PM
  • First meeting

    First meeting
  • 2/24/2014 12:00:00 PM
  • Kick-off meeting

    Kick-off meeting
  • 4/6/2014 11:00:00 AM
  • Second meeting

    Second meeting
  • 4/6/2014 11:00:00 AM
  • Initial results discussion

    Initial results discussion
  • 4/13/2014 11:00:00 AM
  • Cabbages planted

    Cabbages planted
  • 4/22/2014 11:00:00 AM
  • Leeks planted

    Leeks planted
  • 7/1/2014 11:00:00 AM
  • Cabbages harvested

    Cabbages harvested
  • 7/1/2014 11:00:00 AM
  • Cabbages harvested

    Cabbages harvested
  • 8/19/2014 11:00:00 AM
  • Leeks harvested

    Leeks harvested
  • 9/21/2014 11:00:00 AM
  • Final meeting

    Final results presented and discussed

    Final meeting
  • 9/21/2014 11:00:00 AM
  • Final Results Discussion

    Final Results Discussion
  • 9/29/2014 11:00:00 AM
  • Identify what has been learned

    Identify what has been learned
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  • Discussion

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  • Achievements

    September 2014

    Final meeting

    By September, the leek and cabbage crops had been harvested, with only a small strip of the leek trial left standing – the aim of which being to monitor any pests or diseases that might present themselves during a longer growing period.

    The results of the trial (pest and disease occurrence, yield etc.) were presented and discussed by the group. Useful feedback was received from participants, and alternative options were discussed. For example, one individual had achieved positive results from a small experiment comparing the use of leaf-mould compost and a conventional growing substrate (New Horizon) for brassica transplants. Suitable methods for small trials and experiments such as this were also reflected upon; on the one hand to maximise the usability of results, and on the other to optimise the efficiency of labour and budget investments.

    During a visit to the remaining leeks standing in the field (in which no noticeable differences in levels of pests and diseases were observed), Iain Tolhurst summarised the results and achievements of the trial.

    From a practical point of view, it was agreed the trial revealed that homemade woodchip not only performed well compared against peat based commercial product, but was also financially comparable.

    Milestone: Final Results Discussion

    September 2014

    Results compilation

    • In each replication 26 cabbages were harvested. No significant differences are noticeable in the data. However, the cabbages raised in substrates with added Biochar yielded slightly heavier/larger cabbages, particularly those ones raised in woodchip compost and Biochar.

    • Quality assessment was performed by the grower himself, ranking the harvested crop of each replication with a number between 1 and 10 (1 being very low quality and 10 being highest quality). No significant differences were found, with the average quality of the four variations ranging between 7 and 8.

    • Regarding slug damage (also assessed by the grower), no significant differences between the four substrates were observed. Once again a scale ranging from 0-10 was used, with 0 standing for no damage and 10 standing for very high slug damage. However, a slight trend towards a higher pest occurrence in plants raised in substrates with added Biochar can be seen (the range of numbers within these replications being larger).

    Milestone: Final Results Discussion

    April 2014

    Discussion of first results

    The transplants were fully developed in their growing trays, with the cabbages almost ready for planting out in the field. The results of the substrate analysis were discussed by the group, together with the first measurements of plant health and growth. Unfortunately, even though some of the participants had been inspired to set up their own comparison trials or to produce their own compost, no additional experiments had been started in the first two months.

    Height measurements taken three weeks after pricking out showed no difference in the length of cabbage plant shoots. With the leeks, however, the plants grown in Klasmann substrate (both with and without added Biochar) appear to have grown quicker as a longer shoot length was measured.

    Milestone: Initial results discussion

    February 2014

    Samples sent for testing

    All four substrate mixes were sampled during the pricking out process at the end of February 2014 and their nutrient content, pH, density, and heavy metal concentrations analysed in a laboratory (NRM).

    Milestone: Initial results discussion

    February 2014

    Introduction for new members

    This meeting introduced members to the trial. Though methods had been agreed beforehand, trial design and approach were discussed with the attendees. This was followed in the afternoon by a 3 hour workshop led by Iain Tolhurst, during which he gave an overview of the production of compost and woodchip compost on his holding. The aim of the workshop was to motivate growers to produce their own growing media, and to encourage groups of growers to test other materials on their holdings and share their experiences at subsequent field labs later in the year.

    Iain Tolhurst described how he uses his own woodchip compost both to raise transplants and as a fertiliser and source of additional organic matter in his polytunnels and fields.

    Milestone: Kick-off meeting

    December 2013

    Idea formation

    Iain Tolhurst and Thames Organic Growers joined together to form the idea for this field lab after recognising that a more robust trial of Iain’s compost was needed.

    Milestone: Idea Formed

  • Findings

    September 2014

    Findings Overview

    The trial has revealed clear results showing that woodchip compost can be successfully used to replace a commercial growing substrate containing peat. The results indicate that growth, health, and even yield of the assessed crops were comparable, with only small differences in weight and quality (in some cases the plants raised in woodchip compost and biochar performed better than the control), and suggest that woodchip compost can provide a good alternative to commercially available, peat-based growing media.

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