Orchards researching the benefits of mulching

Projects to improve soil health with various different amendments is a common theme in many farmer-led research projects. One group of top fruit growers have set up a field lab to test the benefits of various amendments on soil health in their orchards. Innovative Farmers Network Coordinator, Emma Hurrell, visited RHS Wisley, to meet some of the triallists and find out about their progress in the ‘Amendments for soil health in top fruit’ field lab.

Jim Arbury of RHS Wisley giving a tour of the fieldlab

The trial
RHS Wisely are one of 6 triallists testing the range of different soil amendments and their impacts on soil health. They are measuring, amongst other things, yield increases, soil health, weed and pest control, water retention, disease resilience, and fruit quality.

The amendments they are trialling are:
• Woodchip, both ramial and compost
• Biochar
• Local non-enriched biochar
• Arbuscular mycorrhizal fungi
• Anaerobic digestate

Results from the first year of testing
Jim Arbury of RHS Wisley gave an update on the success of each of the single species woodchip that they had used in their orchard trial. Jim’s team are looking to increase organic matter in their soils and control weeds. As part of the ongoing maintenance at RHS Wisley site the team have access to single species woodchip, including alder, holly and hornbeam.

On the afternoon tour of the orchard Jim noted that holly saplings had sprung up in the row under holly woodchip, and there were also quite a lot of mallow weeds. Whilst this might mean additional weeding, the holly mulch did appear to hold moisture in the soil better than alder or compost. The most successful of the Wisley trials this year was the Hornbeam woodchip, which showed the best weed control. It is not clear if the success of the Hornbeam woodchip was down to the species used or because it was laid to a depth of 10cm, and this will be examined further in the next year of trials. For RHS Wisley the use of mulching could potentially mean less use of herbicide in the orchards if it proves an effective weed control, as well the added benefit of improvements in soil health.

Ideas to save labour costs of mulching
For some, one of the barriers to applying woodchip mulch is the time cost, however RHS Wisley is well placed because they have access to volunteer labour as well as staffing. Because volunteer time at Wisley isn’t recorded down to the detail of each task it’s difficult for the team to cost up the time spent on mulching, and they acknowledged in a bigger system manual application of woodchip mulch would be prohibitively time intensive. The growers discussed potential mechanisation to make woodchip application more feasible. There was even a suggestion that several growers could collectively buy a machine, sharing the cost.

Elsewhere in the trial
During the meeting we heard some results from other trialists, who are applying several treatments, including woodchip, biochar and fabric permeable membrane. They have already seen a difference in the trees treated with woodchip: where they used a permeable membrane topped with woodchip they have seen an average extension of 28.1cm per year, compared to the untreated control with an average of 25.1cm. These first year results may not be highly significant, but it’s promising to see some early results in this first year of trials. The orchards will be continuing their testing into 2019 to see if the trend continues.

Farmer led research
Innovative Farmers facilitates practical projects led by farmers and growers, supporting farmers to innovate on their terms, responding to the challenges farmers face whilst also empowering them to work with researchers and find solutions to real world problems. If you have an idea and want to set up a farmer-led research group, join us. 

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