Soil fertility plan overview
The soil fertility strategy for the Farming with Fungi market garden is built around the principle of provisioning the hyphosphere: deliberately supporting the zone of soil influenced by mycorrhizal hyphae and their interactions with plant roots, bacteria, and other soil organisms. Rather than treating fertility as a matter of nutrient replacement, the project approaches fertility as an ecological process, rooted in carbon flow, biological relationships, and long-term co-adaptation between plants and soil life.
At its core, the soil fertility plan seeks to minimise disturbance, maximise biological continuity, and use site-derived materials wherever possible. This aligns the fertility system with the wider experimental aims of the project, particularly the investigation of arbuscular mycorrhizal fungi (AMF) in permanent and semi-permanent cropping systems.
Provisioning the hyphosphere
The concept of provisioning the hyphosphere draws on recent ecological thinking around mycorrhizal networks and soil food webs, particularly the work of Michael Phillips and others who emphasise the central role of fungal-mediated nutrient exchange. In this framework, fertility inputs are evaluated not only for their nutrient content, but for how they influence hyphal growth, root–fungal signalling, and microbial recruitment in the extra-radical soil zone.
Practically, this means prioritising:
- continuous living roots where possible
- minimal soil disturbance
- carbon-rich surface inputs
- biologically buffered nutrient amendments
Mycorrhizal inoculum production
A central component of the soil fertility plan is the on-site production of arbuscular mycorrhizal fungal inoculum. The project follows the Rodale Institute technique, adapted to local conditions and materials.
Indigenous AMF are collected from associated host plants growing on and around the site. These fungi are then propagated using host grasses, primarily sorghum–sudangrass and rye grass, grown in controlled conditions. The grasses are interplanted and allowed to develop dense root systems, encouraging AMF colonisation and sporulation.
The resulting inoculum is incorporated into seed composts and potting mixes used for raising transplants. This allows plant-specific or crop-family-specific inoculants to be introduced at the earliest stages of plant development, encouraging early establishment of mycorrhizal associations.
Where possible, the project is transitioning from vermiculite-based propagation substrates towards the use of biochar as a structural and microbial carrier component. Biochar is used as a partial substitute in inoculum and potting mixes, with the aim of improving long-term carbon stability, microbial habitat provision, and nutrient buffering within the soil system.
Detailed methods for inoculum production are described elsewhere on the website and are treated as a core experimental component of the project.
Living mulches and fresh grass mulch
Living mulches and surface mulching form a second major pillar of the soil fertility strategy. These practices are informed by ecological farming literature, including work associated with The Ecological Farmer, and are used to maintain soil cover, regulate moisture, and provide continuous carbon inputs to soil organisms.
Fresh grass mulch is sourced from surrounding feild areas and applied directly to growing beds. Grass is cut over a period of days to a week and applied in thin layers, gradually building up to a depth of approximately 5 cm. This staged application is essential to avoid anaerobic conditions and to ensure rapid microbial processing of the material.
When applied correctly, fresh grass mulch provides:
- readily available carbon for soil microbes
- protection of soil structure
- suppression of weed germination
- moderation of soil temperature and moisture
In addition to cut grass, living mulches are used within and between beds, including clovers and other low-growing species. These living covers maintain root presence in the soil for extended periods and contribute to the continuity of the hyphal network across seasons.
Battery powered (18v and 36v) strimmer and mower are used to maintain this system.
Korean Natural Farming and fermented biofertilisers
The soil fertility plan also incorporates selected techniques from Korean Natural Farming (KNF), adapted to the project’s emphasis on site specificity and fungal ecology. Central to this approach is the cultivation and use of indigenous microorganisms (IMO).
Indigenous microorganisms are cultured on a substrate of wheat bran and molasses, providing a carbohydrate-rich medium for microbial proliferation. These IMO cultures are then used as starters for the fermentation of plant materials harvested on site.
The project deliberately avoids importing off-site plant materials such as seaweed. Instead, fermented plant juices are produced using species that grow vigorously and abundantly within the local environment. These include:
- comfrey
- nettles
- grasses
- brambles (blackberry)
The selection of plants is based on their vitality, nutrient accumulation patterns, and ecological fit with the site. These fermented plant preparations are used primarily as foliar feeds, delivering nutrients in a biologically buffered form while also acting as microbial and signalling inputs.
Where soil testing indicates specific micronutrient limitations, fermented plant extracts are carefully amended with trace mineral inputs. These amendments are added at very low concentrations and always within a biological carrier, reducing the risk of toxicity or disruption to mycorrhizal associations.
Integration with cropping systems
The soil fertility plan is tightly integrated with the cropping design of the market garden. Permanent succession blocks, rotational comparison plots, undersowing strategies, and mulching regimes are all treated as interacting components of a single system rather than discrete practices.
By combining early-stage mycorrhizal inoculation, continuous soil cover, minimal disturbance, and biologically mediated nutrient delivery, the project aims to test whether fertility can be maintained or enhanced without reliance on external inputs or routine soil cultivation.
Objectives and evaluation
The soil fertility plan supports several core objectives of the Farming with Fungi project:
- reducing reliance on off-site fertility inputs
- supporting long-term soil carbon accumulation
- enhancing nutrient cycling efficiency through fungal pathways
- increasing crop resilience to environmental stress
- generating transferable knowledge for small-scale market gardening systems
Soil testing, crop performance data, and observational monitoring are used to evaluate the effectiveness of the approach over time. The fertility plan is treated as adaptive, with practices refined in response to measured outcomes and on-the-ground experience.
Together, these elements form a coherent, biologically grounded soil fertility system that reflects the experimental, ecological, and practical aims of the Farming with Fungi project.