Natural fertilizer: mycorrhizae revolutionize agriculture

Fungal mycelium represents the largest and most sophisticated biological communication network in existence, so much so that scientists have nicknamed it "nature's internet". This analogy isn't accidental: just as the internet connects devices worldwide, fungal hyphae connect different plants, creating a true "wood wide web" that allows the exchange of nutrients and information.

A study published in Nature Scientific Reports revealed how some mycelial networks can extend for hundreds of meters underground, forming connections between dozens of different plants, even of different species. This underground network enables:

The main ecological functions of fungi

• Decomposition of organic matter: fungi are the primary decomposers of the biosphere, capable of transforming plant waste into fertile humus through the production of specific enzymes like ligninases and cellulases.
• Nutrient cycling: they make phosphorus, nitrogen, and micronutrients available through mineralization processes that no other organism can perform with the same efficiency.
• Soil structure: fungal hyphae create aggregates that improve soil porosity and water retention capacity, reducing erosion.
• Plant protection: they compete with pathogens and induce systemic resistance through the production of natural antibiotics and the activation of defense mechanisms in host plants.

Recently, researchers at the University of Basel discovered that some fungal species can sequester heavy metals and organic contaminants, contributing to the natural remediation of polluted soils.

Mycorrhizae represent one of the most ancient and widespread symbioses in nature, with over 90% of vascular plants establishing this mutualistic relationship with soil fungi. The term "mycorrhiza" comes from the Greek mykes (fungus) and rhiza (root), perfectly describing this intimate union between different kingdoms.

According to researchers at the International Mycorrhiza Research Network, there are seven main types of mycorrhizae, but the most important for agriculture are:

Main types of mycorrhizae

How mycorrhizal symbiosis works

The mechanism is fascinating: the fungus gives the plant water and mineral nutrients (especially phosphorus and nitrogen) acting as a true natural fertilizer, while receiving in return sugars produced by photosynthesis. This exchange occurs through specialized structures:

• Arbuscules: in endomycorrhizae, they penetrate root cells increasing the exchange surface up to 100 times
• Fungal mantle: in ectomycorrhizae, it wraps around roots forming a protective barrier
• Hartig net: hyphae that insinuate between root cells creating a zone of metabolic exchange

A study by the USDA Agricultural Research Service demonstrated that mycorrhizal plants can absorb up to 200% more phosphorus than non-colonized ones, with evident benefits for growth and production. Moreover, they show:

• Increased resistance to water stress (up to 40% more survival in drought conditions)
• Better tolerance to soil salinity
• Reduction in root disease incidence up to 70%

The fertile potential of spent substrates

For mushroom cultivation enthusiasts, the problem of substrate disposal after harvest is well known. What many consider waste can instead become an exceptional soil amendment, rich in still active mycelium and precious organic matter.

Research conducted by the Fungi Foundation shows that edible mushroom substrates (like Pleurotus or Shiitake) still contain:

• 30-50% of the original mycelial biomass, still vital and capable of colonizing new organic matrices
• Degradative enzymes useful for decomposition, including cellulases, hemicellulases, and ligninases
• Humic substances that improve soil structure and cation exchange capacity
• Micronutrients released during fungal growth, including zinc, copper, and manganese in easily absorbable forms

Techniques for optimal reuse

Direct field method: The spent substrate can be spread directly on the ground (2-5 cm thick) and lightly buried. Ideal for vegetable gardens and orchards in autumn, it allows slow degradation during winter. Per hectare, 5-10 tons of substrate can be used.

Enriched composting: Mix the substrate with green waste (1:3 ratio) and let mature for 3-6 months. The result is an exceptional compost with:

• Balanced pH (6.5-7.5)
• Organic matter content over 60%
• Beneficial microbial populations 10 times higher than traditional compost

Preparation of "mycelium tea": Soak 1 kg of substrate in 10 liters of water for 48 hours, filter and use as foliar or root fertilizer. Contains:

• Hydrolytic enzymes
• Natural phytohormones (auxins, gibberellins)
• Natural antibiotics against root pathogens

A study published in Applied Soil Ecology found that using spent Pleurotus ostreatus substrates increased lettuce yield by 27% compared to traditional chemical fertilizers, with significant improvement in antioxidant content.

Mycorrhizal inoculation

To maximize the benefits of mycorrhizae, plants can be deliberately inoculated with selected strains. The procedure requires attention to several factors:

1. Choose the right product: there are specific formulations for different types of plants (vegetables, shrubs, trees). Endomycorrhizae (Glomus spp.) are ideal for vegetables and herbaceous plants, while ectomycorrhizae (Pisolithus, Laccaria) are suitable for trees and shrubs.
2. Prepare the root system: avoid phosphatic fertilizers 2 weeks before inoculation, as high phosphorus concentrations inhibit mycorrhizal colonization.
3. Apply in contact with roots: during transplanting is the ideal time. For established plants, make small holes in the soil (15-20 cm deep) and insert the inoculum.
4. Maintain optimal conditions: constant moisture in the first weeks favors symbiosis establishment. Avoid deep soil tillage that could damage the mycelial network.

The International Society of Root Research recommends dosages of 50-100 g of inoculum per tree and 5-10 g per vegetable plant. For extensive crops, 2-5 kg of inoculum per hectare can be used.

Effectiveness monitoring

To verify inoculation success:

• After 4-6 weeks, observe root samples under a microscope (100-400x magnification) to check for mycorrhizal structures
• Monitor vegetative growth and stress resistance
• Evaluate reduction in phosphatic fertilizer use (up to 50% less)

Fungal cultivation to improve soil

Some fungal species are particularly useful for soil fertility and can be specifically cultivated for this purpose:

• Trichoderma spp.: natural antagonists of root pathogens like Fusarium and Pythium. Can be cultivated on bran-based substrates and then distributed in soil.
• Pleurotus spp.: excellent lignin decomposers, ideal for transforming woody residues into fertile humus. Their cultivation on straw or sawdust produces both edible mushrooms and enriched substrate.
• Stropharia rugosoannulata: indicator of healthy soil, particularly effective in improving clayey and compacted soils.

An innovative protocol involves creating permanent "fungal beds" in the vegetable garden:

1. Prepare an area with a 20 cm layer of shredded woody material
2. Inoculate with Pleurotus or Stropharia mycelium
3. After mushroom production, plant vegetables directly in the bed
4. Renew the surface layer with new material every year

This technique, developed by the Fungi Perfecti Research Center, has shown 35% increases in zucchini and cucumber production, with significant weed reduction.

From science to science fiction: current research frontiers

Mycorrhizal applications are revolutionizing various fields, opening unimaginable perspectives:

Regenerative agriculture

Projects like those at the Rodale Institute demonstrate that mycorrhiza-based agricultural systems can:

• Sequester up to 3 tons of CO2 per hectare per year
• Reduce chemical fertilizer use by 40-60%
• Increase resilience to climate change

Phytoremediation of polluted soils

Some mycorrhizae can help plants tolerate and accumulate heavy metals. USDA research has identified Glomus strains that:

• Reduce cadmium and lead bioavailability up to 70%
• Favor metal extraction by hyperaccumulator plants
• Stabilize contaminants in less toxic forms

Extraterrestrial cultivation

NASA is studying mycorrhizal systems for future Mars bases, as reported on the official NASA website. Experiments show that:

• Mycorrhizae can improve plant growth in simulated regolith
• Some fungi are resistant to cosmic radiation
• Symbiotic systems could be fundamental for supporting closed ecosystems

Plant communication

Revolutionary studies show that mycorrhizal networks allow plants to:

• Exchange alarm signals against herbivores and pathogens
• Share resources between related individuals
• Regulate interspecific competition

This "plant intelligence" mediated by fungi is redefining our understanding of ecosystems.