Explainer: Microbiomes, soil health & ecosystems

Why It Matters

Beneath every square metre of healthy grassland live roughly 4.5 billion bacteria, 1 million fungi, and 10,000 to 50,000 distinct bacterial species, making soil the most biodiverse habitat on the planet (European Commission Joint Research Centre, 2024). These microbial communities regulate nutrient cycling, decompose organic matter, suppress plant pathogens, and sequester between 0.5 and 1.5 tonnes of CO₂ per hectare per year (Lal, 2024). Yet the Food and Agriculture Organization (FAO, 2025) estimates that 33 percent of global soils are already degraded, costing the world economy more than $10 trillion annually in lost ecosystem services. Restoring and maintaining soil microbiome function is therefore not a niche scientific concern; it sits at the intersection of food security, climate mitigation, and biodiversity conservation. For sustainability professionals, understanding the mechanisms behind microbiome health unlocks actionable strategies ranging from regenerative agriculture and carbon credit protocols to next-generation biofertilisers that can reduce synthetic nitrogen use by 20 to 50 percent (Pivot Bio, 2025).

Key Concepts

Soil microbiome. The collective community of bacteria, archaea, fungi, protists, and viruses inhabiting a soil ecosystem. Functional diversity, not just taxonomic richness, determines how effectively a microbiome cycles carbon, nitrogen, and phosphorus.

Mycorrhizal networks. Symbiotic associations between plant roots and fungal hyphae that extend root surface area by up to 700 times. Arbuscular mycorrhizal fungi (AMF) colonise over 80 percent of terrestrial plant species and facilitate phosphorus uptake while transporting carbon into stable soil aggregates (SPUN, 2025).

Soil organic carbon (SOC). Carbon stored in soil organic matter, comprising roughly 2,500 gigatonnes globally, more than twice the carbon held in the atmosphere and vegetation combined. SOC levels serve as a proxy for microbial activity and overall soil health.

Microbial inoculants. Commercial formulations of living bacteria or fungi applied to seeds, roots, or soil to enhance nutrient availability, suppress disease, or improve stress tolerance. The global biostimulant and inoculant market reached an estimated $12.5 billion in 2025 and is projected to surpass $14 billion by 2028 (MarketsandMarkets, 2025).

Metagenomics and eDNA. Culture-independent molecular techniques that sequence all genetic material extracted directly from an environmental sample. These methods reveal the full functional potential of a microbiome rather than just the fraction of organisms that can grow in laboratory culture.

Soil health indicators. Standardised metrics including soil respiration rate, water-stable aggregates, active carbon fraction, and microbial biomass carbon. The USDA Natural Resources Conservation Service and the FAO Global Soil Partnership both endorse multi-indicator scorecards that combine biological, chemical, and physical parameters.

How It Works

Soil microbiomes operate through a set of interconnected biogeochemical cycles. When plant roots exude sugars and organic acids into the rhizosphere, they recruit specific microbial taxa that, in return, solubilise phosphorus, fix atmospheric nitrogen, and produce growth-promoting hormones. Nitrogen-fixing bacteria such as Rhizobium convert N₂ gas into ammonium at an estimated global rate of 40 to 100 million tonnes per year, supplying roughly half the nitrogen that enters terrestrial food webs (Herridge et al., 2024). Mycorrhizal fungi, meanwhile, transfer phosphorus and micronutrients to plant hosts while receiving up to 20 percent of the plant's photosynthetically fixed carbon, which they deposit as glomalin and other glycoproteins that bind soil particles into stable aggregates.

Carbon sequestration follows two primary pathways. The first is the formation of mineral-associated organic matter (MAOM), where microbial necromass and metabolites bind to clay and silt surfaces and can persist for decades to centuries. The second is particulate organic matter (POM), which consists of partially decomposed plant residues and is more vulnerable to disturbance. Research from the Max Planck Institute for Biogeochemistry (2025) shows that microbial carbon-use efficiency, the fraction of consumed carbon that microbes incorporate into biomass rather than respire as CO₂, ranges from 30 to 60 percent depending on substrate quality and environmental conditions. Higher carbon-use efficiency translates directly into greater SOC accumulation.

In practice, farmers and land managers influence these processes through tillage intensity, cover cropping, crop rotation diversity, and organic amendment application. Reducing tillage preserves fungal hyphal networks and macroaggregate structure. Diverse cover-crop mixes sustain microbial activity during fallow periods and can increase microbial biomass carbon by 15 to 30 percent within two to three growing seasons (Rodale Institute, 2025).

What's Working

Microbial inoculants at commercial scale. Pivot Bio's PROVEN nitrogen-fixing microbe, applied to more than 4 million acres of US corn in 2025, replaces 25 to 40 pounds of synthetic nitrogen per acre while maintaining or improving yields (Pivot Bio, 2025). Indigo Agriculture's microbial seed treatments have been deployed across 10 million acres globally, with field trials showing yield improvements of 5 to 10 percent in water-stressed environments.

Metagenomic soil mapping. The Society for the Protection of Underground Networks (SPUN) has mapped mycorrhizal biodiversity hotspots across 55 countries using eDNA sampling, identifying priority conservation zones and informing restoration strategies. In parallel, the Earth Microbiome Project has catalogued over 300,000 microbial genomes, providing reference databases for agronomic and ecological applications (Thompson et al., 2024).

Carbon credit protocols integrating soil biology. Verra's VM0042 methodology now accepts soil organic carbon measurements verified through stratified sampling and laboratory analysis, with over 15 million hectares enrolled in soil-carbon projects globally as of early 2026 (Verra, 2026). Nori and Indigo Ag's carbon programmes have issued credits backed by measured SOC gains on regenerative farms across the US Midwest, with prices ranging from $20 to $35 per tonne of CO₂e.

Policy momentum. The EU Mission "A Soil Deal for Europe" allocated €320 million through 2027 for research and innovation in soil health, including microbiome diagnostics. India's National Mission for Sustainable Agriculture has distributed microbial consortia to over 2 million smallholder farmers since 2023, and Brazil's ABC+ programme incentivises biological nitrogen fixation across 40 million hectares of pasture and cropland (FAO, 2025).

What Isn't Working

Inoculant inconsistency. Field performance of commercial microbial products varies widely depending on soil type, climate, existing microbial communities, and application timing. A meta-analysis published in Nature Food (Kaminsky et al., 2024) found that microbial inoculants failed to produce statistically significant yield benefits in 40 percent of field trials, largely because products developed in controlled environments do not always establish in complex, competitive soil ecosystems.

SOC measurement uncertainty. Detecting meaningful changes in soil organic carbon requires sampling at sufficient spatial density and temporal intervals. Measurement costs of $15 to $30 per sample and the need for multi-year baselines create barriers to scaling carbon credit programmes. Remote sensing proxies for SOC remain insufficiently validated for credit-grade accuracy (Verra, 2026).

Degradation outpacing restoration. While regenerative practices can rebuild soil organic matter at rates of 0.3 to 1.0 tonne of carbon per hectare per year, erosion, intensive tillage, and monoculture continue to degrade soils 10 to 40 times faster than natural formation rates in many regions. The UNCCD Global Land Outlook (2024) reports that 12 million hectares of productive land are lost annually.

Data fragmentation. Soil microbiome data are generated by disparate academic groups, private companies, and government agencies using incompatible protocols. The absence of standardised sampling, extraction, and bioinformatic pipelines makes it difficult to compare results across studies or build predictive models at landscape scale.

Key Players

Established Leaders

• Novozymes (now Novonesis) — Global leader in biological solutions; produces enzyme and microbial products for agriculture, with 2024 agricultural biology revenue exceeding $800 million.
• Corteva Biologicals — Acquired Symborg and Stoller to build a portfolio of mycorrhizal and biostimulant products deployed across 20+ million acres.
• BASF Agricultural Solutions — Offers the Velondis and Vault HP lines of biological seed treatments; invested over $300 million in biologicals R&D since 2022.
• UPL BioSolutions — Markets microbial and botanical products in 130+ countries with a dedicated biologicals revenue stream exceeding $500 million.

Emerging Startups

• Pivot Bio — Nitrogen-fixing microbes engineered for row crops; deployed on 4+ million acres in the US.
• SPUN (Society for the Protection of Underground Networks) — Non-profit mapping global mycorrhizal networks using eDNA to guide conservation.
• Trace Genomics — AI-powered soil diagnostics providing pathogen, nutrient, and microbiome assessments from a single soil sample.
• Biome Makers — Functional microbiome analysis platform (BeCrop) used by agronomists in 45+ countries to guide soil management.

Key Investors/Funders

• Breakthrough Energy Ventures — Backed Pivot Bio's $430 million Series D in 2024.
• Leaps by Bayer — Impact investment arm funding microbiome and soil-health startups.
• European Commission (Horizon Europe) — €320 million allocated to the Soil Mission through 2027.
• Bill & Melinda Gates Foundation — Funding smallholder-focused biological nitrogen fixation research in sub-Saharan Africa and South Asia.

Sector-Specific KPI Benchmarks

Action Checklist

• Baseline your soil microbiome. Commission metagenomic or functional microbiome analysis (e.g., Biome Makers BeCrop or Trace Genomics) to understand current microbial diversity, pathogen pressure, and nutrient-cycling capacity before intervening.
• Adopt cover cropping and reduced tillage. Multi-species cover-crop mixes and no-till or minimum-till practices are the most reliably effective interventions for building microbial biomass and SOC, typically showing measurable gains within two to three seasons.
• Evaluate inoculants with on-farm trials. Request independent efficacy data from suppliers, run strip trials across representative soil types on your operation, and track yield, input cost, and soil-test changes over at least two seasons before scaling.
• Integrate soil carbon into your climate strategy. Enrol eligible land in recognised soil-carbon programmes (Verra VM0042, Nori, or national equivalents) and align soil management with Scope 3 supply-chain decarbonisation targets.
• Invest in long-term monitoring. Budget for annual soil health assessments using multi-indicator scorecards. Use consistent sampling protocols (same GPS points, depth, and season) to track trends and demonstrate impact to investors and regulators.
• Engage with landscape-scale initiatives. Join collaborative programmes such as the EU Soil Mission, the 4 per 1000 Initiative, or regional soil health partnerships to access funding, share data, and influence standards.

FAQ

How long does it take to see measurable improvements in soil microbiome health? Most regenerative interventions, such as cover cropping, reduced tillage, and compost application, produce detectable increases in microbial biomass carbon and soil respiration within two to three growing seasons. Meaningful changes in soil organic carbon typically require three to five years of consistent management, because SOC accumulates slowly at 0.3 to 1.0 tonnes of carbon per hectare per year. Inoculant effects on crop performance can appear within a single season, but establishing a persistent shift in the resident microbial community may take longer.

Are microbial inoculants a reliable replacement for synthetic fertilisers? Not yet as a full replacement, but they are an effective complement. Products like Pivot Bio's nitrogen-fixing microbes can reduce synthetic nitrogen inputs by 25 to 40 pounds per acre on corn without yield loss. However, meta-analyses show that inoculant performance varies with soil type, climate, and existing microbial communities. The most robust strategy combines biological inputs with reduced (not eliminated) synthetic fertiliser rates, guided by soil testing and adaptive management.

What role does the soil microbiome play in climate change mitigation? Soils store approximately 2,500 gigatonnes of carbon, more than twice the combined carbon in the atmosphere and all living vegetation. Microbial communities mediate the balance between carbon stabilisation (through mineral-associated organic matter formation) and carbon release (through decomposition and respiration). Enhancing microbial carbon-use efficiency and protecting existing soil carbon stocks through better land management could contribute 3 to 8 gigatonnes of CO₂e in mitigation potential annually, according to the IPCC Sixth Assessment Report. Soil carbon sequestration is considered one of the most scalable and cost-effective nature-based climate solutions.

How can sustainability professionals verify soil health claims from suppliers? Request third-party field trial data with replicated controls, ideally across multiple soil types and climate zones. Check whether products carry recognised certifications or registrations (e.g., OMRI listing for organic systems). Use independent soil diagnostic services to benchmark microbial activity before and after product application. Cross-reference supplier claims with peer-reviewed literature and meta-analyses rather than relying solely on proprietary data.

What is the connection between soil microbiomes and biodiversity above ground? Soil microbial diversity directly supports plant diversity by enabling nutrient uptake, suppressing pathogens, and structuring soil physically for root growth. Diverse plant communities in turn support pollinators, invertebrates, birds, and mammals. Research by SPUN (2025) has shown that areas with high mycorrhizal fungal diversity correlate with above-ground biodiversity hotspots. Conversely, soil degradation and microbiome simplification contribute to habitat loss and reduced ecosystem resilience.

Sources

• European Commission Joint Research Centre. (2024). State of Soil Biodiversity in Europe. EU Publications Office.
• FAO. (2025). Status of the World's Soil Resources: Technical Summary Update. Food and Agriculture Organization of the United Nations.
• Herridge, D.F., Peoples, M.B., & Boddey, R.M. (2024). Global inputs of biological nitrogen fixation in agricultural systems. Plant and Soil, 483(1–2), 1–18.
• Kaminsky, L.M., Trexler, R.V., Malik, R.J., Hockett, K.L., & Bell, T.H. (2024). The inherent conflicts in developing soil microbial inoculants. Nature Food, 5(3), 194–202.
• Lal, R. (2024). Soil carbon sequestration as a climate change mitigation strategy. Geoderma, 445, 116872.
• MarketsandMarkets. (2025). Agricultural Biologicals Market: Global Forecast to 2028. MarketsandMarkets Research.
• Max Planck Institute for Biogeochemistry. (2025). Microbial carbon use efficiency and soil organic matter persistence. Annual Report 2024–2025.
• Pivot Bio. (2025). PROVEN Platform: 2025 Season Performance Summary. Pivot Bio Inc.
• Rodale Institute. (2025). Farming Systems Trial: 40-Year Results on Soil Health and Carbon. Rodale Institute.
• SPUN. (2025). Global Mycorrhizal Network Mapping: Methods and Conservation Priorities. Society for the Protection of Underground Networks.
• Thompson, L.R., et al. (2024). Earth Microbiome Project: Expanded reference database and analytical framework. Nature, 625, 412–420.
• UNCCD. (2024). Global Land Outlook 2: Land Restoration for Recovery and Resilience. United Nations Convention to Combat Desertification.
• Verra. (2026). VM0042 Methodology for Improved Agricultural Land Management. Verra Standards.