µSoil and µSoil+: Organic Biofertilisers from the NRU Two-Stage Process
Two product routes – one two-stage process
µSoil and µSoil+ are produced by the same two-stage process: anaerobic digestion under the NRU protocol with Bionic µChar (Stage 1) followed by controlled aerobic composting (Stage 2). The difference lies in the intensity of nitrogen enrichment and co-substrate composition.
| Property | µSoil Standard | µSoil+ |
|---|---|---|
| Nitrogen content | Defined NPK specification; CE-eligible under EU FPR PFC 1 | Higher nutrient value; full NRU system with stronger nitrogen binding |
| Carbon matrix | Controlled µChar fraction; high Humus-C content | Same µChar base; higher overall nutrient value |
| Nitrogen form | Char-adsorbed and humus-complexed; controlled slow-release | Enhanced slow-release profile through full NRU system |
| Regulatory pathway | CE-eligible in principle under EU FPR CMC 14 (revision pending) + PFC 1 | CE-eligible in principle under EU FPR CMC 14 (revision pending) + PFC 1(C)(II) (slow-release fertiliser) |
Stage 1: NRU Protocol – Nitrogen Retention in Digestion
Bionic µChar is added to the biogas reactor. The high adsorption capacity of µChar (documented in BLG GmbH process analytics) produces three simultaneous effects: ammonium nitrogen is directly adsorbed onto the surface and carried through the process as a slow-release carrier; pH buffering keeps the NH₄⁺/NH₃ equilibrium in the non-inhibitory range and retains the large majority of total nitrogen through the digestion stage; and methane yield is increased in parallel.
The digestate leaving Stage 1 is not a fertiliser for direct field application. It is a concentrated, hygienised intermediate with a known nitrogen content — the optimal feedstock for Stage 2.
Stage 2: µSoil Composting – Nitrogen Concentration in the Solid Product
The nitrogen-loaded digestate is combined with co-substrates and a fresh µChar top-up, adjusted to a C:N ratio optimal for thermophilic composting, and composted aerobically. The cation exchange capacity of µChar prevents ammonia volatilisation during the hot composting phase and accelerates humification. Nitrogen retention through the two-stage process substantially exceeds conventional digestate or composting routes according to NRU White Paper v11 and BLG GmbH process modelling (literature comparison; project-specific field validation pending).
µSoil Product Properties
| Property | Description |
|---|---|
| Physical form | Solid; baggable or bulk delivery — no liquid logistics |
| NPK specification | Defined N, P and K contents; CE-eligible under EU FPR PFC 1 |
| µChar content | Controlled fraction; CE-eligible in principle under CMC 14 (EU FPR 2019/1009, revision pending) |
| Nitrogen form | Char-adsorbed and humus-complexed; controlled slow-release |
| Hygienisation | PFPR-compliant through the AD stage (≥55°C, ≥10 days); EU FPR pathogen standard met at Stage 1 |
| Stable carbon | High fixed carbon content in µChar; certifiable long-term carbon storage |
| Carbon balance | Net carbon-negative; CRCF crediting pathway applicable |
Agricultural Benefits
- Slow-release nitrogen: demand-driven release through root exudates and microbial activity — no uncontrolled ammonia loss on application
- Higher nitrogen use efficiency compared to liquid digestate application, which loses a substantial fraction of nitrogen through volatilisation
- No liquid logistics: solid, storable, transportable and applicable year-round
- Stable soil carbon: high fixed carbon content in µChar; contribution to long-term humus formation and CO₂ sequestration
- CE-marking under EU FPR: single conformity pathway for the entire EU market
- Pathogen-free: hygienisation standard met through the AD stage at Stage 1
Further Technical Documentation
The complete technical and scientific basis of the NRU–µSoil process — including process parameters, nitrogen balances, comparison with conventional digestate routes, economic model and regulatory roadmap — is documented in the NRU–µSoil Policy White Paper. The document is available in the Downloads section.