Soil Carbon Amendment and US Ag
USDA Natural Resources Conservation Service Conservation Practice Standard 336 — Soil Carbon Amendment: EQIP/CSP (and related) cost-share for applying biochar and/or compost to improve soil health and store carbon. This is a conservation practice standard, not a carbon-credit methodology. Pair with Soil and Agriculture, Application Rates and Methods, Biochar Compost and Manure Blends, Double Counting and Credit Ownership.
Official documents (outbound)
| Document | URL |
|---|---|
| National CPS 336 page (downloads + state links) | https://www.nrcs.usda.gov/resources/guides-and-instructions/soil-carbon-amendment-ac-336-conservation-practice-standard |
| National standard PDF (Nov 2022) | https://www.nrcs.usda.gov/sites/default/files/2022-11/336-NHCP-CPS-Soil-Carbon-Amendment-2022.pdf · defines NRCS practice 336 |
| Planning FAQ (April 2026) | https://nrcs-prod.azureedge.us/sites/default/files/2026-04/soil-carbon-amendment-ac-336-faq.pdf · answers CPS 336 planning questions |
| Soil Carbon Amendments overview / tools | https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soil/soil-health/soil-carbon-amendments |
| Producer funding quick guide (Farmland Info hosting) | https://farmlandinfo.org/wp-content/uploads/sites/2/2023/12/biochar_funding_for_US_producers_quick_guide_.pdf |
| ABI / biochar.org funding guidelines PDF (2026) | https://biochar.org/wp-content/uploads/2026/06/Biochar-Guidelines-Funding-2026-final.pdf |
What CPS 336 is for
Stated purposes include improve/maintain SOM, sequester/enhance soil C stocks, improve aggregate stability, and improve habitat for soil organisms; producers may also seek moisture and productivity co-benefits (FAQ). Sandy, acidic, less-healthy soils are called out as more likely to respond.
Biochar eligibility specs (practice)
From national standard Table 3 / narrative (2022 PDF):
- Produced >350 °C under limited oxygen (pyrolysis or gasification)
- Organic carbon (C_org) > 10% dry weight
- H:C_org < 0.7 (molar) — lower preferred for sequestration
- Metals and pathogens within Table limits; report ash, liming equivalent, nutrients, etc.
- IBI Certified seal or documented Table 3 methods — but FAQ: certificate alone is not enough; planner still needs the spec sheet (FAQ)
Explicit exclusions / restrictions
- No biosolids / municipal waste biochar or compost under 336 (PFAS and related concerns) (FAQ)
- Residues that should remain for soil cover or forest health cannot be diverted into paid 336 feedstock pathways (FAQ)
- Humic/fulvic products are not stand-alone carbon amendments under 336 (may be inoculants) (FAQ)
Planning rates and FY2024 scenarios
FAQ: 4–10 cubic yards per acre is a general starting range; characteristics of soil and amendment drive the final rate (FAQ).
| FY2024 scenario (FAQ Table 1) | Compost | Biochar |
|---|---|---|
| 100% Biochar (acres unit) | — | 4 yd³/ac |
| 20% biochar / 80% compost | 4.4 t/ac | 0.8 yd³/ac |
| 40% biochar / 60% compost | 3.3 t/ac | 1.6 yd³/ac |
| 60% biochar / 40% compost | 2.2 t/ac | 2.4 yd³/ac |
| 80% biochar / 20% compost | 1.1 t/ac | 3.2 yd³/ac |
| Compost off-site | 3 t/ac | — |
Cubic-yard and small-area (ft²) scenarios exist for non-standard rates. Dry weight of 1 yd³ biochar ≈ 135–540 lb (FAQ).
Payment construction example: FY2023 60/40 blend scenario ~$160/yd³ average-cost build (state-varying; not invoice-matched) (Farmland Info guide).
Application practice (NRCS)
- Incorporate when possible (tillage, trench, drill, beds, fertigation); surface-only risks wind/water loss (FAQ)
- Inoculate with compost, compost tea, or manure (2022 PDF)
- Pasture OK; native rangeland only if facilitating CPS 550 or 342 (FAQ)
- Lifespan 1 year; up to 5 applications over a contract (FAQ)
- Ranking improves when bundled with other soil-health practices (cover crops, no-till, rotations, etc.) (FAQ)
Full methods note: Application Rates and Methods.
Other US / ag resources
Named soil deployments (vineyards, credit projects): Real World Soil Projects.
Ag pathway checklist (operator-oriented)
- Feedstock: Prefer documented wastes/residues; respect residue-retention rules.
- Produce & test: Meet CPS 336 Table 3 / EBC-WBC / IBI-style specs; target low H:C_org for CDR eligibility.
- Choose registry early if also selling credits: Verra VM0044 · Puro CORC200+ · Isometric Biochar Protocol · CSI Global Biochar C-Sink.
- Secure offtake & credit ownership in farmer / applicator contracts.
- Stack carefully: NRCS payments ≠ carbon credits; prevent double claiming (Double Counting and Credit Ownership).
- Apply: Incorporate; watch pH, EC, P loading, slope; prefer compost blends (Biochar Compost and Manure Blends).
- MRV: Batch IDs, weigh tickets, geotagged application, multi-year records (MRV Stack).