What Materials Go Into a Terramation Vessel? (colloquially referred to as human composting)

A terramation vessel is not simply a container that holds a body. It is a carefully loaded, biochemically balanced system. What goes into the vessel — alongside the person who has died — directly determines whether the process will work, how quickly it will proceed, and what quality of soil results. For families considering natural organic reduction (NOR), understanding what does and does not go into the vessel is both practically important and, for many, emotionally meaningful.

What materials go into a terramation vessel and why does each one matter?

Every NOR vessel contains the unembalmed body, wood chips (for carbon and aeration structure), straw (for carbon and moisture regulation), and alfalfa hay (to initiate microbial activity). Together they achieve the optimal 25:1–30:1 carbon-to-nitrogen ratio for efficient decomposition. Families may also add fresh flowers, herbs, seeds, or natural fiber items. Synthetic fabrics, metals, silicone, pacemakers, embalmed remains, and plastics cannot go in.

Wood chips, straw, and alfalfa hay are not optional additions — they provide the carbon balance, aeration structure, and moisture regulation that make the NOR process function.
The optimal 25:1–30:1 carbon-to-nitrogen ratio is achieved by combining the nitrogen-rich body with carbon-rich bulking agents; getting this ratio wrong slows decomposition or causes odor.
Families may include fresh flowers, aromatic herbs, seeds, and natural fiber shrouds — all of which decompose without interfering with the process.
Synthetic fabrics, metals, pacemakers, silicone implants, plastic, and embalmed remains cannot go into the vessel — they contaminate the soil or inhibit microbial activity.
The body is layered on a substantial bed of bulking agents, then fully encased — this layering sequence supports oxygen flow and even heat distribution.
Dental metals and orthopedic hardware that cannot be removed are separated from the finished soil by screening at the end of the process.

What Are the Core Materials in Every Terramation Vessel?

Every NOR vessel contains two categories of material: the body itself and the organic bulking agents that surround it. These are not optional additions — bulking agents are essential to the process.

The body: Unembalmed (or minimally prepared) human remains work best for NOR. The body’s proteins, fats, and soft tissues provide the primary nitrogen source in the composting system. No metal casket is used — the vessel itself is the container.

Bulking agents — wood chips, straw, and alfalfa hay: These organic materials form the carbon-rich counterpart to the nitrogen-rich body. Wood chips provide structure, creating air pockets throughout the mass so oxygen can circulate. Straw adds carbon and helps regulate moisture. Alfalfa hay provides both carbon and trace nitrogen, and helps initiate microbial activity.

Together, these materials are calibrated to achieve a carbon-to-nitrogen (C:N) ratio of approximately 25:1 to 30:1 — the optimal range for efficient aerobic decomposition, consistent with USDA composting guidance.

Why Is the Carbon-to-Nitrogen Ratio So Important?

The C:N ratio is the single most important chemical parameter in terramation. Microbial communities require both carbon (as an energy source) and nitrogen (to build cell proteins). When the ratio is correct, microbes multiply rapidly, generate metabolic heat, drive temperatures into the thermophilic range (131–160°F / 55–70°C), and break down organic matter efficiently.

When the ratio is too carbon-heavy, decomposition slows because microbes are nitrogen-limited. When it is too nitrogen-heavy, excess ammonia is produced — which means odor, nutrient loss, and a less stable end product.

A human body, with its high protein content, is nitrogen-rich on its own. The C:N ratio of soft tissue and organs is well below the optimal range for composting. Wood chips and straw bring the overall mixture into balance — which is why they are not interchangeable with random organic material. Carbon content, moisture absorption capacity, and particle size all matter.

For more on the biochemistry underlying this balance, see our article on the chemistry of terramation.

What Can Families Place in the Vessel?

One of the aspects of NOR that many families find meaningful is the ability to include some personal items alongside their loved one. Most NOR providers allow — and many encourage — organic materials that support or are neutral to the decomposition process.

Flowers: Fresh flowers, especially those without synthetic dyes or chemical preservatives, are commonly included. They contribute organic matter and nitrogen as they break down.

Herbs: Aromatic herbs — rosemary, lavender, sage — are frequently placed in the vessel. They carry personal meaning and decompose without issue.

Seeds: Some families include seeds of plants their loved one cared for — a deeply symbolic choice, since those seeds may eventually sprout in the returned soil.

Natural fiber shrouds: Undyed cotton, linen, or wool shrouds can be used to wrap the body. Natural fibers decompose readily and do not interfere with the process.

Other organic materials: Some providers allow small amounts of other natural items — dried leaves, untreated wood, or other plant material. Families should always confirm what their specific provider accepts.

The guiding principle is simple: if it is fully organic and would break down in a high-quality compost environment, it is likely acceptable. If it would not break down — or if its breakdown produces harmful compounds — it is not.

What Cannot Go Into the Vessel?

Understanding what cannot go into the vessel is just as important as knowing what can. Certain materials will slow the process, produce lower-quality soil, or pose safety concerns.

Synthetic clothing and textiles: Polyester, nylon, and other synthetic fibers do not break down in the NOR process. They would end up as persistent contaminants in the finished soil. Natural fiber clothing or a shroud is fine; synthetic fabrics are not.

Metal jewelry and accessories: Metals do not decompose and would contaminate the soil. Metal items are removed before the process begins — a step handled by the provider. Families typically receive metal jewelry back separately.

Silicone implants: Silicone does not biodegrade under NOR conditions. Breast implants, for example, must be removed prior to the process — similar to how they are handled in cremation. Providers have protocols for this.

Pacemakers and certain medical devices: Pacemakers must be removed before NOR — they can contain batteries that could pose a hazard. Other implanted electronic or battery-powered devices are in the same category. This is a standard pre-process step, similar to requirements for cremation.

Embalmed remains: This deserves particular emphasis. Formaldehyde — the primary embalming chemical — is toxic to the microbial communities that drive NOR. Embalmed bodies are generally incompatible with the NOR process. For a detailed discussion, see our article on embalmed bodies and terramation.

Treated or painted wood: Treated lumber and painted wood may contain preservatives or compounds that inhibit microbial activity or contaminate the soil. Only natural, untreated wood materials belong in the vessel.

Plastic of any kind: Plastic does not decompose and would contaminate the finished soil.

How Is the Vessel Loaded?

The layering process matters. Most NOR providers follow a specific sequence: a substantial bed of bulking agents — typically wood chips, straw, and alfalfa — is laid first, creating a foundation that will support the body and begin generating microbial activity. The body is then placed on this bed. Additional bulking agents are layered over and around the body, fully encasing it in organic material.

This layering approach ensures that the body is surrounded by material that will regulate moisture, maintain oxygen flow, and provide the carbon balance needed for efficient decomposition.

The total volume of organic material in a loaded vessel is substantial — a large portion of the vessel’s capacity is occupied by bulking agents rather than the body itself. This is by design.

What Vessel Is Used for Terramation?

NOR takes place inside a purpose-built enclosed vessel specifically designed to control temperature, moisture, and aeration throughout the process. TerraCare’s Chrysalis™ vessel is designed with these requirements in mind — maintaining the conditions that allow aerobic microbial decomposition to proceed efficiently while meeting regulatory standards for pathogen reduction.

The Chrysalis™ is not simply a container. It is an engineered system: insulated to retain metabolic heat, equipped to monitor internal conditions, and designed to support the specific loading sequences that optimize the decomposition process.

For more on how temperature and moisture conditions are managed inside the vessel, see our article on temperature and moisture conditions in NOR.

Why Does Material Selection Affect Soil Quality?

The chemistry of the finished soil is directly determined by what went into the vessel. This is not a trivial point. If synthetic materials are included, they either contaminate the soil or must be screened out. If the C:N ratio was off, the soil may be nitrogen-poor, or may contain residual ammonia from incomplete decomposition. If moisture was not managed correctly during decomposition, the humus fraction of the finished soil may be lower quality.

NOR providers typically screen the finished material before returning it to families — removing any remaining bone fragments, any metals or non-organic material that may have been overlooked, and ensuring the soil meets quality standards. But the best outcomes start with proper vessel loading. The materials that go in determine the soil that comes out.

The typical yield from a terramation is approximately one-half cubic yard of soil — a deeply generous return that many families scatter in meaningful outdoor spaces or use to plant trees or gardens.

For a broader look at how this all fits together, visit our complete guide to natural organic reduction.

Can families attend or participate in the vessel-loading process?

Practices vary by provider. Some NOR providers offer families the opportunity to participate in placing flowers, herbs, or meaningful organic items alongside their loved one. This is one of the aspects of terramation that families often find deeply meaningful. Ask your specific provider what their family participation protocols look like.

Does the type of wood chip matter?

Yes. Not all wood is equal in a composting context. Untreated, non-aromatic wood chips from deciduous trees are typically preferred. Aromatic wood species like cedar or walnut may contain compounds that inhibit microbial activity in large quantities. NOR providers source their bulking agents specifically for the process.

What happens to dental fillings and metal in teeth?

Dental amalgam (silver fillings) and crowns contain metals that do not decompose. After the NOR process, any remaining dental metals are typically screened out from the finished soil along with any other metal debris. This is a standard part of the process. For more detail, see our article on dental fillings and metal during terramation.

Is the body wrapped or clothed during terramation?

Most providers use a natural fiber shroud or allow the body to be placed unclothed directly on the bed of bulking agents. Natural fiber clothing — undyed cotton, linen, wool — can also be acceptable. The key requirement is that no synthetic fabrics are used.

Can families request specific organic materials be included?

Many providers welcome family requests for specific flowers, herbs, or meaningful plant materials. It is always worth asking. Providers have final say on what can be safely included, but most are accommodating of personal and cultural significance when organic materials are involved.

Learn more about terramation providers near you

Ready to explore terramation options? Contact TerraCare Partners

Sources

Washington State Legislature — WAC 246-500 (NOR Rules): https://app.leg.wa.gov/wac/default.aspx?cite=246-500
U.S. Environmental Protection Agency — Composting: https://www.epa.gov/composting
NFDA — 2025 Cremation and Burial Report: https://nfda.org/news/statistics
USDA NRCS — Soil Health and Organic Matter: https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soil/soil-health
Green Burial Council — Standards and Education: https://www.greenburialcouncil.org/
Washington State University Extension: https://extension.wsu.edu/
U.S. EPA — A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule: https://www.epa.gov/biosolids/guide-biosolids-risk-assessments-epa-part-503-rule
Washington State Department of Health — NOR: https://doh.wa.gov/
USDA Agricultural Research Service: https://www.ars.usda.gov/