Safely Composting Meat-Eater Manure & Bones: The Complete Guide

What Can You Really Compost? Solving the Carnivore Waste Dilemma

The dilemma hits every eco-conscious gardener eventually: you're staring at a pile of dog waste or those leftover marrow bones from dinner, wondering, "Can I compost this?" With contradictory advice flooding gardening forums and social media, it's no wonder many of us feel paralyzed by indecision.

This confusion isn't just frustrating—it can impact your garden's health and safety. Improper composting of animal products can introduce harmful pathogens into your soil, potentially contaminating the very food you're working so hard to grow sustainably.

In this guide, you'll discover exactly which animal wastes can safely enter your compost bin, how to process them correctly (often in as little as 4-6 weeks), and what to do with materials that should never touch your garden soil. Let's transform your uncertainty into confidence with science-backed methods that work for your busy lifestyle.

Quick Reference Guide: Manure Composting Essentials

Material	C:N Ratio	Processing Time	Benefits	Safety Level
Chicken manure	10:1	3-6 months	High nitrogen (1.1%), balanced nutrients	Safe with hot composting
Duck manure	8:1	3-4 months	Excellent moisture retention, good K content	Safe with hot composting
Rabbit manure	12:1	0-3 months	Can be used directly, slow-release N	Very safe (cold compost ok)
Horse manure	30:1	4-6 months	Good structure builder, balanced nutrients	Safe (watch for weed seeds)
Goat/sheep manure	20:1	2-3 months	High in K and micronutrients	Very safe (cold compost ok)
Pig manure	14:1	6-12 months	High in nitrogen and phosphorus	Use extreme caution
Dog/cat waste	13:1	N/A	NOT FOR GARDEN USE	Never use in food gardens
Bones	0:1	1-3 years	High calcium and phosphorus	Requires special methods

Why Meat-Eater Manure Requires Special Handling: 4 Critical Risks

Carnivore and omnivore waste fundamentally differs from herbivore manure in ways that directly impact your composting success. Understanding these differences explains why that rabbit manure can go straight into your garden while dog waste needs specialized treatment.

The primary concern centers around pathogen persistence. Meat-eater manure typically contains higher concentrations of dangerous organisms like E. coli O157:H7, Salmonella, and various parasites including Toxocara (roundworms) that can survive standard composting conditions.

Research from the USDA confirms that these pathogens require specific temperature thresholds—typically 140°F (60°C) sustained for at least 5 consecutive days—to be neutralized. Most backyard compost piles never reach these temperatures, especially in cooler climates or smaller setups.

A common myth suggests that "all manure is the same" or that "compost naturally kills all pathogens." The science clearly demonstrates otherwise. The diet of the animal directly influences both the nutrient composition and the microbial profile of their waste, creating significant safety variations between different manure types.

5 Types of Animal Manure You Can Safely Compost (And 3 You Should Never Use)

Safe to Compost with Proper Methods:

1. Chicken manure – Though technically omnivorous, chickens produce waste that can be safely composted when properly heated. Rich in nitrogen, it reaches usability in 3-6 months and provides approximately 1.1% nitrogen to your garden.

2. Duck manure – Similar to chicken waste but slightly wetter, requiring additional carbon materials. Properly composted in 3-4 months.

3. Rabbit manure – The "perfect" garden waste, these herbivore pellets can even be applied directly to gardens without composting, though 2-3 months of aging improves results.

4. Horse manure – While horses are herbivores, their manure often contains weed seeds requiring hot composting. Ready in 4-6 months when properly managed.

5. Goat/sheep manure – These "cold" manures contain fewer pathogens and can be composted in just 2-3 months, making them ideal for busy gardeners.

Compost with Extreme Caution:

Pig manure – Though potentially usable, pig waste requires sustained high temperatures (145°F/63°C for at least 3 days) due to its pathogen profile and potential pharmaceutical residues. Not recommended for beginners.

Never Compost for Food Gardens:

1. Dog waste – Contains persistent pathogens that standard home composting cannot reliably eliminate.

2. Cat waste – Harbors Toxoplasma gondii, which can survive most composting methods and poses serious health risks, especially to pregnant women.

3. Human waste – Requires specialized composting systems (humanure) and should never be processed in standard garden compost.

How to Speed Up Composting of Acceptable Manures: 6-Step Process

Creating a proper hot compost system transforms potentially problematic manures into garden gold in as little as 4-6 weeks, compared to the 6-12 months required for cold composting methods.

1. Build for Maximum Heat Generation

Create a pile at least 3'×3'×3' (1 cubic yard) to achieve self-insulating properties necessary for high-temperature composting. Smaller piles simply won't generate sufficient heat.

2. Balance Your Materials Precisely

Maintain a carbon-to-nitrogen ratio between 25:1 and 30:1 for optimal decomposition. For chicken manure (high nitrogen), add approximately 3 parts carbon materials (leaves, straw, or cardboard) to 1 part manure by volume.

3. Monitor Temperature Daily

Use a 24" compost thermometer ($15-25) to track internal temperatures. Your goal is to maintain 140-150°F (60-65°C) for at least 5 consecutive days to kill pathogens. Most piles reach peak heat within 2-4 days after building.

4. Turn at Strategic Intervals

When temperatures begin to drop (usually after 3-5 days at peak heat), turn the pile completely to introduce oxygen and bring outer materials to the center. This process typically takes 15-20 minutes and should be repeated 3-4 times during the active composting phase.

5. Test for Completion

Properly finished manure compost should:

• Have an earthy smell (never ammonia or putrid odors)
• Show no recognizable original materials
• Maintain a stable temperature near ambient conditions
• Pass the simple squeeze test (holds shape but doesn't release water)

6. Age Before Application

Even after hot composting, allow manure compost to cure for an additional 2-4 weeks before applying to food gardens. This aging process stabilizes nutrients and further reduces pathogen risk.

What to Do With Non-Compostable Pet Waste: 4 Safe Alternatives

When dealing with waste that shouldn't enter your garden compost, several effective alternatives exist that maintain your commitment to sustainability:

1. Install a Dedicated Pet Waste Composter

Commercial systems like the Doggie Dooley ($40-60) or DIY in-ground digesters isolate pet waste from your garden ecosystem. These systems use bacterial action to break down waste but produce material unsuitable for food gardens.

2. Explore Municipal Programs

Many cities now offer specific pet waste collection services or accept bagged pet waste in designated municipal composting programs that reach industrial-grade temperatures (over 160°F/71°C for extended periods).

3. Use Biodegradable Disposal Methods

If composting isn't possible, biodegradable bags combined with municipal waste collection minimize environmental impact. Look for bags certified compostable under ASTM D6400 standards ($15-20 for a 3-month supply).

4. Consider Septic-Compatible Flushing

Some communities permit flushing dog waste (never cat waste or litter) down toilets connected to municipal sewage systems, where treatment processes can safely handle the pathogens.

Can You Compost Marrow Bones? What Works and What Doesn't

Marrow bones present unique composting challenges due to their high fat content and dense structure. While technically organic, they decompose extremely slowly in most home systems.

Why Bones Resist Standard Composting

Marrow bones can take 1-3 years to fully decompose in typical backyard systems due to their density and calcium phosphate structure. The fatty marrow component can also attract pests and create anaerobic pockets in your compost.

Methods That Can Handle Bones Effectively

Industrial composting facilities maintain temperatures above 160°F (71°C) for extended periods, successfully breaking down bones within 3-6 months. Home composters can accelerate bone decomposition through these approaches:

1. Grinding/crushing – Breaking bones into smaller pieces (under 1" fragments) increases surface area for microbial activity.

2. Pre-cooking – Boiling bones for stock removes fats and begins the breakdown process before composting.

3. Bokashi pre-treatment – Fermenting bones with bokashi bran for 2-3 weeks before adding to compost significantly accelerates decomposition.

Better Alternatives for Bone Recycling

Rather than struggling to compost bones, consider these more effective options:

1. Make bone broth (extracting 90% of nutrients in just 24 hours)
2. Dry and grind for DIY bonemeal fertilizer (approximately 15% phosphorus)
3. Bury directly in non-food garden areas (6-12" deep)
4. Offer cleaned bones to appropriate pets as treats

Building Your First Hot Compost System: A Weekend Project

Creating an effective hot composting system capable of safely processing acceptable manures requires minimal investment but proper setup. Here's how to build one in a single weekend:

1. Select your container – Either build a 3'×3' bin from pallets/hardware cloth or use a dedicated hot compost tumbler ($100-200).

2. Gather materials in advance – You'll need approximately:

   • 3 parts "browns" (carbon materials like leaves, straw, cardboard)
   • 1 part "greens" (nitrogen sources including acceptable manures)
   • Water source
   • Compost thermometer
   • Pitchfork or turning tool

3. Layer materials strategically – Begin with 4-6" of coarse carbon materials for drainage, then alternate thin layers (2-3") of nitrogen and carbon materials, moistening each layer to sponge-like dampness.

4. Activate the system – Once built, water the entire pile until moisture appears at the base but doesn't stream out. Internal temperatures should begin rising within 24-48 hours.

5. Implement your monitoring routine – Check temperatures daily and maintain a simple log. Turn the pile when temperatures peak and begin to fall, typically every 3-5 days during the active phase.

Ensuring Garden Safety: Your Composting Success Checklist

Successful composting of animal products requires attention to detail and commitment to safety protocols:

• Temperature verification – Always confirm your pile reaches and maintains pathogen-killing temperatures (140°F/60°C minimum for 5+ days)

• Complete processing – Never rush manure compost to your garden; ensure it completes both hot composting and curing phases

• Application timing – Apply finished manure compost at least 120 days before harvesting any crops that contact soil

• Record keeping – Maintain a simple compost journal tracking temperatures, turning dates, and completion times to refine your process

• Separate systems – Never mix pet waste composting with garden composting systems

Remember that proper composting transforms potential waste into valuable soil amendments while eliminating health risks. When in doubt about a material's safety, err on the side of caution—your garden's health and your family's safety depend on it.

FAQ: Common Questions About Composting Animal Products

Can dog poop be composted for flower gardens (not vegetable gardens)?

No, dog waste should never be used in any garden compost. The pathogens present can survive in soil for years and can be transferred through contact with flowers, tools, or shoes. Use dedicated pet waste systems instead.

How hot does compost need to get to kill pathogens in chicken manure?

Chicken manure requires temperatures of at least 140°F (60°C) maintained for a minimum of 5 consecutive days to kill potential pathogens like Salmonella. Most home systems can achieve this with proper pile size and composition.

Is it safe to add eggshells to compost if I'm concerned about salmonella?

Yes, eggshells are safe to compost. The composting process, especially hot composting, will eliminate Salmonella bacteria potentially present on shells. Crushing shells speeds decomposition significantly.

How long before I can use composted manure in my vegetable garden?

After proper hot composting and curing (typically 8-12 weeks total), the USDA recommends applying finished manure compost at least 120 days before harvesting crops that contact soil, or 90 days for crops growing above ground.

What happens if my compost pile never reaches high temperatures?

If your pile stays below 120°F (49°C), you're cold composting, which won't reliably kill pathogens in manure. Either rebuild your pile with more nitrogen materials and greater volume, or extend composting time to 1-2 years for potentially problematic materials.