A composting bin

Can I put blood in my compost bin?


It's complicated, whether you can put blood into your composting bin, so read on!

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Get the right balance of brown and green composting materials in your bin with our expert guide.

Composting With Blood, Bones, and Animal Products: A Comprehensive Guide

Understanding the Benefits and Risks of Composting Animal-Based Materials

We all know that composting is an excellent way to recycle organic waste and create nutrient-rich soil for our gardens. However, when it comes to composting animal-based products like blood, bones, and meat, many of us have questions about safety and effectiveness. In this article, we'll explore the ins and outs of composting with these materials, providing you with the knowledge and techniques to do it successfully. To learn more about the basics of composting, check out the EPA's guide to composting at home.

Can You Compost Blood?

Blood meal and dried blood can be valuable additions to your compost pile, as they provide a quick source of nitrogen to balance carbon-rich materials. However, we recommend taking some precautions to avoid attracting pests and ensuring safe decomposition:

  • Use a hot composting system, maintaining temperatures between 130-150°F to kill pathogens. A compost thermometer can help you monitor the temperature of your pile.
  • Bury the blood in the center of the pile, mixed thoroughly with carbon-rich browns like leaves or straw.
  • Consider freezing blood before adding it to your compost, allowing it to thaw and incorporate fully.
  • Keep an eye out for pest activity, as rats and flies may be attracted to the blood.
  • For maximum safety, use aged or composted blood that is at least one year old.

Incorporating Bone Meal and Other Animal Byproducts

In addition to blood, we can also compost other animal byproducts like bone meal and fish meal. These materials are excellent sources of nitrogen and can help to achieve the optimal carbon-to-nitrogen ratio of 25-30:1 for active composting. When adding these products to your pile, keep the following in mind:

  • Start with thin layers sprinkled lightly over carbon-rich materials to avoid burning plants with excess nitrogen.
  • As with blood, incorporate animal meals fully into the center of the pile, avoiding heavy surface applications.
  • Shred or grind bones into small pieces to speed up decomposition. A compost shredder can be a useful tool for this purpose.

Composting Meat, Bones, and Fat: Extra Precautions

Composting meat, bones, and fatty food scraps requires additional care to prevent the spread of harmful bacteria and pathogens. We recommend the following steps:

  • Bury meat and bones deep in the hot center of the pile, where very high temperatures can break down fat and kill bacteria. A compost aerator can help maintain proper airflow and temperature.
  • Chop or shred these materials into small pieces to allow for thorough decomposition.
  • Limit the amount of meat added to your compost, avoiding large volumes and monitoring for odors and scavengers.
  • Ensure that the finished compost has no recognizable meat bits before applying it to your garden.

Tips for Safe and Effective Animal Product Composting

To further ensure the success of your composting efforts, we suggest following these additional guidelines:

  • Maintain aerobic conditions by turning and mixing your compost regularly to prevent anaerobic pockets where pathogens can survive.
  • Use compost activators like alfalfa, manure, or nitrogen fertilizers to promote a hot, active pile. A compost starter can jumpstart the decomposition process.
  • Introduce beneficial microbes by adding composted manure, old compost, or garden soil to your pile.
  • Follow proper curing and aging timelines before using animal-product composts on edible gardens.

Troubleshooting Common Issues

Despite our best efforts, we may sometimes encounter problems when composting animal products. Here are some common issues and their solutions:

  • Odor: Insufficient oxygen, excess nitrogen, or too much meat/fat can cause unpleasant smells. Turn the pile and add carbon-rich browns to balance the mixture.
  • Pests: If persistent pests are attracted to your compost, try using traps, deterrents, or barriers. If issues continue, consider eliminating meat and animal products from your pile.
  • Slow decomposition: Mix in nitrogen fertilizers or meals, add moisture if the pile is too dry, and turn and aerate the pile to speed up the process.
  • Ammonia smell: Too much green, nitrogen-rich material can cause an ammonia odor. Add more carbon-rich browns until the smell dissipates.

Frequently Asked Questions

Is it safe to use composted blood as fertilizer in my vegetable garden?

Yes, composted blood that has been aged for at least one year and heated to at least 130°F is generally safe for garden use. Always wear gloves when handling the compost.

How much bone meal can I put in my compost pile?

A thin sprinkling of 1-2 cups of bone meal per cubic foot of compost is recommended to avoid overwhelming the carbon balance.

What is the best way to compost meat and fat trimmings?

Chop meat, fat, and bones into small pieces, bury them deep in the center of a hot, active pile, and limit the amount to 2-3% of the total pile volume. Turn frequently and monitor for odors.

Can I put butcher waste like blood, bones, and meat trimmings in my backyard compost bin?

We don't recommend composting large amounts of butcher waste in small-scale systems, as very high temperatures are needed to break down these materials safely. Municipal or commercial facilities are better equipped to handle this waste.

How long should I wait before planting in soil amended with animal product compost?

Wait 3-6 months after applying animal product composts before planting edibles, ensuring that the compost reached 130-150°F for pathogen removal. Test compost maturity before planting sensitive crops.

By understanding the proper techniques and precautions for composting blood, bones, and animal products, we can safely recycle these nutrient-rich materials into a valuable soil amendment for our gardens. With careful monitoring and maintenance of optimal composting conditions, we can create a high-quality, sustainable growing medium that supports healthy plant growth.

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